Advances in Chemistry
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Open Access journal
ISSN (Print) 2356-6612 - ISSN (Online) 2314-7571
Published by Hindawi [333 journals]
- In Silico Molecular Docking Analysis of Natural Pyridoacridines as
Abstract: Docking studies are proved to be an essential tool that facilitates the structural diversity of natural products to be harnessed in an organized manner. In this study, pyridoacridines containing natural anticancer pigments were subjected to docking studies using Glide (Schrodinger). Investigations were carried out to find out the potential molecular targets for these selected pigments. The docking was carried out on different cancer macromolecules involved in different cell cycle pathways, that is, CDK-2, CDK-6, Bcl-2, VEGFR-2, IGF-1R kinase, and G-Quadruplexes. CDK-6 was found to be the most suitable anticancer target for the pyridoacridines. In addition, effectiveness of the study was further evaluated by performing docking of known inhibitors against their respective selected macromolecules. However, the results are preliminary and experimental evaluation will be carried out in near future.
PubDate: Mon, 19 Dec 2016 12:35:15 +000
- A DFT Study of Some Structural and Spectral Properties of
4-Methoxyacetophenone Thiosemicarbazone and Its Complexes with Some
Transition Metal Chlorides: Potent Antimicrobial Agents
Abstract: Recent studies have shown that 4-methoxyacetophenone thiosemicarbazone (MAPTSC) and its complexes with some transition metal chlorides are potent antimicrobial agents. To deepen the understanding of their structure-activity relationships necessary for rational drug design, their structural and spectral properties, along with thione-thiol tautomerism of MAPTSC, have been studied herein using the density functional theory (DFT). From our results, the thione tautomer of MAPTSC is more stable than the thiol counterpart in ethanolic solution, and thione-to-thiol tautomerization is highly precluded at ambient temperature (25°C) by a high barrier height ≈46.41 kcal/mol. MAPTSC can therefore exist as a mixture of the thione (major) and thiol (minor) tautomers in ethanolic solution at room and higher temperatures. Conformational analysis has revealed five possible conformers of the thione tautomer, of which two are stable enough to be isolated at 25°C. Based on our computed values of MAPTSC-metal(II) binding energies, enthalpies, and Gibbs free energies, the thione tautomer of MAPTSC exhibits a higher affinity for the d8 metal ions Ni(II), Pd(II), and Pt(II) and can therefore efficiently chelate them in chemical and biological systems. Natural population analysis has revealed ligand-metal charge transfer in the MAPTSC complexes studied. A good agreement has been found between calculated and experimentally observed spectral properties (IR, UV-Vis, and NMR).
PubDate: Mon, 21 Nov 2016 14:25:53 +000
- Density Functional Investigation of the Inclusion of Gold Clusters on a
CH3S Self-Assembled Lattice on Au(111)
Abstract: We employ first-principles density functional theoretical calculations to address the inclusion of gold (Au) clusters in a well-packed CH3S self-assembled lattice. We compute CH3S adsorption energies to quantify the energetic stability of the self-assembly and gold adsorption and dissolution energies to characterize the structural stability of a series of Au clusters adsorbed at the SAM-Au interface. Our results indicate that the inclusion of Au clusters with less than four Au atoms in the SAM-Au interface enhances the binding of CH3S species. In contrast, larger Au clusters destabilize the self-assembly. We attribute this effect to the low-coordinated gold atoms in the cluster. For small clusters, these low-coordinated sites have significantly different electronic properties compared to larger islands, which makes the binding with the self-assembly energetically more favorable. Our results further indicate that Au clusters in the SAM-Au interface are thermodynamically unstable and they will tend to dissolve, producing Au adatoms incorporated in the self-assembly in the form of CH3S-Au-SCH3 species. This is due to the strong S-Au bond which stabilizes single Au adatoms in the self-assembly. Our results provide solid insight into the impact of adatom islands at the CH3S-Au interface.
