Multibranched benzylidene cyclopentanonedyes with large two-photon absorption cross-sections

Abstract

Multibranched benzylidene cyclopentanone dyes with a triphenylamine core were synthesized. Their two-photon optical properties were characterized using a Ti:sapphire femtosecond laser. The results showed that the two-photon absorption cross-sections (δ) of these compounds were increased with increasing numbers of branches. The largest δ value of the three-branched compound 3 was 3298 GM which was almost six times larger than that of a model compound, 2,5-bis-[4-(dimethylamino)benzylidene]cyclopentanone (BDMA). The sensitizing efficiencies of three new dyes in photopolymerization systems were all higher than that of BDMA matching with the commercial initiator 4,4′-dimethyldiphenyliodinium hexafluorophosphate (Omnicat 820). The two-photon polymerization initiated by the bimolecular system composed of compound 3 and Omnicat 820 was investigated under femtosecond laser pulses.