Browsing by Author "P. Bharati"

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Mn(II) complexes of 1-(4-methoxybenzoyl)-4-phenyl-3-thiosemicarbazide containing o-phenanthroline and 2,2-bipyridine as co-ligands: Synthesis, crystal structure, spectral characterization, photoluminescence and electrochemical studies
(Elsevier B.V., 2023) Ram Nayan Gautam; Ananya Tiwari; Seema Gupta; M.K. Bharty; Vellaichamy Ganesan; Sundeep Kumar; P. Bharati; R.J. Butcher
Here, two complexes [Mn(Hmpth)2(bpy)] (1) and [Mn(Hmpth)2(o-phen)](2) with 1-(4-methoxybenzoyl)-4-phenyl-3-thiosemicarbazide (H2mpth) have been synthesized which contains 2-2′-bipyridine (bpy)/ o-phenanthroline (o-phen) as co-ligand. The ligand, H2mpth and its Mn(II) complexes have been characterized by IR, NMR, magnetic behaviour and single crystal X-ray data. In both complexes, the metal ions adopt a distorted octahedral geometry. Here, role of co-ligands (2,2-bpy and o-phen) on the optoelectronic properties of Mn(II) complexes is investigated for the first time. Complex 1 exhibits high fluorescence intensity as compared to ligand H2mpth and complex 2. The order of fluorescent behaviour found as complex 1 > complex 2 > H2mpth. Thermal behaviour of complexes were also studied. The electrochemical characteristics of Mn(II) complexes is studied using cyclic voltammetry technique after immobilizing it on the glassy carbon electrode modified with Nafion-multi-walled carbon nanotubes. The cyclic voltammetry studies indicate a reversible one electron transfer process corresponding to the Mn2+/3+ redox processes. © 2023
Mononuclear Ag(I), dinuclear and polymeric Hg(II) complexes of 3-mercapto-4-methyl-4H-1,2,4-triazole: Syntheses, spectral, X-ray, photoluminescence and thermal analysis
(Elsevier Ltd, 2013) A. Bharti; P. Bharati; M.K. Bharty; R.K. Dani; Sanjay Singh; N.K. Singh
The reactions of AgNO3, PhHgOAc and HgCl2 with Hmmtrz gave three new complexes, [Ag(mmtrz)(PPh3)2] ·Hmmtrz (1), [Hg2(mmtrz)4(Hmmtrz)2] (2) and [Hg(mmtrz)2]n (3) (Hmmtrz = 3-mercapto-4-methyl-4H-1, 2,4-triazole), which have been isolated and well characterised by CHN analyses, IR, NMR, single crystal X-ray and TG-DTA data. Complex 1 adopts a distorted trigonal planar arrangement in which Ag(I) is bonded through the thiolato sulfur atom of the mmtrz anion and two phosphorus atoms of PPh3, along with one unit of the ligand held via a weak Ag⋯S contact. Complex 2 has been formed by symmetrization or dimerisation in chloroform solution via the reaction 4[PhHgL]-[Hg2L4] + 2HgPh2. In the dimeric complex 2, each Hg(II) centre has a distorted tetrahedral geometry bonded through two thiolato sulfur atoms of two terminal ligands, one nitrogen and one thiol sulfur (SH) from a neutral bridging ligand, forming an eight-membered ring around two Hg(II) centers. The one dimensional metal-organic coordination polymer of complex 3 is obtained by the reaction of HgCl2 with Hmmtrz in methanol, in which Hg(II) adopts a tetrahedral geometry bonded through two thiolato sulfur and two nitrogen atoms from two ligands. Complexes 1 and 2 are stabilized by intermolecular π⋯π interactions. Supramolecular organisation through hydrogen bonding is present in these complexes. Complexes 1 and 3 are fluorescent materials upon excitation at 263 and 327 nm respectively, exhibiting a weak emission at 389 nm and a medium-strong emission at 421 nm as a consequence of intraligand π-π transitions. The course of the thermal degradations of complexes 1 and 3 has been investigated by TG-DTA. Thermogravimetric analysis of complex 1 shows a single weight loss to give Ag2S, indicating that the complex might be useful as a precursor for the synthesis of pure Ag2S nanoparticles and thin films. © 2013 Elsevier Ltd. All rights reserved.
