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Acta Crystallographica Section A: Foundations and Advances     Hybrid Journal   (Followers: 10)
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials     Hybrid Journal   (Followers: 7)
Acta Crystallographica Section C: Structural Chemistry     Hybrid Journal   (Followers: 6)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 8)
Acta Crystallographica Section E : Crystallographic Communications     Open Access   (Followers: 5)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 12)
Crystal Growth & Design     Hybrid Journal   (Followers: 19)
Crystal Research and Technology     Hybrid Journal   (Followers: 7)
Crystallography Reports     Hybrid Journal   (Followers: 3)
Crystallography Reviews     Hybrid Journal   (Followers: 5)
Crystals     Open Access   (Followers: 5)
IUCrJ     Open Access  
Journal of Applied Crystallography     Hybrid Journal   (Followers: 7)
Journal of Chemical Crystallography     Hybrid Journal   (Followers: 3)
Journal of Crystal Growth     Hybrid Journal   (Followers: 9)
Journal of Crystallization Process and Technology     Open Access   (Followers: 8)
Liquid Crystals     Hybrid Journal   (Followers: 3)
Liquid Crystals Today     Hybrid Journal   (Followers: 3)
Materials and Devices     Open Access   (Followers: 1)
Molecular Crystals and Liquid Crystals     Hybrid Journal   (Followers: 3)
Polymer crystallization     Hybrid Journal   (Followers: 1)
Progress in Crystal Growth and Characterization of Materials     Full-text available via subscription   (Followers: 8)
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Journal of Chemical Crystallography
Journal Prestige (SJR): 0.209
Citation Impact (citeScore): 1
Number of Followers: 3  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1572-8854 - ISSN (Online) 1074-1542
Published by Springer-Verlag Homepage  [2657 journals]
  • Dinuclear Co(II)-Muconate Complex Displaying Distorted-Trigonal Prismatic
           Geometry, 2D Supramolecular Array and Weak Antiferromagnetism

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      Abstract: Dinuclear complex [Co2(H2O)4(dmb)2(muc)][muc] (1) (muc = muconate; dmb = 5,5′-dimethyl-2,2′-bipyridine), was obtained by self-assembly solution reaction, under ambient conditions, and it was structurally characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction. The complex 1 crystallizes in the monoclinic system in the C2/c space group. Noticeably, the six-coordinated Co(II) centers display a distorted-trigonal prismatic configuration. This uncommon coordination geometry is attained due to the hydrogen bonding interactions of the crystalline structure of 1, yielding thus a 2D supramolecular array. Magnetic properties measurements reveal that metaprism 1 exhibits weak antiferromagnetic ordering with θ(C-W) = -14.4 K and an E2 = 0.032 cm−1 accordingly to Curie–Weiss model and Rueff phenomenological approach, respectively. Graphic Influence of the 2D supramolecular array in the distorted trigonal prismatic geometry of a dinuclear Co(II)-muconate complex exhibiting weak antiferromagnetic exchange.
      PubDate: 2021-10-07
       
  • Preparation, Properties and Crystal Structure of syn-Isomer of
           2,6-Dichlorophenyl-cyanoxime, H(2,6-diCl-PhCO): Potent Carbonyl Reductase
           Inhibitor

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      Abstract: The oximino(2,6-dichlorophenyl)acetonitrile, H(2,6-diCl-PhCO) has been synthesized in a reasonably high yield of 60%, and characterized using a variety of physical, electrochemical, spectroscopic methods and X-ray analysis. This compound belongs to the family of cyanoximes; a new subclass of oximes with the general formula NC–C(=N–OH)–R (where R is an electron-withdrawing group) which recently emerged as new biologically active compounds. This cyanoxime represents a disubstituted arylcyanoxime that was found to be a powerful inhibitor of the Carbonyl Reductase enzyme involved in the developing of resistance to anticancer treatment, and the making of cardiotoxic derivatives of anthracyclines that are currently used in medicine. The oximino(2,6-dichlorophenyl)acetonitrile, H(2,6-diCl-PhCO) is a weak acid with pKa = 6.17 and does not dissociate in organic polar protic and aprotic solvents. The cyanoxime was obtained as a microcrystalline mixture of two diastereomers (anti- and syn-) and deprotonates in solutions with the formation of yellow anions which exhibit solvatochromic behavior. However, one specific diastereomer—syn—was isolated in crystalline form from a solvent system as colorless blocks overlayed with pentane ether solution in a monoclinic system in a P2/c (#13) space group with unit cell parameters: a = 8.1720(2), b = 8.8013(3), c = 13.0146(4) and β = 102.546(3); Z = 4. A single crystal was studied using filtered CuKa radiation, providing Rint value of 0.0348 from a full-sphere of reflections. A crystal structure was solved using direct methods, and well refined to R1 = 0.0459, wR2 = 0.1268 and GOF = 1.107. The studied specimen of oximino(2,6-dichlorophenyl)acetonitrile, H(2,6-diCl-PhCO), represents a highly non-planar, rare syn-diastereomer in which the oxime fragment is positioned towards the chlorinated phenyl group. In the crystal, the compound forms a columnar structure extended along the c-direction by using slipped π–π stacking interactions. Columns are interconnected via H-bonding between the oxime OH-group and N atom of the nitrile group with the following parameters: N–H = 1.841 Å, and 169.20° N···H–O angle. No thermal interconversion of syn- into anti- diastereomer was observed upon heating of crystals of one isomer under flow of Ar. Graphic
      PubDate: 2021-09-28
       