PubDate: Mon, 17 Oct 2016 14:00:03 +000
- Physico-Chemical Characteristics and Level of Some Selected Metal in
Abstract: The physico-chemical properties and level of some essential metals of four edible oils, two imported (Viking and Avena) and two processed in Ethiopia (Selam and Nur) oil samples, were analyzed using classical wet chemical method and flame atomic absorption spectroscopy techniques, respectively. The result of physico-chemical properties shows that acid value in Avena and Viking oils which is mgKOH/g and mgKOH/g, respectively, from palm oil variety and in Selam and Nur oils mgKOH/g and mgKOH/g, respectively, from noug oil variety, saponification value in Avena and Viking oils which is mgKOH/g and mgKOH/g, respectively, and in Selam and Nur oils mgKOH/g and mgKOH/g, respectively, iodine value in Viking and Avena oils which is g and g, respectively, and Nur and Selam oils g and g, respectively, and peroxide value in Viking and Avena oils which is meq/kg and meq/kg, respectively, from palm oil variety and in Selam and Nur oils meq/kg and meq/kg, respectively, from noug oil variety were obtained. The level of essential metals in edible oil samples was analyzed after wet digestion. The results show that levels of Cu in Viking and Avena oils that were mg and mg, respectively, and in Selam and Nur oils mg and mg, respectively, and the levels of Zn in Viking and Avena oils that were mg and mg, respectively, and in Selam and Nur oils mg and mg, respectively, were obtained. The physico-chemical properties and level of essential metal revealed that four edible oils were acceptable to human consumption.
PubDate: Sun, 25 Sep 2016 07:33:47 +000
- Relationship of QTAIM and NOCV Descriptors with Tolman’s Electronic
Abstract: The -donor properties of various P-donor ligands have been studied at the PBEPBE level of theory, which has proved to be accurate in computing the symmetric carbonyl stretching frequencies in nickel(0)-tricarbonyl complexes containing P-donor ligands. The delocalization index from the QTAIM methodology and the energy component associated with the NOCV deformation density representing the donor interaction give the best correlation with Tolman’s electronic parameters, whereas the electron density at the bond critical point and the Wiberg bond index are connected with the donor strength of the ligands to a lesser extent.
PubDate: Wed, 07 Sep 2016 16:42:38 +000
- Synthesis, Characterization, and Biological Activity of Nickel (II) and
Palladium (II) Complex with Pyrrolidine Dithiocarbamate (PDTC)
Abstract: The synthesis of square planar Ni(II) and Pd(II) complexes with pyrrolidine dithiocarbamate (PDTC) was characterized by elemental, physiochemical, and spectroscopic methods. Two complexes were prepared by the reaction of nickel acetate and palladium acetate with pyrrolidine dithiocarbamate (PDTC) in 1 : 2 molar ratio. The bovine serum albumin (BSA) interaction with complexes was examined by absorption and fluorescence spectroscopic techniques at pH 7.4. All the spectral data suggest that coordination of the pyrrolidine dithiocarbamate (PDTC) takes place through the two sulphur atoms in a symmetrical bidentate fashion. All the synthesized compounds were screened for their antimicrobial activity against some species of pathogenic bacteria (Escherichia coli, Vibrio cholerae, Streptococcus pneumonia, and Bacillus cereus). It has been observed that complexes have higher activity than the free ligand.
PubDate: Sun, 04 Sep 2016 10:02:40 +000
- Effect of Pharmaceutically Active Compound Nitroxoline on the Corrosion of
Mild Steel in an Acidic Environment
Abstract: The effect of Nitroxoline, antibiotic drug, was tested as a corrosion inhibitor for mild steel (MS) in an acidic environment by chemical method (mass loss measurement) and electrochemical methods such as electrochemical impedance spectroscopy and potentiodynamic polarization. The surface morphology of mild steel was investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, and atomic force microscopy techniques. From the chemical and electrochemical methods, the resistance of corrosion was increased with the addition of Nitroxoline concentration. Tafel curves indicate that the pharmaceutically active compound is a cathodic type inhibitor. An adsorption of Nitroxoline on the surface of mild steel was obeyed by Langmuir isotherm. SEM, EDX, and AFM techniques prove the adsorption process. All the obtained results confirmed that the investigated compound Nitroxoline acts as a good inhibitor for the corrosion of mild steel in an acidic environment.
