The photophysical properties and two-photon absorption of novel triphenylamine-based dendrimers

Novel triphenylamine-based dendrimers were synthesized and characterized by FT-IR, elemental analysis, 1H NMR spectroscopy, and MALDI-TOF mass spectrometry. The linear photophysical properties including absorption, one-photon induced fluorescence and the fluorescence lifetimes in different solvents were investigated. The two-photon induced fluorescence behavior was recorded in toluene solution, employing a Ti:sapphire femtosecond laser pulse. The dendrimers both emit strong blue–green fluorescence under irradiation. Two-photon excited state fluorescence cross-sections were also obtained. The two dendrimers displayed a large two-photon absorption. The polytriphenylamine dendrimer shows larger two-photon excited state fluorescence cross-sections in toluene relative to the tristriphenylamine analog, indicating that there is cooperative enhancement originating from inter-branch coupling and an increase of light-harvesting ability with increasing dendrimer size.

Research highlights
► Novel triphenylamine-based dendrimers were synthesized and characterized.
► Photophysical properties and two-photon induced fluorescence were investigated.
► Two-photon absorption cross-section of dendrimers were obtained.
► We find evidence how inter-branch coupling results in cooperative enhancement.