  • Cu(NH2SO3) π-Complexes with Allyl Derivatives of 1,3,4-Thiadizoles:
           Synthesis and Structural Formation Through Weak Interactions

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      Abstract: This work is directed toward the synthesis and structure characterization of the two novel copper(I) sulfamate π,σ-complexes [Cu2(Thiaz2)2(NH2SO3)2] (1) and [Cu2(Thiaz3)(NH2SO3)2]·2H2O (2) based on 2-amino-5-allylthio-1,3,4-thiadiazole (Thiaz2) and N2,N5-di(allyl)-1,3,4-thiadiazole-2,5-diamine (Thiaz3) ligands. Structural analysis of 1 was performed in comparison with the earlier-studied, similar complex [Cu2(Thiaz1)2(NH2SO3)2] (3) (Thiaz1-2-allylamino-5-methyl-1,3,4-thiadiazole). In the structures of 1–3, the respective organic molecule fully realizes its coordination ability being attached to the metal centres through two nitrogen atoms of 1,3,4-thiadiazole core as well as by one η2-allyl groups in 1 and 3 or by two η2-allyl groups in 2. In crystal structures of 1 & 2, [Cu2(Thiaz)2(NH2SO3)2] dimers are interconnected by N–H⋯O hydrogen bonds into layers, while water molecules in 2 connect NH2SO3− anions into hydrogen-bonded ribbon which together with N–H⋯O bonds of Thiaz3 amino-groups stitch organometallic fragments into a framework. To depict H-bonded interaction in the structures 1–3 Hirshfeld surface analysis has been performed. Graphic The synthesis and X-ray structures of Cu(NH2SO3) π,σ-complexes based on allyl-substituted 1,3,4-thiadiazole ligands are presented and weak interactions are specially discussed.
      PubDate: 2021-09-28
       
  • Synthesis of Dysprosium Oxychloride (DyOCl)

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      Abstract: Dysprosium oxychloride, DyOCl, was synthesized using a simple hydrolysis method with DyCl3·6H2O. X-ray powder diffraction (XRD) data was used to determine the crystal structure. The DyOCl compound is isostructural to the matlockite (PbFCl) crystal structure and crystallizes in the tetragonal P4/nmm (#129) space group. The crystal structure contains the alternating cationic layers of (DyO)n and anionic layers of nCl− along the c-axis. The structural data including unit cell, volume, and density of DyOCl were compared to other rare-earth oxychloride data from the Inorganic Crystal Structure Database (ICSD) and our previous study on TbOCl. Fourier-transform infrared spectroscopy was performed on DyOCl and peaks observed at 543 and 744 cm−1 were attributed to Dy–O and Dy–Cl. Scanning electron microscopy analysis showed irregularly shaped crystals. Hot-stage XRD, thermogravimetry, as well as differential scanning calorimetry coupled to a gas chromatograph and a mass spectrometer (evolved gas analysis) were performed on DyCl3·6H2O to understand the phase transformation to DyOCl (and Dy2O3) as a function of temperature and time at temperature. Graphic DyOCl compound with the tetragonal P4/nmm space group is composed of the alternating layers of (DyO)n and nCl− along the c-axis.
      PubDate: 2021-09-24
       
  • N,N′-Di(pyridine-4-yl)-pyridine-3,5-dicarboxamide, a Pincer-Type
           Tricationic Compound; Synthesis, Crystal Structure, Hirshfeld Surface
           Analysis, and Computational Chemistry Studies

