First Principle Attempt towards the Thermodynamic Stability of Telluroformaldehyde and its Heavier Analogs: H(2-n)X(n)A=Te (X=H, F, Cl and Br; A=C, Si and Ge; n=0-2)

AbstractH(2-n)X(n)A=Te (X=H, F, Cl and Br; A=C, Si and Ge; n=0-2), the novel heavy congeners of formaldehyde, have been studied in the gas phase using MP2/def2-TVZP and BP86/def2-TVZP methods. Emphasis has been laid on the bond strengths and the standard heats of formation (ΔHf°) of the mentioned telluro-ketones to reveal their thermodynamic stabilities and further assist in their isolations. The bond strengths have been evaluated in terms of the σ-bond energy, π-bond energy and the bond dissociation enthalpy, D°, using isodesmic reaction schemes. The methodology employed has satisfactorily reproduced the bond strengths and the ΔHf° of formaldehyde and silanone. The findings from this work indicate that the D° of the F2A=Te (A=C, Si and Ge) molecules are comparable to that of H2C=O and thus their respective stabilities are expected to be equivalent to that of formaldehyde. Besides, the fluorinated telluro-ketones are predicted to possess a unique thermodynamic stability since they have the most exothermic ΔHf° in their respective series while the H2A=Te ketones have the most endothermic ΔHf°. In addition, the silanetellones are found to be thermodynamically more stable than their corresponding telluroformaldehyde and germanetellone analogs. Since reported data for H(2-n)X(n)A=Te (X=H, F, Cl and Br; A=C, Si and Ge; n=0-2) is non-existent in terms of the thermodynamic data, the findings of this work should supplement the literature with reliable information

Quantification of Sugars in Soft Drinks and Fruit Juices by Density, Refractometry, Infrared Spectroscopy and Statistical Methods

The amount of sugar in soft drinks and fruit juices has been quantified by density, refractometric and infrared spectroscopic methods. Density and refractometric methods can be used to obtain only the total amount of sugar. However, infrared spectroscopy distinguishes itself as a fast and reliable method for quantitative analysis. Fourier-transformedspectroscopy in combination with a mathematical treatment of the spectra of samples allows the amount of different sugars such as glucose, fructose and sucrose to be determined. Keywords: Sugar, Density, Refractrometry, Mid-FTIR, Partial least squares South African Journal of Chemistry Vol.57 2004: 24-2

Molecular insights of metal-metal interactions in transition metal complexes using computational methods

Computational methods were used to analyse the interactions around the metal centres in three transition metal (TM) complexes for which the X-ray data are available. We were particularly interested in understanding the metal–metal interactions. We used concepts of bond order, natural population, quantum theory of atom in molecules, electron localisation functions (ELFs) and non-covalent interactions (NCIs). Our results indicate that these tools can be used effectively to help in having insights into the bonding of TM complexes.The Higher Education Commission (HEC) of Mauritius and the South African National Research Foundation.https://www.degruyter.com/journal/key/pac/htmlam2022Chemistr

Aza-macrocyclic complexes of Group 1 cations:synthesis, structures and density functional theory study

The Group 1 complexes, [M(Me6[18]aneN6)][BArF] (M = Li–Cs; Me6[18]aneN6 = 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaazacyclooctadecane; BArF = tetrakis{3,5-bis(trifluoromethyl)-phenyl}borate), are obtained in high yield by reaction of the macrocycle with M[BArF] in anhydrous CH2Cl2 solution, and characterised spectroscopically (1H, 13C{1H}, 7Li, 23Na, and 133Cs NMR), by microanalysis and, for M = Li, K, and Rb, by single crystal X-ray analysis. The structures show N6-coordination to the metal ion; the small ionic radius for Li+ leads to a puckered conformation. In contrast, the K+ ion fits well into the N6 plane, with the [BArF]? anions above and below, leading to two K+ species in the asymmetric unit (a hexagonal planar [K(Me6[18]aneN6)]+ cation and a ‘[K(Me6[18]aneN6)(?1-BArF)2]? anion’, with long axial K?F interactions). The Rb+ ion sits above the N6 plane, with two long axial Rb?F interactions in one cation and two long, mutually cis Rb?F interactions in the other. The unusual sandwich cations, [M(Me3tacn)2]+ (M = Na, K; distorted octahedral, N6 donor set) and half-sandwich cations [Li(Me3tacn)(thf)]+ (distorted tetrahedron, N3O donor set), [Li(Me4cyclen)(OH2)]+, and [Na(Me4cyclen)(thf)]+ (both distorted square pyramids with N4O donor sets) were also prepared (Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane, Me4cyclen = 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane). Density functional theory (DFT) calculations, using the BP86 and B3LYP functionals, show that the accessibility of the [M(Me3tacn)2]+ sandwich cations depends strongly on the M+ ionic radius, such that it is sufficiently large to avoid steric clashing between the Me groups of the two rings, and small enough to avoid very acute N–M–N chelate angles. The calculations also show that coordination to the Group 1 cation involves significant donation of electron density from the p-orbitals on the N atoms of the macrocycle, rather than purely electrostatic interactions

