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Journal Cover Inorganics
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  This is an Open Access Journal Open Access journal
   ISSN (Online) 2304-6740
   Published by MDPI Homepage  [156 journals]
  • Inorganics, Vol. 5, Pages 62: Investigation of the Spin Crossover
           Properties of Three Dinulear Fe(II) Triple Helicates by Variation of the
           Steric Nature of the Ligand Type

    • Authors: Alexander Craze, Natasha Sciortino, Mohan Badbhade, Cameron Kepert, Christopher Marjo, Feng Li
      First page: 62
      Abstract: The investigation of new spin-crossover (SCO) compounds plays an important role in understanding the key design factors involved, informing the synthesis of materials for future applications in electronic and sensing devices. In this report, three bis-bidentate ligands were synthesized by Schiff base condensation of imidazole-4-carbaldehyde with 4,4-diaminodiphenylmethane (L1), 4,4′-diaminodiphenyl sulfide (L2) and 4,4′-diaminodiphenyl ether (L3) respectively. Their dinuclear Fe(II) triple helicates were obtained by complexation with Fe(BF4)2·6H2O in acetonitrile. The aim of this study was to examine the influence of the steric nature of the ligand central atom (–X–, where X = CH2, S or O) on the spin-crossover profile of the compound. The magnetic behaviours of these compounds were investigated and subsequently correlated to the structural information from single-crystal X-ray crystallographic experiments. All compounds [Fe2(L1)3](BF4)2 (1), [Fe2(L2)3](BF4)2 (2) and [Fe2(L3)3](BF4)2 (3), demonstrated approximately half-spin transitions, with T1/2 values of 155, 115 and 150 K respectively, corresponding to one high-spin (HS) and one low-spin (LS) Fe(II) centre in a [LS–HS] state at 50 K. This was also confirmed by crystallographic studies, for example, bond lengths and the octahedral distortion parameter (∑) at 100 K. The three-dimensional arrangement of the HS and LS Fe(II) centres throughout the crystal lattice was different for the three compounds, and differing extents of intermolecular interactions between BF4− counter ions and imidazole N–H were present. The three compounds displayed similar spin-transition profiles, with 2 (–S–) possessing the steepest nature. The shape of the spin transition can be altered in this manner, and this is likely due to the subtle effects that the steric nature of the central atom has on the crystal packing (and thus inter-helical Fe–Fe separation), intermolecular interactions and Fe–Fe intra-helical separations.
      Citation: Inorganics
      PubDate: 2017-09-21
      DOI: 10.3390/inorganics5040062
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 63: Metal Substitution Effect on a
           Three-Dimensional Cyanido-Bridged Fe Spin-Crossover Network

    • Authors: Kenta Imoto, Shinjiro Takano, Shin-ichi Ohkoshi
      First page: 63
      Abstract: We report the CoII-substitution effect on a cyanido-bridged three-dimensional FeII spin-crossover network, Fe2[Nb(CN)8](4-pyridinealdoxime)8·2H2O. A series of iron–cobalt octacyanidoniobate, (FexCo1−x)2[Nb(CN)8](4-pyridinealdoxime)8·zH2O, was prepared. In this series, the behavior of FeII spin-crossover changes with the CoII concentration. As the CoII concentration increases, the transition of the spin-crossover becomes gradual and the transition temperature of the spin-crossover shifts towards a lower temperature. Additionally, this series shows magnetic phase transition at a low temperature. In particular, (Fe0.21Co0.79)2[Nb(CN)8](4-pyridinealdoxime)8·zH2O exhibits a Curie temperature of 12 K and a large coercive field of 3100 Oe.
      Citation: Inorganics
      PubDate: 2017-09-24
      DOI: 10.3390/inorganics5040063
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 64: Improved Cluster Structure Optimization:
           Hybridizing Evolutionary Algorithms with Local Heat Pulses

    • Authors: Johannes Dieterich, Bernd Hartke
      First page: 64
      Abstract: Cluster structure optimization (CSO) refers to finding the globally minimal cluster structure with respect to a specific model and quality criterion, and is a computationally extraordinarily hard problem. Here we report a successful hybridization of evolutionary algorithms (EAs) with local heat pulses (LHPs). We describe the algorithm’s implementation and assess its performance with hard benchmark CSO cases. EA-LHP showed superior performance compared to regular EAs. Additionally, the EA-LHP hybrid is an unbiased, general CSO algorithm requiring no system-specific solution knowledge. These are compelling arguments for a wider future use of EA-LHP in CSO.
      Citation: Inorganics
      PubDate: 2017-09-29
      DOI: 10.3390/inorganics5040064
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 65: Stabilization of ZrO2 Powders via ALD of
           CeO2 and ZrO2

    • Authors: Chao Lin, Xinyu Mao, Tzia Onn, Joonbaek Jang, Raymond Gorte
      First page: 65
      Abstract: ZrO2 powders were modified by atomic layer deposition (ALD) with CeO2 and ZrO2, using Ce(TMHD)4 and Zr(TMHD)4 as the precursors, in order to determine the effect of ALD films on the structure, surface area, and catalytic properties of the ZrO2. Growth rates were measured gravimetrically and found to be 0.017 nm/cycle for CeO2 and 0.031 nm/cycle for ZrO2. The addition of 20 ALD cycles of either CeO2 or ZrO2 was found to stabilize the surface area of the ZrO2 powder following calcination to 1073 K and to suppress the tetragonal-to-monoclinic transition. Shrinkage of ZrO2 wafers was also suppressed by the ALD films. When used as a support for Pd in CO oxidation, the CeO2-modified materials significantly enhanced rates due to interactions between the Pd and the CeO2. Potential applications for modifying catalyst supports using ALD are discussed.
      Citation: Inorganics
      PubDate: 2017-10-03
      DOI: 10.3390/inorganics5040065
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 66: Preparation and Molecular Structure of a
           Cyclopentyl-Substituted Cage Hexasilsesquioxane T6 (T =
           cyclopentyl-SiO1.5) Starting from the Corresponding Silanetriol

    • Authors: Jürgen Kahr, Ferdinand Belaj, Rudolf Pietschnig
      First page: 66
      Abstract: Cyclopentyl substituted silanetriol can be prepared and isolated. Its condensation yields the corresponding disiloxanetetrol as a primary condensation product. Further condensation leads to the hexameric polyhedral silsesquioxane cage T6. The latter has been mentioned in the literature before however, lacking structural data. All compounds have been characterized with multinuclear NMR spectroscopy and, in addition, the molecular structures have been determined in the case of the disiloxanetetrol and the hexasilsesquioxane via single crystal X-ray diffraction.
      Citation: Inorganics
      PubDate: 2017-10-04
      DOI: 10.3390/inorganics5040066
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 67: Optimization of Electrochemical Performance
           of LiFePO4/C by Indium Doping and High Temperature Annealing

    • Authors: Ajay Kumar, Parisa Bashiri, Balaji Mandal, Kulwinder Dhindsa, Khadije Bazzi, Ambesh Dixit, Maryam Nazri, Zhixian Zhou, Vijayendra Garg, Aderbal Oliveira, Prem Vaishnava, Vaman Naik, Gholam-Abbas Nazri, Ratna Naik
      First page: 67
      Abstract: We have prepared nano-structured In-doped (1 mol %) LiFePO4/C samples by sol–gel method followed by a selective high temperature (600 and 700 °C) annealing in a reducing environment of flowing Ar/H2 atmosphere. The crystal structure, particle size, morphology, and magnetic properties of nano-composites were characterized by X-ray diffraction (XRD), scanning electron microsopy (SEM), transmission electron microscopy (TEM), and 57Fe Mössbauer spectroscopy. The Rietveld refinement of XRD patterns of the nano-composites were indexed to the olivine crystal structure of LiFePO4 with space group Pnma, showing minor impurities of Fe2P and Li3PO4 due to decomposition of LiFePO4. We found that the doping of In in LiFePO4/C nanocomposites affects the amount of decomposed products, when compared to the un-doped ones treated under similar conditions. An optimum amount of Fe2P present in the In-doped samples enhances the electronic conductivity to achieve a much improved electrochemical performance. The galvanostatic charge/discharge curves show a significant improvement in the electrochemical performance of 700 °C annealed In-doped-LiFePO4/C sample with a discharge capacity of 142 mAh·g−1 at 1 C rate, better rate capability (~128 mAh·g−1 at 10 C rate, ~75% of the theoretical capacity) and excellent cyclic stability (96% retention after 250 cycles) compared to other samples. This enhancement in electrochemical performance is consistent with the results of our electrochemical impedance spectroscopy measurements showing decreased charge-transfer resistance and high exchange current density.
      Citation: Inorganics
      PubDate: 2017-10-10
      DOI: 10.3390/inorganics5040067
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 68: The Decomposition Products of Sulfur
           Hexafluoride (SF6) with Metals Dissolved in Liquid Ammonia

    • Authors: Holger Deubner, Florian Kraus
      First page: 68
      Abstract: Sulfur hexafluoride is a highly chemically inert gas with several important industrial applications. It is stable against fused alkali, oxygen and ammonia, even at several hundred degrees Celsius. In this work, the reactions between metals (Li–Cs, Sr, Ba, Eu, Yb) dissolved in liquid ammonia and SF6 are reported, leading to mono- or bivalent fluorides and sulfides. To this end, SF6 was passed into a cooled solution of the respective metal in liquid ammonia. The identity of the products was confirmed by powder X-ray diffraction and IR spectroscopy. The reactions could lead to a cheap and effective disposal method of the present amounts of stored SF6, for possible generation of H2S and HF.
      Citation: Inorganics
      PubDate: 2017-10-13
      DOI: 10.3390/inorganics5040068
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 69: Investigation of the Thermodynamic
           Properties of Surface Ceria and Ceria–Zirconia Solid Solution Films
           Prepared by Atomic Layer Deposition on Al2O3

    • Authors: Tzia Onn, Xinyu Mao, Chao Lin, Cong Wang, Raymond Gorte
      First page: 69
      Abstract: The properties of 20 wt % CeO2 and 21 wt % Ce0.5Zr0.5O2 films, deposited onto a γ-Al2O3 by Atomic Layer Deposition (ALD), were compared to bulk Ce0.5Zr0.5O2 and γ-Al2O3-supported samples on which 20 wt % CeO2 or 21 wt % CeO2–ZrO2 were deposited by impregnation. Following calcination to 1073 K, the ALD-prepared catalysts showed much lower XRD peak intensities, implying that these samples existed as thin films, rather than larger crystallites. Following the addition of 1 wt % Pd to each of the supports, the ALD-prepared samples exhibited much higher rates for CO oxidation due to better interfacial contact between the Pd and ceria-containing phases. The redox properties of the ALD samples and bulk Ce0.5Zr0.5O2 were measured by determining the oxidation state of the ceria as a function of the H2:H2O ratio using flow titration and coulometric titration. The 20 wt % CeO2 ALD film exhibited similar thermodynamics to that measured previously for a sample prepared by impregnation. However, the sample with 21 wt % Ce0.5Zr0.5O2 on γ-Al2O3 reduced at a much higher P O 2 and showed evidence for transition between the Ce0.5Zr0.5O2 and Ce0.5Zr0.5O1.75 phases.
      Citation: Inorganics
      PubDate: 2017-10-15
      DOI: 10.3390/inorganics5040069
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 70: Redox-Induced Aromatic C–H Bond
           Functionalization in Metal Complex Catalysis from the Electrochemical
           Point of View

    • Authors: Yulia Budnikova, Yulia Dudkina, Mikhail Khrizanforov
      First page: 70
      Abstract: This review generalizes and specifies the oxidizing ability of a number of oxidants used in palladium (Pd)-catalyzed aromatic C–H functionalizations. The redox potentials have been analyzed as the measure of oxidant strength and applied to the reasoning of the efficiency of known reactions where catalytic cycles include cyclometalated palladium complexes (and other organopalladium key intermediates).
      Citation: Inorganics
      PubDate: 2017-10-16
      DOI: 10.3390/inorganics5040070
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 71: Unique Hydrogen Desorption Properties of
           LiAlH4/h-BN Composites

    • Authors: Yuki Nakagawa, Shigehito Isobe, Takao Ohki, Naoyuki Hashimoto
      First page: 71
      Abstract: Hexagonal boron nitride (h-BN) is known as an effective additive to improve the hydrogen de/absorption properties of hydrogen storage materials consisting of light elements. Herein, we report the unique hydrogen desorption properties of LiAlH4/h-BN composites, which were prepared by ball-milling. The desorption profiles of the composite indicated the decrease of melting temperature of LiAlH4, the delay of desorption kinetics in the first step, and the enhancement of the kinetics in the second step, compared with milled LiAlH4. Li3AlH6 was also formed in the composite after desorption in the first step, suggesting h-BN would have a catalytic effect on the desorption kinetics of Li3AlH6. Finally, the role of h-BN on the desorption process of LiAlH4 was discussed by comparison with the desorption properties of LiAlH4/X (X = graphite, LiCl and LiI) composites, suggesting the enhancement of Li ion mobility in the LiAlH4/h-BN composite.
      Citation: Inorganics
      PubDate: 2017-10-25
      DOI: 10.3390/inorganics5040071
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 72: Si–H Bond Activation of a Primary Silane
           with a Pt(0) Complex: Synthesis and Structures of Mononuclear
           (Hydrido)(dihydrosilyl) Platinum(II) Complexes