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      Abstract: The synthesis, structure, and spectroscopic characterization of a pincer-type compound; N,N′-di(pyridine-4-yl)-pyridine-3,5-dicarboxamide is described. The tricationic pro-ligand (C20H22N5O2)3+ bearing two pendant alkylated 4-pyridyl arms at the 3,5-positions of the central pyridyl group features three triflate anions (CF3SO3−) in the asymmetric unit. Two of the triflate ligands in the structure are connected to the pincer cation by strong N–H⋯O hydrogen bonds. The central N-methyl moiety is planar to a r.m.s deviation of 0.01, and the two adjacent N-methylpyridine moieties are out of the plane with dihedral angles of 33.62° (3) and 86.08° (3). The molecular packing structure of the compound shows an 18-molecule aggregate in a 3-dimensional supramolecular synthon stabilized by intermolecular N–H⋯O and C–H⋯O contacts. The Hirshfeld surface analysis and fingerprint plots show that the OH/HO contacts resulting from C–H⋯O intermolecular interactions contributed significantly to the overall surface interaction with a total percentage contribution of 35.4%. The pairwise interaction energy calculations were implemented with a Gaussian plugin in Crystal Explorer 17 at the B3LYP/6-31G(d,p) level of theory. Energy profile diagrams and interaction energy values indicate that the crystal structure was stabilized by a combination of electrostatic and dispersion forces in the crystal lattice. Graphic The crystal structure of a tricationic pro-ligand N,N′-di(pyridine-4-yl)-pyridine-3,5-dicarboxamide is described. The structures features three triflate anions in the asymmetric unit with two of the triflate ligands in the structure connected to the pincer pro-ligand by strong N–H⋯O hydrogen bonds. Hirshfeld surface interaction and pairwise interaction energies are explored.
      PubDate: 2021-09-13
       
  • Supramolecular Properties Directed by Weak Interactions in a Copper (II)
           Complex Based on 8-Hydroxy Quinoline-Pyridine Binary Ligand Systems:
           Crystal Structure and Hirshfeld Surface Analyses

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      Abstract: The neutral Cu(II) complex [Cu(O,N-Q)2(N-4-MePy)2] (1) harvested from 8-hydroxy quinoline (8HQ) and 4-methyl pyridine (4-MePy) has been synthesized and structurally characterized. Single-crystal X-ray diffraction analysis reveals that 1 exhibits slightly distorted octahedral geometry and O–H···O hydrogen bonds link the asymmetric units forming an infinite chain geometry of C(6) graph-set-motif along with significant C–H···π and π···π stacking interactions revealing an interesting supramolecular packing assembly. A study of dnorm, shape index (S), curvedness (C) based Hirshfeld surfaces (HSs) and two-dimensional fingerprint (FP) plots at the molecular and atomic level quantify significant intermolecular contacts experienced by the neutral copper complex and the nature of ligand coordination to the metal centre. From molecular HS analysis and 2D FP plots, it was observed that C···H/H···C (33.9%) and H···H interactions (55.1%) have the major contribution compared to overall non-covalent interactions. The contribution of O···H/H···O (4.3%) and C···C (3.8%) contacts are minimum, but these interactions play vital role in the direction and organization of crystal packing. Graphic This manuscript outlines the impact of weak intermolecular interactions found in metal-based supramolecular assemblies.
      PubDate: 2021-09-13
       
  • Rb2Co1.85Ge1.15O6: The First Quaternary, Noncentrosymmetric Rubidium
           Cobalt Germanate

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      Abstract: Deep blue, prism-shaped, X-ray diffraction quality single crystals of a new quaternary rubidium cobalt germanate, exact composition Rb2Co1.85Ge1.15O6, were grown by soaking a pre-reacted polycrystalline powder in a molten RbCl/RbF eutectic flux (melting point = 546 °C) at 700 °C in a silver reaction vessel. The complex was characterized by single crystal X-ray diffraction and its elemental composition was semi-quantitatively confirmed by energy dispersive spectroscopy (EDS). Rb2Co1.85Ge1.15O6 crystallizes in the noncentrosymmetric orthorhombic space group C2221 with lattice parameters a = 6.5971(2) Å, b = 9.8791(3) Å and c = 10.8819(3) Å in the K2ZnSi2O6 structure type. The crystal structure consists of a three-dimensional network, composed of Co and mixed Co/Ge tetrahedra, and features cavities occupied by Rb cations. Graphic X-ray diffraction quality single crystals of a novel rubidium cobalt germanate, Rb2Co1.85Ge1.15O6, were grown by soaking a pre-reacted powder, targeted for preparing Rb4.51Co2.35Ge5.10O15F1.96, in a RbCl-RbF eutectic melt at 700 °C. The complex was characterized by single crystal X-ray diffraction and found to crystallize in the orthorhombic space group C2221 in the K2ZnSi2O6 structure type.
      PubDate: 2021-09-01
       
