Browsing by Author "Suryabhan Singh"

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A Cu(ii) mediated new desulfurization pathway involving elimination of ethylene sulfide
(2014) Neha Sareen; Suryabhan Singh; Subrato Bhattacharya
Reaction of thiodiacetate anion (tda) with [Cu(TMEDA)(NO3) 2] (TMEDA = N,N,N′N′-tetramethyl ethylene-diamine) in a stoichiometric ratio afforded the complex {[Cu(TMEDA)(tda)]·(H 2TMEDA)(NO3)2·H2O} (1). When [Cu(TMEDA)(NO3)2] was added in excess, it yielded a μ-oxalato complex {[Cu2(TMEDA)2(μ-ox)(H 2O)2](NO3)2·2CH 3CN} (2). The reaction involves a facile room temperature desulfurization of the thiodiacetate moiety via elimination of ethylene sulfide (thiirane). © 2014 The Royal Society of Chemistry.
Lanthanum-based double perovskite oxides as cobalt-free catalyst for bifunctional application in electrocatalytic oxygen reactions
(Elsevier Ltd, 2024) Divya Pratap Singh; Sanjukta Mukherjee; Sweta Bhagat; Nandita Singh; Monika Singh; Akhilesh Kumar Singh; Ashish Kumar Singh; Uday Pratap Azad; Suryabhan Singh; Lalrintluangi; Ved Prakash Singh
Electrochemical water splitting by use of suitable electrocatalysts is an important process to establish water as sustainable energy material. Similarly, the Oxygen reduction reaction is an important step involved in fuel cells. Hence, suitable catalysts are required for low-cost and high-performance activity towards both processes. In this work, we synthesized Cobalt-free Lanthanum-based double Perovskites oxides La0.5Sr0.5Fe0.8Cu0.2O3 and La0.5Sr0.5Fe0.8Zn0.2O3 by sol-gel method followed by calcination at different temperatures (800 °C, 900 °C and 1000 °C). Prepared double Perovskite oxide materials exhibit bifunctional catalytic activity towards both oxygen evolution reaction and oxygen reduction reaction. Calcination temperatures and composition have a significant impact on catalytic performance because of morphological control along with tuning of surface composition. Powder X-ray diffraction study has been performed to characterize the materials and phases/composition of materials was further analyzed by Rietveld refinement. The morphology of the best catalyst was analyzed by SEM, EDS mapping and XPS analysis. The catalytic performances of the catalysts were examined using electrochemical methods such as linear sweep voltammetry, cyclic voltammetry and electrochemical impedance spectroscopy in 0.1 M KOH solution. Preparation of noble-metal/cobalt-free catalysts is important finding towards establishing water as potential source for hydrogen production. © 2023 Hydrogen Energy Publications LLC
Modulation of catalytic activity of BSCF towards electrochemical oxygen reactions using different synthetic approaches
(Elsevier Ltd, 2024) Sweta Bhagat; Nandita Singh; Monika Singh; Ashish Kumar Singh; Suryabhan Singh; Uday Pratap Azad; Akhilesh Kumar Singh
This study is focused on the synthesis of the perovskite oxide materials, particularly Ba0.5Sr0.5Co0.8Fe0.2O3-δ, using different synthetic approaches (sol-gel and co-precipitation techniques) and different complexing agents and fuels and their applications for electrochemical water splitting and fuel cells. Prepared perovskite oxide materials exhibits dual catalytic behaviour as it shows the catalytic activity toward the oxygen evolution and reduction reactions in alkaline solution. The Ba0.5Sr0.5Co0.8Fe0.2O3-δ electrocatalyst exhibits remarkable efficiency and durability for the OER in basic electrolytes, with a Tafel slope of 70.38 mV/dec for Best catalyst. The best ORR activity observed for Ba0.5Sr0.5Co0.8Fe0.2O3-δ synthesized using citric acid shows Tafel slope of 356.43 mV/dec. These oxide materials also show enhanced efficiency in capacitive applications. Additionally, the prepared perovskite oxide materials have been characterized by Powder X-ray diffraction, Le-Bail refinement, scanning electron microscopy, Energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy analysis, and high-resolution Transmission Electron Microscopy. Electrochemical techniques such as linear sweep voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy techniques were used to assess the catalytic performance of the prepared electrocatalysts in 0.1M KOH solution. © 2024 Hydrogen Energy Publications LLC
N-(Prop-2-yn-1-yl)-1,3-benzothiazol-2-amine
(2011) Alka Agarwal; Manavendra Kumar Singh; Suryabhan Singh; S. Bhattacharya; Satish K. Awasthi
In the title compound, C 10H 8N 2S, the 2-amino-benzothia-zole and propyne groups are not coplanar [dihedral angle = 71.51 (1)°]. The crystal structure is stabilized by strong inter-molecular N-H⋯N hydrogen bonds and C-H⋯C, C-H⋯π and F-type aromatic-aromatic [centroid-centroid distance = 3.7826 (12) Å] interactions are also observed.
