The synthesis and single and two-photon excited fluorescence of a new quasi-quadrupolar organoborane compound

A new acceptor-π-acceptor quadrupolar compound with a dimesitylboryl as acceptor and 2,7-dithienylfluorene as the conjugated bridge has been synthesized using the Suzuki–Miyaura coupling reaction. Its single and two-photon related photo-physical properties were experimentally examined. The combination of a large two-photon cross-section (δ = 1150 GM at 730 nm in hexane), high emission quantum yield (Ф = 0.81 in hexane) and a strong binding constant with fluoride anions (K1 = 3.0 × 105 mol−1 L) make this compound attractive for application as a two-photon excited fluorescent chemosensor for fluoride anions.