Mechanistic aspects of ligand substitution on [(H2O)(tap)2RuORu(tap)2(H2O)]2+ {tap=2-(m-tolylazo)pyridine} ion by three glycine-containing dipeptides in aqueous medium at physiological pH

Journal of Chemical Sciences

Subala Mondal¹  Biplab K Bera¹  Parnajyoti Karmakar¹  Subhasis Mallick¹  Alak K Ghosh1¹  Arup Mandal¹ 

[1] Department of Chemistry, The University of Burdwan, Burdwan 713 104, India$$

关键词: Ligand substitution;    dipeptides;    cis-diaqua-bis-{2-(m-tolylazo)pyridine} ruthenium(II);    kinetics.;   

DOI  :  

来源: Indian Academy of Sciences

【 摘 要 】

The interaction of the title complex with selected glycine-containing dipeptides(L-L'H) such as glycyl-glycine(L-L1H), glycyl-L-alanine (L-L2H) and glycyl-L-leucine(L-L3H) has been studied spectrophotometrically in aqueous medium as a function of [substrate complex], [ligand] and temperature. The reaction has been monitored at 600 nm where the spectral difference between the reactant and product is a maximum. At pH 7.4, the interaction with studied dipeptides shows two parallel steps. i.e., it shows a non-linear dependence on the concentration of dipeptides; both processes are ligand-dependent. The rate constants for the processes are: k1 ∼ 10−3 s-1 and k2 ∼ 10−5 s-1. The activation parameters were calculated from Eyring plots. Based on the kinetic and activation parameters an associative interchange mechanism is proposed for the interaction processes. From the temperature dependence of the outer sphere association equilibrium constant, the thermodynamic parameters were also calculated. The product of the reaction has been characterized by IR and ESI-mass spectroscopic analysis.

【 授权许可】

Unknown