Synthesis, molecular docking and tyrosinase inhibitory activity of the decorated methoxy sulfonamide chalcones : in vitro inhibitory effects and the possible binding mode

In this study, a series of sulfonamide chalcones derivatives was synthesized and its chemical structures were confirmed by spectral characteristics. The synthesized compounds were evaluated for their tyrosinase inhibitory activities along with molecular docking study. The tyrosinase inhibitory results indicated that compounds 5b, 5c, 5f, 5g and 5h displayed the significant tyrosinase inhibitory activity and comparable to the standard drug (kojic acid). Compound 5c exhibits the most potent tyrosinase inhibition among the synthesized compounds with IC50 = 0.43±0.07 mM, L-DOPA as the substrate, and better than that of the standard kojic acid (IC50 = 0.60±0.20 mM). Molecular docking studies showed that the binding mode of some compounds is in the tyrosinase binding pocket surrounding the copper in the active site. The correlation between the docking results with IC50 values showed that the binding mode prediction of the test compounds would also be convincing. This comprehensive study allows for a possible mechanism for the antityrosinase activity of the sulfonamide chalcones. These sulfonamide chalcones bind to copper atoms of tyrosinase which responsible for the catalytic activity of tyrosinase. These compounds may be used as a lead for rational drug designing for the multi-functional tyrosinase inhibitor

Novel triazine-functionalized tetra-imidazolium hexafluorophosphate salt : synthesis, crystal structure and DFT study

Please read abstract in the article.Research data for this article available at: CCDC Cambridge Crystallographic Data Center Crystallographic data (https://www.ccdc.cam.ac.uk/structures/search?id=doi:10.5517/ccdc.csd.ccz83y8&sid=DataCite)Universiti Sains Malaysia (USMhttp://www.elsevier.com/ locate/molstruc2020-12-15hj2020Chemistr

Advice from the Scientific Advisory Board of the Organisation for the Prohibition of Chemical Weapons on riot control agents in connection to the Chemical Weapons Convention

Compounds that cause powerful sensory irritation to humans were reviewed by the Scientific Advisory Board (SAB) of the Organisation for the Prohibition of Chemical Weapons (OPCW) in response to requests in 2014 and 2017 by the OPCW Director-General to advise which riot control agents (RCAs) might be subject to declaration under the Chemical Weapons Convention (the Convention). The chemical and toxicological properties of 60 chemicals identified from a survey by the OPCW of RCAs that had been researched or were available for purchase, and additional chemicals recognised by the SAB as having potential RCA applications, were considered. Only 17 of the 60 chemicals met the definition of a RCA under the Convention. These findings were provided to the States Parties of the Convention to inform the implementation of obligations pertaining to RCAs under this international chemical disarmament and non-proliferation treaty.Peer reviewe

advice from the scientific advisory board of the organisation for the prohibition of chemical weapons on isotopically labelled chemicals and stereoisomers in relation to the chemical weapons convention