  • Methods, Syntheses and Characterization of Diaryl, Aryl Benzyl, and
           Dibenzyl Sulfides

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      Abstract: Twenty-four aryl benzyl sulfides, diaryl sulfides and dibenzyl sulfides were synthesized by four methods and characterized by 1H NMR, FT-IR and Gas chromatography. The reaction conditions of different synthesis methods were studied from the aspects of time, solvent, base and dispersant. The molecular structures of benzylphenyl sulfide (2S), (4-tert-butylbenzyl)(4-methylphenyl) sulfide (4S), (4-methylbenzyl)(4-methylphenyl) sulfide (9S), di(4-methylphenyl) sulfide (11S), (3,5-dimethylphenyl)(4-methyl phenyl) sulfide (15S), and dibenzyl sulfide (19S) [22] have been determined by single-crystal X-ray crystallography. Compounds 2S and 15S crystallize in the monoclinic space group P21/c, with a = 12.278(3), b = 15.894(3), c = 5.6056(11) Å, β = 94.532(2)°, and Z = 4 for 2S, and a = 9.800(9), b = 7.950(7), c = 16.690(15) Å, β = 100.890(12)°, and Z = 4 for 15S. The unit cell of 4S has a triclinic Pī symmetry with the cell parameters a = 6.0436(10), b = 8.7871(14), c = 15.535(2) Å, α = 81.921(2)°, β = 81.977(2)°, γ = 80.889(2)°, and Z = 2. Compounds 9S and 11S both crystallize in the orthorhombic space group P212121, with a = 6.188(3), b = 8.041(4), c = 26.005(14) Å, and Z = 4 for 9S, and a = 5.835(2), b = 8.010(3), c = 25.131(9) Å, and Z = 4 for 11S. Graphic Twenty-four aryl sulfide compounds with different substituents were synthesized and characterized, and the molecular structures of six different sulfide compounds have been determined by single-crystal X-ray crystallography.
      PubDate: 2021-09-01
       
  • Syntheses and Crystal Structures of Two Classes of
           Aluminum-Lanthanide-Sodium Heterotrimetallic 12-Metallacrown-4 Compounds:
           Individual Molecules and Dimers of Metallacrowns

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      Abstract: Two series of aluminum-lanthanide-sodium 12-metallacrown-4 compounds have been synthesized and characterized by single-crystal X-ray analysis. For the individual LnNa(ben)4[12-MCAl(III)N(shi)-4] molecules, where LnIII = Eu (1), Gd (2), Tb (3), Dy (4), Ho (5), Er (6), Tm (7), Yb (8), Lu (9), and Y (10), ben− is benzoate, MC is metallacrown, and shi3− is salicylhydroximate, two independent molecules are present in each unit cell. The aluminum(III) ions and shi3− ligands comprise the MC framework, while the LnIII and Na+ ions bind opposite of each other across the central MC cavity. The benzoate anions serve to tether the LnIII ion to the MC framework. When benzoate is replaced with the dicarboxylate anion isophthalate (iph2−), two [12-MCAl(III)N(shi)-4] units are connected to form a dimer of MCs: {LnNa[12-MCAl(III)N(shi)-4]}2(iph)4, where LnIII = Eu (11), Gd (12), Tb (13), Dy (14), Ho (15), Ho (16), Er (17), Yb (18), and Lu (19). As in 1–10, the aluminum(III) ions and shi3− ligands produce the MC frameworks, and one LnIII ion binds to each central MC cavity. However, there are two binding modes for the sodium ions. For 12–15 and 18, the sodium ions bind to the central MC cavity opposite of the LnIII ions as in 1–10. For 11, 16, 17, and 19, the sodium ions bind to the side of the MC framework by bonding to the phenolate and carboxylate oxygen atoms of two shi3− ligands and to the carboxylate oxygen atom of an iph2− ligand. In these structures, the MC cavity is vacant opposite of the LnIII ions. The substitution of isophthalate for benzoate does not significantly alter the [12-MCAl(III)N(shi)-4] framework as the size of the central MC cavity is not significantly different between analogous lanthanide individual and dimer MCs. However, the identity of the central LnIII ion does determine how close the LnIII ion can approach the mean plane of the oxime oxygen atoms (OoxMP) of the MC cavity. As the ion radius of the central LnIII ion decreases, the LnIII ion is able to more closely approach the OoxMP. For the individual MCs 1–10, the EuIII of 1 is the farthest away from the OoxMP (1.55 Å) and this value steadily decreases to 1.44 Å for the LuIII ion of 9. This same trend is true for the dimer MCs as the EuIII ion of 11 is 1.45 Å from the OoxMP and the LuIII ion of 19 is 1.36 Å from the OoxMP. Though the location of the sodium ions in the dimer MCs does influence the LnIII-OoxMP distance as the absence of the sodium ion in the MC cavity allows the LnIII ion to approach the MC cavity even closer. In 15 a sodium ion is opposite the HoIII ion and the HoIII-OoxMP distance is 1.47 Å, while in 16 the sodium ion is bound to the side of the MC and the HoIII-OoxMP distance is 1.40 Å. Graphic The complex GdNa[12-MCAl(III)N(shi)-4]}2(iph)
      PubDate: 2021-09-01
       
