Blue two-photon excited fluorescence of several D-π-D, A-π-A, and D-π-A compounds featuring dimesitylboryl acceptor

Several donor-π-donor (D-π-D), acceptor-π-acceptor (A-π-A), and donor-π-acceptor (D-π-A) types of organic compounds with fluorene as π bridge and dimesitylboryl group as electron acceptor, which show strong two-photon excited blue fluorescence, have been synthesized and structurally investigated. The symmetric A-π-A type of compound exhibits the shortest wavelength of two-photon excited fluorescence (TPEF) at λem=405 nm under the excitation of λex=730 nm; the unsymmetric D-π-A type of compound with diphenylamino as donor exhibits the most intense TPEF at blue region (λem=484 nm) with a two-photon absorption cross-section of 425 GM under λex=800 nm.