Synthesis, photophysical properties and TD-DFT calculation of four two-photon absorbing triphenylamine derivatives

In this study, linear absorption, single-photon excited fluorescence, fluorescence quantum yields, fluorescence lifetime and two-photon excited fluorescence of a series of triphenylamine derivatives (L1, L2, L3 and L4) have been measured. L1 and L3 are D-π-A type dyes, while L2 and L4 are D-π-D-π-A type dyes (D = donor, A = acceptor). The investigated compounds consist of triphenylamine-bearing donor-substituted and/or systematically extended π-conjugated length, which are designed to gain insight into the effect of the ethoxyl unit and π-linkage length on the linear and nonlinear optical properties. The influence of solvent polarity on the photophysical properties was investigated. Employing time-dependent density functional theory (TD-DFT) calculations, the structure-property relationships are discussed.