Nanotechnology applications in pandemic prediction
(Elsevier, 2025) Nandita Singh; Kalyani Dewangan; Jitendra Sahu; Uday Pratap Azad; Divyanshu Singh; Sweta Bhagat; Ashish Kumar Singh; Suryabhan Singh; Sunil Kumar Singh; Ananya Srivastava; Divya Pratap Singh
The necessity for novel ways utilizing nanotechnology in antiviral tactics is demonstrated by the continuous fight against viral infections, which has been brought to light by the COVID-19 outbreak. With so many potential applications-biosensors, vaccines, disinfectants, and nanoparticles/functionalized nanoparticles have become increasingly attractive tool in the battle against viral epidemics. The function of nanoparticles in pandemic control is assessed in this book chapter, and their possible uses, advantages, and drawbacks are examined. The significance of nanotechnology in managing viral outbreaks, namely in vaccine development, is the first topic we cover. Although the use of metallic nanoparticles to functionalize protective face masks has become popular as a sustainable substitute for throwaway masks, improving virus filtering and cutting down on waste generation, incorrect disposal of these masks might pollute the environment and even cause ecological damage. In our second section, we will discuss various types of nanoparticles or functionalized nanoparticles-based sensors to detect the pandemic associated viruses at very early stage. For this purpose, along with various types of nanoparticle based-sensors, the selection of appropriate electrochemical techniques is also equally important for the better performance of the constructed biosensors. Along with COVID-19 we will discuss other pandemics such as swine flu, HIV/AIDS, and black death. We must reduce such possible dangers and environmental effects in order to properly control outbreaks. For this reason, it is essential to comprehend the benefits and drawbacks of using nanoparticles while creating efficient plans for controlling pandemics moving forward. © 2025 Elsevier Inc. All rights reserved.
New ternary compounds containing Zn-Cu and Zn-Ag from single molecular source precursors
(2014) Suryabhan Singh; Jyotsna Chaturvedi; Subrato Bhattacharya
Heterobimetallic complexes [(PPh3)Cu(SCOPh) 3Zn(PPh3)] and [(PPh3)2Ag(SCOPh) 2Zn(SCOPh)(0.5H2O)] were used as single molecular sources for the syntheses of ternary compounds. These complexes upon pyrolysis at 350 °C in the solid state yielded ZnS/CuS and ZnS/Ag2S alloys respectively. In oleylamine solution decomposition of the complexes took place at 165 °C only leading to the formation of the corresponding sulfide nanoparticles. The bulk sulfide materials have been characterized by SEM-EDX, XPS and powder X-ray diffraction techniques. The nanoparticles have been characterized by EDS-elemental mapping and HRTEM. © 2014 The Royal Society of Chemistry.
