Sandipan Sarkar

A highly selective fluorescent chemosensor for zinc ion and imaging application in living cells.

A new 2,6-bis(5,6-dihydrobenzo[4,5]imidazo[1,2-c]quinazolin-6-yl)-4-methylphenol (1) serves as a highly selective and sensitive fluorescent probe for Zn(2+) in a HEPES buffer (50 mM, DMSO:water = 1:9 (v/v), pH = 7.2) at 25 °C. The increase in fluorescence in the presence of Zn(2+) is accounted for by the formation of dinuclear Zn(2+) complex [Zn(2)(C(35)H(25)N(6)O)(OH)(NO(3))(2)(H(2)O)] (2), characterized by X-ray crystallography. The fluorescence quantum yield of the chemosensor 1 is only 0.019, and it increases more than 12-fold (0.237) in the presence of 2 equiv of the zinc ion. Interestingly, the introduction of other metal ions causes the fluorescence intensity to be either unchanged or weakened. By incubation of cultured living cells (A375 and HT-29) with the chemosensor 1, intracellular Zn(2+) concentrations could be monitored through selective fluorescence chemosensing.

Separation of the 90Sr–90Y pair with cerium(IV) iodotungstate cation exchanger

A new inorganic ion exchanger, cerium(IV) iodotungstate, has been synthesized and characterized by elemental analysis and IR spectroscopy. This inorganic material is very stable thermally, chemically and with respect to radiation. Its ion exchange capacity for alkali and alkaline earth metal ions has been studied. (90)Y has been successfully separated from its parent (90)Sr in the equilibrium mixture with this exchanger at pH 6.0 with 0.0063 M EDTA solution as an eluent.

Copper(II) complexes of tridentate SNO ligands: synthesis, characterization and crystal structure

A new series of binary copper(II) complexes, [Cu(L)2] (2) [where L is a monobasic tridentate methylthioazophenolate having NSO donor sets], has been synthesized. The reddish brown colored complexes have been characterized by elemental analyses, spectroscopic and other physico-chemical tools. The detailed structure analysis of one of the complexes, [Cu(1a)2] (2a), by single-crystal X-ray crystallography shows that thioether-S donor center participates in coordination with the copper(II) ion with a weak interaction with long Cu–S(thioether) bond distances [2.956(2) Å and 2.925(2) Å]. Electrochemical study of the complexes in methanol using TBAP as supporting electrolyte shows that heterogeneous electron-transfer rate is low at the applied potential.

A novel aluminum vanadate ion exchanger and its use for separation of 137mBa, 115mIn and 110mAg from 137Cs, 115Cd and 198Au, respectively

A newly designed inorganic ion exchanger, based on aluminum vanadate, has been synthesized and characterized by elemental analysis, spectroscopic tools and powdered X-ray diffraction. The insoluble poorly polycrystalline material is highly stable towards thermal and radiation doses and in various chemical environments. The data of exchange capacities of the solid material for the different alkali and alkaline metal ions determined by batch technique show that the compound can be employed as an ion exchanger. The successful radiochemical separations of the no carrier added daughter nuclides; (137m)Ba and (115m)In from their respective parents present in equilibrium mixtures have been carried out using this material. Elutions of (137m)Ba and (115m)In were performed using 0.0426molL(-1) ascorbic acid solution and 4.0molL(-1) HCl, respectively, after sorption of the equilibrated mixtures (137)Cs-(137m)Ba at 0.01molL(-1) HCl medium and (115)Cd-(115m)In at pH 7.0, respectively. In another column operation, it has been observed that the separation of gold and silver is possible with the help of the eluents, 0.01% alcoholic solution of Rhodamine-B for gold and 0.5% thiourea solution in 0.1molL(-1) HClO(4) for silver, respectively, after the sorption of no carrier added onto this material at pH 2.0, at a no carrier added level.

Syntheses, crystal structures, and DNA-binding of some nickel(II) complexes of 1,3-bis(2-pyridylmethylthio)propane and pseudohalides

A series of neutral octahedral nickel(II) complexes of 1,3-bis(2-pyridylmethylthio)propane (L) and pseudohalide (X), formulated as [NiII(L)X2] (where X = azide (1), cyanate (2), and isothiocyanate (3)), was synthesized. The complexes were characterized by physico-chemical and spectroscopic methods, and 1 and 3 also by single-crystal X-ray diffraction analyses. The structural study shows nickel in a distorted octahedral geometry comprised of the tetradentate NSSN ligand with trans pyridines and monocoordinated pseudohalides in cis positions. In dimethylformamide solution, the complexes had quasi-reversible NiII/NiIII redox couples in cyclic voltammograms with E 1/2 values of +0.732, +0.747, and +0.815 V for 1, 2, and 3, respectively. To examine the biological activities of these complexes, interaction of 3 with calf thymus DNA was studied spectroscopically, showing groove-binding interaction.

