Synthesis and nonlinear optical properties of several new two-photon photopolymerization initiators about dibenzothiophene derivatives

A lot of two-photon absorption (TPA) materials with larger TPA cross-sections have been prepared in the past years, but the structure with dibenzothiophene as acceptor or π-center has a rare research. In the paper, we firstly synthesized an important intermediate: 3-formyldibenzothiophene with a higher yield and got its four derivatives. Furthermore, we investigated their nonlinear optical properties including singe-photon induced fluorescence, quantum yields, life-times and two-photon induced fluorescence. TPA cross-sections of the derivatives from 730 to 870 nm at intervals of 10 nm have been measured by using the two-photon induced fluorescence method. As a result, we found that the compounds except trans-4-(3-vinyl-dibenzothiophene)-4′-N-methylpyridinium iodine (abbreviated as VBPMPI) could all initiate the polymerization of CN97E60 (Sartomer Co. Product), and they were proved to be effective two-photon photopolymerization initiators. A microstructure has been fabricated by using VBPMOB as the initiator. At the same time, the possible photopolymerization mechanisms were explored with VBPBAB and VBPMOB as examples.