Correia dos Santos M M, Famila Vila, Simões Gonçalves M L
Centro de Química Estrutural, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisbon, Portugal.
Anal Biochem. 2002 Apr 15;303(2):111-9. doi: 10.1006/abio.2002.5580.
Copper complexation by the 1,4-benzodiazepines medazepam, diazepam, flurazepam, nitrazepam, and clonazepam was investigated using differential pulse polarography and cyclic voltammetry at a mercury electrode in 0.10 M KNO3 and pH 7.0 +/- 0.1. Because the 1,4-benzodiazepines are easily reduced at a mercury electrode through the two-electron reduction of the 4,5-azomethine functional group, copper reduction, as well as that of the ligands, was analyzed under varying experimental conditions. In most situations adsorption phenomena occurred and their influence on voltammetric signals had to be carefully analyzed. The voltammetric behavior was then interpreted in terms of complex formation. The results showed that all benzodiazepines can act as ligands toward copper(II) ions, forming 1:1 and 1:2 complexes with similar stabilities. The stoichiometric acidity constants of the benzodiazepines under study were also determined by potentiometric titration in water-ethanol medium and 0.10 M KNO3 and then extrapolated to 0% concentration of ethanol.
采用差分脉冲极谱法和循环伏安法，在0.10 M硝酸钾和pH 7.0±0.1的条件下，于汞电极上研究了1,4 - 苯二氮䓬类药物美达西泮、地西泮、氟西泮、硝西泮和氯硝西泮与铜的络合作用。由于1,4 - 苯二氮䓬类药物可通过4,5 - 甲亚胺官能团的双电子还原在汞电极上轻易被还原，因此在不同实验条件下分析了铜以及配体的还原情况。在大多数情况下会出现吸附现象，必须仔细分析其对伏安信号的影响。然后根据络合物的形成来解释伏安行为。结果表明，所有苯二氮䓬类药物都可作为铜（II）离子的配体，形成稳定性相似的1:1和1:2络合物。还通过在水 - 乙醇介质和0.10 M硝酸钾中进行电位滴定，测定了所研究苯二氮䓬类药物化学计量酸度常数，然后外推至乙醇浓度为0%的情况。