    • Authors: Norio Nakata, Nanami Kato, Noriko Sekizawa, Akihiko Ishii
      First page: 72
      Abstract: A hydrido platinum(II) complex with a dihydrosilyl ligand, [cis-PtH(SiH2Trip)(PPh3)2] (2) was prepared by oxidative addition of an overcrowded primary silane, TripSiH3 (1, Trip = 9-triptycyl) with [Pt(η2-C2H4)(PPh3)2] in toluene. The ligand-exchange reactions of complex 2 with free phosphine ligands resulted in the formation of a series of (hydrido)(dihydrosilyl) complexes (3–5). Thus, the replacement of two PPh3 ligands in 2 with a bidentate bis(phosphine) ligand such as DPPF [1,2-bis(diphenylphosphino)ferrocene] or DCPE [1,2-bis(dicyclohexylphosphino)ethane] gave the corresponding complexes [PtH(SiH2Trip)(L-L)] (3: L-L = dppf, 4: L-L = dcpe). In contrast, the ligand-exchange reaction of 2 with an excess amount of PMe3 in toluene quantitatively produced [PtH(SiH2Trip)(PMe3)(PPh3)] (5), where the PMe3 ligand is adopting trans to the hydrido ligand. The structures of complexes 2–5 were fully determined on the basis of their NMR and IR spectra, and elemental analyses. Moreover, the low-temperature X-ray crystallography of 2, 3, and 5 revealed that the platinum center has a distorted square planar environment, which is probably due to the steric requirement of the cis-coordinated phosphine ligands and the bulky 9-triptycyl group on the silicon atom.
      Citation: Inorganics
      PubDate: 2017-10-25
      DOI: 10.3390/inorganics5040072
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 73: 3-Methylindole-Based Tripodal Tetraphosphine
           Ruthenium Complexes in N2 Coordination and Reduction and Formic Acid
           Dehydrogenation

    • Authors: Fenna van de Watering, Nicol Heijtbrink, Jarl van der Vlugt, Wojciech Dzik, Bas de Bruin, Joost Reek
      First page: 73
      Abstract: The ruthenium(II) complexes RuCl2L1H, RuCl2L1CF3, RuCl2L1OMe and RuCl2L2H were synthesized from [Ru(η6-benzene)Cl(μ-Cl)]2 and the corresponding tripodal tris-3-methylindolephosphine-based ligands L1H, L1CF3, L1OMe, and L2H. Stoichiometric reduction of these complexes with KC8 yielded the corresponding ruthenium(0) dinitrogen complexes. The latter complexes were studied in the N2 reduction with chlorosilanes and KC8, yielding stoichiometric amounts of the silylamines. The synthesized ruthenium(II) complexes are also active catalysts for the formic acid dehydrogenation reaction.
      Citation: Inorganics
      PubDate: 2017-10-30
      DOI: 10.3390/inorganics5040073
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 74: Tetrahydroborates: Development and Potential
           as Hydrogen Storage Medium

    • Authors: Julián Puszkiel, Sebastiano Garroni, Chiara Milanese, Fabiana Gennari, Thomas Klassen, Martin Dornheim, Claudio Pistidda
      First page: 74
      Abstract: The use of fossil fuels as an energy supply becomes increasingly problematic from the point of view of both environmental emissions and energy sustainability. As an alternative, hydrogen is widely regarded as a key element for a potential energy solution. However, different from fossil fuels such as oil, gas, and coal, the production of hydrogen requires energy. Alternative and intermittent renewable sources such as solar power, wind power, etc., present multiple advantages for the production of hydrogen. On one hand, the renewable sources contribute to a remarkable reduction of pollutants released to the air. On the other hand, they significantly enhance the sustainability of energy supply. In addition, the storage of energy in form of hydrogen has a huge potential to balance an effective and synergetic utilization of the renewable energy sources. In this regard, hydrogen storage technology presents a key roadblock towards the practical application of hydrogen as “energy carrier”. Among the methods available to store hydrogen, solid-state storage is the most attractive alternative both from the safety and the volumetric energy density points of view. Because of their appealing hydrogen content, complex hydrides and complex hydride-based systems have attracted considerable attention as potential energy vectors for mobile and stationary applications. In this review, the progresses made over the last century on the development in the synthesis and research on the decomposition reactions of homoleptic tetrahydroborates is summarized. Furthermore, theoretical and experimental investigations on the thermodynamic and kinetic tuning of tetrahydroborates for hydrogen storage purposes are herein reviewed.
      Citation: Inorganics
      PubDate: 2017-10-31
      DOI: 10.3390/inorganics5040074
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 75: Synthesis of 1,3-Diols from Isobutene and
           HCHO via Prins Condensation-Hydrolysis Using CeO2 Catalysts: Effects of
           Crystal Plane and Oxygen Vacancy

    • Authors: Zhixin Zhang, Yehong Wang, Jianmin Lu, Min Wang, Jian Zhang, Xuebin Liu, Feng Wang
      First page: 75
      Abstract: We herein report the synthesis of 3-methyl-1,3-butanediol from isobutene and HCHO in water via a Prins condensation-hydrolysis reaction over CeO2, which is a water-tolerant Lewis acid catalyst. The CeO2 exhibits significant catalytic activity for the reaction, giving 95% HCHO conversion and 84% 3-methyl-1,3-butanediol selectivity at 150 °C for 4 h. The crystal planes of CeO2 have a significant effect on the catalytic activity for the Prins reaction. The (110) plane shows the highest catalytic activity among the crystal planes investigated (the (100), (110), and (111) planes), due to its higher concentration of Lewis acid sites, which is in line with the concentration of oxygen vacancies. Detailed characterizations, including NH3-TPD, pyridine-adsorbed FT-IR spectroscopy, and Raman spectroscopy, revealed that the concentration of Lewis acid sites is proportional to the concentration of oxygen vacancies. This study indicates that the Lewis acidity induced by oxygen vacancy can be modulated by selective synthesis of CeO2 with different morphologies, and that the Lewis acidity and oxygen vacancy play an important role in Prins condensation and hydrolysis reaction.
      Citation: Inorganics
      PubDate: 2017-11-07
      DOI: 10.3390/inorganics5040075
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 76: Ceria: Recent Results on Dopant-Induced
           Surface Phenomena

    • Authors: Nicole Knoblauch, Heike Simon, Lars Dörrer, Daniel Uxa, Peter Fielitz, Jens Wendelstorf, Karl-Heinz Spitzer, Martin Schmücker, Günter Borchardt
      First page: 76
      Abstract: Redox studies on dense zirconia-doped ceria pellets were carried out by thermogravimetric investigations and dilatometry. Up to 1600 K reduction parameters determined by both methods correspond to each other. At higher temperatures, however, thermogravimetry overestimates the degree of reduction since mass loss is not only due to oxygen exsolution but also to selective evaporation of CeO2 whose vapour pressure is considerably higher than that of ZrO2. As a consequence surface segregation of zirconia occurs in (Ce,Zr)O2−δ pellets leading to a porous surface zone of Ce2Zr2O7 pyrochlore which gradually grows in thickness. Surface enrichment of zirconia is detrimental for splitting CO2 or H2O since re-oxidation temperatures of (Ce,Zr)O2−δ are known to be shifted towards lower temperatures with increasing ZrO2 content. Thus, very harsh reduction conditions should be avoided for the (Ce,Zr)O2−δ redox system. The kinetics investigations comprised the high temperature reduction step (T ≅ 1600 K) and the “low” temperature oxidation reaction with a carbon dioxide atmosphere (T ≅ 1000 K). The reduction kinetics (at around 1600 K and an oxygen activity of 7 × 10−4 in the gas phase) directly yield the (reduction) equilibrium exchange rate of oxygen in the order of 10−7 mol·O/(cm3·s) as the kinetics are surface controlled. The oxidation step at around 1000 K, however, occurs in the mixed control or in the diffusion control regime, respectively. From oxygen isotope exchange in combination with SIMS depth profiling oxygen exchange coefficients, K, and oxygen diffusivities, D, were determined for so-called equilibrium experiments as well as for non-equilibrium measurements. From the obtained values for K and D the (oxidation) equilibrium exchange rates for differently doped ceria samples were determined. Their dependency on the oxygen activity and the nature and the concentrations of a tetravalent dopant (Zr) and trivalent dopants (La, Y, Sm) could be semi-quantitatively rationalised on the basis of a master equation for the equilibrium surface exchange rate.
      Citation: Inorganics
      PubDate: 2017-11-08
      DOI: 10.3390/inorganics5040076
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 77: Biodegradation of Cosmetics Products: A
           Computational Study of Cytochrome P450 Metabolism of Phthalates

    • Authors: Fabián Cantú Reinhard, Sam de Visser
      First page: 77
      Abstract: Cytochrome P450s are a broad class of enzymes in the human body with important functions for human health, which include the metabolism and detoxification of compounds in the liver. Thus, in their catalytic cycle, the P450s form a high-valent iron(IV)-oxo heme cation radical as the active species (called Compound I) that reacts with substrates through oxygen atom transfer. This work discusses the possible degradation mechanisms of phthalates by cytochrome P450s in the liver, through computational modelling, using 2-ethylhexyl-phthalate as a model substrate. Phthalates are a type of compound commonly found in the environment from cosmetics usage, but their biodegradation in the liver may lead to toxic metabolites. Experimental studies revealed a multitude of products and varying product distributions among P450 isozymes. To understand the regio- and chemoselectivity of phthalate activation by P450 isozymes, we focus here on the mechanisms of phthalate activation by Compound I leading to O-dealkylation, aliphatic hydroxylation and aromatic hydroxylation processes. We set up model complexes of Compound I with the substrate and investigated the reaction mechanisms for products using the density functional theory on models and did a molecular mechanics study on enzymatic structures. The work shows that several reaction barriers in the gas-phase are close in energy, leading to a mixture of products. However, when we tried to dock the substrate into a P450 isozyme, some of the channels were inaccessible due to unfavorable substrate positions. Product distributions are discussed under various reaction conditions and rationalized with valence bond and thermodynamic models.
      Citation: Inorganics
      PubDate: 2017-11-12
      DOI: 10.3390/inorganics5040077
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 78: Mechanistic Implications for the
           Ni(I)-Catalyzed Kumada Cross-Coupling Reaction

    • Authors: Linda Iffland, Anette Petuker, Maurice van Gastel, Ulf-Peter Apfel
      First page: 78
      Abstract: Herein we report on the cross-coupling reaction of phenylmagnesium bromide with aryl halides using the well-defined tetrahedral Ni(I) complex, [(Triphos)NiICl] (Triphos = 1,1,1-tris(diphenylphosphinomethyl)ethane). In the presence of 0.5 mol % [(Triphos)NiICl], good to excellent yields (75–97%) of the respective coupling products within a reaction time of only 2.5 h at room temperature were achieved. Likewise, the tripodal Ni(II)complexes [(κ2-Triphos)NiIICl2] and [(κ3-Triphos)NiIICl](X) (X = ClO4, BF4) were tested as potential pre-catalysts for the Kumada cross-coupling reaction. While the Ni(II) complexes also afford the coupling products in comparable yields, mechanistic investigations by UV/Vis and electron paramagnetic resonance (EPR) spectroscopy indicate a Ni(I) intermediate as the catalytically active species in the Kumada cross-coupling reaction. Based on experimental findings and density functional theory (DFT) calculations, a plausible Ni(I)-catalyzed reaction mechanism for the Kumada cross-coupling reaction is presented.
      Citation: Inorganics
      PubDate: 2017-11-14
      DOI: 10.3390/inorganics5040078
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 79: Synthesis of a Dichlorodigermasilane: Double
           Si–Cl Activation by a Ge=Ge Unit

    • Authors: Tomohiro Sugahara, Norihiro Tokitoh, Takahiro Sasamori
      First page: 79
      Abstract: Halogenated oligosilanes and oligogermanes are interesting compounds in oligosilane chemistry from the viewpoint of silicon-based-materials. Herein, it was demonstrated that a 1,2-digermacyclobutadiene derivative could work as a bis-germylene building block towards double Si–Cl activation to give a halogenated oligometallane, a bis(chlorogermyl)dichlorosilane derivative.
      Citation: Inorganics
      PubDate: 2017-11-14
      DOI: 10.3390/inorganics5040079
      Issue No: Vol. 5, No. 4 (2017)
       
  • Inorganics, Vol. 5, Pages 40: Metal–Organic Frameworks and Their
           Derivatives for Photocatalytic Water Splitting

    • Authors: Fuzhan Song, Wei Li, Yujie Sun
      First page: 40
      Abstract: Amongst many strategies for renewable energy conversion, light-driven water splitting to produce clean H2 represents a promising approach and has attracted increasing attention in recent years. Owing to the multi-electron/multi-proton transfer nature of water splitting, low-cost and competent catalysts are needed. Along the rapid development of metal–organic frameworks (MOFs) during the last two decades or so, MOFs have been recognized as an interesting group of catalysts or catalyst supports for photocatalytic water splitting. The modular synthesis, intrinsically high surface area, tunable porosity, and diverse metal nodes and organic struts of MOFs render them excellent catalyst candidates for photocatalytic water splitting. To date, the application of MOFs and their derivatives as photocatalysts for water splitting has become a burgeoning field. Herein, we showcase several representative MOF-based photocatalytic systems for both H2 and O2 evolution reactions (HER, OER). The design principle of each catalytic system is specifically discussed. The current challenges and opportunities of utilizing MOFs for photocatalytic water splitting are discussed in the end.
      PubDate: 2017-06-28
      DOI: 10.3390/inorganics5030040
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 41: Computing Free Energies of Hydroxylated
           Silica Nanoclusters: Forcefield versus Density Functional Calculations

