K. Hussain Reddy

Synthesis, spectral studies and nuclease activity of mixed ligand copper(II) complexes of heteroaromatic semicarbazones/thiosemicarbazones and pyridine

Abstract Pyridine adducts of copper(II) complexes with thiosemicarbazones and semicarbazones have been synthesized and characterized using elemental analyses, molar conductance, IR spectra, magnetic measurements, electronic and ESR spectra. Copper(II) adducts show quasi-reversible responses (Δ E p =100 mV) in cyclic voltammograms with E 1/2 =0.510–0.535 V versus Ag|AgCl at room temperature in N , N -dimethylformamide, attributable to a Cu III /Cu II couple. The spectral studies support the distorted octahedral geometry of these copper(II) adducts. The nucleolytic cleavage activity of all the copper(II) adducts was carried out on double-stranded pBR 322 circular plasmid DNA by using the gel electrophoresis experiment in the presence and absence of oxidant (H 2 O 2 ). In the absence of oxidant a less discernible DNA cleavage was observed, whereas in the presence of oxidant (H 2 O 2 ) all adducts showed increased nuclease activity.

Analytical properties of 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone: simultaneous spectrophotometric determination of copper(II) and nickel(II) in edible oils and seeds

The analytical properties of 1-phenyl-1,2-propanedione-2-oxime thiosemi-carbazone (PPDOT) are described for the first time. The reagent gives colour reactions with copper(II) and nickel(II) in sodium acetate-acetic acid buffer medium. The copper complex shows maximum absorbance at 465 nm while the nickel complex at 395 nm. Therefore, these colour reactions have been advantageously used for the simultaneous spectrophotometric determination of copper(II) and nickel(II) in synthetic mixture and also in edible oils and seeds.

Transition metal complexes of benzil-α-monoxime (BMO); X-ray structure determination of Co(BMO)3

Abstract Cobalt(III), nickel(II) and copper(II) complexes of benzil-α-monoxime (BMO) have been synthesized and characterized by elemental analyses, conductivity, magnetic susceptibility measurements, IR and electronic spectral data. The molar conductivity data show them to be non-electrolytes. The monoanionic bidentate behavior of BMO is inferred from IR spectral studies. The electronic spectral data suggest planar geometry for nickel(II) and copper(II) complexes. The nickel complex assumes an octahedral structure in a coordinating solvent (N,N-dimethylformamide (DMF)). The [Co(BMO)3] complex has been isolated as a single crystal and its structure was determined by X-ray diffraction. X-ray data confirms the presence of a fac-octahedral configuration for this complex. Electrochemical studies suggest that the cobalt complex undergoes two single one-electron reduction steps corresponding to Co(III)→Co(II) and Co(II)→Co(I).

Heavy metal ion uptake properties of polystyrene-supported chelating polymer resins

Metal ion uptake properties of polystyrene-supported chelating polymer resins functionalized with (i) glycine, (ii) hydroxy benzoic acid, (iii) Schiff base and (iv) diethanol amine have been investigated. The effects of pH, time and initial concentration on the uptake of metal ions have been studied. The uptake of metal ion depends on pH. The resins are more selective at pH 10 for Pb(II) and Hg(II), whereas at pH 6 they are found to be Cd(II) and Cr(VI) selective. Metal ion uptake properties of resins follow Freundlich’s equation. The resins are recyclable and are therefore employed for the removal of heavy metal pollutants from industrial waste water.

Nuclease activity of 2-substituted heteroaromatic thiosemicarbazone and semicarbazone copper(II) complexes

Copper(II) Schiff base complexes derived from furan-2-carboxaldehyde, 2-furylmethyl ketone, thiophene-2-carboxaldehyde and methyl-2-thienyl ketone with semicarbazide and thiosemicarbazide have been prepared and characterized by analytical, i.r., electronic, e.s.r. and c.v. spectral data. The electronic spectral d–d band position varies from 744–415 nm in pyridine and 872–371 nm in DMF. E.s.r. g∥ values lie between 2.1439 and 2.3149 at LNT. All complexes undergo quasi-reversible one-electron electrochemical reduction (CuIII/CuII) in the 0.42–0.52 V potential range. The electron transfer is much faster in thiosemicarbazone complexes compared to semicarbazone complexes. All these copper(II) complexes showed increased nuclease activity in presence of oxidant.