PubDate: Mon, 29 Aug 2016 07:09:26 +000
- Analyses of the Calendaring Process for Performance Optimization of Li-Ion
Abstract: Olivine structure LiFePO4 (LFP) was synthesized via solid state processes, using Li2CO3, NH4H2PO4, and FeC2O4·H2O and C12H22O11 as precursor materials. The effects of calendaring are analyzed in terms of electrochemical performance, cycle life, surface morphology, and ac impedance analysis. The resulting LFP electrode was divided into calendared and uncalendared samples. Under electrochemical impedance testing, the calendared and uncalendared electrodes exhibited a charge transfer resistance of 157.8 Ω and 182.4 Ω, respectively. The calendared electrode also exhibited a higher discharge capacity of about 130 mAh/g at compared to a discharge capacity of 120 mAh/g at for the uncalendared electrode.
PubDate: Thu, 25 Aug 2016 11:17:48 +000
- A Computational and Experimental Study of the Conformers of Pyrrolidinium
Ionic Liquid Cations Containing an Ethoxy Group in the Alkyl Side Chain
Abstract: We investigate the conformers of the N-methoxyethyl-N-methylpyrrolidinium () and N-ethoxyethyl-N-methylpyrrolidinium () ionic liquid cations by means of DFT calculations at the B3LYP/ level and we calculate their infrared vibration frequencies. The comparison with the absorbance spectra of two ionic liquids containing these ions indicates good performance of such a combination of theory and basis set. The lowest energy conformer of each pyrrolidinium cation displays equatorial-envelope geometry; however, in contrast with the prototypical PYR14, the main alkyl side chain is not in an all-trans configuration, but it tends to be bent. Moreover, calculations indicate that the LUMO orbital extends more along the alkyl side chain in and than in the parent ion 1-butyl-1-methylpyrrolidinium (PYR14).
PubDate: Sun, 31 Jul 2016 10:55:39 +000
- Zirconium-Doped Fungal Sorbents: Preparation, Characterization, Adsorption
Isotherm, and Kinetic and Mathematical Modelling Study for Removal of
Abstract: The present study involves usage of more efficient and eco-friendly zirconium-doped, fluoride-resistant fungal biosorbents for removal of excess fluoride from groundwater. It was observed that >94% fluoride removal was possible at optimal conditions for the four fungal species studied. The adsorption isotherm studies indicated that zirconium-doped Aspergillus ficuum SIT-CH-2, Aspergillus terreus SIT-CH-3, and Aspergillus flavipes SIT-CH-4 were best described by Freundlich isotherm and zirconium-doped Penicillium camemberti SIT-CH-1 fitted well with Langmuir adsorption isotherm equation. The pseudo-second-order kinetics model showed the best fit for all of the four zirconium-doped fungal species for the fluoride biosorption.
PubDate: Mon, 18 Jul 2016 17:03:34 +000
- Structural Analysis and Reactivity of Tetramethylcopper(III) Complex
towards Nitrogen Donor Ligands by Density Functional Theory
Abstract: DFT studies are carried out on some ligand substitution reactions of tetramethylcuprate(III) (TMC) complex with five different nitrogen donor ligands as probe ligands. The geometry optimization of the possible nine model systems and the frequency calculations are carried out at DFT level using LANL2DZ basis set. The selected structural parameters of optimized model systems of Cu(III) complexes are reported and discussed. The change in the M-C bond distance in TMC due to substitution by probe ligands is explained. Natural population analysis (NPA) has been carried out for these complexes to establish the charge of copper in these complexes. A detailed population analysis of valence orbitals of copper complexes supports the existence of d8 configuration for metal in complexes and there is evidence for the transmission of electrons from the nitrogen donor atom to , , and 4s orbitals. Bond order calculations have been performed for all the complexes to probe the interaction between Cu(III) and the ligand. The stability of the complexes is ascertained from the computed chemical hardness. In order to understand the nature of Cu(III)-L (L = N donors) and Cu(III)-Me bonds in different complexes, Energy Decomposition Analysis (EDA) has been carried out for all the complexes chosen in the theoretical study. Thermodynamic feasibility of these reactions is investigated in terms of free energy changes of these reactions.
PubDate: Thu, 14 Jul 2016 16:59:40 +000
- Synthesis, Crystal Structure, and Antimicrobial Properties of
Abstract: A nickel(II) complex with hexamethylenetetramine and thiocyanate ion as coligands has been synthesized and characterised by infrared spectroscopy and ultraviolet-visible spectroscopic techniques. The crystal structure of the complex was determined by single crystal X-ray diffraction and the ligands were found to coordinate terminally through N-atoms. The ligand and the complex were screened for their activity against resistant strains of bacteria (Salmonella enteric, Shigella flexneri, Escherichia coli, and Staphylococcus aureus) and fungi (Candida albicans, Candida krusei, Candida parapsilosis, and Candida neoformans).