    • Authors: Antoni Macià Escatllar, Piero Ugliengo, Stefan Bromley
      First page: 41
      Abstract: We assess the feasibility of efficiently calculating accurate thermodynamic properties of (SiO2)n·(H2O)m nanoclusters, using classical interatomic forcefields (FFs). Specifically, we use a recently parameterized FF for hydroxylated bulk silica systems (FFSiOH) to calculate zero-point energies and thermal contributions to vibrational internal energy and entropy, in order to estimate the free energy correction to the internal electronic energy of these nanoclusters. The performance of FFSiOH is then benchmarked against the results of corresponding calculations using density functional theory (DFT) calculations employing the B3LYP functional. Results are reported first for a set of (SiO2)n·(H2O)m clusters with n = 4, 8 and 16, each possessing three different degrees of hydroxylation (R = m/n): 0.0, 0.25 and 0.5. Secondly, we consider five distinct hydroxylated nanocluster isomers with the same (SiO2)16·(H2O)4 composition. Finally, the free energies for the progressive hydroxylation of three nanoclusters with R = 0–0.5 are also calculated. Our results demonstrate that, in all cases, the use of FFSiOH can provide estimates of thermodynamic properties with an accuracy close to that of DFT calculations, and at a fraction of the computational cost.
      PubDate: 2017-06-29
      DOI: 10.3390/inorganics5030041
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 42: Silver(I) Extraction with Benzo-18-Crown-6
           Ether from Water into 1,2-Dichloroethane: Analyses on Ionic Strength of
           the Phases and their Equilibrium Potentials

    • Authors: Yoshihiro Kudo, Satoshi Ikeda, Saya Morioka, Shuntaro Tomokata
      First page: 42
      Abstract: Extraction constants (Kex & Kex±) for the extraction of silver picrate (AgPic) by benzo-18-crown-6 ether (B18C6) into 1,2-dichloroethane (DCE) were determined at 298 K and various ionic strength (I)-values of a water phase with or without excess HNO3. Here the symbols, Kex and Kex±, were defined as [AgLPic]DCE/P and [AgL+]DCE[Pic−]DCE/P with P = [Ag+][L]DCE[Pic−] and L = B18C6, respectively; [ ]DCE refers to the concentration of the corresponding species in the DCE phase at equilibrium. Simultaneously, KD,Pic (= [Pic−]DCE/[Pic−]) and K1,DCE (= Kex/Kex±) values for given I and IDCE values were determined, where the symbol IDCE shows I of the DCE phase. Also, equilibrium potential differences (Δφeq) based on the Pic− transfer at the water/DCE interface were obtained from the analysis of the KD,Pic [= KD,PicS exp{−(F/RT) Δφeq}] values; the symbol KD,PicS shows KD,Pic at Δφeq = 0 V. On the basis of these results, I dependences of logKex and logKex± and IDCE ones of logK1,DCE and logKex± were examined. Extraction experiments of AgClO4 and AgNO3 by B18C6 into DCE were done for comparison. The logKex±-versus-Δφeq plot for the above Ag(I) extraction systems with Pic−, ClO4−, and NO3− gave a good positive correlation.
      PubDate: 2017-06-30
      DOI: 10.3390/inorganics5030042
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 43: A DFT Study on the O2 Adsorption Properties
           of Supported PtNi Clusters

    • Authors: Lauro Paz-Borbón, Francesca Baletto
      First page: 43
      Abstract: We present a systematic study on the adsorption properties of molecular oxygen on Pt, Ni and PtNi clusters previously deposited on MgO(100) by means of density functional theory calculations. We map the different adsorption sites for a variety of cluster geometries, including icosahedra, decahedra, truncated octahedra and cuboctahedra, in the size range between 25–58 atoms. The average adsorption energy depends on the chemical composition, varying from 2 eV for pure Ni, 1.07 for pure Pt and 1.09 for a Pt s h e l l Ni c o r e nanoalloy. To correlate the adsorption map to the adsorption properties, we opt for a geometrical descriptor based on the metallic coordination up to the second coordination shell. We find an almost linear relationship between the second coordination shell and adsorption energy, with low coordination sites, such as those located at the (111)/(111) and (111)/(100) cluster edges-displaying adsorption energies above 1 eV, while higher coordination sites such as (111) cluster facets have an interaction of 0.4 eV or lower. The inclusion of van der Waals corrections leads to an overall increase of the O 2 adsorption energy without an alteration of the general adsorption trends.
      Citation: Inorganics
      PubDate: 2017-07-04
      DOI: 10.3390/inorganics5030043
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 44: Synthesis and In Vitro (Anticancer)
           Evaluation of η6-Arene Ruthenium Complexes Bearing Stannyl Ligands

    • Authors: Olivier Renier, Connor Deacon-Price, Joannes Peters, Kunsulu Nurekeyeva, Catherine Russon, Simba Dyson, Siyabonga Ngubane, Judith Baumgartner, Paul Dyson, Tina Riedel, Haleden Chiririwa, Burgert Blom
      First page: 44
      Abstract: Treatment of the known half-sandwich complexes of the type [(η6-C6H6)RuCl2(P(OR)3)] (R = Me or Ph) with SnCl2 yielded three new half-sandwich ruthenium complexes (C1–C3): [(η6-C6H6)RuCl(SnCl3)(P(OMe)3)] (C1), [(η6-C6H6)RuCl(SnCl3)(P(OPh)3)] (C2) and the bis-stannyl complex [(η6-C6H6)Ru(SnCl3)2(P(OMe)3)] (C3) by facile insertion of SnCl2 into the Ru–Cl bonds. Treatment of the known complexes [(η6-C6H6)RuCl(SnCl3)(PPh3)] and [(η6-C6H6)RuCl2(PPh3)] with 4-dimethylaminopyridine (DAMP) and ammonium tetrafluoroborate afforded the complex salts: [(η6-C6H6)Ru(SnCl3)(PPh3)(DAMP)]+BF4− (C4) and [(η6-C6H6)RuCl(PPh3)(DAMP)]+BF4− (C5) respectively. Complexes C1–C5 have been fully characterized by spectroscopic means (IR, UV–vis, multinuclear NMR, ESI–MS) and their thermal behaviour elucidated by thermal gravimetric analysis (TGA). Structural characterization by single crystal X-ray crystallography of the novel complex C2 and [(η6-C6H6)RuCl2(P(OPh)3)], the latter having escaped elucidation by this method, is also reported. Finally, the cytotoxicity of the complexes was determined on the A2780 (human ovarian cancer), A2780cisR (human ovarian cis-platin-resistant cancer), and the HEK293 (human embryonic kidney) cell lines and discussed, and an attempt is made to elucidate the effect of the stannyl ligand on cytotoxicity.
      Citation: Inorganics
      PubDate: 2017-07-13
      DOI: 10.3390/inorganics5030044
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 45: Supramolecular Control of Spin Crossover
           Phenomena Using Various Amphiphiles

    • Authors: Keita Kuroiwa
      First page: 45
      Abstract: An aspect of nanochemistry that has attracted significant attention is the formation of nanoarchitectures from the self-assembly of metal complexes, based on the design of compounds having cooperative functionalities. This technique is currently seen as important within the field of nanomaterials. In the present review, we describe the methods that allow tuning of the intermolecular interactions between spin crossover (SCO) complexes in various media. These approaches include the use of lipophilic derivatives, lipids, and diblock copolypeptide amphiphiles. The resulting supramolecular assemblies can enhance the solubility of various SCO complexes in both organic and aqueous media. In addition, amphiphilic modifications of coordination systems can result in metastable structures and dynamic structural transformations leading to unique solution properties, including spin state switching. The supramolecular chemistry of metal complexes is unprecedented in its scope and potential applications, and it is hoped that the studies presented herein will promote further investigation of dynamic supramolecular devices.
      Citation: Inorganics
      PubDate: 2017-07-14
      DOI: 10.3390/inorganics5030045
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 46: Computational Studies on the Selective
           Polymerization of Lactide Catalyzed by Bifunctional Yttrium NHC Catalyst

    • Authors: Yincheng Wang, Andleeb Mehmood, Yanan Zhao, Jingping Qu, Yi Luo
      First page: 46
      Abstract: A theoretical investigation of the ring-opening polymerization (ROP) mechanism of rac-lactide (LA) with an yttrium complex featuring a N-heterocyclic carbine (NHC) tethered moiety is reported. It was found that the carbonyl of lactide is attacked by N(SiMe3)2 group rather than NHC species at the chain initiation step. The polymerization selectivity was further investigated via two consecutive insertions of lactide monomer molecules. The insertion of the second monomer in different assembly modes indicated that the steric interactions between the last enchained monomer unit and the incoming monomer together with the repulsion between the incoming monomer and the ligand framework are the primary factors determining the stereoselectivity. The interaction energy between the monomer and the metal center could also play an important role in the stereocontrol.
      Citation: Inorganics
      PubDate: 2017-07-20
      DOI: 10.3390/inorganics5030046
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 47: Design and Control of Cooperativity in
           Spin-Crossover in Metal–Organic Complexes: A Theoretical Overview

    • Authors: Hrishit Banerjee, Sudip Chakraborty, Tanusri Saha-Dasgupta
      First page: 47
      Abstract: Metal organic complexes consisting of transition metal centers linked by organic ligands, may show bistability which enables the system to be observed in two different electronic states depending on external condition. One of the spectacular examples of molecular bistability is the spin-crossover phenomena. Spin-Crossover (SCO) describes the phenomena in which the transition metal ion in the complex under the influence of external stimuli may show a crossover between a low-spin and high-spin state. For applications in memory devices, it is desirable to make the SCO phenomena cooperative, which may happen with associated hysteresis effect. In this respect, compounds with extended solid state structures containing metal ions connected by organic spacer linkers like linear polymers, coordination network solids are preferred candidates over isolated molecules or molecular assemblies. The microscopic understanding, design and control of mechanism driving cooperativity, however, are challenging. In this review we discuss the recent theoretical progress in this direction.
      Citation: Inorganics
      PubDate: 2017-07-20
      DOI: 10.3390/inorganics5030047
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 48: Synthesis, Crystal Structures and Magnetic
           Properties of Composites Incorporating an Fe(II) Spin Crossover Complex
           and Polyoxometalates

    • Authors: Satoshi Kuramochi, Takuya Shiga, Jamie Cameron, Graham Newton, Hiroki Oshio
      First page: 48
      Abstract: [Fe(dppOH)2]2+ (dppOH = 2,6-di(pyrazol-1-yl)-4-(hydroxymethyl)pyridine) is known to show spin crossover (SCO) behavior and light-induced excited spin state transitions (LIESST). Here, we show that the SCO properties of the [Fe(dppOH)2]2+ complex can be altered by a crystal engineering approach employing counter anion exchange with polyoxometalate (POM) anions. Using this strategy, two new composite materials (TBA)[Fe(dppOH)2][PMo12O40] (1) and [Fe(dppOH)2]3[PMo12O40]2 (2) (TBA = tetra-n-butylammonium) have been isolated and studied by single crystal X-ray diffraction and magnetic susceptibility measurements. 1 was found to be in a high spin state at 300 K and showed no spin crossover behavior due to a dense packing structure induced by hydrogen bonding between the hydroxyl group of the dppOH ligands and the POM anions. Conversely, 2 contains two crystallographically unique Fe centers, where one is in the low spin state whilst the other is locked in a high spin state in a manner analogous to 1. As a result, 2 was found to show partial spin crossover behavior around 230 K with a decrease in the χmT value of 1.9 emu·mol−1·K. This simple approach could therefore provide a useful method to aid in the design of next generation spin crossover materials.
      Citation: Inorganics
      PubDate: 2017-07-22
      DOI: 10.3390/inorganics5030048
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 49: High-Temperature Wide Thermal Hysteresis of
           an Iron(II) Dinuclear Double Helicate

    • Authors: Shiori Hora, Hiroaki Hagiwara
      First page: 49
      Abstract: Two new dinuclear iron(II) complexes (1·PF6 and 1·AsF6) of the general formula [FeII2(L2C3)2](X)4·nH2O·mMeCN (X = PF6, n = m = 1.5 for 1·PF6 and X = AsF6, n = 3, m = 1 for 1·AsF6) have been prepared and structurally characterized, where L2C3 is a bis-1,2,3-triazolimine type Schiff-base ligand, 1,1′-[propane-1,3-diylbis(1H-1,2,3-triazole-1,4-diyl)]bis{N-[2-(pyridin-2-yl)ethyl]methanimine}. Single crystal X-ray structure analyses revealed that 1·PF6 and 1·AsF6 are isostructural. The complex-cation [FeII2(L2C3)2]4+ of both has the same dinuclear double helicate architecture, in which each iron(II) center has an N6 octahedral coordination environment. Neighboring helicates are connected by intermolecular π–π interactions to give a chiral one-dimensional (1D) structure, and cationic 1D chains with the opposite chirality exist in the crystal lattice to give a heterochiral crystal. Magnetic and differential scanning calorimetry (DSC) studies were performed only for 1·AsF6, since the thermal stability in a high-temperature spin crossover (SCO) region of 1·PF6 is poorer than that of 1·AsF6. 1·AsF6 shows an unsymmetrical hysteretic SCO between the low-spin–low-spin (LS–LS) and high-spin–high-spin (HS–HS) states at above room temperature. The critical temperatures of warming (Tc↑) and cooling (Tc↓) modes in the abrupt spin transition area are 485 and 401 K, respectively, indicating the occurrence of 84 K-wide thermal hysteresis in the first thermal cycle.
      Citation: Inorganics
      PubDate: 2017-07-28
      DOI: 10.3390/inorganics5030049
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 50: Control of Spin-Crossover Phenomena in
           One-Dimensional Triazole-Coordinated Iron(II) Complexes by Means of
           Functional Counter Ions

