One-photon photophysics and two-photon absorption of 4-[9,9-Di(2- ethylhexyl)-7-diphenylaminofluoren-2-yl]-2,2′:6′, 2″-terpyridine and their platinum chloride complexes

摘要

The synthesis, one-photon photophysics and two-photon absorption (2PA) of three dipolar D-π-A 4-[9,9-di(2-ethylhexyl)-7-diphenylaminofluoren-2-yl]-2, 2′:6′,2″-terpyridine and their platinum chloride complexes with different linkers between the donor and acceptor are reported. All ligands exhibit ~1π,π* transition in the UV and ~1π,π*/1ICT (intramolecular charge transfer) transition in the visible regions, while the complexes display a lower-energy ~1π,π*/1CT (charge transfer) transition in the visible region in addition to the high-energy ~1π,π* transitions. All ligands and the complexes are emissive at room temperature and 77 K, with the emitting excited state assigned as the mixed ~1π, π* and 1CT states at RT. Transient absorption from the ligands and the complexes were observed. 2PA was investigated for all ligands and complexes. The two-photon absorption cross-sections (θ_2) of the complexes (600-2000 GM) measured by Z-scan experiment are much larger than those of their corresponding ligands measured by the two-photon induced fluorescence method. The ligand and the complex with the ethynylene linker show much stronger 2PA than those with the vinylene linker.