Synthesis and properties of new two-photon absorption chromophores containing 3,5-dicyano-2,4,6-tristyrylpyridine as the core

This paper reports the synthesis of a series of donor-substituted 3,5-dicyano-2,4,6-tristyrylpyridine derivatives, having two-dimensional branched D-π-A structures, as new two-photon absorption (TPA) chromophores. These chromophores are stilbene-type chromophores containing the same acceptor group but end-capped with different aromatic groups as the donors. Measured as the two-photon-induced fluorescence in chloroform solvent, using a femtosecond multipass Ti∶sapphire amplifier as the irradiation source, the TPA cross section values of some compounds are on the order of 10−48 cm4 s photon−1. These chromophores also have relatively high two-photon-excited fluorescence (TPEF) action cross sections. Pumped by the laser at 800 nm, these chromophores show efficient two-photon-induced orange-red fluorescence emission. The experimental results indicate that the different end-capped functional electronic donors and the number of branches of these chromophores affect their one-photon properties, two-photon up-conversion emission behavior and TPA cross section values. Especially, with increasing numbers of branches, λabsmax and λspfmax exhibit bathochromic shifts, while their two-photon absorption cross sections also increase. Compared with the two-branched chromophore 6, the tribranched chromophore 4 shows a larger TPA cross section, and the cooperative enhancement of the TPA cross section from 6 to 4 is 1.2-fold at 800 nm.