Phenylmercury(II) methylferrocenyldithiocarbamate-functionalized dye-sensitized solar cells with hydroxy as an anchoring group
(Springer Science and Business Media, LLC, 2015) Ratna Chauhan; Gabriele Kociok-Köhn; Manoj Trivedi; Suryabhan Singh; Abhinav Kumar; Dinesh P. Amalanerkar
A new heterobimetallic phenylmercury(II) dithiocarbamate complex having the ferrocenyl moiety (C5H5)Fe(C5H4) (Fc), PhHgS2CN(CH2Fc)CH2CH2OH, (1) has been prepared and characterized by elemental analyses, UV–vis, IR, 1H and 13C NMR spectroscopies and X-ray crystallography. The crystal structure of 1 showed a linear core at the Hg(II) centre of the molecule bounded by the sulfur atom of the dithiocarbamate ligand and carbon atom of the aromatic ring. Weak intermolecular Hg···S interactions lead to “head to tail” dimer in this compound and presence of hydroxyl group generates one-dimensional chain network. This ferrocenyl-based organomercury(II) dithiocarbamate complex compound comprising of a –OH moiety showed improved light-harvesting properties as a photosensitizer in dye-sensitized solar cells (DSSCs). The short-circuit current and open-circuit potential obtained with this compound were 6.95 mA/cm2 and −0.645 V, respectively, resulting in the enhanced overall conversion efficiency of 3.2 %.; [Figure not available: see fulltext.] © 2014, Springer-Verlag Berlin Heidelberg.
ROS and RNS induced apoptosis through p53 and iNOS mediated pathway by a dibasic hydroxamic acid molecule in leukemia cells
(Elsevier B.V., 2014) Kaushik Banerjee; Avishek Ganguly; Paramita Chakraborty; Avijit Sarkar; Suryabhan Singh; Mitali Chatterjee; Subrato Bhattacharya; Soumitra Kumar Choudhuri
Anticancer drugs induce apoptosis to cancer cells and also exhibit undesired toxicity to normal cells. Therefore development of novel agents triggering apoptosis and have low toxicity towards normal cells is most important. Hydroxamic acids suppress tumour cell growth through apoptosis but the underlying mechanism is poorly understood. Herein, we describe the apoptotic potential of a dibasic hydroxamic acid derivative, viz., oxayl bis (N-phenyl) hydroxamic acid (OBPHA), which induces apoptosis through generation of both ROS and NO in doxorubicin resistant T-lymphoblastic leukemia, CEM/ADR5000 cells. Present study discloses that OBPHA selectively kills cancerous cells irrespective of their drug resistant phenotype. We also determined the crystal structure of OBPHA to understand the structural requirements for apoptosis; the study reveals that the presence of substituted hydroxamic acid groups (-CO-NH-OH) favours the generation of NO possibly through auto degeneration. Along with the induction of caspase 3 mediated intrinsic apoptosis; OBPHA also activates p53 dependent signalling cascade and downregulates HDAC3 expression in a time dependent manner possibly due to increased ROS and NO production and simultaneous decrease in cellular GSH level. Thus ROS and NO mediated downstream signalling are essential for the anticancer effect of OBPHA. Therefore OBPHA, having a structurally relevant pharmacophore provides important insight into the development of new ROS and RNS generating chemicals inducing p53 dependent apoptosis. © 2013 Elsevier B.V. All rights reserved.
Silver(I) catalyzed oxidation of thiocarboxylic acids into the corresponding disulfides and synthesis of some new Ag(I) complexes of thiophene-2-thiocarboxylate
(Elsevier Ltd, 2011) Suryabhan Singh; Jyotsna Chaturvedi; Subrato Bhattacharya; Heinrich Nöth
Aromatic thiocarboxylic acids in presence of a base on treatment with silver nitrate under ambient conditions were oxidized to the corresponding disulfides. The reactions were found to be catalyzed by Ag+ ions. The catalytic oxidation is paralleled by the Ag(SCOAr) complex formation reaction which could be considerably subsided by adjustment of the reaction conditions. Attempts to use [Ag(PPh3)2]+ or [Ag(PPh 3)]+ ion as the catalyst were unsuccessful as these resulted in the formation of the corresponding thiocarboxylate complexes. The products, ArCOSSCOAr (1, 2), [Ag(SCOAr)(PPh3)2] (3, 4) and [Ag(SCOAr)(PPh3)]4 (5) (Ar = C6H5, C4H3S) were characterized by single crystal X-ray analysis. Compounds 3 and 4 are monomeric while 5 is a cyclic tetramer in the crystalline phase. © 2010 Elsevier Ltd. All rights reserved.
