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Materials which are chemically, energetically and operationally acceptable for arsenic water treatment are highly required. In this study a hybrid material (SICC) of aminated starch, oxyhydroxide of iron and OMMT clay has been demonstrated for arsenic treatment. This new material was highly efficient in arsenic water treatment which could reduce arsenic concentration far below detection limits. All binding interactions during material preparation and arsenic sorption were exclusively characterized with FT-IR, XRD and other spectroscopic tools. A molecular modeling on the basis of density functional theory was carried out to verify the above findings. Influence of material dose, treatment time, initial ion concentration, varying temperatures, etc., on extent of sorption was studied in detail. The thermodynamic parameters viz. ΔG (>–11 kJ/mol), ΔH (42.48 kJ/mol), ΔS (177.6 JK−1 mol−1) and E a (59.16 kJ/mol) determined the feasibility of the process, its endothermic behavior and most importantly the chemical nature of the sorption accompanied by ion-exchange to some extent. The sorption followed a monolayer chemisorption pattern as determined by the Langmuir model (R2 = 0.973, R L = 0.081) with a qmax = 2.04 at 303 K. The binding of As(III) on the material was governed by a pseudo second order kinetic model. HIGHLIGHTS Properties of the hybrid material were enhanced synergistically.; Suspended materials were negligibly small in hybrid material.; Material with 10% clay loading accompanied by Iron(III) oxyhydroxide stabilization was found best in all respects.; Arsenic on SICC was predominantly chemisorbed accompanied by ion exchange to some extent.; The sorption process was spontaneous and endothermic in nature.

A visible-light-induced synthesis of N-hydroxybenzimidoyl cyanides from aromatic terminal alkenes is achieved by using Eosin Y as an organic photoredox catalyst. The process goes via a radical pathway with successive incorporation of two nitrogen atoms, one each from tert-butyl nitrite and ammonium acetate. The final product is achieved by the concomitant installation of an oxime and a nitrile group. DFT calculation supports a biradical pathway and all the proposed steps. A few useful synthetic transformations of N-hydroxybenzimidoyl cyanide are also illustrated.

A TBHP mediated carbonylation–peroxidation of styrene, α-peroxidation of α-substituted unsymmetrical internal alkenes and concurrent peroxidation–carbonylation–cycloalkylation/cycloetherifiction of internal cyclic alkene (indene) have been developed.

The stable activity of catalysts is an important issue in catalysis, particularly aqueous-phase reforming (APR) of renewable oxygenates, of biomass origin, to get H2. Sintering of metal nanoparticl...

Thermosetting composites were prepared from chemically modified soybean oil and wood flour by compression molding technique. Resins prepared from epoxidized soybean oil (ESO) and softwood powder were used as matrix and reinforcing agent, respectively. ESO was modified initially by methacrylic acid and finally by methacrylic anhydride. For comparison, both neat resin and resin blended with styrene were used in the composite preparation. The probable interaction among the resin, styrene and wood flour was established by Fourier transform infrared spectroscopy, supported by density functional theory calculations. Surface morphology of the composites was evaluated by scanning electron microscope. The flexural strength of composites with styrene-based co-monomer was in the range of 60.47–72.04 MPa, whereas that of composites without styrene was between 25.68 and 37.62 MPa. The tensile strength of styrene-blended composites was varied between 22.15 and 35.87 MPa, whereas the tensile strength was in the range of 13.68–20.48 MPa for styrene-free composites. Styrene-blended composites showed an improvement in mechanical, thermal, water resistance and flame retardant properties over those of composites having no styrene. The higher the amount of methacrylic anhydride in the resin, the higher was the overall improvement in properties of composites.

A visible-light-induced synthesis of

A series of potassium salt-loaded MgAl hydrotalcites were synthesized by wet impregnation of KNO3, KF, KOH, K2CO3, and KHCO3 salts over calcined MgAl hydrotalcite (Mg–Al = 3:1). The samples were characterized by X-ray diffraction, Fourier transform infrared, thermogravimetry–differential thermal analysis, scanning electron microscopy, and N2 absorption–desorption techniques to investigate their structural properties. The results showed formation of well-developed hydrotalcite phase and reconstruction of layered structure after impregnation. The prepared hydrotalcites possess mesopores and micropores having pore diameters in the range of 3.3–4.0 nm and Brunauer–Emmett–Teller surface area 90–207 m2 g–1. Base strengths calculated from Hammett indicator method were found increasing after loading salts, where KOH-loaded hydrotalcite showed base strength in the range of 12.7 < H– < 15, which was found to be the preferred catalyst. Subsequently, KOH loading was increased from 10 to 40% (w/w) and catalytic activity was evaluated for the Knoevenagel condensation reaction at room temperature. Density functional theory calculations show that among all of the oxygen atoms present in the hydrotalcite, the O atom attached to the K atom has the highest basic character. In this study, 10% KOH-loaded hydrotalcite showing 99% conversion and 100% selectivity was selected as the preferred catalyst in terms of base strength, stability, and catalytic efficiency.

