Spectroscopic Studies on the Reactions of Copper(II) Ion with Quinone Form of Polyvalent Porphyrin

Abstract

Reactions of Cu(II) ion with quinone, 5, 15-di-(3, 5-di-tert-butyl-4-hydroxyphenyl)-10, 20-di-(3, 5-du-tert-butyl-4-quinomethen)porpho-10, 20-dimethene (2) were investigated using UV/vis and electron spin resonance (ESR) spectroscopic methods.Formation of tetrakis(3, 5-di-tert-butyl-4-hydroxyphenyl)porphyrinatocopper(II) [Cu(II)T^tBHPP, 4] from the reaction of Cu(II) ion with 2 was determined by UV/vis and ESR measurements. However, the direct reaction product, Cu(II)-quinone complex (3), was not detected. These results suggest that 3 which may be formed at the initial reaction step between Cu(II) ion and 2 is gradually reduced by excess Cu(II) ion to yield 4. The reaction scheme between Cu(II) ion and the quinone is discussed.