    • Authors: Akira Sugahara, Hajime Kamebuchi, Atsushi Okazawa, Masaya Enomoto, Norimichi Kojima
      First page: 50
      Abstract: The spin-crossover (SCO) phenomenon between a high-spin and a low-spin state has attracted much attention in the field of materials science. Among the various kinds of SCO complexes, the triazole-bridged iron(II) polymeric chain system, [Fe(II)(R-trz)3]X2·xH2O (where trz is triazole and X is the anion), exhibiting the SCO phenomenon with thermal hysteresis around room temperature, has been extensively studied from the viewpoint of molecular memory and molecular devices. In connection with this system, we have controlled the SCO phenomenon according to the characteristic properties of counter ions. In the case of X being CnH2n+1SO3−, the spin transition temperature (T1/2) increases with increasing the length (n) of the alkyl chain of the counter ion and saturates above n = 5, which is attributed to the increase in the intermolecular interaction of the alkyl chains of CnH2n+1SO3−, called the fastener effect. The hysteresis width of T1/2 decreases with increasing n, showing the even-odd, also known as parity, effect. In the cases where X is toluenesulfonate (tos: CH3C6H4SO3−) and aminobenzenesulfonate (abs: NH2C6H4SO3−), T1/2 and its hysteresis width vary drastically with the structural isomerism (ortho-, metha-, and para-substitution) of counter ions, which implies the possibility of photoinduced spin transition by means of the photoisomerization of counter ions. From this strategy, we have synthesized [Fe(II)(NH2-trz)3](SP150)2·2H2O (SP150 = N-alkylsulfonated spiropyran) and investigated the SCO phenomenon. Moreover, we have developed [Fe(II)(R-trz)3]@Nafion films exhibiting spin transition around room temperature, where the Nafion membrane behaves as a counter anion as well as a transparent substrate, and investigated the photogenerated high-spin state below 35 K. The lifetime of the photogenerated high-spin state strongly depends on the intensity of irradiated light.
      Citation: Inorganics
      PubDate: 2017-08-19
      DOI: 10.3390/inorganics5030050
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 51: Heteroleptic and Homoleptic Iron(III)
           Spin-Crossover Complexes; Effects of Ligand Substituents and
           Intermolecular Interactions between Co-Cation/Anion and the Complex

    • Authors: Wasinee Phonsri, Luke Darveniza, Stuart Batten, Keith Murray
      First page: 51
      Abstract: The structural and magnetic properties of a range of new iron(III) bis-tridentate Schiff base complexes are described with emphasis on how intermolecular structural interactions influence spin states and spin crossover (SCO) in these d5 materials. Three pairs of complexes were investigated. The first pair are the neutral, heteroleptic complexes [Fe(3-OMe-SalEen)(thsa)] 1 and [Fe(3-MeOSalEen)(3-EtOthsa)] 2, where 3-R-HSalEen = (E)-2-(((2-(ethylamino)ethyl)imino)methyl)-6-R-phenol and 3-R-H2thsa = thiosemicarbazone-3-R-salicylaldimine. They display spin transitions above room temperature. However, 2 shows incomplete and gradual change, while SCO in 1 is complete and more abrupt. Lower cooperativity in 2 is ascribed to the lack of π–π interactions, compared to 1. The second pair, cationic species [Fe(3-EtOSalEen)2]NO3 3 and [Fe(3-EtOSalEen)2]Cl 4 differ only in the counter-anion. They show partial SCO above room temperature with 3 displaying a sharp transition at 343 K. Weak hydrogen bonds from cation to Cl− probably lead to weaker cooperativity in 4. The last pair, CsH2O[Fe(3-MeO-thsa)2] 5 and Cs(H2O)2[Fe(5-NO2-thsa)2] 6, are anionic homoleptic chelates that have different substituents on the salicylaldiminate rings of thsa2−. The Cs cations bond to O atoms of water and the ligands, in unusual ways thus forming attractive 1D and 3D networks in 5 and 6, respectively, and 5 remains HS (high spin) at all temperatures while 6 remains LS (low spin). Comparisons are made to other literature examples of Cs salts of [Fe(5-R-thsa)2]− (R = H and Br).
      Citation: Inorganics
      PubDate: 2017-08-01
      DOI: 10.3390/inorganics5030051
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 52: Pybox-Iron(II) Spin-Crossover Complexes with
           Substituent Effects from the 4-Position of the Pyridine Ring (Pybox =
           2,6-Bis(oxazolin-2-yl)pyridine)

    • Authors: Akifumi Kimura, Takayuki Ishida
      First page: 52
      Abstract: Spin-crossover (SCO) behavior of a series of [Fe(X-pybox)2](ClO4)2 was investigated, where X-pybox stands for 4-X-substituted 2,6-bis(oxazolin-2-yl)pyridine with X = H, Cl, Ph, CH3O, and CH3S. We confirmed that the mother compound [Fe(H-pybox)2](ClO4)2 underwent SCO above room temperature. After X was introduced, the SCO temperatures (T1/2) were modulated as 310, 230, and 330 K for X = Cl, Ph, and CH3S, respectively. The CH3O derivative possessed the high-spin state down to 2 K. Crystallographic analysis for X = H, Cl, CH3O, and CH3S was successful, being consistent with the results of the magnetic study. Distorted coordination structures stabilize the HS (high-spin) state, and the highest degree of the coordination structure distortion is found in the CH3O derivative. A plot of T1/2 against the Hammett substituent constant σp showed a positive relation. Solution susceptometry was also performed to remove intermolecular interaction and rigid crystal lattice effects, and the T1/2’s were determined as 260, 270, 240, 170, and 210 K for X = H, Cl, Ph, CH3O, and CH3S, respectively, in acetone. The substituent effect on T1/2 became very distinct, and it is clarified that electron-donating groups stabilize the HS state.
      Citation: Inorganics
      PubDate: 2017-08-08
      DOI: 10.3390/inorganics5030052
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 53: Halogen Substituent Effect on the
           Spin-Transition Temperature in Spin-Crossover Fe(III) Compounds Bearing
           Salicylaldehyde 2-Pyridyl Hydrazone-Type Ligands and Dicarboxylic Acids

    • Authors: Takumi Nakanishi, Atsushi Okazawa, Osamu Sato
      First page: 53
      Abstract: Four Fe(III) spin-crossover (SCO) compounds, [Fe(HL1)2](HCl4TPA) (1-Cl), [Fe(HL1)2](HBr4TPA) (1-Br), [Fe(HL2)2](HCl4TPA) (2-Cl), and [Fe(HL2)2](HBr4TPA) (2-Br) (HL1 = 4-chloro-2-nitro-6-(1-(2-(pyridine-2-yl)hydrazono)ethyl)phenolate; HL2 = 4-bromo-2-nitro-6-(1-(2-(pyridine-2-yl)hydrazono)ethyl)phenolate; HCl4TPA = 2,3,5,6-tetrachloro-4-carboxybenzoate; and HBr4TPA = 2,3,5,6-tetrabromo-4-carboxybenzoate), were synthesized to investigate the halogen substituent change effect in salicylaldehyde 2-pyridyl hydrazone-type ligands and dicarboxylic acids in SCO complexes to the spin-transition temperature. Crystal structure analyses showed that these compounds were isostructural. In addition, a one-dimensional hydrogen–bonded column was formed by the dicarboxylic acid anion and weak hydrogen bonds between the Fe(III) complexes. From Mössbauer spectroscopy and magnetic property measurements, these compounds were confirmed to exhibit gradual SCO. The spin-transition temperature can be shifted by changing the halogen substituent in the salicylaldehyde 2-pyridyl hydrazone-type ligands and dicarboxylic acids without changing the molecular arrangement in the crystal packing.
      Citation: Inorganics
      PubDate: 2017-08-12
      DOI: 10.3390/inorganics5030053
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 54: Spin-Singlet Transition in the Magnetic
           

    • Authors: Kazuyuki Takahashi, Takahiro Sakurai, Wei-Min Zhang, Susumu Okubo, Hitoshi Ohta, Takashi Yamamoto, Yasuaki Einaga, Hatsumi Mori
      First page: 54
      Abstract: To develop a new spin-crossover functional material, a magnetic hybrid compound [Fe(qsal)2][Ni(mnt)2] was designed and synthesized (Hqsal = N-(8-quinolyl)salicylaldimine, mnt = maleonitriledithiolate). The temperature dependence of magnetic susceptibility suggested the coexistence of the high-spin (HS) Fe(III) cation and π-radical anion at room temperature and a magnetic transition below 100 K. The thermal variation of crystal structures revealed that strong π-stacking interaction between the π-ligand in the [Fe(qsal)2] cation and [Ni(mnt)2] anion induced the distortion of an Fe(III) coordination structure and the suppression of a dimerization of the [Ni(mnt)2] anion. Transfer integral calculations indicated that the magnetic transition below 100 K originated from a spin-singlet formation transformation in the [Ni(mnt)2] dimer. The magnetic relaxation of Mössbauer spectra and large thermal variation of a g-value in electron paramagnetic resonance spectra below the magnetic transition temperature implied the existence of a magnetic correlation between d-spin and π-spin.
      Citation: Inorganics
      PubDate: 2017-08-16
      DOI: 10.3390/inorganics5030054
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 55: Modification of Cooperativity and Critical
           Temperatures on a Hofmann-Like Template Structure by Modular Substituent

    • Authors: Takashi Kosone, Takeshi Kawasaki, Itaru Tomori, Jun Okabayashi, Takafumi Kitazawa
      First page: 55
      Abstract: In a series of Hofmann-like spin crossover complexes, two new compounds, {Fe(3-F-4-Methyl-py)2[Au(CN)2]2} (1) and {Fe(3-Methyl-py)2[Au(CN)2]2} (2) (py = pyridine) are described. The series maintains a uniform 2-dimentional (2-D) layer structure of {Fe[Au(CN)2]2}. The layers are combined with another layer by strong aurophilic interactions, which results in a bilayer structure. Both coordination compounds 1 and 2 at 293 K crystallize in the centrosymmetric space groups P21/c. The asymmetric unit contains two pyridine derivative ligands, one type of Fe2+, and two types of crystallographically distinct [Au(CN)2]− units. Compound 1 undergoes a complete two-step spin transition. On the other hand, 2 maintains the characteristic of the high-spin state. The present compounds and other closely related bilayer compounds are compared and discussed in terms of the cooperativity and critical temperature. The bilayer structure is able to be further linked by substituent-substituent contact resulting in 3-dimentional (3-D) network cooperativity.
      Citation: Inorganics
      PubDate: 2017-08-16
      DOI: 10.3390/inorganics5030055
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 56: (18-Crown-6)potassium(I)
           Trichlorido[28-acetyl-3-(tris-(hydroxylmethyl)amino-ethane)betulinic
           ester-κN]platinum(II): Synthesis and In Vitro Antitumor Activity

    • Authors: Goran Kaluđerović, Mirna Bulatović, Tamara Krajnović, Reinhard Paschke, Bojana B. Zmejkovski, Danijela Maksimović-Ivanić, Sanja Mijatović
      First page: 56
      Abstract: Synthesis of platinum(II) conjugate with acetylated betulinic acid tris(hydroxymethyl)aminomethane ester (BATRIS) is presented (BATRISPt). HR-ESI-MS and multinuclear NMR spectroscopy, as well as elemental analysis were used for characterization of BATRISPt. Cytotoxicity (3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), crystal violet (CV), and sulforhodamine B (SRB) assays) of BA, BATRIS, BATRISPt, and cisplatin were assessed on seven different tumor cell lines: melanoma B16, colon HCT116 and DLD-1, adenocarcinoma HeLa, breast MCF-7, and anaplastic thyroid tumor 8505C and SW1736; as well as normal MRC-5 fibroblasts. Furthermore, the effect of the mentioned compounds on the apoptosis (Annexin V/PI assay) and autophagy induction (acridine orange (AO) assay) as well as caspase 3, 8, and 9 activation were investigated on the selected B16 melanoma cell line. BATRISPt showed lower activity than BA, BATRIS, or cisplatin. All tested compounds triggered apoptosis in B16 cells. Induction of autophagy was observed in B16 cells exposed only to BATRIS. On the other hand, new conjugate activates caspases 8 and 9 in B16 cells with higher impact than BATRIS or cisplatin alone.
      Citation: Inorganics
      PubDate: 2017-08-19
      DOI: 10.3390/inorganics5030056
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 57: Hydrogen Storage Stability of Nanoconfined
           MgH2 upon Cycling

    • Authors: Priscilla Huen, Mark Paskevicius, Bo Richter, Dorthe Ravnsbæk, Torben Jensen
      First page: 57
      Abstract: It is of utmost importance to optimise and stabilise hydrogen storage capacity during multiple cycles of hydrogen release and uptake to realise a hydrogen-based energy system. Here, the direct solvent-based synthesis of magnesium hydride, MgH2, from dibutyl magnesium, MgBu2, in four different carbon aerogels with different porosities, i.e., pore sizes, 15 < Davg < 26 nm, surface area 800 < SBET < 2100 m2/g, and total pore volume, 1.3 < Vtot < 2.5 cm3/g, is investigated. Three independent infiltrations of MgBu2, each with three individual hydrogenations, are conducted for each scaffold. The volumetric and gravimetric loading of MgH2 is in the range 17 to 20 vol % and 24 to 40 wt %, which is only slightly larger as compared to the first infiltration assigned to the large difference in molar volume of MgH2 and MgBu2. Despite the rigorous infiltration and sample preparation techniques, particular issues are highlighted relating to the presence of unwanted gaseous by-products, Mg/MgH2 containment within the scaffold, and the purity of the carbon aerogel scaffold. The results presented provide a research path for future researchers to improve the nanoconfinement process for hydrogen storage applications.
      Citation: Inorganics
      PubDate: 2017-08-23
      DOI: 10.3390/inorganics5030057
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 58: N-Heterocyclic Carbene Coinage Metal
           Complexes Containing Naphthalimide Chromophore: Design, Structure, and
           Photophysical Properties