PubDate: Thu, 14 Jul 2016 12:24:40 +000
- A BTT-Based Colorimetric Dual Sensor for Hg(II) and Selected Anions with
Molecular Logic Operations
Abstract: A benzotrithiophenes (BTT) based colorimetric sensor (2) was synthesized via a simple one-step reaction process, and its recognition properties towards several biologically important anions and cations were investigated by naked eye observation and spectroscopic methods of UV-vis and 1H NMR analysis in DMSO. The molar addition of anions such as F−, AcO−, and induced a marked red shift of the charge transfer band ( nm, from 440 nm to 534 nm) concomitant with a clearly visible “naked eye” detectable colorimetric activities (from orange to pink). However, the molar addition of did not induce significant spectral changes, compared to F− and AcO−. Furthermore, the molar addition of Hg2+ to 2 resulted in hypochromic shift at 440 nm and the eventual disappearance of a low energy band at 534 nm, concomitant with the colorimetric activities (from orange to yellow). Moreover, both spectral and color changes induced by the addition of anions (F− and AcO−) were all reversible by the molar addition of metal cations of . The reversibility properties triggered the logic operation studies, and, subsequently, the complementary IMP/INH logic functions based on color and spectral switching (ON/OFF) were confirmed. Conclusively, 2 can thus be utilized as a colorimetric molecular switch modulated by AcO−/.
PubDate: Tue, 21 Jun 2016 15:05:45 +000
- Alternative Synthesis of 1,8-Difluoroanthracene via the Balz-Schiemann
Abstract: An alternative and improved method for the synthesis of 1,8-difluoroanthracene 5 is described. The precursor 1,8-difluoro-9,10-anthraquinone 4 was synthesized by precipitating the water-soluble 1,8-diazonium-9,10-anthraquinone fluoroborate 3 using isopropanol, before thermally decomposing it via the Balz-Schiemann reaction to yield 4 in the form of pure sublimed crystals. Compound 5 was later synthesized with 84% yield by reducing 4 in a Zn/NH4OH mixture. Using isopropanol to quantitatively precipitate water-soluble diazonium fluoroborate salts was also used to synthesize other fluoroanthraquinone derivatives with improved yields.
PubDate: Tue, 03 May 2016 11:27:36 +000
- Antioxidants Activity and Color Evaluation of Date Fruit of Selected
Cultivars Commercially Available in the United States
Abstract: Dates (Phoenix dactylifera L.) are nutrient-rich fruit consumed throughout the world, either directly or in several food products. Six commercially available date cultivars in the US were analyzed for total phenolics, antioxidant activity using ABTS, DPPH, FRAP, and ORAC assays, and instrumental color. Total phenolics content varied from 33 to 125 mg GAE/100 g dry weight, with the highest in Barni (Saudi Arabia). Antioxidant values as determined by the ABTS in Deglet Nour (Algeria), Deglet Nour (California), Deglet Noor (Tunisia), Shahia (Tunisia), Barni (Saudi Arabia), and Khudri (Saudi Arabia) were 1300, 1047, 796, 452, 776, and 341 μmol TE/g dry weight, respectively. Antioxidative properties as measure by DPPH, FRAP, and ORAC varied from 3.27 to 3.54, 3.29 to 5.22, and 189 to 243 μmol TE/g dry basis, respectively. Fruit and pulp color of Deglet Nour (Algeria) was lighter whereas pulp of Barni (Saudi Arabia) was the darkest. Antioxidant values varied with different techniques used and also followed a different pattern than that of phenolics content.
PubDate: Sun, 21 Jun 2015 10:04:20 +000
- Telomerization of Vinyl Chloride with Chloroform Initiated by Ferrous
Chloride-Dimethylacetamide under Ultrasonic Conditions
Abstract: Telomerization of vinyl chloride with chloroform was investigated using ferrous chloride-dimethylacetamide system, and 42.1% yield, more than four times the one reported before, was achieved. The addition of ultrasound further improved the reaction and yield was raised to 51.9% with trace byproducts at highly reduced reaction time and temperature. Ferrous chloride-dimethylacetamide under ultrasonic irradiation acts as a very efficient catalyst system for the 1 : 1 telomerization.
