Suryabhan Singh

The chemistry of cadmium-thiocarboxylate derivatives: synthesis, structural features, and application as single source precursors for ternary sulfides.

Novel heterobimetallic complexes [(PPh(3))(2)Cu(μ-SCOPh)(2)Cd(SCOPh)] (2a), [(PPh(3))(2)Cu(μ-SCOth)(2)Cd(SCOth)] (2b), [(PPh(3))(2)Ag(μ-SCOth)(2)Cd(SCOth)] (3a), [(PPh(3))(2)Ag(μ-SCOth)(2)Cd(H(2)O)(SCOth)] (3b), [(PPh(3))(2)Ag(μ-SCOPh)(2)Cd(SCOPh)] (3c), and a bimetallic complex [PPh(3)Cd(μ-SCOth)SCOth](2)·CH(2)Cl(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 CuCd(7)S(8), CuCd(10)S(11), Ag(2)Cd(8)S(9), and Ag(2)Cd(5)S(6), which have been characterized by SEM-EDX and X-ray diffractometry. Photophysical properties and electrical conductivities of the sulfides have also been studied.

Phenylmercury(II) methylferrocenyldithiocarbamate-functionalized dye-sensitized solar cells with hydroxy as an anchoring group

AbstractA 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 6.95xa0mA/cm2 and −0.645xa0V, respectively, resulting in the enhanced overall conversion efficiency of 3.2xa0%.n Graphical AbstractA new heterobimetallic phenylmercury(II) dithiocarbamate complex incorporating the ferrocenyl moiety (C5H5)Fe(C5H4) (Fc), PhHgS2CN(CH2Fc)CH2CH2OH, (1) has been prepared and its light-harvesting property was investigated in dye-sensitized solar cells (DSSCs).

ROS and RNS induced apoptosis through p53 and iNOS mediated pathway by a dibasic hydroxamic acid molecule in leukemia cells

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.

Studies of structural diversity due to inter-/intra-molecular hydrogen bonding and photoluminescent properties in thiocarboxylate Cu(I) and Ag(I) complexes

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.

Solid polymer electrolytes based on Li+/ionic liquid for lithium secondary batteries

Ionic liquid (IL)-based solid polymer electrolytes (SPEs) were synthesized by solution cast technique using polymer polyethylene oxide (PEO), lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) salt, and IL 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl) imide (BMIMTFSI). The obtained polymer electrolytes (PEO + 20xa0wt.% LiTFSI) + x wt.% BMIMTFSI where xxa0=xa00, 5, 10, 15, and 20 were characterized by DSC, TGA, SEM, XRD, FTIR, electrochemical impedance spectroscopy (EIS), cyclic voltammetry, chronoamperometry, and chronocharge-discharge. Ionic conductivity of optimized composition SPE (PEO + 20xa0wt.% LiTFSI) + 20xa0wt.% BMIMTFSI is ∼1.5xa0×xa010−4xa0Sxa0cm−1 at 30xa0°C and follows Arrhenius-type thermally activated behavior. The prepared SPEs are free-standing and flexible with excellent thermal and mechanical stabilities. SEM, XRD, and DSC studies show that the amorphicity of SPEs increases on increasing IL content due to the plasticization effect of IL. The assembled cell exhibits good electrochemical stability and cationic transference number tLi+∼0.27

New ternary compounds containing Zn–Cu and Zn–Ag from single molecular source precursors

{t}_{{mathrm{Li}}^{+}}sim 0.27

Silver(I) catalyzed oxidation of thiocarboxylic acids into the corresponding disulfides and synthesis of some new Ag(I) complexes of thiophene-2-thiocarboxylate

. The capacity of cell, Li | PEO + 20xa0wt.% LiTFSI + 20xa0wt.% BMIMTFSI | LiMn2O4, shows a stable cyclic performance and high Coulombic efficiency.

Synthesis and Structural Studies of Organotin(IV) and Organolead(IV) Thiophene-2-thiocarboxylate

In the title compound, C10H8N2S, the 2-aminobenzothiazole and propyne groups are not coplanar [dihedral angle = 71.51u2005(1)°]. The crystal structure is stabilized by strong intermolecular N—H⋯N hydrogen bonds and C—H⋯C, C—H⋯π and F-type aromatic–aromatic [centroid–centroid distance = 3.7826u2005(12)u2005Å] interactions are also observed.