Peroxydisulfate activation by [RuII(tpy)(pic)(H2O)]+. Kinetic, mechanistic and anti-microbial activity studies

The oxidation of Ru(II)(tpy)(pic)H(2)O](+) (tpy = 2,2',6',2'-terpyridine; pic(-) = picolinate) by peroxidisulfate (S(2)O(8)(2-)) as precursor oxidant has been investigated kinetically by UV-VIS, IR and EPR spectroscopy. The overall oxidation of Ru(II)- to Ru(IV)-species takes place in a consecutive manner involving oxidation of Ru(II)(tpy)(pic)H(2)O](+) to Ru(III)(tpy)(pic)(OH)](+), and its further oxidation of to the ultimate product Ru(IV)(tpy)(pic)(O)](+) complex. The time course of the reaction was followed as a function of S(2)O(8)(2-)], ionic strength (I) and temperature. Kinetic data and activation parameters are interpreted in terms of an outer-sphere electron transfer mechanism. Anti-microbial activity of Ru(II)(tpy)(pic)H(2)O](+) complex by inhibiting the growth of Escherichia coli DH5α in presence of peroxydisulfate has been explored, and the results of the biological studies have been discussed in terms of the Ru(IV)(tpy)(pic)(O)](+) mediated cleavage of chromosomal DNA of the bacteria.