Browsing by Author "Bhattacharya, Subrato"
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Publication Glycosyl Triazole Based Pyridinamide/CuI-Catalyzed Coupling of 2-Halobenzamides with Active Methylene Compounds(Georg Thieme Verlag, 2023) Singh, Sumit K.; Kumar, Sunil; Yadav, Mangal S.; Bhattacharya, Subrato; Tiwari, Vinod K.This report describes a convenient method for the Cu(I)- catalyzed tandem synthesis of dihydrophenanthridinediones and substituted isoquinolinones with the assistance of efficient glycosyl 1,2,3-triazole-based pyridinamide ligands. The catalytic system effectively works for the coupling of N-substituted 2-halobenzamides with various active methylene compounds to form biologically relevant heterocyclic scaffolds in high to excellent yields. The consecutive path of the reaction including intermolecular C C cross-coupling followed by intramolecular cyclization efficiently takes place at low catalytic loading. These glycosyl triazole-appended pyridinamides were synthesized in good yields by a CuI/DIPEA-mediated regioselective CuAAC click reaction. The notable features of the method include low catalytic loading, the use of cost-effective and biocompatible ligands, high reaction yield, and easily accessible starting materials that make the protocol more versatile. � 2023 Georg Thieme Verlag. All rights reserved.Publication Indium(III) and organotin(IV) 2-(methoxycarbonyl)benzenethiolates: Synthesis, structure and properties(Elsevier B.V., 2022) Kumar, Krishna; Tiwari, Priyanka; Moharana, Srikanta; Kant, Rajni; Bhattacharya, SubratoTwo compounds In(mts)3, 1 and triphenyltin(mts), 2 [where mts = 2-(methoxycarbonyl) ben- zenethiolate] were synthesized and characterized. Both the compounds crystallize in the monoclinic system; 1 with space group P21/c and 2 with space group P21/n. Molecule 1 has a distorted trigonal bipyramidal geometry around the In(III) center. In the case of 1, out of the three mts ligands, two bind (S and O) bidentately while the third one binds mainly through its S atom, whereas 2 has a tetrahedral geometry around Sn(IV) center in which the mts ligand is bonded through its S atom only. Hirshfeld analyses were carried out to understand the nature of weak interactions responsible for the deviation from the ideal geometry of both compounds. Quantum chemical calculations were carried out at the DFT level using B3LYP functional in order to get the optimized geometry and vibrational frequencies. Natural bond orbital analyses (NBO) were performed to explore hyper-conjugative interaction energies, HOMO-LUMO, and various inter and intramolecular transitions. The thermodynamic profiles and electrostatic potential surfaces of the compounds have been investigated. Bulk properties such as dielectric loss/constant and AC conductivities have also been explored. � 2022 Elsevier B.V.Publication Nickel(II) carbothioate complex incorporated graphene oxide-polyvinylidene fluoride ternary composite film: Preparation, structural features, dielectric, and electrical characteristics(Springer, 2023) Kumar, Krishna; Moharana, Srikanta; Shrivastav, Akash; Bhattacharya, SubratoGraphene oxide-based materials are well known for their electrical properties. Novel ternary composite films (PVDF-GO-FK-31) were prepared by introducing a metal complex, for the first time, in a graphene oxide-PVDF polymer matrix (where PVDF = polyvinylidene fluoride; GO = graphene oxide; FK-31 = [Ni(PPh3)2(SCOf)2] (SCOf = furan-2-thiocarboxylate). In these composites, the graphene oxides show strong interfacial bonding with the PVDF matrix due to the incorporation of the FK-31 molecules. The experimental results showed that the incorporation of FK-31 into the PVDF-GO matrix greatly improved the dielectric constant and suppressed dielectric loss values. The composites thus may be used as dielectric materials for electronic capacitors. Graphical Abstract: For the first time, a ternary composite was prepared by incorporating a newly synthesized square planar nickel(II) complex in a graphene oxide-PVDF polymer matrix and its dielectric and electric properties were studied. With increasing concentration of the complex in the ternary composite its dielectric constant and electrical conductivity increases while the dielectric loss decreases.[Figure not available: see fulltext.]