Coordination behavior of symmetrical hexadentate O2N2S2-donor Schiff bases toward zinc (II): synthesis, characterization, and crystal structure

Two series of zinc(II) complexes of two Schiff bases (H2L1 and H2L2) formulated as [Zn(HL1/HL2)]ClO4 (1a and 1b) and [Zn(L1/L2)] (2a and 2b), where H2L1 = 1,8-bis(salicylideneamino)-3,6-dithiaoctane and H2L2 = 1,9-bis(salicylideneamino)-3,7-dithianonane, have been prepared and isolated in pure form by changing the chemical environment. Elemental, spectral, and other physicochemical results characterize the complexes. A single crystal X-ray diffraction study confirms the structure of [Zn(HL1)]ClO4 (1a). In 1a, zinc(II) has a distorted octahedral environment with a ZnO2N2S2 chromophore.

Trichloro-mono- β -diketonato oxorhenium(V) complexes: synthesis, characterization and crystal structure

Oxorhenium(V) complexes of β-diketonate systems have been synthesized and isolated in pure form. The red complexes n-Bu4N[ReO(R1COCHCOR2)Cl3] (acac, R1=R2=CH3; bzac, R1=CH3 and R2=C6H5; bzbz, R1=R2=C6H5) have been characterized by elemental analyses, spectroscopic and other physico-chemical tools. One complex, n-Bu4N[ReO(bzbz)Cl3] (1c) has been subjected to single-crystal X-ray analysis. In the structure of the anion, the metal has a six-coordinate octahedral environment in which the bidentate β-diketone ligand is cis and trans to the terminal oxygen.

Synthesis, characterization, crystal structure and DNA-binding study of four cadmium(II) pyridine-carboxamide complexes

AbstractTreatment of perchlorate or nitrate salt of cadmium(II) with carboxamide derivatives (L) generated four novel mononuclear metal complexes, represented as [Cd(L )4](ClO4)2 (1a and 1b) and [Cd(L)2(ONO2)2] (2a and 2b) in appreciable yields (L = L1 = N-(furan-2-ylmethyl)-2-pyridine carboxamide and L = L2 = N-(thiophen-2-ylmethyl)-2-pyridine carboxamide). The complexes have been characterized by FT-IR, UV-Visible, elemental analysis and single crystal X-ray crystallographic analysis which revealed eight coordinated cadmium ions, but in different coordination environments, depending on the counter anion used. In addition, electronic absorption, fluorescence spectroscopy and viscosity measurements revealed a significant interaction of the four complexes with CT-DNA via intercalative/groove binding mode. The intrinsic binding constant Kb obtained varies from 0.4 × 10 4 to 1.11 × 10 5 M−1. The results suggest that neutral complexes 2a and 2b bind to DNA in an intercalative mode. On the other hand, cationic complexes 1a and 1b bind with DNA via weak electrostatic/covalent interaction. Graphical AbstractSynthesis and characterization of four mononuclear eight coordinated cadmium(II) complexes with newly explored carboxamide derivatives and study of interaction with calf-thymus DNA are reported. The results suggest that neutral complexes 2a and 2b bind to DNA in an intercalative mode. On the other hand, cationic complexes 1a and 1b interact with DNA via weak intercalative or groove binding mode.

Synthesis and characterization of mononuclear copper(II) complex of tetradentate N2S2 donor set and the study of DNA and bovine serum albumin binding

One mononuclear copper(II) complex, containing neutral tetradentate NSSN-type ligands, of formulation [Cu II(L 1)Cl]ClO 4 (1), was synthesized and isolated in pure form [where L 1˭ 1,3-bis(3-pyridylmethylthio)propane]. Green-colored copper(II) complex was characterized by physicochemical, spectroscopic methods and conductivity measurement. These experimental data matched well with the proposed structure of the complex. Biological activity of the complex (1) toward calf thymus DNA and bovine serum albumin has been examined systematically and groove-binding behavior of the Copper(II) complex 1 with calf thymus DNA has been observed from the spectral study.

Preparation, characterization, and evaluation of an inorganic ion exchanger in separation of carrier-free 137mBa from 137Cs

A novel inorganic ion exchanger, aluminum tungstate, was prepared and characterized by spectroscopic tools and elemental analysis. The compound is resistant to heat and radiation and is stable in diverse chemical environments. This material exhibits an excellent adsorption of parent-daughter 137Cs-137mBa. The newly prepared crystalline inorganic ion exchanger was employed for separation of the carrier-free 137mBa from 137Cs using 0.0426 M ascorbic acid solution as eluting agent. Trend in elution is encouraging to apply the system as radionuclide generator.