Potentiometric and Spectroscopic Studies on Aluminium(III) Complexes of Some Catechol Derivatives

概要

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The interactions of aluminium(III) ion with the triprotic catechol derivatives (H_3L), 2,3-dihydroxybenzoic acid (2,3-DHBA), 3,4-dihydroxyphenylacetic acid (3,4-DHPA), 3,4-dihydroxybenzoic acid (3,4-DHBA), and 3,4-dihydroxyhydrocinnamic acid (3,4-DHHCA) were investigated in aqueous solution at 25.0 ℃. The Calvin-Bjerrum titration method was adopted for the determination of formation constants of proton-ligand and aluminium(III)-ligand complexes. Potentiometric and spectroscopic results indicated that these catechol derivatives exhibit a true bidentate character. The chelation occurs via their catecholate sites, with the exception of 2,3-DHBA. In the case of 2,3-DHBA complexes, the dominant species are either the salicylate type (COO^-, O^-) or catecholate type (O^-, O^-) complex. The protonation constants of ligands and their formation constants of Al(III) complexes were also correlated. The order of decreasing stabilities of complexes is : 3,4-DHPA>3,4-DHBA>3,4-DHHCA>2,3-DHBA.
公益社団法人日本薬学会の論文
2004-08-01