    • Authors: Pierre-Henri Lanoë, Btissam Najjari, Florine Hallez, Geoffrey Gontard, Hani Amouri
      First page: 58
      Abstract: A series of novel N-heterocyclic carbene coinage metal complexes containing a naphthalimide (NI) chromophore has been prepared and fully characterized. Two types of molecules are described those where the NI unit is directly attached to the carbene unit with the general formulae [(L1)–M–X], M = Cu, X = Cl (1a); M = Ag, X = I (1b) and M = Au, X = Cl, (1c). While in the second family, a π-extended carbene ligand precursor L2–H+I− (3) was prepared where the NI unit is distant from the imidazole unit via a phenyl-alkyne bridge. Only two N-heterocyclic carbene metal complexes were prepared [(L2)–M–Cl], M = Cu (2a) and M = Au (2c). The related silver carbene compound could not be isolated. The molecular structure of the carbene complex 1c was determined and confirmed the formation of the target compound. Interestingly, the structure shows the presence of an aurophilic interaction Au···Au at 3.407 Å between two individual molecules. The photophysical properties of the compounds were investigated in solution at room temperature. Preliminary results suggested that all compounds are luminescent and act as blue emitters (420–451 nm). These transition emissions can be attributed to the intraligand origin of the NI chromphore. Moreover, the carbene complexes featuring L2 ligand with π-extended system were found to be more luminescent.
      Citation: Inorganics
      PubDate: 2017-08-24
      DOI: 10.3390/inorganics5030058
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 59: Assembly of Mn(III) Schiff Base Complexes
           with Heptacyanorhenate (IV)

    • Authors: Taisiya Sukhikh, Kira Vostrikova
      First page: 59
      Abstract: A pioneering research on a self-assembly of the magneto-anisotropic module [Re(CN)7]3− with the Mn(III) complexes involving Salen type (N,N′-ethylenebis(salicylideneiminate)) Schiff base (SB) ligands was performed using the known [Mn(3MeOSalen)(H2O)2]2(ClO4)2·H2O (1) and the firstly synthesized [Mn2(5MeSalen)2OAc]PF6 (2). In the case of 1, a slow diffusion of the component solutions led to the ionic compound Ph4P[Mn(3MeOSalen)(H2O)2]2[Re(CN)7]·6H2O (3). The direct mixing of the same solutions has resulted in the microcrystalline nearly insoluble solid [Mn(3MeOSalen)(H2O))4Re(CN)7]ClO4·1.5MeCN·6.5H2O, which is likely to comprise the pentanuclear clusters [(MnIII(SB)(H2O))4Re(CN)7]+. The use of 2 resulted in a 2D-network assembly of octanuclear clusters, [{(Mn(5MeSalen))6(H2O)2Re(CN)7}2Re(CN)7]Cl2(PF6)·H2O (4), incorporating one Re-center in a pentagonal bipyramid coordination environment, while another has strongly distorted capped trigonal prism as a coordination polyhedron. The latter was observed for the first time for Re(IV) complexes. A synthetic challenge to obtain the 0D assemblies with Re:Mn ≥ 3 has yielded a hexanuclear complex [Mn(5MeSalen)H2O(i-PrOH)][(Mn(5MeSalen))5H2O(i-PrOH)2Re(CN)7](PF6)2(OAc)·2i-PrOH (5) being 1D chain via a bridging phenoxyl group. Owing to a low solubility of the final product, an addition of a bulk anion Ph4B− to the MeCN/MeOH solution of [Re(CN)7]3−and 1 in ratio 1:6 resulted in rhenium-free matter [Mn(3MeOSalen)(H2O)2][Mn(3MeOSalen)(H2O)MeCN](Ph4B)2·5MeCN (6).
      Citation: Inorganics
      PubDate: 2017-09-01
      DOI: 10.3390/inorganics5030059
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 60: Structural Dynamics of Spin Crossover in
           Iron(II) Complexes with Extended-Tripod Ligands

    • Authors: Philipp Stock, Dennis Wiedemann, Holm Petzold, Gerald Hörner
      First page: 60
      Abstract: Selective manipulation of spin states in iron(II) complexes by thermal or photonic energy is a desirable goal in the context of developing molecular functional materials. As dynamic spin-state equilibration in isolated iron(II) complexes typically limits the lifetime of a given spin state to nanoseconds, synthetic strategies need to be developed that aim at inhibited relaxation. Herein we show that modulation of the reaction coordinate through careful selection of the ligand can indeed massively slow down dynamic exchange. Detailed structural analysis of [FeL]2+ and [ZnL]2+ (L: tris(1-methyl-2-{[pyridin-2-yl]-methylene}hydrazinyl)phosphane sulfide) with crystallographic and computational methods clearly reveals a unique trigonal-directing effect of the extended-tripod ligand L during spin crossover, which superimposes the ubiquitous [FeN6] breathing with trigonal torsion, akin to the archetypal Bailar twist. As a consequence of the diverging reaction coordinates in [FeL]2+ and in the tren-derived complex [Fe(tren)py3]2+, their thermal barriers differ massively, although the spin crossover energies are close to identical. As is shown by time-resolved transient spectroscopy and dynamic 1H-NMR line broadening, reference systems deriving from tren (tris-(2-aminoethyl)amine), which greatly lack such trigonal torsion, harbor very rapid spin-state exchange.
      Citation: Inorganics
      PubDate: 2017-09-05
      DOI: 10.3390/inorganics5030060
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 61: Structure and Spin State of Iron(II)
           Assembled Complexes Using 9,10-Bis(4-pyridyl)anthracene as Bridging Ligand
           

    • Authors: Saki Iwai, Keisuke Yoshinami, Satoru Nakashima
      First page: 61
      Abstract: Assembled complexes, [Fe(NCX)2(bpanth)2]n (X = S, Se, BH3; bpanth = 9,10-bis(4-pyridyl)anthracene), were synthesized. The iron for the three complexes was in temperature-independent high spin state by 57Fe Mössbauer spectroscopy and magnetic susceptibility measurement. X-ray structural analysis revealed the interpenetrated structure of [Fe(NCS)2(bpanth)2]n. In the local structure around the iron atom, the coordinated pyridine planes were shown to be a parallel type, which is in accordance with the results investigated by density functional theory (DFT) calculation. This complex (X = S) has CH–π interactions between the H atom of coordinated pyridine and the neighboring anthracene of the other 2D grid. It was suggested that the interpenetrated structure was supported by the stabilization of CH–π interaction, and this intermolecular interaction forced the relatively unstable parallel structure. That is, the unstable local structure is compensated by the stabilization due to intermolecular interaction, which controlled the spin state as high spin state.
      Citation: Inorganics
      PubDate: 2017-09-12
      DOI: 10.3390/inorganics5030061
      Issue No: Vol. 5, No. 3 (2017)
       
  • Inorganics, Vol. 5, Pages 18: Adsorption and Oxidation of Aromatic Amines
           on Metal(II) Hexacyanocobaltate(III) Complexes: Implication for
           Oligomerization of Exotic Aromatic Compounds

    • Authors: Rachana Sharma, Md. Asif Iqubal, Sohan Jheeta, Kamaluddin
      First page: 18
      Abstract: Based on the hypothesis on the presence of double metal cyanides in the primordial oceans, a series of nano-sized metal(II) hexacyanocobaltate(III) (MHCCo) with the general formula: M3[Co(CN)6]2•xH2O (where M = Zn, Fe, Ni and Mn) has been synthesized. Surface interaction of aromatic amines, namely aniline, 4-chloroaniline, 4-methylaniline and 4-methoxyaniline with MHCCo particles has been carried out at the concentration range of 100–400 μM at pH~7.0. The percentage binding of aromatic amines on MHCCo surface was found to be in the range of 84%–44%. The trend in adsorption was in accordance to the relative basicity of the studied amines. At the experimental pH, amines reacted rapidly with the surface of the iron(II) hexacyanocobaltate, producing colored products that were analyzed by Gas Chromatography Mass Spectroscopy (GC-MS). GC-MS analysis of the colored products demonstrated the formation of dimers of the studied aromatic amines. Surface interaction of aromatic amines with MHCCo was studied by Fourier Transform Infrared (FT-IR) spectroscopy and Field Emission Scanning Electron Microscopy (FE-SEM). The change in amine characteristic frequencies, as observed by FT-IR, suggests that interaction took place through the NH2 group on amines with metal ions of hexacyanocobaltate complexes. FE-SEM studies revealed the adherence of 4-methoxyaniline on zinc hexacyanocobaltate particles surface. We proposed that MHCCo might have been formed under the conditions on primitive Earth and may be regarded as an important candidate for concentrating organic molecules through the adsorption process.
      PubDate: 2017-03-24
      DOI: 10.3390/inorganics5020018
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 19: Na1+yVPO4F1+y (0 ≤ y≤ 0.5) as Cathode
           Materials for Hybrid Na/Li Batteries

    • Authors: Nina Kosova, Daria Rezepova
      First page: 19
      Abstract: Using Rietveld-refined X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and electrochemical cycling, it was established that among sodium vanadium fluorophosphate compositions Na1+yVPO4F1+y (0 ≤ y ≤ 0.75), the single-phase material Na1.5VPO4F1.5 or Na3V2(PO4)2F3 with a tetragonal structure (the P42/mnm S.G.) is formed only for y = 0.5. The samples with y < 0.5 and y > 0.5 possessed different impurity phases. Na3V2(PO4)2F3 could be considered as a multifunctional cathode material for the fabrication of lithium-ion and sodium-ion high-energy batteries. The reversible discharge capacity of 116 mAh•g−1 was achieved upon cycling Na3V2(PO4)2F3 in a hybrid Na/Li cell. Decrease in discharge capacity for the other samples was in accordance with the amount of the electrochemically active phase Na3V2(PO4)2F3. Na3V2(PO4)2F3 showed good cycleability and a high rate of performance, presumably due to operation in the mixed Na/Li electrolyte. The study of the structure and composition of charged and discharged samples, and the analysis of differential capacity curves showed a negligible Na/Li electrochemical exchange, and a predominant sodium-based cathode reaction. To increase the degree of the Na/Li electrochemical exchange in Na3V2(PO4)2F3, it needs to be desodiated first in a Na cell, and then cycled in a lithium cell. In this case, the electrolyte would be enriched with the Li ions.
      PubDate: 2017-03-27
      DOI: 10.3390/inorganics5020019
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 20: Investigation of the Structures and Energy
           Landscapes of Thiocyanate-Water Clusters

    • Authors: Lewis Smeeton, John Hey, Roy Johnston
      First page: 20
      Abstract: The Basin Hopping search method is used to find the global minima (GM) and map the energy landscapes of thiocyanate-water clusters, (SCN−)(H2O)n with 3–50 water molecules, with empirical potentials describing the ion-water and water-water interactions. (It should be noted that beyond n = 23, the lowest energy structures were only found in 1 out of 8 searches so they are unlikely to be the true GM but are indicative low energy structures.) As for pure water clusters, the low energy isomers of thiocyanate-water clusters show a preponderance of fused water cubes and pentagonal prisms, with the weakly solvated thiocyanate ion lying on the surface, replacing two water molecules along an edge of a water polyhedron and with the sulfur atom in lower coordinated sites than nitrogen. However, by comparison with Density Functional Theory (DFT) calculations, the empirical potential is found to overestimate the strength of the thiocyanate-water interaction, especially O–H⋯S, with low energy DFT structures having lower coordinate N and (especially) S atoms than for the empirical potential. In the case of these finite ion-water clusters, the chaotropic (“disorder-making”) thiocyanate ion weakens the water cluster structure but the water molecule arrangement is not significantly changed.
      PubDate: 2017-03-31
      DOI: 10.3390/inorganics5020020
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 21: Photophysics of BODIPY Dyes as
           Readily-Designable Photosensitisers in Light-Driven Proton Reduction

    • Authors: Laura Dura, Maria Wächtler, Stephan Kupfer, Joachim Kübel, Johannes Ahrens, Sebastian Höfler, Martin Bröring, Benjamin Dietzek, Torsten Beweries
      First page: 21
      Abstract: A series of boron dipyrromethene (BODIPY) dyes was tested as photosensitisers for light-driven hydrogen evolution in combination with the complex [Pd(PPh3)Cl2]2 as a source for catalytically-active Pd nanoparticles and triethylamine as a sacrificial electron donor. In line with earlier reports, halogenated dyes showed significantly higher hydrogen production activity. All BODIPYs were fully characterised using stationary absorption and emission spectroscopy. Time-resolved spectroscopic investigations on meso-mesityl substituted compounds revealed that reduction of the photo-excited BODIPY by the sacrificial agent occurs from an excited singlet state, while, in halogenated species, long-lived triplet states are present, determining electron transfer processes from the sacrificial agent. Quantum chemical calculations performed at the time-dependent density functional level of theory indicate that the differences in the photocatalytic performance of the present series of dyes can be correlated to the varying efficiency of intersystem crossing in non-halogenated and halogenated species and not to alterations in the energy levels introduced upon substitution.
      PubDate: 2017-04-05
      DOI: 10.3390/inorganics5020021
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 22: Insights into Molecular
           Beryllium–Silicon Bonds

    • Authors: Dominik Naglav, Briac Tobey, Kevin Dzialkowski, Georg Jansen, Christoph Wölper, Stephan Schulz
      First page: 22
      Abstract: We present the synthesis of two silyl beryllium halides HypSiBeX∙(thf) (HypSi = Si(SiMe3)3, X = Cl 2a, I 4a) and the molecular structure of 2a as determined by single crystal X-ray diffraction. Compounds 2a and 4a were characterized via multi-nuclear NMR spectroscopy (1H, 9Be, 13C, 29Si), and the bonding situation was further investigated using quantum chemical calculations (with the addition of further halides X = F 1b, Cl 2b, Br 3b, I 4b). The nature of the beryllium silicon bond in the context of these compounds is highlighted and discussed.
      PubDate: 2017-04-10
      DOI: 10.3390/inorganics5020022
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 23: Chemical Tuning and Absorption Properties of
           Iridium Photosensitizers for Photocatalytic Applications