Nuclease activity of mixed ligand complexes of copper(II) with heteroaromatic derivatives and picoline

New picoline adducts with carbamic acid [(furan-2-yl)methylene]hydrazide–CuII (CFMH) (1); thiocarbamic acid [(furan-2-yl)methylene]hydrazide–CuII (TFMH) (2); carbamic acid [(furan-2-yl)ethylidene]hydrazide–CuII (CFEH) (3), thiocarbamic acid [(furan-2-yl)ethylidene]hydrazide–CuII (TFEH) (4); carbamic acid [(thiophene-2-yl) methylene]hydrazide–CuII (CTMH) (5), thiocarbamic acid [(thiophene-2-yl)methylene]hydrazide–CuII (TTMH) (6), carbamic acid [(thiophene-2-yl)ethylidene]hydrazide–CuII (CTEH) (7), thiocarbamic acid [(thiophene-2-yl)ethylidene]hydrazide–CuII (TTEH) (8) have been prepared and characterized by analytical, i.r., electronic, e.s.r. and c.v. spectral data. The electronic spectra suggest distorted octahedral geometry for all the picoline adducts. E.s.r. g∥ values lie between 2.251–2.286 at l.n.t. All the adducts undergo a quasi-reversible one-electron reduction in the range +0.47 to +0.51 V versus s.c.e., attributable to the CuIII/CuII redox couple. The electron transfer is much faster in the semicarbazone complexes than in the thiosemicarbazone complexes. All adducts showed increased nuclease activity in the presence of oxidant; the nuclease activity is compared with that of the parent copper(II) complexes.

Spectrophotometric determination of palladium with 5,6-dimethyl-1,3-indanedione-2-oxime.

A rapid, sensitive and selective method has been developed for the determination of palladium with 5,6-dimethyl-1,3-indanedione-2-oxime in acetate buffer (pH 5.5). Beers law is obeyed over the range 0.15-4.17 mug/ml palladium(II). The molar absorptivity at 370 nm is 2.98 x 10(4) 1.mole(-1).cm(-1). The method has been applied for the determination of palladium in synthetic mixtures corresponding to PtIr and Oakay alloys. An interesting feature of the system is the abnormal shape of the Job and molar-ratio plots obtained.

Coordination compounds in biology

Vitamin B12 is an important coordination compound in biology. It is an interesting biomolecule in the sense that no other vitamin contains a metal ion. This is the only naturally occurring organometallic compound found in biology. An intriguing aspect of vitamin B12 is the great stability of the metal-carbon bond. A great deal of new and interesting inorganic chemistry has been uncovered while studying systems pertinent to B12. In this article some salient features of this unique molecule (B12) and its model compounds are presented.

Rapid Spectrophotometric Determination Of Osmium With Cyclohezane 1,3-Dione Bisthiosemicarbazone Monohydrochloride: Simultaneous Determination of Osmium and Platinum

Abstract A simple, sensitive and rapid spectrophotometric method has been developed for the determination of osmium using cyclohexane 1,3-dione bisthiosemicarbazone mono-hydrochloride (1,3-CHDT.HCl). The method is based on the instantaneous colour reaction between 1,3-CHDT. HCl and osmium(VIII) in sodium acetate—acetic acid buffer medium (pH range 3–6). The osmium complex shows maximum absorbance at 375 nm and considerable absorbance at 510 nm. Although the complex formed between platinum(IV) and reagent (1,3-CHDT.HCl) shows maximum absorbance at 375 nm, it does not show any absorbance at 510 nm. Simultaneous determination of osmium and platinum is carried out when present alone and in presence of other foreign (associated) ions. Some physico-chemical and analytical characteristics of osmium and platinum complex are described. Interference of various foreign ions have studied and osmium is estimated selectively in the presence of constituents of platinum ores.

Synthesis, characterization, electrochemistry and axial ligation properties of macrocyclic divalent metal complexes of acetylacetone buckled with different diamines

Abstract A series of macrocyclic nickel(II) copper(II) complexes using acetylacetone and different aliphatic and aromatic diamines (1,2-diamino ethane, 1,2-diamino propane, 1,2-diamino benzene, 1,3-diamino benzene and 3,4-diamino toluene) has been synthesized by the template method. These complexes were characterized by elemental analysis, conductivity measurements, electronic, infrared and NMR spectral data. The molar conductivity data show them to be non-electrolytes. The electronic spectral data in toluene (a non-coordinating solvent) suggest square planar geometry for these complexes. The axial coordination in these complexes is supported by their electronic spectra in dimethylformalide (DMF, a coordinating solvent). Various ESR parameters for all copper complexes have been calculated showing an axial d x 2 − y 2 ground state. The electrochemical behaviour of these complexes has been studied by cyclic voltammetry.