Solvent dependent crystallization of a few Hg(II) thiocarboxylates
(2012) Suryabhan Singh; Jyotsna Chaturvedi; Subrato Bhattacharya
During the process of crystallization of newly synthesized heterobimetallic complexes [(Ph 3P) 2Cu(μ-SCOR) 2Hg(SCOR)] [R = Ph (1), th (thiophene) (2)] Hg(II) thiocarboxylate complexes were isolated. In chloroform/diethyl ether a phosphine migration led to the formation of Hg(Ph 3P)(SCOPh) 2 (3) and Hg(Ph 3P)(SCOth) 2 (4) while in chloroform/n-hexane the binary Hg(II) complexes, Hg(SCOPh) 2 (5) and Hg(SCOth) 2 (6) were isolated. In another reaction a heterobimetallic complex, Hg(SCOPh) 2TiCl 4 (7) was obtained as the end product. Molecular structures of 3, 4 and 6 were studied by single crystal X-ray diffraction. The crystals of 4 provided an interesting example of polytopal isomerism. Structures and electronic transitions have been explained on the basis of DFT calculations. © 2012 Elsevier B.V. All rights reserved.
Studies of structural diversity due to inter-/intra-molecular hydrogen bonding and photoluminescent properties in thiocarboxylate Cu(i) and Ag(i) complexes
(Royal Society of Chemistry, 2014) Suryabhan Singh; Subrato Bhattacharya
Seven new copper(i) thiocarboxylate and two silver thiocarboxylate complexes, containing 2-mercaptobenzimidazole (MB) and 2-mercapto-2-thiazoline (MT) have been synthesized and characterized by elemental analysis, IR, 1H NMR, 13C NMR and UV-Visible spectroscopic techniques. Molecular structures of all the complexes have been examined by single crystal X-ray diffraction analysis. In the case of complexes 1 ([(PPh3)2Cu(SCOMe)MB]) and 3 ([(PPh3)2Cu(SCOth)MB]), the direction of hydrogen bonding is changed from intra-molecular to inter-molecular by increasing the size of the R-group of the thiocarboxylate ligands. 7 ([Cu2(μ-SCOPh)2(μ-MT)(MT)]2) is a tetranuclear complex in which the distance between the two copper atoms is shorter than the sum of the covalent radii of the two atoms without having a formal covalent bond between them, as evidenced by NBO (DFT) calculation and bond critical point calculations using the AIM theory. In complex 8 two different molecules, [(PPh3)2Ag(SCOPh)MT] and [(PPh3)2Ag(SCOPh)] co-crystallized in the same lattice. The unit cell of complex 9 also possesses two structurally different molecules with the same molecular formula. Emission spectra of the complexes have been studied in both solution and solid states. Electronic spectral behaviors of the complexes 1 and 7 have been explained by TDDFT calculations. © the Partner Organisations 2014.
Studies of synthesis, structural features of Cu(i) thiophene-2- thiocarboxylates and unprecedented desulfurization of Cu(ii) thiocarboxylate complexes
(2012) Suryabhan Singh; Jyotsna Chaturvedi; Subrato Bhattacharya
Thiophene-2-thiocarboxylate complexes of Cu(i), [(Ph 3P) 2Cu(SCOth)] (1) and H[(Ph 3P) 2Cu(SCOth) 2] (2) (where th = thiophene) were synthesized and characterized structurally by X-ray crystallography. Electronic absorption and emission spectral properties of the two compounds have been studied. Cu(ii) complexes, [(TMEDA)Cu(SCOth) 2] (3b) and [(Phen)Cu(SCOth) 2] (4a) (where TMEDA = tetramethylethylenediamine; Phen = 1,10-phenanthroline) were prepared and characterized by spectroscopic measurements. 3b and 4a underwent desulfurization under ambient conditions readily yielding the corresponding carboxylate complexes [(TMEDA)Cu(O 2Cth) 2] (3a) and [(Phen)Cu(O 2Cth) 2H 2O] (4b). 3a and 4b have been characterized crystallographically. © 2012 The Royal Society of Chemistry.
