Animesh Chattopadhyay

Kinetics and mechanism of reactions of some essential amino acids with cis-diaqua(1,3-diaminopropane)-platinum(II) ion: a potent anticancer agent

Abstract The substitution of both coordinated water molecules of cis-diaqua(1,3-diaminopropane)platinum(II) complex by a series of amino acids, viz. l-asparagine, l-glutamic acid, and glycine was investigated as a function of ligand concentration, temperature, and pH and found to occur in two consecutive reaction steps. The mechanism of the substitution reactions appears associative in nature as supported by the large and negative values of ΔS≠. The kinetic study has been substantiated by product isolation, UV, IR, and ESI-MS spectroscopic analysis and rate parameters have been evaluated under different reaction conditions.Graphical Abstract

Substitution reactions of [Pd(bipy)(malonate)] explored with a different set of ligands: Kinetic and mechanistic interpretation in aqueous medium and at pH 7.4

AbstractA brief overview of mechanistic studies of the reactions of Pd(II)-bipy-malonate complex with different set of ligands, viz., (N, S), (S, O) and (S) donor molecules is reported here. The kinetics of complex-formation reactions of three sulphur containing bio-relevant ligands thioglycolic acid[L1],thiourea[L2] and thiosemicarbazide [L3] were studied with innermetallic [Pd(bipy)(malonate)] complex at physiological condition. The effect of the nucleophilicity of the chosen nucleophiles was studied for the reactant complex under pseudo-first order conditions as a function of nucleophile concentration and temperature using stopped-flow technique. This article describes the results obtained for substitution reactions of bi-functional Pd(II) complex with different biomolecules, under varying experimental conditions. The kinetic studies showed that the malonate ring departs from the coordination zone of palladium centre via two-step mechanism. The first step depends on the concentration of the incoming ligand for all the ligands. But in the second step thiourea is ligand dependent where as other two are independent of the ligand concentration. Hence, it can be concluded that the second step is the chelation step for L1 and L3. The mechanism for the substitution of the coordinated malonate molecule is associative, as demonstrated by the negative values of ΔS≠. Such type of complexes are less toxic than chloro-, which in turn hydrolyses to aqua or aqua complexes as they are prevented from oligomer formation at physiological pH. Graphical AbstractStudies of kinetic and mechanistic pathways for the reactions of Pd(II)-bipy-malonate complex with thioglycolic acid, thiourea and thiosemicarbazide have been carried out. Innermetallic [Pd(bipy)(malonate)] complex reacts with above mentioned sulphur containing ligands at physiological condition and these substitution reactions are associative in nature.

Kinetic and mechanistic aspects of ligand substitution on cis -diaqua ( cis -1,2-diaminocyclohexane)platinum(II) with three glycine-containing dipeptides

The kinetics of the interaction of glycyl-L-valine(L1-L′H), glycyl-L-isoleucine (L2-L′H) and glycyl-L-glutamine(L3-L′H) with cis-[Pt(cis-dach)(OH2)2]2+ (dach = 1,2-diaminocyclohexane) have been studied spectrophotometrically as a function of [cis-[Pt(cis-dach)(OH2)2]2+], [ligand], pH and temperature at constant ionic strength, where the complex exists predominantly as the diaqua species and the dipeptides as a zwitterion. The substitution reactions show two consecutive steps: the initial is the ligand-assisted anation and the subsequent step is chelation. The activation parameters for both steps were evaluated using Eyrings equation. The low DLH1 ≠ and large negative value of ΔS1 ≠ as well as ΔH2 ≠ and ΔS2 ≠ indicate an associative mode of activation for both the aqua ligand substitution processes. The products of the reactions have been characterised using IR and ESI-mass spectroscopic analysis. The title complex is already established as an anticancer drug; but its reactivity with all biomolecules will confirm its therapeutic activity (i.e. its efficacy versus toxicity).

Relative reactivity of N,N-donor ligands in substitution reactions of cis-diaqua(2-aminomethylpiperidine)platinum(II): a detailed kinetic and mechanistic study

The reactivity of cis-

Kinetic and mechanistic studies on the interaction of azide ion with cis -diaqua-bis(bipyridyl) ruthenium(II) complex and hydroxopentaaqua rhodium(III) complex in aqueous medium

[\hbox {Pt}(\hbox {pipen})(\hbox {H}_{2}\hbox {O})_{2}]^{2+}

Kinetic and Mechanistic Investigations on Some N,N-Chelated Pt(II) Oxalate Complexes with Some “S” Containing Biorelevant Ligands at Physiological Condition

[Pt(pipen)(H2O)2]2+ (

Mechanistic aspects of ligand substitution on the cis-diaqua-chloro-tris(dimethyl sulfoxide)ruthenium(II) complex by some sulfur-containing bioactive ligands in aqueous medium

\hbox {pipen} = 2\hbox {-aminomethylpiperidine}