화학공학소재연구정보센터
Molecular Crystals and Liquid Crystals, Vol.433, 73-85, 2005
Provitamin D-2 and provitamin D-3 photo transformations in cholesteric liquid crystal mixtures induced by UV radiation
Shifts of selective reflection peaks under UV irradiation (which can be observed as color changes) are reported for induced cholesteric systems (nematic + optically active dopant) additionally doped with ergosterol (provitamin D-2) or 7-dehydrocholesterol (provitamin D-3). the effect is based on the photoinduced conversion of ergosterol into vitamin D2, and 7-dehydrocholesterol into vitamin D3, with the vitamins and provitamins having opposite signs of their helical twisting power. The observed shifts of the selective reflection peaks (more than 190 nm after 45 min of UV irradiation) allow both instrumental and visual monitoring of biologically active UV radiation.