Role of Anation on the Mechanism of Proton Reduction Involving a Pentapyridine Cobalt Complex: A Theoretical Study

Kinetic and thermodynamic aspects of proton reduction involving pentapyridine cobalt­(II) complex were investigated with the help of quantum chemical calculations. Free energy profile of all possible mechanistic routes for proton reduction was constructed with the consideration of both anation and solvent bound pathways. The computed free energy profile shows that acetate ion plays a significant role in modulating the kinetic aspects of Co­(III)–hydride formation which is found to be the key intermediate for proton reduction. Upon replacing solvent by acetate ion, one electron reduction and protonation of Co^I species become more rapid along with slow displacement reaction. Most favorable pathways for hydrogen evolution from Co­(III)–hydride species is also investigated. Among the four possible pathways, reduction followed by protonation of Co­(III)–hydride (RPP) is found to be the most feasible pathway. On the basis of QTAIM and NBO analyses, the electronic origin of most favorable pathway is explained. The basicity of cobalt center along with thermodynamic stability of putative Co^III/II–H species is essentially a prime factor in deciding the most favorable pathway for hydrogen evolution. Our computed results are in good agreement with experimental observations and also provided adequate information to design cobalt-based molecular electrocatalysts for proton reduction in future

Optimization of microwave-assisted extraction of bioactive polyphenolic compounds from <em>Marsilea quadrifolia </em>L. using RSM and ANFIS modelling

204-221Extraction of bioactive compounds, rich in plant secondary metabolites as a form of polyphenolic compounds has gained utmost important in the food and pharmaceutical industries due to their antioxidant properties. Microwave-assisted extraction (MAE) was utilized for maximum extraction of bioactive polyphenolic compounds from Marsilea quadrifolia L. with consuming less toxic solvent. A central composite rotatable design (CCRD) based on response surface methodology (RSM) and adaptive neuro-fuzzy inference system (ANFIS) were followed to design and optimize the experimental parameters to get highest yield of bioactive polyphenolic compounds from M. quadrifolia L. The quantitative effects of experimental parameters such as methanol concentration (X1), microwave power (X2), irradiation temperature (X3) and irradiation time (X4) were investigated to obtain the maximum yields of total phenolic (TPC), total flavonoid contents (TFC) and antioxidant properties. The optimum conditions were observed at methanol concentration (X1= 87.5 %), microwave power (X2= 25 %), irradiation temperature (X3= 60 ºC) and irradiation time (X4= 15 min). Under these conditions, the highest yields of TPC (y1)= 693.28 mg gallic acid equivalents (GAE)/g), TFC (y2)= 84.86 mg rutin equivalents (RU)/g), % DPPHsc (y3)= 81.06 %, %ABTSsc (y4)= 71.34% and FRAP (y5)= 68.09 μg mol (Fe (II)/g) has been attained. Further, the experimental results were highly acknowledged with predicted values of RSM and ANFIS. The analysis of LC-ESI-MS spectrum confirmed 6 major bioactive compounds, namely, Betasitosterol, Tridecyliodide, 2,3,7,8 tetracholorodibenzofuaran, Chlorogenic acid, Pentachlorophenylacetate and Triacontyl hexacosanoate in the optimized extract of M. quadrifolia L. The optimized extract can be used as an alternative of synthetic antioxidants for product manufacturing in food and pharmaceutical industries

A Novel Hydrogen-Bonded Duplex Made up of Water Molecules and Halide Ions in the Sandwich Inclusion Structures of (C10H8N3S)+ X 2H2O [X=Cl-, Br-].

The X-ray crystal structures of thiabendazolium halide dihydrates (C10H8N3S)(+). X . 2H(2)O [X = Cl-, Br-] 1, 2 reveal a novel hydrogen-bonded duplex consisting of alternate edge-sharing (H2O . X)(2) quadrilaterals and (2H(2)O . X)(2) hexagons; notably these duplexes exist as host lattices and sandwich thiabendazole molecules into two different supramolecular architectures by similar N ... X and N ... O hydrogen bonds

Optimization of microwave-assisted extraction of bioactive polyphenolic compounds from Marsilea quadrifolia L. using RSM and ANFIS modelling

