A COMPLEXING APPROACH TO INDUCING SOL-GEL PROCESS OF INSOLUBLE CU ETHOXIDE - EVOLUTION OF LOCAL ENVIRONMENT OF CU COMPLEX SPECIES

A stable gel was obtained from a methoxyethanol solution of Cu ethoxid e using glacial acetic acid as a complexing agent with addition of wat er. Electron spin resonance, infrared and visible spectra of Cu comple x species in solutions and gels were measured. The following results c an be deduced from these spectra. (1) The structural characteristic of the primary Cu complex species in the methoxyethanol solution of Cu e thoxide with acetic acid (Cu/HOAC = 1:1) is a dimeric species, Cu2(OR) 2(OAC)2(HOR)4, with small internuclear spacing and the same structure as that in crystalline hydrated copper acetate. (2) The primary Cu com plex species transform to a hydrolyzed dimeric species, Cu2(OH)2(OAC)2 (H2O)6, with large internuclear spacing through both hydrolysis and ch ange in its coordination configuration. (3) The olation reaction occur s among the hydrolyzed species and finally results in the formation of a stable transparent gel. (4) The structural form of the hydrolyzed C u complex species remains in fresh gel, while the structural form of C u complex species in xerogel is similar to that of the primary Cu comp lex species.