[Zurück]

S. Moi, S. Mahata, S. Mukherjee, I. Mitra, R. Bhaduri, K. Chandra, S. Mandal, W. Linert:
"Influence of steric and electronic effect of carrier ligand on kinetics & mechanism of Pt(II) complexes with L-cysteine and its substituted derivatives: Their experimental and DFT-based theoretical study",";
Inorganica Chimica Acta, 498 (2019), S. 119117 - 119128.

The present research work focuses on influences of steric and electronic effect on the kinetic and mechanistic investigation of the cytotoxic Pt(II) complexes with sulfur containing bio-molecules, which is relevant in order to understand the drug-reservoir activity of the complexes. To evaluate the steric and electronic effect of carrier ligand on substitution kinetics of Pt(II) complexes, 2Åã and 3Åã bidentate amine (DMEEDA) have been considered. Pt(II)-dichloro complex [Pt(DMEEDA)Cl2], 1 and its hydrolysed form [Pt(DMEEDA)(H2O)2](ClO4)2, 2 have been synthesised and characterised, wherein DMEEDA stands for N,N-Dimethyl-N′-ethylethylenediamine, a bidentate carrier ligand with different alkyl substituents. The diaqua platinum complex 2 has been considered for detailed kinetic investigation with biologically important intercellular thiol L-cysteine (L-cys) and its derivative N-acetyl- L-cysteine (N-ac-L-cys) under pseudo first order condition at pH 4.0 in aqueous medium. The product complexes [Pt(DMEEDA)(L-cys)](ClO4), 3 and [Pt(DMEEDA)(N-ac-L-cys)], 4 have been isolated and characterised. The activation parameters (ΔHǂ and ΔSǂ) for both the steps underlying the thiol assisted substitution reactions have been calculated. Theoretical Density Functional Theory (DFT) has been undertaken to optimise the complexes for HOMO-LUMO energy calculation, TD-DFT and natural bond orbital (NBO) analysis to strengthen the experimental findings. Various electronic properties of the complexes, called DFT-based descriptors have been calculated from frontier molecular orbital energies to predict their adduct formation ability with DNA. TD-DFT study has been undertaken to generate both the simulated spectra of UV-Vis and IR to compare with the corresponding experimental spectral results. To justify the chelation via (S,O), not through other possible modes, NBO analysis has been considered for the complex 3 and 4, which is also supported by spectroscopic observation.

Pt(II)-thiol interaction Kinetics and mechanism, Natural bond orbital analysis, TD-DFT DFT-based descriptors

http://dx.doi.org/10.1016/j.ica.2019.119117.