Computational Sciences - Research Publications

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Author: search.filters.author.Giri K.Has files: Yes

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    Effect of arsenate substitution on phosphate repository of cell: A computational study
    (Royal Society Publishing, 2018) Singh A.; Giri K.
    The structural analogy with phosphate derives arsenate into various metabolic processes associated with phosphate inside the organisms. But it is difficult to evaluate the effect of arsenate substitution on the stability of individual biological phosphate species, which span from a simpler monoester form like pyrophosphate to a more complex phosphodiester variant like DNA. In this study, we have classified the physiological phosphate esters into three different classes on the basis of their structural differences. This classification has helped us to present a concise theoretical study on the kinetic stability of phosphate analogue species of arsenate against hydrolysis. All the calculations have been carried out using QM/MM methods of our Own N-layer Integrated molecular Orbital molecular Mechanics (ONIOM). For quantum mechanical region, we have used M06-2X density functional with 6-31+G(2d,2p) basis set and for molecular mechanics we have used the AMBER force field. The calculated rate constants for hydrolysis show that none of the phosphate analogue species of arsenate has a reasonable stability against hydrolysis.
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    Solvent-free synthesis of 5-(aryl/alkyl)amino-1,2,4-triazines and ?-arylamino-2,2?-bipyridines with greener prospects
    (Royal Society of Chemistry, 2017) Kopchuk D.S.; Chepchugov N.V.; Kovalev I.S.; Santra S.; Rahman M.; Giri K.; Zyryanov G.V.; Majee A.; Charushin V.N.; Chupakhin O.N.
    A green and highly efficient method has been developed for the synthesis of 5-(aryl/alkyl)amino-1,2,4-triazines and ?-arylamino-2,2?-bipyridines according to the principles of atom economy. It has been performed by two consecutive solvent-free reaction pathways: the ipso-substitution of a cyano-group in 5-cyano-1,2,4-triazines and the aza-Diels-Alder reaction of the resulting 5-arylamino-1,2,4-triazines with 1-morpholinocyclopentene used as a dienophile. Solvent and catalyst-free conditions, operational simplicity, the compatibility with various functional groups, nonchromatographic purification technique, and high yields are the notable advantages of this procedure. The present methodology possesses a low E-factor.
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    A PASE Approach towards (Adamantyl-1)-, Alkyl- and (Het)Aryl-Substituted [1, 2,4]triazolo[1, 5-d][1, 2,4]triazines: A Sequence of Two Solvent-Free Reactions Bearing Lower E-Factors
    (Wiley-Blackwell, 2018) Krinochkin, A.P; Kopchuk, D.S; Giri K.; Shtaitz, Y.K.; Starnovskaya, E.S.; Khalymbadzha, I.A; Drokin, R.A; Ulomsky, E.N.; Santra, S.; Zyryanov, G.V.; Rusinov, V.L.; Chupakhin, O.N.
    A Pot, Atom, Step Economic (PASE) approach is reported towards [1, 2,4]triazolo[1, 5-d][1, 2,4]triazines, substituted with the azole ring with pharmacophore residues, such as 1-adamantyl or 2-furanyl moieties, naproxen residues, as well aliphatic and (het)aromatic substituents, starting from easily available 1,2,4-triazine-5-carbonitriles and carboxylic acids hydrazides. This approach involves a sequence of two solvent-free reactions accompanied by the Dimroth rearrangement on the last step. The structures of the final Dimroth rearrangement products were confirmed based on the DFT studies as well as the single crystal X-ray analysis for the admantane-substituted product. In addition, this method possesses lower E-factors.