Department of Chemistry

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http://khandolacollege.ndl.gov.in/handle/123456789/37

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Browsing Department of Chemistry by Author "Dhuri, Sunder N."

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    Bis(4-aminopyridinium) and bis(2-amino-6-methylpyridinium) cations stabilised by [MS4]2− anions: Synthesis, crystal structures, Hirshfeld surface analysis and sulfur transfer reactions
    (Elsevier, 2025) D’Souza, Milagrina; Harmalkar, Nikita N.; Chari, Vishnu R.; Vernekar, Beena K.; Dhuri, Sunder N.
    Four new organic ammonium tetrasulfidometallates: (4-aminopyridinium)2[MoS4]·H2O 1, (4-aminopyridinium)2[WS4]·H2O 2, (2-amino-6-methylpyridinium)2[MoS4] 3, and (2-amino-6-methylpyridinium)2[WS4] 4 have been synthesized by a well-known base promoted cation exchange method. All compounds were characterized by elemental analysis, IR/Raman/UV–Vis spectroscopy, thermogravimetric analysis, and X-ray crystallography. The structures of 1 and 2 consist of unique tetrahedral [MoS4]2− and [WS4]2− dianions, which are charge-balanced by crystallographically independent 4-aminopyridinium monocations. Additionally, both have a lattice water molecule, which contributes to the overall stability of their structures. In compounds 3 and 4, 4-aminopyridinium of 1 and 2 are replaced by 2-amino-6-methylpyridinium cation and lack lattice water. The different H-bonding interactions viz Nsingle bondH⋯S, Csingle bondH⋯S, Nsingle bondH⋯O and Osingle bondH⋯O are observed in 1 and 2, which are reduced to two viz. Nsingle bondH⋯S and Csingle bondH⋯S in 3 and 4. The weak interactions (Nsingle bondH⋯O and Osingle bondH⋯O) originating from lattice water further interlink cations with [MoS4]2− and [WS4]2− anions forming extended networks in 1 and 2. To understand the importance of intermolecular interactions in the structures of 1–4, the Hirshfeld surface analyses were performed. The enrichment ratio (E) in the structures of compounds 1–4 was obtained. Compounds 1–4 were tested for their sulfur transfer ability. Only compound 1 showed a predominant disulfide product formation in reaction with 1,3-dibromopropane.
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    Crystal structure, biological and docking studies of solvothermally isolated novel Schiff base
    (Elsevier, 2023) Vernekar, Beena K.; Kotkar, Gayatri D.; D'souza, Luann R.; Hathwar, Venkatesha R.; Dhuri, Sunder N.
    Solvothermal condensation of 4-hydroxy-3-methoxy benzaldehyde and ethylenediamine resulted in single crystals of the novel Schiff base N,N'-Bis(4-hydroxyl-3-methoxybenzylidene)ethane-1,2-diamine (H2L) while the conventional method yielded microcrystalline H2L. Single crystals of H2L were characterized by various techniques, including single crystal X-ray diffraction. The structural analysis revealed crystallization of H2L in the monoclinic P21 space group with z = 4 and z′ = 2 indicating the presence of two independent H2L molecules in the asymmetric unit of the crystal structure connected by O6-H6…N2 weak contacts involving H and N atoms of the hydroxyl and amine groups respectively. The biological activities, namely DNA binding and cell viability studies of H2L, were performed. H2L exhibited potent activity against mushroom tyrosinase enzyme. In this work, in-silico docking studies have been conducted to evaluate the effective binding modes of H2L with 2y9x mushroom tyrosinase protein. The docking studies revealed minimum binding energy of -6.43 kcal mol−1 for H2L compared to the value of -3.64 kcal mol−1 for standard Kojic acid. The antibacterial performance of H2L was tested, and the results are presented.
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    Experimental and Theoretical Investigation on the Extractive Mass Transfer of Eu3+ Ions Using Novel Amide Ligands in 1-Hexyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide
    (American Chemical Society, 2023) Ghosh, Ayan; Pandey, Amit; Sengupta, Arijit; Kathirvelu, Velavan; Harmalkar, Sarvesh S.; Dhuri, Sunder N.; Singh, Keisham S.; Ghanty, Tapan K.