    • Authors: Olga Bokareva, Tobias Möhle, Antje Neubauer, Sergey Bokarev, Stefan Lochbrunner, Oliver Kühn
      First page: 23
      Abstract: Cyclometalated Ir(III) complexes are of particular interest due to the wide tunability of their electronic structure via variation of their ligands. Here, a series of heteroleptic Ir-based photosensitizers with the general formula [Ir(C^N)2(N^N)]+ has been studied theoretically by means of an optimally-tuned long-range separated density functional. Focusing on the steady-state absorption spectra, correlations between the chemical modification of both ligand types with the natures of the relevant dark and bright electronic states are revealed. Understanding such correlations builds up a basis for the rational design of efficient photocatalytic systems.
      PubDate: 2017-04-12
      DOI: 10.3390/inorganics5020023
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 24: Visible Light-Activated PhotoCORMs

    • Authors: Emmanuel Kottelat, Zobi Fabio
      First page: 24
      Abstract: Despite its well-known toxicity, carbon monoxide (CO) is now recognized as a potential therapeutic agent. Its inherent toxicity, however, has limited clinical applications because uncontrolled inhalation of the gas leads to severe systemic derangements in higher organisms. In order to obviate life-threatening effects and administer the gas by bypassing the respiratory system, CO releasing molecules (CORMs) have emerged in the last decades as a plausible alternative to deliver controlled quantities of CO in cellular systems and tissues. As stable, solid-storage forms of CO, CORMs can be used to deliver the gas following activation by a stimulus. Light-activated CORMs, known as photoCORMs, are one such example. This class of molecules is particularly attractive because, for possible applications of CORMs, temporal and spatial control of CO delivery is highly desirable. However, systems triggered by visible light are rare. Most currently known photoCORMs are activated with UV light, but red light or even infrared photo-activation is required to ensure that structures deeper inside the body can be reached while minimizing photo-damage to healthy tissue. Thus, one of the most challenging chemical goals in the preparation of new photoCORMs is the reduction of radiation energy required for their activation, together with strategies to modulate the solubility, stability and nontoxicity of the organic or organometallic scaffolds. In this contribution, we review the latest advances in visible light-activated photoCORMs, and the first promising studies on near-infrared light activation of the same.
      PubDate: 2017-04-13
      DOI: 10.3390/inorganics5020024
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 25: Nanotechnology of Positive Electrodes for
           Li-Ion Batteries

    • Authors: Xiaoyu Zhang, Ana-Gabriela Porras-Gutierrez, Alain Mauger, Henri Groult, Christian Julien
      First page: 25
      Abstract: This work presents the recent progress in nanostructured materials used as positive electrodes in Li-ion batteries (LIBs). Three classes of host lattices for lithium insertion are considered: transition-metal oxides V2O5, α-NaV2O5, α-MnO2, olivine-like LiFePO4, and layered compounds LiNi0.55Co0.45O2, LiNi1/3Mn1/3Co1/3O2 and Li2MnO3. First, a brief description of the preparation methods shows the advantage of a green process, i.e., environmentally friendliness wet chemistry, in which the synthesis route using single and mixed chelators is used. The impact of nanostructure and nano-morphology of cathode material on their electrochemical performance is investigated to determine the synthesis conditions to obtain the best electrochemical performance of LIBs.
      PubDate: 2017-04-14
      DOI: 10.3390/inorganics5020025
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 26: Potassium C–F Interactions and the
           Structural Consequences in N,N′-Bis(2,6-difluorophenyl)formamidinate
           Complexes

    • Authors: Daniel Werner, Glen Deacon, Peter Junk
      First page: 26
      Abstract: Treatment of K[N(SiMe3)2] with N,N′-bis(2,6-difluorophenyl)formamidine (DFFormH) in toluene, resulted in the formation of [K(DFForm)]∞ (1) as a poorly soluble material. Upon dissolution in thf and layering with n-hexane, 1 was crystallised and identified as a two-dimensional polymer, in which all fluorine and nitrogen atoms, and also part of one aryl group, bridge between four symmetry equivalent potassium ions, giving rise to a completely unique μ4-(N,N′,F,F′):(N,N′):η4(Ar-C(2,3,4,5,6)):(F″,F′′′) DFForm coordination. The two-dimensional nature of the polymer could be deconstructed to one dimension by crystallisation from neat thf at −35 °C, giving [K2(DFForm)2(thf)2]∞ (2), where the thf molecules bridge the monomeric units. Complete polymer dissociation was observed when 1 was crystallised from toluene/n-hexane mixtures in the presence of 18-crown-6, giving [K(DFForm)(18-crown-6)] (3), which showed unprecedented κ(N,Cispo,F) DFForm coordination, rather than the expected κ(N,N′) coordination.
      PubDate: 2017-04-17
      DOI: 10.3390/inorganics5020026
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 27: Pulsed Current Electrodeposition of Silicon
           Thin Films Anodes for Lithium Ion Battery Applications

    • Authors: Bharat Gattu, Rigved Epur, Pavithra Shanti, Prashanth Jampani, Ramalinga Kuruba, Moni Datta, Ayyakkannu Manivannan, Prashant Kumta
      First page: 27
      Abstract: Electrodeposition of amorphous silicon thin films on Cu substrate from organic ionic electrolyte using pulsed electrodeposition conditions has been studied. Scanning electron microscopy analysis shows a drastic change in the morphology of these electrodeposited silicon thin films at different frequencies of 0, 500, 1000, and 5000 Hz studied due to the change in nucleation and the growth mechanisms. These electrodeposited films, when tested in a lithium ion battery configuration, showed improvement in stability and performance with an increase in pulse current frequency during deposition. XPS analysis showed variation in the content of Si and oxygen with the change in frequency of deposition and with the change in depth of these thin films. The presence of oxygen largely due to electrolyte decomposition during Si electrodeposition and the structural instability of these films during the first discharge–charge cycle are the primary reasons contributing to the first cycle irreversible (FIR) loss observed in the pulse electrodeposited Si–O–C thin films. Nevertheless, the silicon thin films electrodeposited at a pulse current frequency of 5000 Hz show a stable capacity of ~805 mAh·g−1 with a fade in capacity of ~0.056% capacity loss per cycle (a total loss of capacity ~246 mAh·g−1) at the end of 500 cycles.
      PubDate: 2017-04-20
      DOI: 10.3390/inorganics5020027
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 28: Alkali and Alkaline Earth Metal Complexes
           Ligated by an Ethynyl Substituted Cyclopentadienyl Ligand

    • Authors: Tim Seifert, Peter Roesky
      First page: 28
      Abstract: Sodium, potassium, and calcium compounds of trimethyl((2,3,4,5-tetramethylcyclopentadien-1-yl)ethynyl)silane (CpMe4(C≡CSiMe3)) were synthesized and characterized by X-ray diffraction and standard analytical methods. The sodium derivative was obtained by deprotonation of CpMe4(C≡CSiMe3)H with Na{N(SiMe3)2} to give a monomeric complex [NaCpMe4(C≡CSiMe3)(THF)3]. In a similar reaction, starting from K{N(SiMe3)2} the corresponding potassium compound [KCpMe4(C≡CSiMe3)(THF)2]n, which forms a polymeric super sandwich structure in the solid state, was obtained. Subsequently, salt metathesis reactions were conducted in order to investigate the versatility of the CpMe4(C≡CSiMe3)− ligand in alkaline earth chemistry. The reaction of [KCpMe4(C≡CSiMe3)(THF)2]n with CaI2 afforded the dimeric complex [CaCpMe4(C≡CSiMe3)I(THF)2]2, in which both CpMe4(C≡CSiMe3)Ca units are bridged by iodide in a μ2 fashion. In-depth NMR investigation indicates that [CaCpMe4(C≡CSiMe3)I(THF)2]2 is in a Schlenk equilibrium with [{CpMe4(C≡CSiMe3)}2Ca(THF)x] and CaI2(THF)2, as is already known for [CaCp*I(THF)2].
      PubDate: 2017-04-20
      DOI: 10.3390/inorganics5020028
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 29: Methanediide Formation via Hydrogen
           Elimination in Magnesium versus Aluminium Hydride Complexes of a
           Sterically Demanding Bis(iminophosphoranyl)methanediide

    • Authors: Christian Sindlinger, Samuel Lawrence, David Cordes, Alexandra Slawin, Andreas Stasch
      First page: 29
      Abstract: Substituted bis(iminophosphoranyl)methanes are CH acidic compounds that can form complexes with formally dianionic central carbon centres. The reaction of H2C(Ph2P=NDip)2 (≡ H2L), Dip = 2,6-diisopropylphenyl, with one equivalent of di-n-butylmagnesium afforded the methanide complex [HLMgnBu] 1. Treatment of Complex 1 with phenylsilane in aromatic solvents at elevated temperatures afforded the methanediide complex [(LMg)2] 2 presumably via the MgH intermediate [(HLMgH)n] (n = 1 or 2). The reaction of 1 with LiAlH4 in diethyl ether yielded the AlH complex [HLAlH2] 3. Alternatively, this complex was also obtained from the reaction of H2L with AlH3∙NMe3. The molecular structures of [HLMgnBu] 1, [(LMg)2] 2, and [HLAlH2] 3 are reported. Complex 3 shows no sign of H2 elimination to a methanediide species at elevated temperatures in contrast to the facile elimination of the putative reaction intermediate [(HLMgH)n] (n = 1 or 2) to form [(LMg)2] 2. The chemical properties of Complex 2 were investigated, and this complex appears to be stable against coordination with strong donor molecules.
      PubDate: 2017-04-22
      DOI: 10.3390/inorganics5020029
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 30: Backbone-Substituted β-Ketoimines and
           Ketoiminate Clusters: Transoid Li2O2 Squares and D2-Symmetric Li4O4
           Cubanes. Synthesis, Crystallography and DFT Calculations

    • Authors: Twyla Gietz, René Boeré
      First page: 30
      Abstract: The preparation and crystal structures of four β-ketoimines with bulky aryl nitrogen substituents (2,6-diisopropylphenyl and 2,4,6-trimethylphenyl) and varying degrees of backbone methyl substitution are reported. Backbone substitution “pinches” the chelate ring. Deprotonation with n-butyllithium leads to dimeric Li2O2 clusters, as primary laddered units, with an open transoid geometry as shown by crystal structures of three examples. The coordination sphere of each lithium is completed by one tetrahydrofuran ligand. NMR spectra undertaken in either C6D6 or 1:1 C6D6/d8-THF show free THF in solution and the chemical shifts of ligand methyl groups experience significant ring-shielding which can only occur from aryl rings on adjacent ligands. Both features point to conversion to higher-order aggregates when the THF concentration is reduced. Recrystallization of the materials from hydrocarbon solutions results in secondary laddering as tetrameric Li4O4 clusters with a cuboidal core, three examples of which have been crystallographically characterised. These clusters are relatively insoluble and melt up to 250 °C; a consideration of the solid-state structures indicates that the clusters with 2,6-diisopropylphenyl substituents form very uniform ball-like molecular structures that will only be weakly solvated.
      PubDate: 2017-04-26
      DOI: 10.3390/inorganics5020030
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 31: Hydrogen Sorption in Erbium Borohydride
           Composite Mixtures with LiBH4 and/or LiH

    • Authors: Michael Heere, Seyed GharibDoust, Matteo Brighi, Christoph Frommen, Magnus Sørby, Radovan Černý, Torben Jensen, Bjørn Hauback
      First page: 31
      Abstract: Rare earth (RE) metal borohydrides have recently been receiving attention as possible hydrogen storage materials and solid-state Li-ion conductors. In this paper, the decomposition and reabsorption of Er(BH4)3 in composite mixtures with LiBH4 and/or LiH were investigated. The composite of 3LiBH4 + Er(BH4)3 + 3LiH has a theoretical hydrogen storage capacity of 9 wt %, nevertheless, only 6 wt % hydrogen are accessible due to the formation of thermally stable LiH. Hydrogen sorption measurements in a Sieverts-type apparatus revealed that during three desorption-absorption cycles of 3LiBH4 + Er(BH4)3 + 3LiH, the composite desorbed 4.2, 3.7 and 3.5 wt % H for the first, second and third cycle, respectively, and thus showed good rehydrogenation behavior. In situ synchrotron radiation powder X-ray diffraction (SR-PXD) after ball milling of Er(BH4)3 + 6LiH resulted in the formation of LiBH4, revealing that metathesis reactions occurred during milling in these systems. Impedance spectroscopy of absorbed Er(BH4)3 + 6LiH showed an exceptional high hysteresis of 40–60 K for the transition between the high and low temperature phases of LiBH4, indicating that the high temperature phase of LiBH4 is stabilized in the composite.
      PubDate: 2017-04-26
      DOI: 10.3390/inorganics5020031
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 32: Study of Cathode Materials for Lithium-Ion
           Batteries: Recent Progress and New Challenges

    • Authors: Florian Schipper, Prasant Nayak, Evan Erickson, S. Amalraj, Onit Srur-Lavi, Tirupathi Penki, Michael Talianker, Judith Grinblat, Hadar Sclar, Ortal Breuer, Christian Julien, Nookala Munichandraiah, Daniela Kovacheva, Mudit Dixit, Dan Major, Boris Markovsky, Doron Aurbach
      First page: 32
      Abstract: Amongst a number of different cathode materials, the layered nickel-rich LiNiyCoxMn1−y−xO2 and the integrated lithium-rich xLi2MnO3·(1 − x)Li[NiaCobMnc]O2 (a + b + c = 1) have received considerable attention over the last decade due to their high capacities of ~195 and ~250 mAh·g−1, respectively. Both materials are believed to play a vital role in the development of future electric vehicles, which makes them highly attractive for researchers from academia and industry alike. The review at hand deals with both cathode materials and highlights recent achievements to enhance capacity stability, voltage stability, and rate capability, etc. The focus of this paper is on novel strategies and established methods such as coatings and dopings.
      PubDate: 2017-04-28
      DOI: 10.3390/inorganics5020032
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 33: Hetero- and Homoleptic Magnesium Triazenides