Square planar Ni(II) complexes of pyridine-4-carbonyl-hydrazine carbodithioate, 1-phenyl-3-pyridin-2-yl-isothiourea and 4-(2-methoxyphenyl) piperazine-1-carbodithioate involving N-S bonding: An approach to DFT calculation and thermal studies
(Elsevier Ltd, 2013) P. Bharati; A. Bharti; M.K. Bharty; B. Maiti; R.J. Butcher; N.K. Singh
Three new complexes [H2en][Ni(pchc)2] (1) (pchc = pyridine-4-carbonyl-hydrazine carbodithioate), [Ni(Hppith)2] (2) (H2ppith = 1-phenyl-3-pyridin-2-yl-isothiourea) and [Ni(mppcdt) 2] (3) {mppcdt = 4-(2-methoxyphenyl)piperazine-1-carbodithioate} have been synthesized and characterized by elemental analyses, IR and single crystal X-ray diffraction data. The ligand H2ppith and complexes [H 2en][Ni(pchc)2] (1) [Ni(Hppith)2] (2) and [Ni(mppcdt)2] (3) crystallize in monoclinic, orthorhombic, monoclinic and triclinic system with space group P21/n, Icab, C2/c and P1, respectively. The nitrogen and sulfur donor sites of the bidentate ligands chelate Ni(II) forming two five-membered CSN2M chelate rings in the complex 1, two six membered C2SN2M rings in complex 2 and the sulfur donor sites of the bidentate ligand chelate Ni(II) forming two four membered CS2M rings in complex 3. The Ni(II) complexes are diamagnetic and have distorted square planar geometry. The crystal structure of the complexes are stabilized by various types of inter and intramolecular extended hydrogen bonding providing supramolecular framework. Results obtained from quantum chemical calculations at the density functional theory level corroborate our experimental findings from IR and UV. The course of the thermal degradation of complexes 1,2 and 3 has been investigated by TG-DTA. Thermogravimetric analyses of the complexes indicate NIO/NIS as the end residue. © 2013 Elsevier Ltd. All rights reserved.
Square planar Pd(II) complexes derived from 1-ethyl-3-phenylthiourea, 3-mercapto-4-methyl-1,2,4-triazole and 2-mercapto-5-methyl-1,3,4-thiadiazole: Syntheses, spectral, structural characterization and photoluminescence properties
(Elsevier S.A., 2016) P. Bharati; A. Bharti; P. Nath; S. Kumari; N.K. Singh; M.K. Bharty
The reaction of PdCl2 with 1-ethyl-3-phenyl-thiourea (Heptu), 3-mercapto-4-methyl-4H-1,2,4-triazole (Hmmtrz) and 2-mercapto-5-methyl-1,3,4-thiadiazole (Hmthd) respectively, yielded three new complexes [Pd(eptu)2] (1), [Pd(Hmmtrz)4]Cl2 (2) and [Pd(Hmthd)4]Cl2·2CHCl3 (3). These complexes have been isolated in pure form and characterized by elemental analyses, IR, NMR and single crystal X-ray diffraction technique. In all compounds the metal ion adopts a square-planar geometry. Two nitrogen and two sulfur atoms from the monoanionic eptu ligand in complex 1 are bonded to Pd(II) centre in trans fashion. Complexes 2 and 3 are salt-like and the metal centre is bonded through four neutral ligands. The electrical neutrality in these complexes is maintained by the presence of two chlorides as counter ions. Migration of hydrogen, within the ligand framework in complexes 2 and 3, from sulfur to nitrogen is observed that resulted in the thione form of the ligand and its coordination to the metal centre in both the complexes. Complex 2 is stabilized by intermolecular C-H⋯N and intramolecular N-H⋯Cl hydrogen bonding leading to an extended structure. Complex 3 is stabilized by intermolecular C-H⋯S hydrogen bonding. Complexes 1-3 are fluorescent materials which upon excitation at 31 000, 38 600 and 32 300 cm-1 exhibit an emission at 25 200, 27 000 and 26 700 cm-1, respectively. © 2016 Elsevier B.V. All rights reserved.
Studies on phenylmercury(II) complexes of nitrogen-sulfur ligands: Synthesis, spectral, structural characterization, TD-DFT and photoluminescent properties
(Elsevier Ltd, 2013) A. Bharti; P. Bharati; Ram Dulare; M.K. Bharty; Dheeraj K. Singh; N.K. Singh
The reactions of phenylmercury(II) acetate with N-phenyl-5-(pyridin-4-yl)- 1,3,4-thiadiazol-2-amine (Hppt) (1) and potassium N(4-methylpiperazine)-1- carbodithioate [K(mpcdt)] yielded [PhHg(ppt)] (2) and [PhHg(mpcdt)] (3). The complexes have been characterized by elemental analyses, IR, UV-Vis, 1H and 13C NMR spectroscopy. The ligand Hppt (1)- and complexes 2 and 3 crystallize in the triclinic, monoclinic and orthorhombic system, space group P1̄, C 2/c and Pbca, respectively. The crystal X-ray studies revealed that complexes 2 and 3 both form a one dimensional metal-organic structure, with a linear N-Hg-Ph and S-Hg-Ph core respectively. The most noteworthy features in complex 2 is that the ligand bound phenylmercury cation is stabilized via intramolecular as well as intermolecular weak Hgâ̄N secondary interactions. Crystal structure of complex 2 is also stabilized via weak πâ̄π and C-Hâ̄π interactions. The crystal structure of complex 3 is stabilized by intermolecular/ intramolecular Hgâ̄S interactions and C-Hâ̄π interactions. The ligands Hppt and [K(mpcdt)] exhibit green emissions and complex 2 shows photoluminescence due to the presence of Hgâ̄N interactions, whilst complex 3 does not show photoluminescence because Hgâ̄S interactions show quenching behaviour in the solid state. The solution state photoluminescence properties of complex 2 indicate that intermolecular as well as intramolecular Hgâ̄N interactions persist even in very dilute solution. The geometrical optimization of Hppt (1), [K(mpcdt)] and complexes 2 and 3 was calculated in the gas phase using density functional theory (DFT) with the B3LYP hybrid functional, and was used to predict their molecular properties. The electronic excitation energies and intensities of the six lowest-energy spin allowed transitions were calculated using time dependent density functional theory (TD-DFT). © 2013 Elsevier Ltd. All rights reserved.
