First photosensitive liquid crystalline dendrimer: Synthesis, phase behavior, and photochemical properties

The first photosensitive liquid crystalline (LC) dendrimer with terminal cinnamoyl groups was synthesized. A new approach to the synthesis of photochromic carbosilane LC dendrimers was elaborated. The method consists of synthesis of dendrimer with terminal hydroxyl groups and then coupling of 4-methoxycinnamoyl chloride to it. It was shown that the LC dendrimer of the first generation forms a smectic A (SmA) phase. The photochemical behavior of the dendrimer in dilute solution and in films was studied. The experimental data show that at least two processes, E-Z photoisomerization and [2+2] photocycloaddition leading to the formation of the three-dimensional network, take place.