Studies of titanocene and zirconocene pyridine-2,6-bis-thiocarboxylates exhibiting partial desulfurization
(Elsevier S.A., 2013) Suryabhan Singh; Subrato Bhattacharya
Attempts to synthesize bent metallocene complexes of pyridine-2,6- bis(thiocarboxylate), Cp2Ti(pdtc) and Cp2Zr(pdtc) yielded partially desulfurized products. In the case of Cp2Ti(IV) two types of products were obtained, in one case desulfurization was at one of the thiocarboxylate groups resulting in a carboxylate group while in the other case it was partial and from both the thiocarboxylate entities. In case of Cp 2Zr(IV) similar partial desulfurization took place from both the thiocarboxylates. The complexes have been characterized by single crystal X-ray diffraction analysis. The ligands pyridine-2-carboxylate-6-thiocarboxylate, pyridine-2,6-dicarboxylate and pyridine-2,6-bis(thiocarboxylate) act as tridentate ligands. With both the metals binding of ligand is through the oxygen (and nitrogen) atoms leaving the sulfur free. Electronic absorption and emission spectra of the compounds have been studied experimentally and explained on the basis of DFT computations. © 2012 Elsevier B.V. All rights reserved.
Supramolecular organotin(IV) framework derived from pyridine-2,6- bis(thiocarboxylate) ligand
(2012) Suryabhan Singh; Subrato Bhattacharya
New trimetallic complexes, [R 2SnPdtc] 3 [where R = Me (1), n-Pr (2) and n-Bu (3), Pdtc = Pyridine-2,6-bis(thiocarboxylate)] have been prepared and characterized by FTIR, and NMR spectroscopies. Molecular structure of the complex 2 has been determined by single crystal X-ray diffraction and interactions of complex 2 with different metal ions in solution have been studied by UV-visible spectroscopic technique. Interactions of metal ions with 2 were dependent on the nature and bonding behavior of the added metal ions. © 2012 Elsevier B.V. All rights reserved.
Syntheses and structural studies of heterobimetallic thiocarboxylate complexes containing zinc and copper
(Elsevier S.A., 2013) Suryabhan Singh; Jyotsna Chaturvedi; A.S. Aditya; N. Rajasekhar Reddy; Subrato Bhattacharya
Anionic zinc(II) complexes, [Zn(SCOR)3]- [R = th (1)] have been used for the synthesis of heterobimetallic complexes, [(PPh 3)Cu(μ-SCOR)3Zn(PPh3)] [R = Ph (2) and th (3)]. All the three complexes have been characterized by FTIR, 1H and 13C NMR spectroscopy. The synthetic reactions involved phosphine migration from Cu(I) to Zn(II) in the cases of 2 and 3. Molecular structures of the complexes have been determined by single crystal X-ray diffraction and the structural features have been explained on the basis of NBO calculations. The Cu-Zn distance in these molecules are shorter than the sum of their covalent radii indicating the existence of a bond between the metals. Electronic spectral behavior of the complexes have been explained by TDDFT calculations. Luminescence properties of 3 has also been studied in solid state. © 2012 Elsevier B.V. All rights reserved.
Syntheses and structural studies of heterobimetallic thiocarboxylate complexes containing zinc and silver
(Elsevier S.A., 2013) Suryabhan Singh; Jyotsna Chaturvedi; Subrato Bhattacharya
Novel heterobimetallic complexes, [(PPh3)2Ag(μ- SCOth)2Zn(SCOth)(H2O)] (1) and {[(PPh3) 2Ag(μ-SCOPh)2Zn(SCOPh)(H2O)][(PPh 3)2Ag(μ-SCOPh)Zn(SCOPh)2]} (2) have been prepared and characterized by FTIR, 1H, 13C and 31P NMR spectroscopy. Molecular structures of the complexes have been determined by single crystal X-ray diffraction technique. In these complexes the two metal atoms (Ag and Zn) are held together by bridging (μ-S or μ-O,S) thiocaboxylate groups. The terminal thiocarboxylate ligand binds monodentately (through S) in 1. Structure of 2 is unique as two different molecules, [(PPh3)2Ag(μ-SCOPh)Zn(SCOPh)2] and [(PPh3)2Ag(μ-SCOPh)2Zn(SCOPh)H 2O] co-crystallize in the same lattice. The terminal thiocarboxylate ligand is monodentate (S) in the latter while bidentate (O,S) in the former molecule. Electronic spectral behaviors of the complexes have been explained by TDDFT calculations. Luminescence properties of both have been studied in solid state. © 2013 Elsevier B.V. All rights reserved.
