Arup Mandal

Kinetic Studies on Interaction of Platinum(II) Complexes with an ‘S’ Containing Ligand in Aqueous Medium

The kinetics of the substitution reactions of [Pt(dach)(H2O)2]2+ and [Pt(en)(H2O)2]2+ (where ‘dach’ and ‘en’ are cis-1,2-diaminocyclohexane and ethylenediamine, respectively) with excess N,N′-diethylthiourea have been studied in aqueous solution by UV–Vis spectrophotometry. The effect of different N–N spectator ligands on the reactivity of platinum(II) complexes was investigated by studying the water lability of the reactant complexes. The kinetic study has been substantiated by product isolation, IR, NMR and ESI-MS spectral analysis and DFT calculations. The reactions follow normal square-planar substitution mainly in an associative way. Rate parameters have been evaluated under different conditions. The substitution rates of the complexes studied can be tuned through the nature of the N–N chelates, which is important in the development of new active compounds for cancer therapy.

Mechanistic and Kinetic Investigations on the Interaction of Model Platinum(II) Complex With Ligands of Biological Significance in Reference to the Antitumor Activity

The kinetics of interaction of cis-[Pt(cis-dach)(H2O)2]2+ (where dach is cis-1,2-diaminocyclohexane) with three different amino acids, namely L-Asparagine (L1H), L-Arginine (L2H), and L-Gluatmic acid (L3H) have been studied spectrophotometrically in the 40–60°C temperature range. The substitution was found to occur in two subsequent reaction steps: the first step is the ligand-assisted anation and the second one is the chelation step. The kinetic study has been substantiated by product isolation, IR, NMR, and ESI-MS spectroscopic analysis.

Kinetics and mechanism of the interaction of glycyl-L-leucine with [(H 2 O)(tap) 2 RuORu(tap) 2 (H 2 O)] 2+ ion at physiological pH

The interaction of glycyl-L-leucine (L-I/H) with [(H2O) (tap)2RuORu(tap)2(H2O)]2+ (tap=2-(m-tolylazo) pyridine) has been studied spectrophotometrically in aqueous medium as a function of [(H2O) (tap)2RuORu(tap)2(H2O)2+], [glycyl-L-leucine], pH and temperature. The reaction was monitored at 600 nm where the spectral difference between the reactant and product is a maximum. At pH 7.4, the interaction with glycyl-L-leucine shows two parallel steps, i.e. it shows a non-linear dependence on the concentration of glycyl-L-leucine; both processes are ligand dependent. The rate constants for the processes are: kl 10−3 s 1 and K2∼10−5 s−1. The activation parameters calculated from Eyring plots are: Δ H#1 = 15.8∓0.6kJ mol−1, ASf = −232 + 2J K 1 mol−1, AH2# =31.7∓3.5kJmol−1, AS* = −216∓ 10J K−1 mol−1. 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, which gave a negative AG° value for both the steps at all temperatures studied, supporting the spontaneous formation of an outer sphere association complex. The product of the reaction has been characterized from IR and ESI-mass spectroscopic analysis.

Kinetic Study of the Interaction of Three Glycine-Containing Dipeptides with Hydroxopentaaquarhodium(III) Ion in Aqueous Medium

The kinetics of the interaction of three glycine-containing dipeptides, namely, glycyl-L-valine (L1-L′H), glycyl-glycine (L2-L′H) and glycyl-L-glutamine (L3-L′H), with [Rh(H2O)5OH]2+ has been studied spectrophotometrically in aqueous medium as a function of the Rh(H2O)5OH2+ and dipeptide concentrations, pH and temperature, at constant ionic strength. At pH = 4.3, the substrate complex exists predominantly as the hydroxopentaaqua species and dipeptides as zwitterions. The reaction has been found to proceed via two parallel paths: both processes are ligand dependent. The rate constants for the processes are of the order: k1∼10−3 s−1 and k2∼10−5 s−1. The activation parameters for both steps were evaluated from Eyring plots. Based on the kinetic and activation parameters an associative interchange mechanism is proposed for both of the interaction processes. The low

Kinetic studies on substitution of cis-diaqua-chloro-tris-(dimethyl sulphoxide)-ruthenium(II) complex with some dipeptides in aqueous medium

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Mechanistic aspects of ligand substitution on cis -diaqua-chloro-tris(dimethyl sulfoxide) ruthenium(II) complex by adenosine and cytidine in aqueous medium

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Kinetic and Mechanistic Studies on the Interaction of Glycyl-L-alanine, Glycyl-L-asparagine, and Glycyl-L-tyrosine with Hydroxopentaaquarhodium(III) Ion

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Displacement of aqua ligands from the hydroxopentaaquarhodium(III) ion by 1-hydroxybenzotriazole (HOBt): A kinetic and mechanistic approach

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Kinetic and mechanistic study of the interaction of diethyldithiocarbamate anion with diaquaethylenediamineplatinum(II) ion in aqueous medium

\Delta S_{1}^{\neq}

Mechanistic aspects of ligand substitution on cis-diaqua(cis-1,2-diaminocyclohexane)platinum(II) by Glycine-l-Leucine

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