PubDate: Mon, 09 Mar 2015 11:28:08 +000
- Anticancer Activities of Mononuclear Ruthenium(II) Coordination Complexes
Abstract: Ruthenium compounds are highly regarded as potential drug candidates. The compounds offer the potential of reduced toxicity and can be tolerated in vivo. The various oxidation states, different mechanism of action, and the ligand substitution kinetics of ruthenium compounds give them advantages over platinum-based complexes, thereby making them suitable for use in biological applications. Several studies have focused attention on the interaction between active ruthenium complexes and their possible biological targets. In this paper, we review several ruthenium compounds which reportedly possess promising cytotoxic profiles: from the discovery of highly active compounds imidazolium [trans-tetrachloro(dmso)(imidazole)ruthenate(III)] (NAMI-A), indazolium [trans-tetrachlorobis(1H-indazole)ruthenate(III)](KP1019), and sodium trans-[tetrachloridobis(1H-indazole)ruthenate(III)] (NKP-1339) to the recent work based on both inorganic and organometallic ruthenium(II) compounds. Half-sandwich organometallic ruthenium complexes offer the opportunity of derivatization at the arene moiety, while the three remaining coordination sites on the metal centre can be functionalised with various coordination groups of various monoligands. It is clear from the review that these mononuclear ruthenium(II) compounds represent a strongly emerging field of research that will soon culminate into several ruthenium based antitumor agents.
PubDate: Thu, 19 Feb 2015 10:07:48 +000
- Synthesis and Structural Studies of a New Complex of
Abstract: A new organic-inorganic hybrid material, [C10H28N4]Bi2Br10, has been synthesized and characterized. The compound crystallizes in monoclinic P21/c space group with a = 11.410(4) Å, b = 11.284(4) Å, c = 12.599(3) Å, β = 115.93(2)°, and V = 1458.8(8) Å3. The structure consists of discrete dinuclear [Bi2Br10]4− anions and [C10H28N4]4+ cations. It consists of a 0-D anion built up of edge-sharing bioctahedron. The crystal net contains N–H⋯Br hydrogen bonds. The differential scanning calorimetry (DSC) reveals an irreversible phase transition at −17°C. The frontier molecular orbital and the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) calculation allow the classification of the material as an insulator.
PubDate: Thu, 12 Feb 2015 07:08:31 +000
- Optical Breakdown in Liquid Suspensions and Its Analytical Applications
Abstract: Micro- and nanoparticles persist in all environmental aquatic systems and their identification and quantification are of considerable importance. Therefore, the application of Laser-induced breakdown to aquatic particles is of interest. Since direct application of this method to water samples is difficult, further understanding of the breakdown is needed. We describe several optical techniques for investigation of laser breakdown in water, including Mach-Zehnder interferometry, shadow, and Schlieren diagnostic. They allow for studying the time dependent structure and physical properties of the breakdown at high temporal and spatial resolutions. Monitoring the formation of microbubbles, their expansion, and the evolution of the associated shockwaves are described. The new understanding is that the plasma column in liquids has a discrete nature, which lasts up to 100 ns. Controlling the generation of nanoparticles in the irradiated liquids is discussed. It is shown that multivariate analysis of laser-induced breakdown spectroscopy allows for differentiation between various groups of suspended particulates.
PubDate: Tue, 10 Feb 2015 12:45:27 +000
- Zr(IV), La(III), and Ce(IV) Chelates with
Synthesis, Spectroscopic Characterization, and Antimicrobial Studies
Abstract: La(III), Zr(IV), and Ce(IV) chelates of 2-[(4-[(Z)-1-(2-hydroxyphenyl)ethylidene]aminobutyl)-ethanimidoyl]phenol were synthesized and characterized by using several physical techniques. The Schiff base was obtained by refluxing of o-hydroxyacetophenone with 1,4-butanediamine in 2 : 1 molar ratio. The CHN elemental analysis results showed the formation of the Schiff base and the chelates has been found to be in 1 : 1 [M : L] ratio. The molar conductance measurements revealed that all the chelates are nonelectrolytes. Structural elucidations of the ligand and its chelates were based on compatible analytical and spectroscopic evidences. The infrared spectral data revealed that the Schiff base coordinates to the metal ions through active sites which are –OH and –C=N groups. According to the electronic spectral data, an octahedral geometry was proposed for the chelates. The synthesized ligand and its metal chelates were screened for their antimicrobial activity against two Gram negative (Escherichia coli, Salmonella kentucky) and two Gram positive (Lactobacillus fermentum, Streptococcus faecalis) bacterial strains, unicellular fungi (Fusarium solani), and filamentous fungi (Aspergillus niger). The activity data showed that the metal chelates have antibacterial and antifungal activity more than the parent Schiff base ligand against one or more bacterial or fungi species. The results also indicated that the metal chelates are higher sensitive antimicrobial agents as compared to the Schiff base ligand.
