Photochromism of 2-Hydroxychalcones in Solid Hydrogel Matrices

Photochromic reactions of some substituted 2-hydroxychalcones [3-(2-hydroxyphenyl)-1-phenyl-2-propen-1-ones] have been studied in solid hydrogel matrices. The results demonstrated good reversibilities for the chalcone-flavylium interconversion. Thus, in an agar-gel matrix the coloration-decoloration could be repeated over 50 cycles without significant fatigue. In a silica sol-gel matrix, a fairly good reversibility was obtained up to ca. 30 cycles; in the later cycles, however, extensive degradations took place.