Synthesis and X-ray structural studies of Cd(II) and Ni(II) complexes of 5-(4-methoxy phenyl), 5-(2-pyridyl) and 5-(2-methoxy phenyl)-1,3,4-oxadiazole-2- thione
(2012) M.K. Bharty; A. Bharti; R.K. Dani; R. Dulare; P. Bharati; N.K. Singh
Three new mixed ligand complexes [Cd(en) 2(4-mpot) 2] (1) [Ni(2-pytone) 2(en) 2] (2) and [Ni(2-mpot) 2(en) 2] (3) {4-mpot = 5-(4-methoxy-phenyl)-1,3,4- oxadiazole-2-thione, 2-pytone = 5-(2-pyridyl)-1,3,4-oxadiazole-2-thione, 2-mpot = 5-(2-methoxy-phenyl)-1,3,4-oxadiazole-2-thione} have been prepared containing en as co-ligand. Potassium N-(4-methoxy benzoyl)-hydrazinecarbodithioate cyclized to 5-(4-methoxy-phenyl)-1,3,4-oxadiazole-2-thiol on addition of tetrabutylammonium bromide which then reacted with Cd(OAc) 2· 2H 2O and ethylenediamine to form complex 1, whereas potassium N-(2-methoxy benzoyl/pyridine-2-carbonyl)-hydrazinecarbodithioates (RCONHNHCSSK) underwent cyclization during complexation in the presence of en to give the complexes of the corresponding 5-aryl-1,3,4-oxadiazole-2-thiones. The complexes have been characterized by physicochemical techniques and single crystal X-ray structure determination. In the complexes the metal center has a six coordinate octahedral arrangement coordinated by 4N atoms of two en and two covalently bonded N atoms of the oxadiazole-2-thione anions. All the complexes contain extended hydrogen bonding providing supramolecular framework. © 2011 Elsevier B.V. All rights reserved.
Synthesis, spectral, thermal and structural characterization of a hexanuclear copper(I) cluster and a cobalt(III) complex of 1-ethyl-3-phenyl-thiourea
(Elsevier Ltd, 2015) A. Singh; M.K. Bharty; P. Bharati; A. Bharti; Sanjay Singh; N.K. Singh
1-Ethyl-3-phenyl-thiourea (Heptu, 1) forms a hexanuclear complex, [Cu6(eptu)6] (2), and a mononuclear complex, [Co(eptu)3] (3), which have been characterized with the aid of elemental analyses, IR, magnetic susceptibility and single crystal X-ray diffraction data. The ligand (1) and [Co(eptu)3] (3) crystallize in the triclinic system whereas [Cu6(eptu)6] (2) crystallizes in the monoclinic system, with the respective space groups P1¯, P21/c and P1¯. The unit cell of complex 2 consists of two identical units, each containing three interacting Cu(I) ions. Out of which Cu1 and Cu2 are tetrahedrally bonded by two sulfur atoms, one nitrogen and one Cu3 ion, whereas each Cu3 ion is bridged between Cu1 and Cu2 and bonded to two sulfur and one nitrogen, having a trigonal bipyramidal geometry. Thus Cu1 and Cu2 have coordination number of four, while Cu3 is five coordinate. The ligand acts as uninegative tridentate in complex 2, bonding through the thioamide nitrogen and sulfur atoms, and bridging between two copper centers, whereas the ligand acts as uninegative chelating N,S bidentate in complex 3, forming three four-membered CNSCo chelate rings. The crystal structures of the ligand and complexes are stabilized by various types of inter and intramolecular hydrogen bonding, providing supramolecular frameworks. The course of the thermal degradation of complex 2 has been investigated by TG-DTA. © 2014 Elsevier Ltd. All rights reserved.