Potentiometric and spectroscopic studies on aluminium(III) complexes of some catechol derivatives


Turkel N., Berker M., Ozer U.

CHEMICAL & PHARMACEUTICAL BULLETIN, vol.52, no.8, pp.929-934, 2004 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 52 Issue: 8
  • Publication Date: 2004
  • Doi Number: 10.1248/cpb.52.929
  • Title of Journal : CHEMICAL & PHARMACEUTICAL BULLETIN
  • Page Numbers: pp.929-934

Abstract

The interactions of aluminium(III) ion with the triprotic catechol derivatives (H3L), 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 25.0degreesC. 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 AI(III) complexes were also correlated. The order of decreasing stabilities of complexes is: 3,4-DHPA>3,4DHBA>3,4-DHHCA>2,3-DHBA.