Complexes of 3,4-dihydroxyphenyl derivatives—X. Copper(II) complexes of chlorogenic acid and related compounds

• Published in: Polyhedron Vol. 8; no. 19; pp. 2345 - 2349
• Main Authors: Kiss, Tamas, Nagy, Gizella, Pécsi, Magdolna, Kozlowski, Henryk, Micera, Giovanni, Erre, Liliana Strinna
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1989; New York, NY Elsevier Science
• Subjects: Chemistry; Coordination compounds; Exact sciences and technology; Inorganic chemistry and origins of life; Preparations and properties; Divalent metal Complexes; Carboxylic acid; Copper II Complexes; Chemical stability; Organic ligand; Phenols; Protonation; Transition metal Complexes; EPR spectrum; Potentiometry
• ISSN: 0277-5387
• DOI: 10.1016/S0277-5387(00)80295-8

The interactions of copper(II) with chlorogenic acid [1,3,4,5-tetrahydroxycyclohexanecarboxylic acid 3-(3,4-dihydroxycinnamate)] and related compounds such as 3,4-dihydroxyphenylacetic acid (3,4-DHPA), 3,4-dihydroxyphenylpropionic acid (3,4-DHPP) and trans-3-(3,4-dihydroxyphenyl)propenoic acid (caffeic acid) in aqueous solution have been investigated by pH-metric and spectroscopic (ESR and electronic absorption) methods. It has been found that these ligands exhibit a real ambidentate character, i.e. in addition to the chelation via the catecholate sites, the separated carboxylate can also coordinate to the copper(II) ion. The simultaneous coordination of both types of binding sites leads to the formation of various oligomeric species.