钴（Ⅲ）的赖氨酸、半胱氨酸配合物的制备与离解动力学

Preparetion and Dissociation Kinetics of CObal (Ⅲ)Complexes with Lysine and Cysteine

以ＣｏＣｌ＿２．６Ｈ＿２Ｏ为原料，Ｈ＿２Ｏ＿２为氧化剂制备钴（Ⅲ）的赖氨酸（Ｌｙｓ）、半胱氨酸（Ｃｙｓ）配合物。发现溶液ｐＨ值对配合物的生成有很大影响，以Ｌｙｓ为配体时，最佳ｐＨ值为７．５～８．５；而以Ｃｙｓ为配体时，最佳ｐＨ值为８．０～９．５．产物的ＩＲ光谱测定表明，两种生物配体均以α－氨基氮原子和羧基氧原子同钴（Ⅲ）键合，Ｌｙｓ中的另一个氮原子和Ｃｙｓ中的硫原子不参加配位。利用分光光度法研究了上述配合物在酸性介质中的离解动力学，发现离解反应呈一级动力学规律，求出离解速率常数和离解反应的活化能。

cobalt(Ⅲ)complexes with lysine (Lys) and cysteine (Cys)were preparedby using CoCl_2· 6H_2O as the reactant and H_2O_2 as the oxidant,The results show that the pHvalues of solution have a great influence on the formation of these two complexes,the optimumpH for the preparation will be in pH 7.5～8.5 when the ligand is Lys and in pH 8.0～9.5 whenthe ligand is Cys。 The IR measurements of the products indicate that the central ion Co(Ⅲ)iscoordinated with each amino-acid by linking with nitrogen atom of NH_2 group and one oxygenatom of COO￣-group,the other N atom in Lys or S atom in Cys does not participate in the ccor-dination。The dissociation kinetics of both cornplexes in acidic media was studied by spectrophcr-tometry and found to obey the first-order kinetic law,The rate constants and activation energiesof the reaction were estimated.