PubDate: Sun, 01 Feb 2015 14:25:00 +000
- Synthesis, Characterization, and Antihypertensive Evaluation of Some Novel
Abstract: A series of 2,2,8,8-tetramethyl-2,3,7,8-tetrahydro-4,6-diamino-3,7-dihydroxy-6,7-epoxy-benzo-[1,2-b:5,4-b′]dipyran derivatives 7a–e and 8a–e were synthesized from resorcinol. All the synthesized compounds were characterized by FTIR, mass spectra, and 1H NMR. These compounds were evaluated for antihypertensive activity using Wister Albino Rat model. Direct antihypertensive activity was performed using the instrument BIOPAC System MP-36 Santa Barbara, California, for recording blood pressure response. Among the title compounds, compounds 7b, 7c, and 7d showed potent antihypertensive activity and other compounds were also found to exert low and moderate antihypertensive activity. The relaxant potency in rat aorta and trachea was used for biological characterization of the benzopyrans. Structure-activity relationships study was investigated around position-4 of the benzopyran nucleus.
PubDate: Thu, 29 Jan 2015 14:31:38 +000
- Effect of C–O Bonding on the Stability and Energetics of High-Energy
Nitrogen-Carbon Molecules N10C2 and N16C2
Abstract: Molecules consisting of nitrogen have been the subject of much attention due to their potential as high-energy materials. Complex molecules consisting entirely of nitrogen can be subject to rapid decomposition, and therefore other atoms are incorporated into the structure to enhance stability. Previous studies have explored the incorporation of carbon atoms into otherwise all-nitrogen cages molecules. The current study involves two such cages, N10C2 and N16C2, whose structures are derived from N12 and N18, respectively. The N10C2 and N16C2 cages in this study are modified by bonding groups O3 and CO3 to determine the effect on the relative energies between the isomers and on the thermodynamic energy release properties. Energetic trends for N10C2 and N16C2 are calculated and discussed.
PubDate: Thu, 25 Dec 2014 00:10:12 +000
- A Review on Current Status of Stability and Knowledge on Liquid
Electrolyte-Based Dye-Sensitized Solar Cells
Abstract: The purpose of this review is to gather the current background in materials development and provide the reader with an accurate image of today’s knowledge regarding the stability of dye-sensitized solar cells. This contribution highlights the literature from the 1970s to the present day on nanostructured TiO2, dye, Pt counter electrode, and liquid electrolyte for which this review is focused on.
PubDate: Thu, 27 Nov 2014 08:52:37 +000
- Conical Intersections Leading to Chemical Reactions in the Gas and Liquid
Abstract: The current status of the role of conical intersections (CoIns) in molecular photochemistry is reviewed with a special emphasis on the procedures used to locate them. Due to space limitations, the extensive literature of the subject is given by referring the reader to representative references, whereas the author group’s work is described in detail. The basic properties of CoIns are outlined and contrasted with those of transition states in thermal reactions. Location of CoIns using the method of Longuet-Higgins sign-inverting loops is described in detail. The concept of “anchors”—valence bond structures that represent stable molecules and other stationary points on the potential energy surface—is introduced and its use in constructing loops is described. The authors’ work in the field is outlined by discussing some specific examples in detail. Mathematical aspects and details are left out. The main significance of the method is that it explains a large body of photochemical reactions (for instance, ultrafast ones) and is particularly suitable for practicing chemists, using concepts such as reaction coordinates and transition states in the search.
PubDate: Sun, 16 Nov 2014 07:39:41 +000
- Speeds of Sound and Excess Molar Volume for Binary Mixture of 1,4-Dioxane
with 1-Heptanol at Five Temperatures
Abstract: Speed of sound and density data for dilute liquid solutions of cyclic ether 1,4-dioxane with 1-heptanol was obtained using the Anton-Paar DSA 5000 at five temperatures = (298.15, 303.15, 308.15, 313.15, and 318.15) K at atmospheric pressure. The excess parameters were calculated from experimental data and fitted with a Redlich-Kister polynomial function and concluded the presence of weak molecular interactions.