AbstractThe Chemical Weapons Convention (CWC) is an international disarmament treaty that prohibits the development, stockpiling and use of chemical weapons. This treaty has 193 States Parties (nations for which the treaty is binding) and entered into force in 1997. The CWC contains schedules of chemicals that have been associated with chemical warfare programmes. These scheduled chemicals must be declared by the States that possess them and are subject to verification by the Organisation for the Prohibition of Chemical Weapons (OPCW, the implementing body of the CWC). Isotopically labelled and stereoisomeric variants of the scheduled chemicals have presented ambiguities for interpretation of the requirements of treaty implementation, and advice was sought from the OPCW's Scientific Advisory Board (SAB) in 2016. The SAB recommended that isotopically labelled compounds or stereoisomers related to the parent compound specified in a schedule should be interpreted as belonging to the same schedule. This advice should benefit scientists and diplomats from the CWC's State Parties to help ensure a consistent approach to their declarations of scheduled chemicals (which in turn supports both the correctness and completeness of declarations under the CWC). Herein, isotopically labelled and stereoisomeric variants of CWC-scheduled chemicals are reviewed, and the impact of the SAB advice in influencing a change to national licensing in one of the State Parties is discussed. This outcome, an update to national licensing governing compliance to an international treaty, serves as an example of the effectiveness of science diplomacy within an international disarmament treaty

innovative technologies for chemical security

AbstractAdvances across the chemical and biological (life) sciences are increasingly enabled by ideas and tools from sectors outside these disciplines, with information and communication technologies playing a key role across 21st century scientific development. In the face of rapid technological change, the Organisation for the Prohibition of Chemical Weapons (OPCW), the implementing body of the Chemical Weapons Convention ("the Convention"), seeks technological opportunities to strengthen capabilities in the field of chemical disarmament. The OPCW Scientific Advisory Board (SAB) in its review of developments in science and technology examined the potential uses of emerging technologies for the implementation of the Convention at a workshop entitled "Innovative Technologies for Chemical Security", held from 3 to 5 July 2017, in Rio de Janeiro, Brazil. The event, organized in cooperation with the International Union of Pure and Applied Chemistry (IUPAC), the National Academies of Science, Engineering and Medicine of the United States of America, the Brazilian Academy of Sciences, and the Brazilian Chemical Society, was attended by 45 scientists and engineers from 22 countries. Their insights into the use of innovative technological tools and how they might benefit chemical disarmament and non-proliferation informed the SAB's report on developments in science and technology for the Fourth Review Conference of the Convention (to be held in November 2018), and are described herein, as are recommendations that the SAB submitted to the OPCW Director-General and the States Parties of the Convention. It is concluded that technologies exist or are under development that could be used for investigations, contingency, assistance and protection, reducing risks to inspectors, and enhancing sampling and analysis

Theoretical and computational chemistry aspects Chemical sciences in the focus ;, v. 3./ edited by Ponnadurai Ramasami.

Based on "The Virtual Conference on Chemistry and its Applications (VCCA-2020) - Research and Innovations in Chemical Sciences: Paving the Way Forward" held in August 2020 and organized by the Computational Chemistry Group of the University of Mauritius. The chapters reflect a wide range of fundamental and applied research in the chemical sciences and interdisciplinary subjects.1 Role of heteroatoms and substituents on the structure, reactivity, aromaticity, and absorption spectra of pyrene: a density functional theory study -- 2 Effect of delocalization of nonbonding electron density on the stability of the M-Ccarbene bond in main group metalimidazol- 2-ylidene complexes: a computational and structural database study -- 3 Educational components in the supervision of chemistry postgraduate students: experiences and reflections -- 4 Chemometric exploratory data analysis for patients with diabetes type 2 and diabetic complications -- 5 Electronic structure theory study of the reactivity and structural molecular properties of halo-substituted (F, Cl, Br) and heteroatom (N, O, S) doped cyclobutane -- 6 Theoretical investigation of the stability, reactivity, and the interaction of methylsubstituted peridinium-based ionic liquids -- 7 Chemical computational approaches for optimization of effective surfactants in enhanced oil recovery -- 8 Determination of bulk and surface properties of liquid Bi-Sn alloys using an improved quasi-lattice theory -- 9 Identification of potential histone deacetylase inhibitory biflavonoids from Garcinia kola (Guttiferae) using in silico protein-ligand interaction -- 10 Thermodynamics of the micellization of quaternary based cationic surfactants in triethanolamine-water media: a conductometry study1 online resourc