Benzopinacol particle formation in lyotropic liquid crystals

The photochemical reaction of diphenyl ketone and isopropanol was investiga ted in homogeneous solution, anionic AOT-water-isopropanol and cationic CTA B-hexanol-water-isopropanol lamellar liquid crystals (LLC). X-ray diffracti on (XRD) and IR spectra identified that same product, benzopinacol, was obt ained from these different systems. However, the shape and size of particle s are different: granular for homogeneous solution, irregular flakelike for CTAB LLC and thin, needlelike for AOT LLC systems. The average diameter (D ) of the particles formed in three systems followed the sequence: D(solutio n) > D(CTAB LLC) > D(AOT LLC). The growth rate of particles was enhanced by increasing the incident light intensity, while the largest average diamete r increased with decreasing light intensity. Comparing the average diameter s of the particles formed in AOT LLC under different intensity of incident light, D(weak light)> D(moderate light)> D(strong light) was obtained. (C) 1999 Elsevier Science S.A. All rights reserved.