    • Authors: Denis Vinduš, Mark Niemeyer
      First page: 33
      Abstract: Using monoanionic triazenide ligands derived from biphenyl and m-terphenyl substituted triazenes Dmp(Tph)N3H (1a), (Me4Ter)2N3H (1b) or Dmp(Mph)N3H (1c) (Dmp = 2,6-Mes2C6H3 with Mes = 2,4,6-Me3C6H2; Me4Ter = 2,6-(3,5-Me2C6H3)2C6H3; Mph = 2-MesC6H4; Tph = 2-TripC6H4 with Trip = 2,4,6-i-Pr3C6H2), several magnesium triazenides were synthesized. Heteroleptic complexes [Mg(N3Ar2)I(OEt2)] (Ar2 = Dmp/Tph (2a), (Me4Ter)2 (2b) were obtained from metalation of the corresponding triazenes with di-n-butylmagnesium followed by reaction with iodine in diethyl ether as the solvent in high yields. Replacing diethyl ether by n-heptane afforded trinuclear compounds [Mg3(N3Ar2)2I4] (3a, 3b) in low yields in which a central MgI2 fragment is coordinated by two iodomagnesium triazenide moieties. Two unsolvated homoleptic magnesium compounds [Mg(N3Ar2)2] (4b, 4c) were obtained from di-n-butylmagnesium and triazenes 1b or 1c in a 1:2 ratio. Depending on the nature of the substituents, the magnesium center either shows the expected tetrahedral or a rather unusual square planar coordination.
      PubDate: 2017-05-01
      DOI: 10.3390/inorganics5020033
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 34: Dye-Sensitized Photocatalytic Water
           Splitting and Sacrificial Hydrogen Generation: Current Status and Future
           Prospects

    • Authors: Pankaj Chowdhury, Ghodsieh Malekshoar, Ajay Ray
      First page: 34
      Abstract: Today, global warming and green energy are important topics of discussion for every intellectual gathering all over the world. The only sustainable solution to these problems is the use of solar energy and storing it as hydrogen fuel. Photocatalytic and photo-electrochemical water splitting and sacrificial hydrogen generation show a promise for future energy generation from renewable water and sunlight. This article mainly reviews the current research progress on photocatalytic and photo-electrochemical systems focusing on dye-sensitized overall water splitting and sacrificial hydrogen generation. An overview of significant parameters including dyes, sacrificial agents, modified photocatalysts and co-catalysts are provided. Also, the significance of statistical analysis as an effective tool for a systematic investigation of the effects of different factors and their interactions are explained. Finally, different photocatalytic reactor configurations that are currently in use for water splitting application in laboratory and large scale are discussed.
      PubDate: 2017-05-18
      DOI: 10.3390/inorganics5020034
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 35: Product Selectivity in Homogeneous
           Artificial Photosynthesis Using [(bpy)Rh(Cp*)X]n+-Based Catalysts

    • Authors: Alexander Mengele, Sven Rau
      First page: 35
      Abstract: Due to the limited amount of fossil energy carriers, the storage of solar energy in chemical bonds using artificial photosynthesis has been under intensive investigation within the last decades. As the understanding of the underlying working principle of these complex systems continuously grows, more focus will be placed on a catalyst design for highly selective product formation. Recent reports have shown that multifunctional photocatalysts can operate with high chemoselectivity, forming different catalysis products under appropriate reaction conditions. Within this context [(bpy)Rh(Cp*)X]n+-based catalysts are highly relevant examples for a detailed understanding of product selectivity in artificial photosynthesis since the identification of a number of possible reaction intermediates has already been achieved.
      PubDate: 2017-05-25
      DOI: 10.3390/inorganics5020035
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 36: Symmetric Assembly of a Sterically
           Encumbered Allyl Complex: Mechanochemical and Solution Synthesis of the
           Tris(allyl)beryllate, K[BeA′3] (A′ = 1,3-(SiMe3)2C3H3)

    • Authors: Nicholas Boyde, Nicholas Rightmire, Timothy Hanusa, William Brennessel
      First page: 36
      Abstract: The ball milling of beryllium chloride with two equivalents of the potassium salt of bis(1,3-trimethylsilyl)allyl anion, K[A′] (A′ = [1,3-(SiMe3)2C3H3]), produces the tris(allyl)beryllate K[BeA’3] (1) rather than the expected neutral BeA’2. The same product is obtained from reaction in hexanes; in contrast, although a similar reaction conducted in Et2O was previously shown to produce the solvated species BeA’2(OEt2), it can produce 1 if the reaction time is extended (16 h). The tris(allyl)beryllate is fluxional in solution, and displays the strongly downfield 9Be NMR shift expected for a three-coordinate Be center (δ22.8 ppm). A single crystal X-ray structure reveals that the three allyl ligands are bound to beryllium in an arrangement with approximate C3 symmetry (Be–C (avg) = 1.805(10) Å), with the potassium cation engaging in cation–π interactions with the double bonds of the allyl ligands. Similar structures have previously been found in complexes of zinc and tin, i.e., M[M′A′3L] (M′ = Zn, M = Li, Na, K; M′ = Sn, M = K; L = thf). Density functional theory (DFT) calculations indicate that the observed C3-symmetric framework of the isolated anion ([BeA′3]−) is 20 kJ·mol−1 higher in energy than a C1 arrangement; the K+ counterion evidently plays a critical role in templating the final conformation.
      PubDate: 2017-05-27
      DOI: 10.3390/inorganics5020036
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 37: First-Principles View on
           Photoelectrochemistry: Water-Splitting as Case Study

    • Authors: Anders Hellman, Baochang Wang
      First page: 37
      Abstract: Photoelectrochemistry is truly an interdisciplinary field; a natural nexus between chemistry and physics. In short, photoelectrochemistry can be divided into three sub-processes, namely (i) the creation of electron-hole pairs by light absorption; (ii) separation/transport on the charge carriers and finally (iii) the water splitting reaction. The challenge is to understand all three processes on a microscopic scale and, perhaps even more importantly, how to combine the processes in an optimal way. This review will highlight some first-principles insights to the above sub-processes, in~particular as they occur using metal oxides. Based on these insights, challenges and future directions of first-principles methods in the field of photoelectrochemistry will be discussed.
      PubDate: 2017-06-01
      DOI: 10.3390/inorganics5020037
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 38: Synthesis of LiAlH4 Nanoparticles Leading to
           a Single Hydrogen Release Step upon Ti Coating

    • Authors: Lei Wang, Kondo-Francois Aguey-Zinsou
      First page: 38
      Abstract: Lithium aluminum hydride (LiAlH4) is an interesting high capacity hydrogen storage material with fast hydrogen release kinetics when mechanically activated with additives. Herein, we report on a novel approach to produce nanoscale LiAlH4 via a bottom-up synthesis. Upon further coating of these nanoparticles with Ti, the composite nanomaterial was found to decompose at 120 °C in one single and extremely sharp exothermic event with instant hydrogen release. This finding implies a significant thermodynamic alteration of the hydrogen properties of LiAlH4 induced by the synergetic effects of the Ti catalytic coating and nanosizing effects. Ultimately, the decomposition path of LiAlH4 was changed to LiAlH4 → Al + LiH + 3/2H2.
      PubDate: 2017-06-07
      DOI: 10.3390/inorganics5020038
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 39: [Bis(Trimethylsilyl)Methyl]Lithium and
           

    • Authors: Markus von Pilgrim, Mihail Mondeshki, Jan Klett
      First page: 39
      Abstract: In contrast to alkyl compounds of lithium, which play an important role in organometallic chemistry, the corresponding heavier alkali metal compounds are less investigated. These compounds are mostly insoluble in inert solvents or undergo solvolysis in coordinating solvents due to their high reactivity. An exception from this typical behavior is demonstrated by bis(trimethylsilyl)methylsodium. This study examines alkane solutions of bis(trimethylsilyl)methyllithium and -sodium by NMR spectroscopic and cryoscopic methods. In addition, structural studies by X-ray crystallography of the corresponding compounds coordinated by O- and N- ligands (tetrahydrofuran and tetramethylethylenediamine) present possible structural motifs of the uncoordinated compounds in solution.
      PubDate: 2017-06-12
      DOI: 10.3390/inorganics5020039
      Issue No: Vol. 5, No. 2 (2017)
       
  • Inorganics, Vol. 5, Pages 3: Acknowledgement to Reviewers of Inorganics in
           2016

    • Authors: Inorganics Editorial Office
      First page: 3
      Abstract: The editors of Inorganics would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016.[...]
      PubDate: 2017-01-10
      DOI: 10.3390/inorganics5010003
      Issue No: Vol. 5, No. 1 (2017)
       
  • Inorganics, Vol. 5, Pages 4: Anticancer Applications and Recent
           Investigations of Metallodrugs Based on Gallium, Tin and Titanium

    • Authors: Younes Ellahioui, Sanjiv Prashar, Santiago Gómez-Ruiz
      First page: 4
      Abstract: For more than 100 years metal complexes have been extensively used in therapy and since the discovery of cisplatin the research in this field has expanded exponentially. The scientific community is always in search of new alternatives to platinum compounds and a wide variety of metallodrugs based on other metals have been reported with excellent therapeutic results. This short review focuses on the work that our research group has carried out since 2007 in collaboration with others and centers on the preparation of organogallium(III) compounds, organotin(IV) derivatives, and titanocene(IV) complexes together with the study of their cytotoxic anticancer properties.
      PubDate: 2017-01-12
      DOI: 10.3390/inorganics5010004
      Issue No: Vol. 5, No. 1 (2017)
       
  • Inorganics, Vol. 5, Pages 5: P-Fluorous Phosphines as
           Electron-Poor/Fluorous Hybrid Functional Ligands for Precious Metal
           Catalysts: Synthesis of Rh(I), Ir(I), Pt(II), and Au(I) Complexes Bearing
           P-Fluorous Phosphine Ligands

    • Authors: Shin-ichi Kawaguchi, Yuta Saga, Yuki Sato, Yoshiaki Minamida, Akihiro Nomoto, Akiya Ogawa
      First page: 5
      Abstract: P-Fluorous phosphine (R2PRf), in which the perfluoroalkyl group is directly bonded to the phosphorus atom, is a promising ligand because it has a hybrid functionality, i.e., electron-poor and fluorous ligands. However, examples of P-fluorous phosphine–metal complexes are still rare, most probably because the P-fluorous group is believed to decrease the coordination ability of the phosphines dramatically. In contrast, however, we have succeeded in synthesizing a series of P-fluorous phosphine–coordinated metal complexes such as rhodium, iridium, platinum, and gold. Furthermore, the electronic properties of R2PnC10F21 are investigated by X-ray analysis of PtCl2(Ph2PnC10F21)2 and the infrared CO stretching frequency of RhCl(CO)(R2PnC10F21)2. IrCl(CO)(Ph2PnC10F21)2- and AuCl(R2PnC10F21)-catalyzed reactions are also demonstrated.
      PubDate: 2017-01-12
      DOI: 10.3390/inorganics5010005
      Issue No: Vol. 5, No. 1 (2017)
       
  • Inorganics, Vol. 5, Pages 6: Influence of Fatty Acid Alkyl Chain Length on
           Anisotropy of Copper Nitride Nano-Crystallites

    • Authors: Takashi Nakamura
      First page: 6
      Abstract: My group developed a simple method to prepare copper nitride fine particles from copper carboxylate in a solvent of long-chain alcohols without the use of high temperatures or high pressures. By selecting copper acetate or copper decanoate as the copper source, my group demonstrated that the morphology of the copper nitride fine particles varied between cubic and plate-like, respectively. Although a hypothesis was proposed to explain the influence of the length of the alkyl chain on the copper decanoate, it is uncertain how much the chain length influences the shape of the fine particles. In this work, I demonstrated the effect of the length of the alkyl chain on particle shape by preparing fine particles from a series of copper sources with different alky chain lengths and characterizing the particles with x-ray diffractometry (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The main findings were as follows: (1) the fine particles were plate-like when the alkyl chain length exceeded 5; (2) the aspect ratio of the plate-like particles increased as the alkyl chain length increased; and (3) growth of the (110) and (111) planes of the copper nitride crystal were selectively inhibited.
      PubDate: 2017-01-16
      DOI: 10.3390/inorganics5010006
      Issue No: Vol. 5, No. 1 (2017)
       
  • Inorganics, Vol. 5, Pages 7: Hydrothermal Treatment of Tannin: A Route to
           Porous Metal Oxides and Metal/Carbon Hybrid Materials

    • Authors: Flavia Braghiroli, Vanessa Fierro, Andrzej Szczurek, Philippe Gadonneix, Jaafar Ghanbaja, Julien Parmentier, Ghouti Medjahdi, Alain Celzard
      First page: 7
      Abstract: In the present paper, porous materials were prepared from the hydrothermal treatment of aqueous solutions of tannin, a renewable phenolic resource extracted from tree barks, containing dissolved salts of transition metals: V, Cr, Ni and Fe. Hydrothermal treatment produced carbonaceous particles doped with the aforementioned metals, and such materials were treated according to two different routes: (i) calcination in air in order to burn the carbon and to recover porous oxides; (ii) pyrolysis in inert atmosphere so as to recover porous metal/carbon hybrid materials. The nature of the metal salt was found to have a dramatic impact on the structure of the materials recovered by the first route, leading either to nano-powders (V, Cr) or to hollow microspheres (Ni, Fe). The second route was only investigated with iron, leading to magnetic Fe-loaded micro/mesoporous carbons whose texture, pore volumes and surface areas gradually changed with the iron content.
      PubDate: 2017-01-24
      DOI: 10.3390/inorganics5010007
      Issue No: Vol. 5, No. 1 (2017)
       
