• DEEPAK CHOPRA

      Articles written in Journal of Chemical Sciences

    • Analysis of intermolecular interactions in 3-(4-fluoro-3-phenoxyphenyl)-1-((4-methylpiperazin-1-yl)methyl)-1H-1,2,4-triazole-5-thiol

      Piyush Panini Rahul Shukla T P Mohan B Vishalakshi Deepak Chopra

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      In the present study, we have prepared and structurally characterized a derivative of 1,2,4 triazoles, namely 3-(4-fluoro-3-phenoxyphenyl)-1-((4-methylpiperazin-1-yl)methyl)-1H-1,2,4-triazole-5-thiol (T-1) via single crystal X-ray diffraction. The crystal structure was observed to be stabilized by the presence of various intermolecular interactions in the crystalline solid such as O-H…S, C-H…F, C-H…S, C-H…N, C-H…O, C-H$\ldots \pi$, $lp\ldots \pi$ and $\pi \ldots \pi$ intermolecular interactions. The interaction energy of these interactions was evaluated through PIXEL method with decomposition of the total energy into the coulombic, polarization, dispersion and repulsion contribution. The study of the nature of H-bonds with sulfur reveals that stabilization due to contribution from polarization plays a significant role. It is noteworthy that the presence of the solvent molecules in the crystal structure were observed to provide stabilization to an otherwise destabilized molecular pair (comprising of two molecules of 1,2,4 triazoles in the asymmetric unit).

    • Understanding the effect of substitution on the formation of S. . .F chalcogen bond

      RAHUL SHUKLA DEEPAK CHOPRA

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      In this study, we have investigated the effect of substitution on the formation of S. . .F non-covalent interactions in XHS. . .FCH₃ complexes (X= −H, −F, −Cl, −OH, −OCH₃, −NH₂, −NHCH₃, −NO₂, −CN) at MP2/aug-cc-pVDZ level of theory. The formation of S. . .F chalcogen bonds was observed in all the cases, except for X = −H. The binding energy of the S. . .F non-covalent interactions is strongly dependent on the nature of the substituent groups. The energy decomposition analysis revealed that electrostatic and exchangeenergy component are the dominant contributors towards the stability of these interactions. The topological analysis established the presence of the S. . .F chalcogen bond due to the presence of a bond critical point exclusively between sulphur and fluorine atoms representing a closed-shell interaction. The natural bondorbital analysis shows that the stability of the interaction comes from a charge transfer from F(lp) to σ* (S-X) orbital transition.

    • Quantitative investigation of intermolecular interactions in dimorphs of 3-Chloro-N-(2-fluorophenyl)benzamide and 2-Iodo-N-(4- bromophenyl)benzamide

      RAHUL SHUKLA SUSANTA K NAYAK DEEPAK CHOPRA M KISHORE REDDY TAYUR N GURU ROW

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      In this study, we have analyzed the role of different intermolecular interactions in the polymorphic modifications of 3-chloro-N-(2-fluorophenyl)benzamide (I) and 2-iodo-N-(4- bromophenyl)benzamide (II). The crystals were obtained via slow evaporation method with the alteration of solvents for crystallization. Thealready reported form [Cryst. Growth Des. (2011) 11:1578] crystallizes in P21sub>/c with Z'=2 [Form IA], while the new form crystallizes in Pna21 with Z'=1 [Form IB]. The latter compound crystallizes in P21/n with Z'=1 [Form IIA] and in Pbca with Z'=1 [Form IIB]. Weak Cl· · ·Cl and C-H· · ·F interactions in the former (IA, IB) and weak I· · ·I and C-H· · ·π interactions in the latter (IIA, IIB) play a vital role in the formation of different polymorphic modifications leading to the observation of conformational and packing polymorphs, respectively. PIXEL calculations show that most of the interactions present in the crystal structures are dispersive in nature. 2D Fingerprint plots revealed that the relative contribution of different intermolecular interactions in different polymorphic forms was different.

    • Synthesis and characterization of a 2D covalent organic framework (COF) of hexagonal topology using boronate linkages

      RAMEES P P PRADIP KUMAR MONDAL DEEPAK CHOPRA

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      A covalent organic framework (COF) has been designed and synthesized successfully by a condensation reaction between hexahydroxytriphenylene hydrate and tetrahydroxydiborane. The characterisation studies reveal that it has good thermal stability and high crystallinity. This is a mesoporous material having a pore size of 2.8 nm and also having a B–B linkage with prospect of potential applications in future

    • Quantitative investigation on the intermolecular interactions present in 8-(4-ethoxyphenyl)-1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione with insight from interaction energies, energy framework, electrostatic potential map and fingerprint analysis

      RAHUL SHUKLA PRABAL BANDOPADHYAY MANISHA SATHE DEEPAK CHOPRA

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      In this study, we have performed a detailed quantitative analysis of the different intermolecular interactions present in 8-(4-ethoxyphenyl)-1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione (I). The molecule crystallizes in the P-1 space group with one molecule in the asymmetric unit. The molecule had a layeredcrystal packing wherein the molecular sheets are primarily formed by hydrogen bonds and the stabilization is dominated via the electrostatic energy contribution. This molecular sheet is then interconnected to other similar sheets via different stacking motifs with significant contribution from dispersion energy components

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