• Brijesh Kumar Mishra

      Articles written in Journal of Chemical Sciences

    • Quantum chemical investigation of the reaction of O(${}^3P_2$) with certain hydrocarbon radicals

      Ashutosh Gupta R P Singh V B Singh Brijesh Kumar Mishra N Sathyamurthy

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      The reaction of ground-state atomic oxygen [O(${}^3P_2$)] with methyl, ethyl, 𝑛-propyl and isopropyl radicals has been studied using the density functional method and the complete basis set model. The energies of the reactants, products, reaction intermediates and various transition states as well as the reaction enthalpies have been computed. The possible product channels and the reaction pathways are identified in each case. In the case of methyl radical the minimum energy reaction pathway leads to the products CO + H2 + H. In the case of ethyl radical the most facile pathway leads to the products, methanal + CH3 radical. For propyl radical (𝑛- and iso-), the minimum energy reaction pathway would lead to the channel containing ethanal + methyl radical.

    • Density functional studies of endosulphan and its interaction with glycine and GABA

      C N Ramachandran Brijesh Kumar Mishra Ashwani Kumar Tiwari

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      Density functional theoretic (DFT) methods are employed to study the interactions between endosulphan and two amino acids, namely glycine and 𝛾 -aminobutyric acid (GABA). Two conformers of each isomer 𝛼- and 𝛽-endosulphan are considered in the study. The DFT methods B3LYP, M05, M05-2X, M06 and M06-2X in conjunction with the basis set 6-31++G∗∗ are used. The complexes of 𝛼- and 𝛽-endosulphan with amino acids are stabilized by a strong hydrogen bond. In addition, there are several weak C-H…O interactions present between the two moieties. Among the DFT methods used, M06-2X method shows the highest stabilization energy for all the complexes. The M06-2X/6-31++G∗∗ method predicts that among the four conformers of endosulphan, the 𝛼 conformer in which the S=O points up, forms the most stable complex with both glycine and GABA, with stabilization energies −15.24 kcal/mol and −14.39 kcal/mol, respectively. The 𝛽 conformer in which the S=O points down, forms the least stable complex with both amino acids with stabilization energies −7.14 and −7.85 kcal/mol, respectively.

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