  • Inorganics, Vol. 5, Pages 8: Manganese(I)-Based CORMs with 5-Substituted
           3-(2-Pyridyl)Pyrazole Ligands

    • Authors: Ralf Mede, Steve Gläser, Benedikt Suchland, Björn Schowtka, Miles Mandel, Helmar Görls, Sven Krieck, Alexander Schiller, Matthias Westerhausen
      First page: 8
      Abstract: The reaction of [(OC)5MnBr] with substituted 3-(2-pyridyl)pyrazoles) 2-PyPzRH (1a-l) in methanol or diethyl ether yields the yellow to orange manganese(I) complexes [(OC)3Mn(Br)(2-PyPzRH)] (2a-l), the substituents R being phenyl (a), 1-naphthyl (b), 2-anthracenyl (c), 1-pyrenyl (d), 4-bromophenyl (e), 3-bromophenyl (f), duryl (g), 2-pyridyl (h), 2-furanyl (i), 2-thienyl (j), ferrocenyl (k), and 1-adamantyl (l). The carbonyl ligands are arranged facially, leading to three chemically different CO ligands due to different trans-positioned Lewis donors. The diversity of the substituent R demonstrates that this photoCORM backbone can easily be varied with a negligible influence on the central (OC)3MnBr fragment, because the structural parameters and the spectroscopic data of this unit are very similar for all these derivatives. Even the ferrocenyl complex 2k shows a redox potential for the ferrocenyl subunit which is identical to the value of the free 5-ferrocenyl-3-(2-pyridyl)pyrazole (1k). The ease of variation of the starting 5-substituted 3-(2-pyridyl)pyrazoles) offers a modular system to attach diverse substituents at the periphery of the photoCORM complex.
      PubDate: 2017-01-25
      DOI: 10.3390/inorganics5010008
      Issue No: Vol. 5, No. 1 (2017)
       
  • Inorganics, Vol. 5, Pages 9: Flux Synthesis, Crystal Structures, and
           Magnetism of the Series La2n+2MnSen+2O2n+2 (n = 0–2)

    • Authors: Simon Peschke, Dirk Johrendt
      First page: 9
      Abstract: Three members of the homologous series of manganese oxyselenides with the general formula La2n+2MnSen+2O2n+2 (n = 0–2) have been synthesized in a NaI/KI flux and characterized by single-crystalX-raydiffraction,powderX-raydiffractionandmagneticmeasurements. Thestructures consist of chains of edge-sharing MnSe4O2-octahedra along the b-axis which are linked together along the a-axis by edge-sharing OLa4- and/or OLa3Mn-tetrahedra forming infinite ribbons of increasing width. mC-La2MnSe2O2 (Pb2HgCl2O2-type, C2/m, a = 11.6621(5) Å, b = 3.9719(1) Å, c = 7.2049(3) Å, β = 121.655(2)◦) represents a new polymorph of this compound. La4MnSe3O4 (P2/m, a = 9.0055(4) Å, b = 4.0186(1) Å, c = 7.1946(3) Å, β = 109.715(2)◦) and La6MnSe4O6 (C2/m, a = 24.760(2) Å,b = 4.0359(3)Å,c=7.1850(6)Å, β =104.162(3)◦)exhibitnewstructuretypes. Magnetic measurements suggest antiferromagnetic order of the moments below about 15 K with effective magnetic moments of 5.53(1), 5.99(1) and 6.01(1) µB per formula unit for n = 1, 2 and 3, respectively.
      PubDate: 2017-01-31
      DOI: 10.3390/inorganics5010009
      Issue No: Vol. 5, No. 1 (2017)
       
  • Inorganics, Vol. 5, Pages 10: Synthesis, Crystal Structure, Polymorphism,
           and Magnetism of Eu(CN3H4)2 and First Evidence of EuC(NH)3

    • Authors: Arno Görne, Janine George, Jan van Leusen, Richard Dronskowski
      First page: 10
      Abstract: We report the first magnetically coupled guanidinate, α-Eu(CN3H4)2 (monoclinic, P21, a = 5.8494(3) Å, b = 14.0007(8) Å, c = 8.4887(4) Å, β = 91.075(6)°, V = 695.07(6) Å3, Z = 4). Its synthesis, polymorphism, crystal structure, and properties are complemented and supported by density-functional theory (DFT) calculations. The α-, β- and γ-polymorphs of Eu(CN3H4)2 differ in powder XRD, while the γ-phase transforms into the β-form over time. In α-Eu(CN3H4)2, Eu is octahedrally coordinated and sits in one-dimensional chains; the guanidinate anions show a hydrogen-bonding network. The different guanidinate anions are theoretically predicted to adopt syn-, anti- and all-trans-conformations. Magnetic measurements evidence ferromagnetic interactions, presumably along the Eu chains. Finally, EuC(NH)3 (isostructural to SrC(NH)3 and YbC(NH)3, hexagonal, P63/m, a = 5.1634(7) Å, c = 7.1993(9) Å, V = 166.23(4) Å3, Z = 2) is introduced as a possible ferromagnet.
      PubDate: 2017-02-07
      DOI: 10.3390/inorganics5010010
      Issue No: Vol. 5, No. 1 (2017)
       
  • Inorganics, Vol. 5, Pages 11: Structural Study of Mismatched Disila-Crown
           Ether Complexes

    • Authors: Kirsten Reuter, Fabian Dankert, Carsten Donsbach, Carsten von Hänisch
      First page: 11
      Abstract: Mismatched complexes of the alkali metals cations Li+ and Na+ were synthesized from 1,2-disila[18]crown-6 (1 and 2) and of K+ from 1,2,4,5-tetrasila[18]crown-6 (4). In these alkali metal complexes, not all crown ether O atoms participate in the coordination, which depicts the coordination ability of the C-, Si/C-, and Si-bonded O atoms. Furthermore, the inverse case—the coordination of the large Ba2+ ion by the relatively small ligand 1,2-disila[15]crown-5—was investigated, yielding the dinuclear complex 5. This structure represents a first outlook on sandwich complexes based on hybrid crown ethers.
      PubDate: 2017-02-09
      DOI: 10.3390/inorganics5010011
      Issue No: Vol. 5, No. 1 (2017)
       
  • Inorganics, Vol. 5, Pages 12: A Cancer Stem Cell Potent
           Cobalt(III)–Cyclam Complex Bearing Two Tolfenamic Acid Moieties

    • Authors: Paul Cressey, Arvin Eskandari, Kogularamanan Suntharalingam
      First page: 12
      Abstract: Cancer stem cells (CSCs) are thought to be responsible for cancer relapse. CSCs are a subtype of cancer cells with the ability to differentiate, self-renew, and form secondary or tertiary tumors. Current cancer treatments—including chemotherapy, radiation, and surgery—effectively remove bulk cancer cells but are unable to eliminate CSCs. Here, we present the synthesis, characterization, and anti-CSC properties of a cobalt(III)–cyclam complex bearing two tolfenamic acid moieties, 3. Notably, 3 displays sub-micromolar potency towards breast CSCs and bulk breast cancer cells. Detailed mechanistic studies show that 3 is taken up readily by breast CSCs, enters the nucleus, causes DNA damage, and induces caspase-dependent apoptosis. Furthermore, 3 inhibits cyclooxygenase-2 (COX-2) expression in CSCs. The mechanism of action of 3 is similar to that of a naproxen-appended cobalt(III)–cyclam complex, 1 recently reported by our group. The advantage of 3 over 1 is that it has the potential to remove whole tumor populations (bulk cancer cells and CSCs) with a single dose.
      PubDate: 2017-02-09
      DOI: 10.3390/inorganics5010012
      Issue No: Vol. 5, No. 1 (2017)
       
  • Inorganics, Vol. 5, Pages 13: K+···Cπ and K+···F Non-Covalent
           Interactions in π-Functionalized Potassium Fluoroalkoxides

    • Authors: Sorin-Claudiu Roşca, Hanieh Roueindeji, Vincent Dorcet, Thierry Roisnel, Jean-François Carpentier, Yann Sarazin
      First page: 13
      Abstract: Secondary interactions stabilize coordinatively demanding complexes of s-block metals [...]
      PubDate: 2017-03-07
      DOI: 10.3390/inorganics5010013
      Issue No: Vol. 5, No. 1 (2017)
       
  • Inorganics, Vol. 5, Pages 14: Light to Hydrogen: Photocatalytic Hydrogen
           Generation from Water with Molecularly-Defined Iron Complexes

    • Authors: Henrik Junge, Nils Rockstroh, Steffen Fischer, Angelika Brückner, Ralf Ludwig, Stefan Lochbrunner, Oliver Kühn, Matthias Beller
      First page: 14
      Abstract: Photocatalytic hydrogen generation is considered to be attractive due to its combination of solar energy conversion and storage. Currently-used systems are either based on homogeneous or on heterogeneous materials, which possess a light harvesting and a catalytic subunit. The subject of this review is a brief summary of homogeneous proton reduction systems using sacrificial agents with special emphasis on non-noble metal systems applying convenient iron(0) sources. Iridium photosensitizers, which were proven to have high quantum yields of up to 48% (415 nm), have been employed, as well as copper photosensitizers. In both cases, the addition or presence of a phosphine led to the transformation of the iron precursor with subsequently increased activities. Reaction pathways were investigated by photoluminescence, electron paramagnetic resonance (EPR), Raman, FTIR and mass spectroscopy, as well as time-dependent DFT-calculations. In the future, this knowledge will set the basis to design photo(electro)chemical devices with tailored electron transfer cascades and without the need for sacrificial agents.
      PubDate: 2017-03-09
      DOI: 10.3390/inorganics5010014
      Issue No: Vol. 5, No. 1 (2017)
       
  • Inorganics, Vol. 5, Pages 15: Synthesis and Catalytic Applications of
           Non-Metal Doped Mesoporous Titania

    • Authors: Syed Islam, Suraj Nagpure, Doo Kim, Stephen Rankin
      First page: 15
      Abstract: Mesoporous titania (mp-TiO2) has drawn tremendous attention for a diverse set of applications due to its high surface area, interfacial structure, and tunable combination of pore size, pore orientation, wall thickness, and pore connectivity. Its pore structure facilitates rapid diffusion of reactants and charge carriers to the photocatalytically active interface of TiO2. However, because the large band gap of TiO2 limits its ability to utilize visible light, non-metal doping has been extensively studied to tune the energy levels of TiO2. While first-principles calculations support the efficacy of this approach, it is challenging to efficiently introduce active non-metal dopants into the lattice of TiO2. This review surveys recent advances in the preparation of mp-TiO2 and their doping with non-metal atoms. Different doping strategies and dopant sources are discussed. Further, co-doping with combinations of non-metal dopants are discussed as strategies to reduce the band gap, improve photogenerated charge separation, and enhance visible light absorption. The improvements resulting from each doping strategy are discussed in light of potential changes in mesoporous architecture, dopant composition and chemical state, extent of band gap reduction, and improvement in photocatalytic activities. Finally, potential applications of non-metal-doped mp-TiO2 are explored in water splitting, CO2 reduction, and environmental remediation with visible light.
      PubDate: 2017-03-11
      DOI: 10.3390/inorganics5010015
      Issue No: Vol. 5, No. 1 (2017)
       
  • Inorganics, Vol. 5, Pages 16: On Mineral Retrosynthesis of a Complex
           Biogenic Scaffold

    • Authors: Ashit Rao, José Arias, Helmut Cölfen
      First page: 16
      Abstract: Synergistic relations between organic molecules and mineral precursors regulate biogenic mineralization. Given the remarkable material properties of the egg shell as a biogenic ceramic, it serves as an important model to elucidate biomineral growth. With established roles of complex anionic biopolymers and a heterogeneous organic scaffold in egg shell mineralization, the present study explores the regulation over mineralization attained by applying synthetic polymeric counterparts (polyethylene glycol, poly(acrylic acid), poly(aspartic acid) and poly(4-styrenesulfonic acid-co-maleic acid)) as additives during remineralization of decalcified eggshell membranes. By applying Mg2+ ions as a co-additive species, mineral retrosynthesis is achieved in a manner that modulates the polymorph and structure of mineral products. Notable features of the mineralization process include distinct local wettability of the biogenic organic scaffold by mineral precursors and mineralization-induced membrane actuation. Overall, the form, structure and polymorph of the mineralization products are synergistically affected by the additive and the content of Mg2+ ions. We also revisit the physicochemical nature of the biomineral scaffold and demonstrate the distinct spatial distribution of anionic biomolecules associated with the scaffold-mineral interface, as well as highlight the hydrogel-like properties of mammillae-associated macromolecules.
      PubDate: 2017-03-15
      DOI: 10.3390/inorganics5010016
      Issue No: Vol. 5, No. 1 (2017)
       
  • Inorganics, Vol. 5, Pages 17: Kudos and Renaissance of s-Block Metal
           Chemistry

    • Authors: Sven Krieck, Matthias Westerhausen
      First page: 17
      Abstract: In recent years, the organometallic and coordination chemistry of the alkali and alkaline earth metals has experienced tremendous progress to tackle the needs of today’s society. Enhanced ecological awareness and global availability favor research on the chemistry of the essential s-block metals. Nowadays, the s-block metals are conquering new chemical fields based on sophisticated theoretical and preparative achievements. Recent investigations show a huge impact of the s-block elements on stoichiometric and catalytic processes.
      PubDate: 2017-03-21
      DOI: 10.3390/inorganics5010017
      Issue No: Vol. 5, No. 1 (2017)
       
 
 
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