• Pradip Kr Bhattacharyya

      Articles written in Journal of Chemical Sciences

    • Effect of external electric field on Cyclodextrin-Alcohol adducts: A DFT study

      Kundan Baruah Pradip Kr Bhattacharyya

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      Effect of external electric fields on the interaction energy between cyclodextrin and alcohol was analyzed in the light of density functional theory (DFT) and density functional reactivity theory (DFRT). Stability of the cyclodextrin-alcohol adducts was measured in terms of DFT based reactivity descriptor, global hardness, electrophilicity, and energy of the HOMO. Stability of adducts was observed to be sensitive towards the strength as well as direction of the applied external electric field. In addition, reactivity pattern follows the maximum hardness and minimum electrophilicity principles.

    • Does oligomerization in fused thiophene affect reactivity and aromaticity?

      Siddhartha Kr Purkayastha Pradip Kr Bhattacharyya

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      Reactivity and aromaticity of a few fused thiophene oligomers and their conformers are discussed in the light of density functional theory (DFT) and conceptual density functional theory. Reactivity parameters, such as hardness (𝜂) and electrophilicity (𝜔), chemical potential (𝜇) and energy of the HOMO (highest occupied molecular orbital) have been studied. Oligomerization raises the 𝐸HOMO of the species, which in turn increases the reactivity of the oligomers. The absorption spectra of the species are analysed using TDDFT (time dependent density functional theory). The absorption peaks show red shift with increasing size of the oligomers. Aromaticity of the species is gauged by nucleus independent chemical shift (NICS). The out-of-plane component, (NICSzz) values advocate higher aromatic character at longer distance whereas, NICS supports the reverse.

    • Reactivity of chitosan derivatives and their interaction with guanine: A computational study


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      The present study delves into the reactivity of a few chitosan derivatives (CSDs) and their interactionwith guanine in vacuum and in different phases. Increase in the polarity of the solvent lowers reactivityof the chosen derivatives (evaluated by using reactivity descriptors). Interaction between the CSDs and guanine(measured by interaction energy) weakens in solvent media and CSD-guanine interaction is weaker thanthe interaction between guanine and unmodified chitosan (CS). Chemical stability of CSD-guanine adductsremains similar to that of CS-guanine adduct in both polar and non-polar media. Moreover, CSD-guanineadducts exhibit comparable thermodynamic stability (quantified by free energy of solvation, δGsol) to that ofunmodified CS-guanine adduct in non-polar solvent but in polar medium they are immensely destabilized incomparison to CS-guanine adduct. Observed theoretical results are expected to provide guidance for futurerelevant experimental research on gene delivery by CS derivatives.

    • On the effect of external perturbation on amino acid salt bridge: a DFT study


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      Effect of external perturbation (in terms of external electric field and solvents) on the stability of lysine-aspartic acid salt bridge was analyzed by density functional theory. Because of solvation, interaction energy in the aqueous phase is much lower as compared to gas phase. Interaction energy as well as stability (measured in terms of global hardness, HOMO energy and total electronic energy) are observed to be sensitive towards the strength and direction of the applied electric field. Gap between HOMO energy of the acids and salt bridge also points towards the feasibility of hydrogen bonding.

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