  • Octahedral Copper(II) Carboxylates with 1,10-Phenanthroline: Synthesis,
           Structural Characterization, DNA-Binding and Anti-Fungal Properties

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      Abstract: Two mono-nuclear axially distorted octahedral copper(II) complexes have been prepared and characterized via FT-IR, UV–Visible, elctrochemical, electron spin resonance and powder and single crystal XRD techniques. The complexes consist of a phenanthroline and two carboxylate ligands each bonded in bidentate fashion. Carboxylates are ortho-nitro-2-phenyl acetate (L1) and para-chloro-2-phenyl acetate (L2). Structural study showed that both complexes possess Jahn–Teller distorted octahedral geometry. The bulk purity was assessed from the matching experimental and simulated powder XRD spectra. The results of spectroscopic techniques are consistent with each other. ESR data revealed single electron occupancy of dx2 − y2 orbital with 2B1g as ground state typical of tetragonally distorted octahedral geometry. Electrochemical solution study showed diffusion controlled electron transfer processes with diffusion co-efficient values of 10.323 × 10–8 cm2s–1 and 0.972 × 10–8 cm2s–1 for 1 and 2. Complexes exhibited excellent DNA-binding activity studied via UV–Visible spectroscopy, cyclic voltammetry, florescence spectroscopy and viscometry yielding Kb values of 1.871 × 104 M–1 (1) and 1.577 × 104 M–1 (2), 0.38 × 104 M–1 (1) and 6.39 × 104 M–1 (2) and 2.1 × 106 M–1 (1) and 2.0 × 06 M–1 (2), respectively, for the first three techniques. Complexes possess good antifungal activity against three fungal strains. Graphic
      PubDate: 2021-09-01
       
  • Syntheses and Crystal Structures of Rare-Earth Oxyapatites Ca2RE8(SiO4)6O2
           (RE = Pr, Tb, Ho, Tm)

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      Abstract: Four different rare-earth oxyapatites of Ca2RE8(SiO4)6O2 (RE = Pr, Tb, Ho, Tm) were synthesized using a solution-based method followed by drying, calcination, and high-temperature sintering in air. X-ray powder diffraction and Raman spectroscopy were performed on the synthesized oxyapatites. The RE oxyapatites crystallize in the hexagonal space group P63/m with similar unit cell parameters, increasing linearly with larger RE cations. The unit cell volumes increase linearly whereas the densities decrease nonlinearly with larger RE cations. Raman spectra showed intense bands of the symmetric bending and stretching modes of SiO4 at ~ 400 and 860 cm−1 regions, respectively. The bands generally shifted to higher frequencies with smaller RE cations in the structures. Graphical Rare-earth oxyapatites Ca2RE8(SiO4)6O2 (RE = Pr, Tb, Ho, Tm) crystallize in the hexagonal space group P63/m, and their unit cell parameters increase linearly with larger RE cations.
      PubDate: 2021-09-01
       
  • Synthesis of the Three Mixed-ligand Metal Complexes and One Organic Salt
           of 3,5-Dinitrobenzoic Acid for Biopharmaceutical Optimization Through
           Monoethanolamine: Structures and DFT Studies of Complexes