Synthesis and structural studies of organotin(IV) and organolead(IV) thiophene-2-thiocarboxylate
(Wiley-VCH Verlag, 2010) Suryabhan Singh; Subrato Bhattacharya; Heinrich Nöth
A few organotin(IV) ([R2SnCl2], [R3SnCl]; R = Me, Ph, nPr, or nBu) and organolead(IV) ([Ph2PbCl2], [Ph3PbCl]) compounds that contain the thiophene-2-thiocarboxylate ligand have been synthesized and characterized by 1H, 13C, 119Sn NMR; FTIR; and UV/Vis spectroscopy. The molecular structures of some of the compounds were studied by single-crystal X-ray diffraction. Structures and electronic transitions have been explained on the basis of DFT calculations. Organotin ([R2SnCl2], [R3SnCl]; R = Me, Ph, nPr, and nBu) and organolead ([Ph2PbCl2], [Ph3PbCl]) compounds that contain the thiophene-2-thiocarboxylate ligand have been synthesized and characterized by spectral and crystallographic studies. Structures and electronic transitions have been explained on the basis of DFT calculations. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Synthesis of triphenyltin(IV) hydrosulfide
(Elsevier S.A., 2011) Suryabhan Singh; Subrato Bhattacharya
Compounds of the type R3SnSH are believed to be unstable (unless sterically protected by very bulky R groups) because of their facile condensation into the corresponding sulfide, (R3Sn)2S. One such compound, Ph3SnSH has been synthesized by an one pot reaction of triphenyltin hydroxide with thiophosgene followed by the hydrolysis of the intermediate triphenyltin chlorothioformate. The product, triphenyltin hydrosulfide has been characterized by IR, 1H, 13C and 119Sn NMR spectral techniques. Single crystal X-ray analysis revealed that the molecule is a discrete monomer containing tin atom at the centre of a distorted tetrahedron. Plausible reaction mechanism for the formation of the molecule has also been reported. © 2010 Elsevier B.V. All rights reserved.
The chemistry of cadmium-thiocarboxylate derivatives: Synthesis, structural features, and application as single source precursors for ternary sulfides
(2011) Jyotsna Chaturvedi; Suryabhan Singh; Subrato Bhattacharya; Heinrich Nöth
Novel heterobimetallic complexes [(PPh3)2Cu(μ- SCOPh)2Cd(SCOPh)] (2a), [(PPh3)2Cu(μ-SCOth) 2Cd(SCOth)] (2b), [(PPh3)2Ag(μ-SCOth) 2Cd(SCOth)] (3a), [(PPh3)2Ag(μ-SCOth) 2Cd(H2O)(SCOth)] (3b), [(PPh3) 2Ag(μ-SCOPh)2Cd(SCOPh)] (3c), and a bimetallic complex [PPh3Cd(μ-SCOth)SCOth]2•CH2Cl 2 (5) (th = thiophene) were prepared and characterized by single crystal X-ray diffraction analysis. A coordination polymer [Cd(SCOPh) 2]n (4) has also been characterized structurally that exhibited metal-like electrical conductivity. The heterobimetallic complexes on pyrolyzing under controlled conditions yielded ternary sulfides of composition CuCd7S8, CuCd10S11, Ag 2Cd8S9, and Ag2Cd5S 6, which have been characterized by SEM-EDX and X-ray diffractometry. Photophysical properties and electrical conductivities of the sulfides have also been studied. © 2011 American Chemical Society.