No abstract

No abstract

Four mononuclear complexes of Cu(II) and Zn(II) having a Schiff-base ligand and 1,10-phenanthroline/2,2 0 -bipyridine have been synthesized and characterized. From electronic spectral and magnetic susceptibility data, octahedral geometry has been proposed for the complexes. DNA-binding behaviors of these complexes are studied by absorption titration, electrochemical, and viscosity methods. The results indicate that the complexes bind to calf thymus DNA in an intercalative mode. The gel electrophoresis results reveal that 1 cleaves pBR322 DNA effectively. The ligand and its complexes have been screened for their antimicrobial activities against a few microorganisms. The data exhibit that they are better antimicrobial agents than the ligand.

No abstract

The kinetics of oxidation of phenyl methyl sulphide (PMS) and several para-substituted phenyl methyl sulphides by pyridinium chlorochromate have been studied in binary solvent mixtures of 60% (v/v) aqueous acetic acid and 50% (v/v) chlorobenzene-nitrobenzene. Acrylonitrile has no effect on the rates of oxidation. In aqueous acetic acid, there is overall second-order reaction. The Hammett p value of -2.1 2 0.09 ( r 0.985, s 0.104) at 50 "C indicates an electron-deficient transition state. In chlorobenzenenitrobenzene there is an association equilibrium prior to the rate-limiting step, followed by irreversible decomposition of the complex into products. The complex formation constants (K) and the complex decomposition rate constants (k, ) have been computed from the double reciprocal plots of 1 /kobs versus 1 /[PMS],. The decomposition rate constants (k,) correlate well with Hammett CJ values (p -1.23 f 0.054, r 0.989, s 0.068 at 50 " C ) . On the basis of the results of the kinetic studies, a suitable mechanism has been proposed.Much attention has been paid recently to the oxidation of organic sulphur compounds to sulphoxide. '-lo The mechanism of these oxidations is largely dependent on the nature of the oxidants. The mechanism of these oxidations can be classified broadly into two types. Mechanism (1) involves reversible complex formation between substrate and oxidant in a fast step followed by slow irreversible decomposition of the complex into product^.^" In mechanism (2) complex formation is a slow step