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      Abstract: The simplest derivatives of benzoic acid show a wide spectrum of the biological action mostly being poor water soluble. In order to demonstrate on example of 3,5-dinitrobenzoic acid (DNBA) a possibility of the simultaneous enhancement of water solubility and antimicrobial activity the complexation (salt formation and metal coordination) approach has been examined. Monoethanolamine (MEA) is selected as the complexing agent. Three isomorphic mixed-ligand complexes of Cu, Ni, Co with DNBA and MEA as well one organic salt in the polymorphic form have been synthesized and their structures are characterized by the element analysis, FTIR and X-ray crystallography. Measurements of water solubility and determination of the antimicrobial activity attest that a solubility of the copper mixed-ligand complex and organic salt is increased about four and eight times with simultaneous enhancement of the bioactivity. The DFT studies by B3LYP/def2-TZVP and B3LYP/6-311G (d,p) showed that Cu, Ni, and Co complexes with DNBA and MEA have high-spin ground electronic states as a doublet, triplet and quartet, respectively. Calculated bond lengths and bond angles of all metal complexes in higher-spin ground electronic states are in good agreement (about R2 = 0.97) with X-ray data. Additionally, the energies of the frontier MOs and frontier electron densities and also electrostatic potential of isostructural complexes have been analyzed by the DFT/6-311G(d,p) method. Graphic The water solubility and bioactivity of poorly soluble 3,5-dinitrobenzoic acid are enhanced by a preparation of three isostructural metal complexes and one polymorphic organic salt with participation of monoethanolamine and DFT study of metal complexes has been carried out.
      PubDate: 2021-09-01
       
  • Crystal Structure of
           Decakis(μ-chloro)-tetrakis(1,2,4-triphenylcyclopentadienyl)-hexakis(tetrahydrofuran)-di-potassium-tetra-neodymium(III)
           Tetrahydrofuran Trisolvate

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      Abstract: The crystal structure of decakis(μ-chloro)-tetrakis(1,2,4-triphenylcyclopentadienyl)-hexakis(tetrahydrofuran)-di-potassium-tetra-neodymium(III) tetrahydrofuran trisolvate, 1, is reported. The centrosymmetric complex 1 has a rare tetranuclear core [Ln4K2Cl10] and crystalizes in triclinic space group (P \(\bar{1}\) ) with unit cell parameters: a = 11.9858(3) Å, b = 14.0698(3) Å, c = 19.8129(4) Å, α = 74.1120(4)°, β = 81.2073(4)°, γ = 83.9521(4)° and Z = 1. The catalytic system based on 1 and nBuMg(O-2,6-tBu2-4-MeC6H2) exhibits moderate activity in coordinative chain transfer polymerization of ethylene. In case of the system 1/nBu2Mg, oligomerisation of ethylene was not detected. Graphic The mono(cyclopentadienyl) complex {[1,2-Ph2-4-(2-MeOC6H4)C5H2]NdCl5K(THF)2}2(THF)3 has been obtained from NdCl3(THF)2.5 and K[1,2-Ph2-4-(2-MeOC6H4)C5H2] (1:1) in THF, crystallized from a THF/hexane mixture, and structurally characterized.
      PubDate: 2021-09-01
       
  • "What is This'" A Structure Analysis Tool for Rapid and
           Automated Solution of Small Molecule Structures

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      Abstract: The structure of organic compounds, including their absolute configuration, is extremely critical to the activity of medicines, aroma chemicals, and agrochemicals. Nearly all of these structures have been determined by single-crystal X-ray diffraction (SC-XRD) analysis. However, it is widely believed that SC-XRD analysis is not versatile since it requires considerable crystal growth and expertise. Recently, crystal growth is becoming less critical by utilizing the microcrystal electron diffraction method (MicroED). However, there is still a gap between the two methods because MicroED has limitations with respect to crystal size and quality of the results. Moreover, modern instruments for SC-XRD analysis have evolved to analyze smaller crystals and are able to deliver a structure easier. Here, we propose a new approach to fill the above gap with the tool named "What is this? (WIT)". WIT is a fully automated process from evaluating the crystal to providing the 'structure'. This method assumes the situation where a researcher happens to obtain a shiny grain during a course of chemical synthesis and wants to know the structure of the molecule making up the grain. Therefore, WIT assumes no chemical information and collects a mere 60% of the full dataset to enable faster characterization of the molecule with enough quality to fulfill the requirement. To assess the utility of WIT, we compared the results obtained by MicroED on a crystal of the same compound and similar in size. In summarizing the results, we propose a possible functional classification of the analyzed structures. Graphic We have developed a new tool, “What is this?” (WIT) for the fully automated structure determination of small molecules concurrent with single crystal data collection and processing. WIT assumes the case where a researcher happens to obtain a shiny grain of unknown composition during a chemical synthesis and opts to try to determine the three-dimensional structure of the molecule making up the grain.
      PubDate: 2021-09-01
       
  • A Cocrystal of Baicalein and 4,4′-Bipyridine with Zipper-Type
           Architecture