    Novel amide ligands in the ionic liquid (1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) were utilized for the liquid–liquid biphasic mass transfer of Eu3+ ions from aqueous acidic waste solution. The cation exchange mechanism was found to be operative with the formation of [Eu(NO3)2L3]+ species (L = 4-chloro-N-(1-methyl-1H-pyrazol-3-yl)picolinamide). However, the presence of an inner-sphere water molecule was revealed by density functional theory (DFT) calculations. The viscosity-induced slower kinetics was evidenced during mass transfer, which was improved by increasing temperature. The process was exothermic in nature. The improvement in the kinetics of extractive mass transfer at higher temperatures is evinced by a reduction in the distribution ratio value. The spontaneity of the reaction was evidenced through the negative Gibbs free energy value, whereas the process enhances the entropy of the system, probably by releasing water molecules at least partially during complexation. The structures of bare ligands and complexes have been optimized by using DFT calculations. A high value of complexation energy, solvation energy, and associated enthalpy and free energy change reveal the efficacy in binding Eu with O and N donor atoms. In addition, natural population analysis, atoms-in-molecules analysis, and energy decomposition analysis have been employed to explore the nature of bonding existing in Eu–O and Eu–N bonds.
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    Invitro cytotoxicity and DNA interaction studies of nickel(II) mefenamato compounds with substituted α-diimines
    (Elsevier, 2025) Vernekar, Beena K.; Harmalkar, Nikita N.; Gaonkar, Sanket K.; Barretto, Delicia A.; Maliwal, Deepika; Pissurlenkar, Raghuvir R.; Bhowmik, Pradip K.; Dhuri, Sunder N.
    Two bioactive nickel(II) compounds of mefenamic acid (Hmef) with substituted α-diimines as co-ligands have been characterised using various spectroscopic methods and evaluated for cytotoxicity, DNA interaction and antioxidant studies, molecular docking and dynamics studies. Single crystal structures of [Ni(Mef-O)2(etobpy)(H2O)] 1 and [Ni(Mef-O)2(dmbpy)(H2O)(DMF)] 2, (etobpy = 4,4′-diethoxy 2,2′-bipyridine, dbmbpy = 4,4′-dimethyl-2,2′-bipyridine and DMF = N, N′-dimethylformamide) have been determined using single crystal X-ray diffraction technique. The mefenamato ligand adopts two types of coordination modes (mono- and bidentate) in 1, while in compound 2 both mef ligands display monodentate behaviour. The Ni(II) ion in both compounds shows a distorted octahedral geometry binding to two N and four O atoms. The cytotoxicity results revealed the activity of 1 and 2 against cancerous HepG2 in a dose-dependent manner. % DPPH free radical scavenging activity of 1 and 2 when performed, they exhibited IC50 values of 17.02±0.85 μM and 19.89±0.73 μM respectively, depicting their antioxidant nature. DNA binding properties of 1 and 2 were assessed by UV absorption spectroscopy, which suggested an intercalating binding between the complexes and the DNA. Both complexes act as potential agents towards DNA cleavage with the dose-dependent rise of Form II and III DNA. Further, Their interactions with DNA were studied using molecular docking and molecular dynamics simulations. Both 1 and 2 are intercalating in the major groove of DNA fragment, destabilizing the double helix strand during simulation, proving as potential candidates for cytotoxicity.
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    Weakly antiferromagnetic vanillin and acetate bridged dinuclear Ni(II) compound exhibiting catecholase-like activity and biological properties
    (Royal Society of Chemistry, 2024) Vernekar, Beena K.; Harmalkar, Nikita N.; Gaonkar, Sanket K.; Sannigrahi, Jhuma; Dhuri, Sunder N.
    A dinuclear nickel compound that features vanillin (van) and acetate (OAc) bridging ligands, [Ni sub(2)(Mu-van) sub(2)(Mu-OAc)(NCS) sub(3)(H sub(2)O)].5H sub(2)O 1, was synthesized and characterized using various techniques. Crystal structure analysis revealed a pair of Ni(II) ions bridged by an acetate anion through a Mu sub(2)-Eta sup(1):Eta sup(1) coordination mode. At the same time, vanillin bridges both nickel(II) centers through phenolic oxygen, separating the two Ni ions by a distance of 3.001(7) angstrom. The temperature-dependent magnetism indicates weak antiferromagnetic behaviour in compound 1, following the Curie-Weiss law with Curie constant C = 1.0145 cm sup(3) K mol sup(-1) and Weiss constant Theta = -4.1 K. Compound 1 was evaluated for its ability to mimic the catechol oxidase enzyme using 3,5-di-tert-butylcatechol as a model substrate with a K sub(cat) value of 157.1 x 102 h sup(-1). Furthermore, compound 1 was tested for its cytotoxicity against HepG2 cancer cells and DNA cleavage properties.