• S Rajagopal

Articles written in Journal of Chemical Sciences

• Separation of electronic and steric effects: Oxidation ofortho-substituted phenyl methyl sulphides by peroxoanions, chromium(VI) and picolinic acid catalysed chromium(VI)

The kinetics of oxidation ofortho-substituted phenyl methyl sulphides by peroxoanions, Cr(VI) and picolinic acid catalysed Cr(VI) have been investigated. Regression analyses of the rate data by using Taft and Charton equations to separate steric effect from electronic effects have been carried out. In peroxoanion oxidations, the localized electronic effect plays a major role. In the uncatalysed and picolinic acid catalysed Cr(VI) oxidations, both localized and delocalized effects are significant. Steric effect plays a minor role in all the oxidations

• A novel nickel trihydroxy isocyanate — preparation and characterisation

The preparation of a novel nickel trihydroxy isocyanate, along with its distinguishing physicochemical characteristics has been reported for the first time.

• Basic aluminium succinate: An alumina precursor formed by precipitation from homogeneous solution

Precipitation from a homogeneous solution of aluminium nitrate by neutralisation using urea in presence of succinic acid leads to the formation of a well-defined alumina precursor, basic aluminium succinate, which on calcination yields microspheroidal γ-alumina with excellent free-flowing characteristics.

• Abstracts of posters presented at the symposium

• Mechanism of permanganate ion oxidation of diaryl sulphoxides — A kinetic study

The oxidation of 4,4′-disubstituted diphenyl sulphoxides by potassium permanganate on Hammett type correlations give a small positive ρ value (0.34). This is in contrast to the oxidation of aryl methyl sulphides (ρ = −1.36) by the permanganate ion. On the basis of rate data a mechanism of nucleophilic attack of MnO4 on the substrate has been proposed.

• Excited state electron transfer reactions of tris(2,2′-bipyridine) chromium (III) ion with organic sulphides

The quenching rate constants,kq, for the excited state electron transfer reactions oftris(2,2′-bipyridine)chromium(III) ion with several aryl methyl sulphides (ArSMe) obtained by the luminescence quenching technique, are accelerated by electron releasing groups and retarded by electron withdrawing groups present in the aryl moiety of ArSMe. The plot ofRT Inkq vs.E1/2 values of different sulphides is linear, indicating the electron transfer nature of the reaction. Studies with alkyl phenyl sulphides demonstrate the importance of the steric effect in these photoredox reactions.

• Abstracts

• Nonadiabaticity in the photoinduced electron transfer reactions of metal complexes

The rate of electron transfer (ET) in a variety of chemical and biological processes is influenced by factors like the free energy change (†G), the donor-acceptor electronic coupling and the medium. The effect of donor-acceptor electronic coupling on the rate of photoinduced intermolecular electron transfer is considered by taking Ru(II) and Cr(III) metal complexes in the excited state as electron acceptors and organic compounds as electron donors. The electronic coupling between the donor and acceptors depends strongly on donor-acceptor distance. The electron transfer distance is varied by introducing alkyl groups of different sizes either on the bipyridine ligand of the metal complex or on the quencher. The semiclassical theory of electron transfer expresses kET as the product of a nuclear and an electronic transmission coefficient (Kn andKel respectively) and an effective nuclear-vibration frequency (vn),kET =vnKel, Kn. The electron transfer reaction becomes nonadiabatic if the donor-acceptor distance is long. The change of electron transfer mechanism from adiabatic to nonadiabatic due to the introduction of bulky groups is explained in terms of semiclassical theory and from the temperature-dependence study of photoinduced electron transfer reactions of metal complexes.

• Excited state reaction of [(2-carboxypyridinato)bis(2,2$\bullet$-bipyridine)ruthenium(II)] ion with phenolate ions

• # Journal of Chemical Sciences

Volume 134, 2022
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019