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      Abstract: A new cocrystal of baicalein, possessing three A-ring-hydroxyl groups and without B-ring-hydroxyl groups and 4,4′-bipyridine (BE·2BPY·H2O) has been prepared and characterized. The structural analyses and Hirshfeld surfaces show that baicalein is hydrogen-bonded to co-crystallized solvent water molecules featuring for example motifs that can be described with graph set R44(8) similar to those reported for the cocrystal of myricetin with 4,4′-bipyridine. A zipper-type architecture is observed in cocrystal BE·2BPY·H2O linking a baicalein, two 4,4′-bipyridine and a solvent water molecules via classical O–H⋯N and O–H⋯O and non-classical C–H⋯O hydrogen bonds into 2D sheets. Additionally, the cocrystal shows better solubility in 0.1 M HCl in comparison to pure baicalein. Graphic Cocrystal of baicalein with zipper-type architecture shows improved solubility compared to baicalein.
      PubDate: 2021-09-01
       
  • RE-Halobenzoic Acid-Terpyridine Complexes, Part V: Synthesis and
           Supramolecular Assembly of Rare-Earth-3,5-Dihalobenzoic Acid-Terpyridine
           Materials and Subsequent Comparison of Non-covalent Interactions

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      Abstract: The synthesis and crystal structures of 48 new rare-earth (RE = La3+—Y3+)-3,5-dihalogenated benzoic acid (3,5-dibromobenzoic acid [3,5-dBrBA] and 3-bromo-5-iodobenzoic acid [3,5-BrIBA])-terpyridine [TPY] complexes are reported. Ligand based supramolecular assembly drives the formation of five distinct structure types across the lanthanide series. Featured in these structures are multiple significant halogen bonding interactions occurring at the terminal halide substituents in the form of halogen–halogen, halogen–oxygen, and halogen–π interactions. This series complements previous efforts to synthesize and evaluate a catalogue of Ln-halobenzoic acid-TPY materials. With these data, a comparison of the influence of halogen interactions on supramolecular assembly is provided. As one might expect, the frequency with which halogen bonding occurs and the displacement of other assembly mechanisms, depends on the number and polarizability of the halogen species. Structures across these series fall into multiple distinct structure types, as defined by tecton geometry. Since these tectons are isostructural across each respective series, trends in halogen bond propensity can be derived. In this comparison, the likelihood of halogen bonding and disruption of π–π stacking is shown to increase as halogen size increases. Graphic Two new series of rare-earth (RE = La3+–Y3+)-3,5-dihalogenated benzoic acid (3,5-dibromobenzoic acid and 3-bromo-5-iodobenzoic acid)-terpyridine complexes are synthesized and compared, with respect to supramolecular assembly, to each other and previously reported RE-halogenated benzoic acid-terpyridine series in order to study the role of halogen bonding in this system.
      PubDate: 2021-09-01
       
  • Synthesis, Crystal Structure and Physicochemical Characterization of Two
           Ni(II)-Famotidine Metal Complexes

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      Abstract: The coordination ability of the antisecretor agent Famotidine (FMT) was explored using Ni(II) as central ion. [NiFMTH-2] and [Ni(FMT)2]Cl2 were obtained by the solvent evaporation method from the corresponding starting solutions at pH 8 and 4, respectively; the crystal structure was elucidated by single crystal X-ray diffraction in both cases.[NiFMTH-2] resulted in a distorted square-planar geometry, where FMT acts as a tetradentate dianionic ligand through nitrogen atoms belonging to the guanidine group, the thiazolic ring and the side chain, and a sulfur atom from the thioether moiety. [Ni(FMT)2]Cl2 exhibits an octahedral environment composed by two FMT molecules that coordinate by nitrogen atoms deriving from guanidine and thiazole ring moieties, and the thioether sulfur atom. The physicochemical characterization was completed by means of FTIR and UV–Vis spectroscopies, and thermal analysis. Solubility measurements were performed and the results could be satisfactorily correlated with the solvation Gibbs free energy (ΔGsolv) values in aqueous solution obtained using the SDM model by DFT calculations. Graphic Ni(II) and famotidine form an octahedral complex at pH 4 where famotidine acts as a tridentate neutral ligand. In basic medium, it behaves as a tetradentate dianion, resulting in a quasi-planar complex. Spectroscopic and thermal data are consistent with single crystal X-ray diffraction structural elucidation. The relative stabilities were assessed by theoretical studies.
      PubDate: 2021-09-01
       
  • Crystal Structure and DFT Calculations of Zn(II)-NN’O Schiff Base
           Complex