Extraction of bioactive compounds, rich in plant secondary metabolites as a form of polyphenolic compounds has gained utmost important in the food and pharmaceutical industries due to their antioxidant properties. Microwave-assisted extraction (MAE) was utilized for maximum extraction of bioactive polyphenolic compounds from Marsilea quadrifolia L. with consuming less toxic solvent. A central composite rotatable design (CCRD) based on response surface methodology (RSM) and adaptive neuro-fuzzy inference system (ANFIS) were followed to design and optimize the experimental parameters to get highest yield of bioactive polyphenolic compounds from M. quadrifolia L. The quantitative effects of experimental parameters such as methanol concentration (X1), microwave power (X2), irradiation temperature (X3) and irradiation time (X4) were investigated to obtain the maximum yields of total phenolic (TPC), total flavonoid contents (TFC) and antioxidant properties. The optimum conditions were observed at methanol concentration (X1= 87.5 %), microwave power (X2= 25 %), irradiation temperature (X3= 60 ºC) and irradiation time (X4= 15 min). Under these conditions, the highest yields of TPC (y1)= 693.28 mg gallic acid equivalents (GAE)/g), TFC (y2)= 84.86 mg rutin equivalents (RU)/g), % DPPHsc (y3)= 81.06 %, %ABTSsc (y4)= 71.34% and FRAP (y5)= 68.09 μg mol (Fe (II)/g) has been attained. Further, the experimental results were highly acknowledged with predicted values of RSM and ANFIS. The analysis of LC-ESI-MS spectrum confirmed 6 major bioactive compounds, namely, Betasitosterol, Tridecyliodide, 2,3,7,8 tetracholorodibenzofuaran, Chlorogenic acid, Pentachlorophenylacetate and Triacontyl hexacosanoate in the optimized extract of M. quadrifolia L. The optimized extract can be used as an alternative of synthetic antioxidants for product manufacturing in food and pharmaceutical industries

Quantum mechanical study on complexation phenomenon of pillar[5]arene towards neutral dicyanobutane

Based on density functional theory calculations, we have addressed the electronic structure, binding and nature of non-covalent interactions between alkylated pillar[5]arene (P[5]A) and 1,4-dicyanobutane (DCB)-based host-guest macrocycles. Neutral 1,4-dicyanobutane-based alkylated DCB_ProP[5]A is found to show higher binding energy when compared to the other three host-guest macrocycles. These complexes are largely stabilised by non-covalent interactions, which are ascertained through NCI and QTAIM analyses. Furthermore, the second-order perturbation energy of NBO analysis show that LP (N) – σ*(C-H) interactions predominate in DCB_ProP[5]A complex. Particularly, alkyl substituents (-methyl, -ethyl and -propyl) are playing a vital role in stabilising the host-guest complexes. In summary, the present work not only exhibits an efficient strategy to build a new family of alkylated P[5]A inclusion complexes but also providing deeper understanding on various non-covalent interactions towards 1,4-dicyanobutane (DCB) guest molecules inside the host environment.</p

Halogen-Based 17β-HSD1 Inhibitors: Insights from DFT, Docking, and Molecular Dynamics Simulation Studies

The high expression of 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1) mRNA has been found in breast cancer tissues and endometriosis. The current research focuses on preparing a range of organic molecules as 17β-HSD1 inhibitors. Among them, the derivatives of hydroxyphenyl naphthol steroidomimetics are reported as one of the potential groups of inhibitors for treating estrogen-dependent disorders. Looking at the recent trends in drug design, many halogen-based drugs have been approved by the FDA in the last few years. Here, we propose sixteen potential hydroxyphenyl naphthol steroidomimetics-based inhibitors through halogen substitution. Our Frontier Molecular Orbitals (FMO) analysis reveals that the halogen atom significantly lowers the Lowest Unoccupied Molecular Orbital (LUMO) level, and iodine shows an excellent capability to reduce the LUMO in particular. Tri-halogen substitution shows more chemical reactivity via a reduced HOMO–LUMO gap. Furthermore, the computed DFT descriptors highlight the structure–property relationship towards their binding ability to the 17β-HSD1 protein. We analyze the nature of different noncovalent interactions between these molecules and the 17β-HSD1 using molecular docking analysis. The halogen-derived molecules showed binding energy ranging from −10.26 to −11.94 kcal/mol. Furthermore, the molecular dynamics (MD) simulations show that the newly proposed compounds provide good stability with 17β-HSD1. The information obtained from this investigation will advance our knowledge of the 17β-HSD1 inhibitors and offer clues to developing new 17β-HSD1 inhibitors for future applications