PubDate: Wed, 05 Nov 2014 10:42:45 +000
- Adsorption Studies of Lead by Enteromorpha Algae and Its Silicates Bonded
Abstract: Lead adsorption by green Enteromorpha algae was studied. Adsorption capacity was 83.8 mg/g at pH 3.0 with algae (E) and 1433.5 mg/g for silicates modified algae (EM). FTIR and thermal analysis of algae materials were studied. Thomas and Yoon-Nelson column model were best for adsorbent (E) and algae after reflux (ER) and Yan model for (EM) with capacity 76.2, 71.1, and 982.5 mg/g, respectively. (ER) and (EM) show less swelling and better flow rate control than (E). Nonlinear methods are more appropriate technique. Error function calculations proved valuable for predicting the best adsorption isotherms, kinetics, and column models.
PubDate: Wed, 05 Nov 2014 00:00:00 +000
- Ionic Liquids: Synthesis and Applications in Catalysis
Abstract: Ionic liquids have emerged as an environmentally friendly alternative to the volatile organic solvents. Being designer solvents, they can be modulated to suit the reaction conditions, therefore earning the name “task specific ionic liquids.” Though primarily used as solvents, they are now finding applications in various fields like catalysis, electrochemistry, spectroscopy, and material science to mention a few. The present review is aimed at exploring the applications of ionic liquids in catalysis as acid, base, and organocatalysts and as soluble supports for catalysts.
PubDate: Wed, 29 Oct 2014 00:00:00 +000
- Complex Molecules at Liquid Interfaces: Insights from Molecular Simulation
Abstract: The behaviour of complex molecules, such as nanoparticles, polymers, and proteins, at liquid interfaces is of increasing importance in a number of areas of science and technology. It has long been recognised that solid particles adhere to liquid interfaces, which provides a convenient method for the preparation of nanoparticle structures or to modify interfacial properties. The adhesion of proteins at liquid interfaces is important in many biological processes and in a number of materials applications of biomolecules. While the reduced dimensions of these particles make experimental investigation challenging, molecular simulations provide a natural means for the study of these systems. In this paper I will give an overview of some recent work using molecular simulation to investigate the behaviour of complex molecules at liquid interfaces, focusing on the relationship between interfacial adsorption and molecular structure, and outline some avenues for future research.
PubDate: Tue, 28 Oct 2014 12:02:58 +000
- Structural Conformational Study of Eugenol Derivatives Using Semiempirical
Abstract: We investigated the conformational structure of eugenol and eugenyl acetate under torsional angle effect by performing semiempirical calculations using AM1 and PM3 methods. From these calculations, we have evaluated the strain energy of conformational interconversion. To provide a better estimate of stable conformations, we have plotted the strain energy versus dihedral angle. So, we have determined five geometries of eugenol (three energy minima and two transition states) and three geometries of eugenyl acetate (two energy minima and one transition state). From the molecular orbital calculations, we deduce that the optimized trans form by AM1 method is more reactive than under PM3 method. We can conclude that both methods are efficient. The AM1 method allows us to determine the reactivity and PM3 method to verify the stability.
PubDate: Mon, 20 Oct 2014 00:00:00 +000
- Space Group Approximation of a Molecular Crystal by Classifying Molecules
for Their Electric Potentials and Roughness on Their Inertial Ellipsoid
Abstract: In order to predict the most probable space group where a molecule crystallizes, it is assumed that molecular shape and electric potential distribution on the molecular surface are the main factors or predictors. However, to compare and classify molecules by these two factors seems to be very difficult for in general such different objects. Thus, in order to compare molecules, they are reduced to their inertial ellipsoid in which surface 26 equally spaced points were chosen where a roughness factor and an electric potential due to all atomic charges of the whole molecule are calculated. By this procedure, different molecules encoded by these two predictor vectors can be compared and classified, showing that molecules that crystallize in the same space group have more similar predictor vectors. This result opens the possibility to predict the more probable spatial group associated with a molecule.
PubDate: Thu, 16 Oct 2014 11:44:42 +000