二甲基锡（IV）与L-半胱氨酸在水溶液中相互作用的热力学和光谱研究。

Thermodynamic and spectroscopic study for the interaction of dimethyltin(IV) with L-cysteine in aqueous solution.

作者信息

Cardiano Paola, De Stefano Concetta, Giuffrè Ottavia, Sammartano Silvio

机构信息

Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica, Università di Messina, Salita Sperone 31, Villaggio S. Agata, 98166 Messina, Italy.

出版信息

Biophys Chem. 2008 Mar;133(1-3):19-27. doi: 10.1016/j.bpc.2007.11.005. Epub 2007 Nov 22.

DOI:10.1016/j.bpc.2007.11.005

PMID:18069116

Abstract

Thermodynamic and spectroscopic properties of the species formed by dimethyltin(IV) cation with L-cysteine (cys) were studied by potentiometric, calorimetric, UV and NMR investigations in aqueous solution. The resulting speciation model showed the formation of five complex species: (CH(3))(2)Sn(cys)H(+), (CH(3))(2)Sn(cys)(0), (CH(3))(2)Sn(cys)OH(-), (CH(3))(2)Sn(cys)(2)H(-), (CH(3))(2)Sn(cys)(2)(2-). The stability and the formation percentages, for the mononuclear mixed species in particular, are very high, in a wide pH range. Thermodynamic parameters indicate that the enthalpy values are exothermic and the enthalpic contribution to the stability is higher than entropic one. Individual UV spectra of cys and dimethyltin(IV)-cys species were calculated. Spectroscopic results of UV and (1)H NMR investigations fully confirm the speciation model. The structures calculated from NMR investigations show that all the species have an eq-(CH(3))(2)-tbp structure.

摘要

通过电位滴定、量热、紫外和核磁共振研究，在水溶液中研究了二甲基锡（IV）阳离子与L-半胱氨酸（cys）形成的物种的热力学和光谱性质。所得的物种形成模型表明形成了五种络合物：(CH(3))(2)Sn(cys)H(+)、(CH(3))(2)Sn(cys)(0)、(CH(3))(2)Sn(cys)OH(-)、(CH(3))(2)Sn(cys)(2)H(-)、(CH(3))(2)Sn(cys)(2)(2-)。在很宽的pH范围内，尤其是单核混合物种的稳定性和形成百分比非常高。热力学参数表明，焓值是放热的，且焓对稳定性的贡献高于熵的贡献。计算了cys和二甲基锡（IV）-cys物种的单独紫外光谱。紫外和(1)H NMR研究的光谱结果充分证实了物种形成模型。核磁共振研究计算得到的结构表明，所有物种都具有eq-(CH(3))(2)-tbp结构。