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      Abstract: The structure of the ZnII complex with NN’O-donor ligand N-(2-pyridyl)methyl-2-hydroxy-3,5-di-tert-butylbenzaldimine (1H) [Zn(C21H27N2O)2]·3CH3OH is described. The Zn (II) metallic centre presents a five-coordinate environment with a square-pyramidal distorted geometry (τ-factor 0.14). One ligand acts as tridentate and another ligand as bidentate [Zn(1-κ3N,N’,O)(1-κ2N,O)]·3CH3OH. The three methanol solvent molecules interact with the zinc complex by hydrogen-bonds (H-bonds). This structure was modelled with Density Functional Theory (DFT) calculations and a good correlation between the experimental parameters and the calculated ones was obtained. Graphic The X-ray diffraction single crystal structure of the Zn(II) complex with NN’O-donor pyridino-imino-phenolate ligand (1H) [Zn(1)2]·3CH3OH is described and compared with the modelled by DFT calculations.
      PubDate: 2021-09-01
       
  • Structural Characterization of Two Polymorphs of
           1-(4-Methylpyridin-2-yl)thiourea and Two Derived 2-Aminothiazoles

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      Abstract: Two polymorphic forms of 1-(4-methylpyridin-2-yl)thiourea (1) and the crystal and molecular structures of the 2-aminothiazoles N-(4-methylpyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine (2) and N-(4-methylpyridin-2-yl)-4-(pyrazin-2-yl)thiazol-2-amine (3), derived from 1 and the respective α-bromoketone via the Hantzsch reaction, are described. Both polymorphic forms 1α (space group P21/c, Z = 4) and 1β (space group P21/n, Z = 8) crystallize in the monoclinic system but exhibit distinctly different intermolecular hydrogen bonding patterns. Compound 2 (orthorhombic, space group Pca21, Z = 8) forms polymeric N–H⋯N hydrogen-bonded zigzag tapes in the polar crystal structure, with a significant twisting between the thiazole and pyridine rings. In contrast, the crystal structure of 3 (monoclinic, space group P21/c, Z = 4) features nearly planar centrosymmetric N–H⋯N hydrogen-bonded dimers, which are laterally joined through long C–H⋯N contacts, affording a π⋯π stacked layered structure. Graphic Two polymorphs of 1-(4-methylpyridin-2-yl)thiourea and the crystal and molecular structures of two 2-aminothiazoles, derived from 1-(4-methylpyridin-2-yl)thiourea and α-bromoketones via Hantzsch reaction, are reported.
      PubDate: 2021-09-01
       
  • On the Crystal Structures of the Polymorphs of Manganese(II) Chloride
           Tetrahydrate: α-MnCl2·4H2O and β-MnCl2·4H2O

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      Abstract: The manganese(II) chloride tetrahydrate MnCl2·4H2O (α-form) crystallizes in the space group P21/n with a = 6.1918(4) Å, b = 9.5230(6) Å, c = 11.1918(6) Å, β = 99.757(3)°, and V = 650.37(7) Å3 (Z = 4). A second polymorph of MnCl2·4H2O (β-form) is mentioned in the literature to be isomorphous with FeCl2·4H2O but its crystal structure was never confirmed. In this study, we report for the first time on the crystal structure of this second polymorph of manganese(II) chloride tetrahydrate, β-MnCl2·4H2O, using room temperature single-crystal X-ray diffraction. The β-form crystallizes in space group P21/c with a = 5.9893(5) Å, b = 7.2877(6) Å, c = 8.5838(7) Å, β = 110.952(4)°, and V = 349.89(5) Å3 (Z = 2), confirming that β-MnCl2·4H2O is isotype to Fe(II)Cl2·4H2O. To the best of our knowledge this is the first compound reported to crystallize in both MnCl2·4H2O-type (α-form) and FeCl2·4H2O-type (β-form) structures. The crystal structure of both α-form and β-form of MnCl2·4H2O consists of discrete octahedra complexes [MnCl2(H2O)4] linked by O–H⋅⋅⋅Cl− hydrogen bonds. However, chlorine atoms are in trans-configuration in the β-form (trans-[MnCl2(H2O)4] complexes) and in cis-configuration in the α-form (cis-[MnCl2(H2O)4] complexes). Moreover, the coordination polyhedra of the manganese(II) atoms are less distorted in the β-form. This leads to two different hydrogen bond networks and to a slightly more compact [MnCl2(H2O)4] complexes arrangement in the α-form. Graphic The title compound is the first representative among divalent metal tetrahydrate halogenides to present both the MnCl2·4H2O-type (α-form) and FeCl2·4H2O-type (β-form) structures, leading to different configuration of complexes [MnCl2(H2O)4], crystal packing, hydrogen bond networks, and possibly magnetic properties.
      PubDate: 2021-09-01
       
 
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