Degradation of HFE-7500 [ n -C 3 F 7 CF(OCH 2 CH 3 )CF(CF 3 ) 2 ] have been studied by OH radicals using Density functional theory (DFT) approach. We have considered two possible OH initiated H-abstraction from CH 3 site and OCH 2 site of titled molecule. All the stationary points of reaction channels are characterized on the potential energy surface (PES) at M06-2X/6–31 + G(d,p) level of theory. It is apparent from PES that H-abstraction from OCH 2 site of the titled molecule is thermodynamically and kinetically more favorable than CH 3 site. The rate constants were evaluated by canonical transition state theory within the temperature range of 200 K–1000 K. Estimation of atmospheric lifetime and global warming potential of the HFE-7500 has been done. Finally, the fate of the alkoxy radical has also been explored at the same level of theory.

A detailed mechanistic investigation for the catalytic oxidation of NO over monometallic palladium dimer and its bimetallic counterparts, PdM (M = Cu, Rh, Ag, Au, Pt) has been performed using DFT. Nitric oxide is a major environmental problem, inclusive of acid rain and photochemical smog formation which is released mainly in automobile exhausts. Thus, removal of poisonous NO is a major challenge and understanding its oxidation at molecular level is of great importance in designing suitable catalysts. Bimetallic nanoparticles are more promising as catalyst due to synergetic effect. A full catalytic cycle has been studied producing two NO2 molecules from two molecules of NO and one O2 molecule. Both the pristine and bimetallic systems catalyse the reaction according to Eley–Rideal mechanism. The bimetallic PdCu system is found to be the most dominant catalytic system with the more active Pd-site (i.e. O2 activated by Pd-site). The present study enlightens the understanding for higher catalytic activity of bimetallic nanoparticle. DFT studies for the catalytic oxidation of NO on pure and bimetallic palladium clusters: Pd2, PdAu, PdAg, PdRh, PdCu, and PdPt. Removal of poisonous NO is a major challenge and understanding its oxidation at molecular level is of great importance in designing suitable catalysts. A full catalytic cycle has been studied producing two NO2 molecules from two NO molecules in presence of air. Energetic calculation reveals that PdCu is the predominant catalytic system with more active Pd-site.

100% triacetin selectivity was achieved in glycerol acetylation with acetic anhydride in 20–50 min in the presence of catalytic amounts of mesoporous sulfonated carbons and zeolite H-Y. Ex ...

Density functional theory (DFT) calculations within the framework of generalized gradient approximation have been used to systematically investigate the adsorption of nitric oxide (NO) molecule on neutral, cationic, and anionic Pdn (n = 1–5) clusters. NO coordinate to one Pd atom of the cluster by the end-on mode, where the tilted end-on structure is more favorable due to the additional electron in the π* orbital. On the contrary, in the neutral and cationic Pd2 system, NO coordinates to the bridge site of cluster preferably by the side-on mode. Charge transfer between Pd clusters and NO molecule and the corresponding weakening of NO bond is an essential factor for the adsorption. The NO stretching frequency follow the order of cationic > neutral > anionic. Binding energy of NO on anionic clusters is found to be greater than those of neutral and cationic clusters. © 2015 Wiley Periodicals, Inc.

Calcineurin (CN) is a major calmodulin binding serine/threonine phosphatase which plays a crucial role in numerous mammalian signal transduction pathways. Calcineurin inhibitors represent a valuable tool for elucidating CN dependent cellular processes. The present work deals with the synthesis and comprehensive characterization of a new polymer anchored peroxo niobium complex, Nb-2(O-2)(6)(carboxylate)(2)]-PA (Nb-2) PA=poly(sodium acrylate)], and identification of a set comprising of neat homoleptic as well as polymer immobilized peroxo complexes of vanadium(V) and niobium(V) as potent CN inhibitors. The in-vitro effect of the complexes on calmodulin mediated dephosphorylation activity of CN was investigated using a physiological substrate of calcineurin, RII-phosphopeptide as well as a non-protein substrate p-nitrophenyl phosphate (p-NPP). Enzyme kinetic analysis data revealed that the compounds inhibit function of CN via uncompetitive pathway with K-i values ranging between 1-3M, suggesting the formation of an enzyme-inhibitor-substrate complex during the course of inhibition.

The density functional theory (DFT) calculations within the framework of generalized gradient approximation have been employed to systematically investigate the geometrical structures, stabilities, and electronic properties of Pd n Si q (n = 1–7 and q = 0, +1, −1) clusters and compared them with the pure $${\text{Pd}}_{n + 1}^{q}$$ (n = 1–7 and q = 0, +1, −1) clusters for illustrating the effect of doping Si atom into palladium nanoclusters. The most stable configurations adopt a three-dimensional structure for both pure and Si-doped palladium clusters at n = 3–7. As a result of doping, the Pd n Si clusters adopt different geometries as compared to that of Pd n+1. A careful analysis of the binding energies per atom, fragmentation energies, second-order difference of energies, and HOMO–LUMO energy gaps as a function of cluster size shows that the clusters $${\text{Pd}}_{4}^{ + }$$ , $${\text{Pd}}_{4}$$ , $${\text{Pd}}_{8}^{ - }$$ , $${\text{Pd}}_{5} {\text{Si}}^{0, + , - }$$ , and $${\text{Pd}}_{7} {\text{Si}}^{0, + , - }$$ possess relatively higher stability. There is enhancement in the stabilities of palladium frameworks due to doping with an impurity atom. In addition, the charge transfer has been analyzed to understand the effect of doped atom and compared further.