. � 2023, Indian Academy of Sciences.Publication On-Site H2O2 Synthesis Using a Series of Ni(II) Furan-2-thiocarboxylate Complexes Integrated on Multi-Walled Carbon Nanotubes: Soft Donor Sites Stimulated Selective Two-Electron Oxygen Reduction(American Chemical Society, 2023) Kumar, Krishna; Singh, Devesh Kumar; Adak, Mrinal Kanti; Ganesan, Vellaichamy; Roy Choudhury, Angshuman; Bhattacharya, SubratoA series of Ni(II) complexes [Ni(tmeda)(fCOS)2] (1a), [Ni(2,2?-bipy)(fCOS)2] (1b), [Ni(1,10-Phen)(fCOS)2] (1c), [Ni(opda)2(fCOS)2] (2), [Ni(dppe)(fCOS)2] (3a), and [Ni(dppee)(fCOS)2] (3b) (fCOS = furan-2-thiocarboxylate) have been synthesized. All the complexes, except 1b, were characterized by single-crystal X-ray diffraction analysis and spectroscopic techniques. In the solid state, the geometry around the Ni(II) center is square planar in the cases of 3a and 3b, while the same is octahedral (with varying degrees of distortion) in all other complexes. The complexes were integrated separately on multi-walled carbon nanotubes (MWCNTs) to prepare their respective composites. Electrochemical characteristics and oxygen reduction response of all the composites were studied. All composites exhibited a two-electron oxygen reduction process. The composite of complex 2 (2@MWCNTs) having S and N donor sites shows the highest onset potential and the highest rate of oxygen reduction. Composites of complexes having P and S coordination sites (3a@MWCNTs and 3b@MWCNTs) show relatively high selectivity toward the two-electron oxygen reduction. The composites of complexes having S, N, and O coordination sites (1a@MWCNTs, 1b@MWCNTs, and 1c@MWCNTs) show moderate selectivity and activity for the two-electron oxygen reduction. 3a@MWCNTs show the optimum combination of activity and selectivity for H2O2 production. Remarkably, all the composites show high durability and may be suitable for the long-term oxygen-reduction process to synthesize H2O2 � 2023 American Chemical Society.Publication Synthesis and structural characterization of Cd(II) complexes based on acetylene dicarboxylate: A 1-D polymer as a precursor to CdO nanoparticles(Elsevier B.V., 2022) Sareen, Neha; Kumar, Krishna; Kant, Rajni; Garai, Somenath; Bhattacharya, SubratoTwo new compounds, [Cd(adc)(L)(H2O)3]2 (1), [Cd(adc)(bipy)2.H2O]n (2) (Where L = N, N?-bis-pyridin-4-ylmethylenehydrazine, adc = acetylene dicarboxylate and bipy = 2,2�-bipyridine) have been isolated in good yields and structurally characterized by IR, single-crystal X-ray diffraction, and thermogravimetric analysis. Direct thermolysis of complex 2 at 500 �C for 1 h under an ambient atmosphere yielded CdO nanoparticles. The nanoparticles were characterized for their size and structure by powder X-ray diffraction, scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (TEM). TEM images show the formation of nanorods as well as nanospheres. The optical band gap determined by the optical absorption method was found to be 3.8 eV. � 2022 Elsevier B.V.Publication Synthesis and structural features of a series of Cu(i) furan-2-thiocarboxylate complexes: efficient �click� catalysts for the synthesis of glycoconjugates and glycocluster(Royal Society of Chemistry, 2022) Kumar, Krishna; Agrahari, Anand K.; Pratap, Rajesh; Tiwari, Vinod K.; Bhattacharya, SubratoCu(i) furan-2-thiocarboxylate complexes [(PPh3)2Cu(fCOS)2] (1), [(PPh3)2Cu(fCOS)2�H2O] (2), [(dppf)Cu(fCOS)�CH3CN] (3), [(PPh3)3Cu2(?-fCOS)(?-Cl)] (4), and [(dppee)Cu(?-fCOS)]2 (5) (where dppee = 1,1?-bis(diphenylphosphinoethene), dppf = 1,1?-bis(diphenylphosphinoferrocene), fCOS? = furan-2-thiocarboxylate ion) have been synthesized. The complexes have been structurally characterized by single-crystal X-ray diffraction analysis and spectroscopic techniques. In the solid state, the coordination geometry around the Cu(i) center is distorted trigonal pyramidal in cases 1 and 2, whereas, the Cu(i) center has trigonal planar geometry in case 3. However, in case 4, the complex forms an unsymmetrical dimer in which one copper center has tetrahedral geometry and the other copper has trigonal planar coordination geometry. Complex 5 is an approximately symmetrical dimer possessing two Cu(i) centers, both of which are in an tetrahedral environment. The catalytic activities of all the complexes have been studied. It was found that complex 1 is a good catalyst in azide-alkyne cycloaddition �click� reactions and could be magnificently utilized for the synthesis of a glycocluster (7j). The general applicability of complex 1 as a catalyst for the regioselective synthesis of a series of glycoconjugate triazoles (7a-7i) has also been evaluated. It has been found that complex 1 is an excellent catalyst that does not require a base and efficiently works at room temperature in a short time. � 2022 The Royal Society of Chemistry.Publication Synthesis and structural features of indium(iii) furan-2-thiocarboxylates showing efficient catalytic activity toward multicomponent reactions via Knoevenagel condensation(Royal Society of Chemistry, 2023) Kumar, Krishna; Kumar Sahani, Raj; Garai, Somenath; Bhattacharya, SubratoA series of furan-2-thiocarboxylate complexes of indium(iii), Et3NH[In(SCOf)4] (1), iPr2NH2[In(SCOf)4] (2), [In(2,2?-bipy)(SCOf)3] (3a), and [In(1,10-phen)(SCOf)3] (3b), have been synthesized and structurally characterized. Complex 4, [In(TMEDA)(SCOf)(SH)2], was obtained by the partial hydrolysis of [In(TMEDA)(SCOf)3] (3). Heterobimetallic complexes [(SCOf)2In(?-SCOf)2Cu(PPh3)2] (5) and [(SCOf)2In(?-SCOf)2Ag(PPh3)2] (6), were also synthesized and characterized. In an attempt to synthesize the binary compound, In(SCOf)3 (7), a thioester fCOSCH2SCOf (8) was obtained serendipitously; thus, a novel convenient approach for thioester synthesis is introduced. The catalytic activities of all the complexes were assessed for Knoevenagel condensation and Knoevenagel initiated MCRs for the synthesis of chromene and imidazopyrimidine derivatives and it was found that complex 2 is a very efficient catalyst (much superior to the previously reported ones). � 2023 The Royal Society of Chemistry.Publication Synthesis and structural studies of Cu(i) methylthiosalicylate complexes and their catalytic application in thiol-yne click reaction(Royal Society of Chemistry, 2022) Kumar, Krishna; Tiwari, Priyanka; Kant, Rajni; Bhattacharya, SubratoThree complexes of Cu(i), [Cu(PPh3)2(mts)] (1), [Cu(dppf)(mts)] (2) and [Cu(dppe)(mts)]2 (3) (mts = methylthiosalicylate; dppf = diphenylphosphinoferrocene; dppe = diphenylphosphinoethane), have been synthesized and characterized. Complexes 1 and 2 are monomeric, while 3 has a dimeric structure. The coordination geometry around Cu(i) in these complexes are trigonal pyramidal/distorted tetrahedral. The catalytic activities of the complexes towards hydrothiolation of alkynes (via thiol-yne click reaction) have been studied. Out of these three complexes, 2 has been found to be an efficient catalyst for the synthesis of unsymmetrical vinyl sulfide. The desired vinyl sulfides are obtained in good to excellent yields, with up to >99% Z stereoselectivity in one case. This protocol tolerates a wide variety of functional groups or substrates, is palladium-free, and does not require the use of expensive or air-sensitive additives. The scope and versatility of the method have been successfully demonstrated with a few examples. � 2022 The Royal Society of Chemistry.Publication Synthesis of a Series of a Few Hydrosulfide Complexes of Cu(I). A ?3-SH-Bridged Rare Cubane-like Tetramer Showing Efficient Catalytic Activity toward Azide-Alkyne Cycloaddition(American Chemical Society, 2021) Nayak, Mousumi; Joshi, Deepak K.; Kumar, Krishna; Singh, Anoop S.; Tiwari, Vinod K.; Bhattacharya, SubratoA cubane-like tetranuclear hydrosulfido complex of Cu(I), [Cu4(SH)4(PPh3)4] (1), has been synthesized by the reaction of Cu(NO3)2�3H2O, NaSCOPh, and Cu(PPh3)2NO3 and characterized structurally. Complex 1 represents the first example of crystallographically characterized ?3-SH-bridged cubanoid hydrosulfide. By direct reactions of [(PPh3)2Cu(NO3)] and NaSH, neutral hydrosulfide complexes [Cu(SH)(PPh3)2]�C6H6 (2), [Cu2(SH)2(PPh3)3] (3), and [Cu2(SH)2(PPh3)4] (4) have also been synthesized and structurally characterized. Complex 2 is monomeric with a terminal hydrosulfide ligand. The other two, 3 and 4, are ?2-SH-bridged unsymmetrical and symmetrical dinuclear complexes, respectively. In the symmetric one (4), both Cu(I) ions are tetrahedrally coordinated while in the unsymmetric one (3), one Cu(I) ion is tetrahedral and the other one has a trigonal-planar coordination geometry. The catalytic activity of a hydrosulfido complex in a "click"azide-alkyne cycloaddition reaction has been explored for the first time, and complex 1 is found to be an efficient catalyst for the regioselective synthesis of glycoconjugate triazoles. �
