Linear and Nonlinear Optical Properties of Quadrupolar Bithiophenes and Cyclopentadithiophenes as Fluorescent Oxygen Photosensitizers

The linear and nonlinear optical properties of two quadrupolar bithiophenes cyclopentadithiophenes have been investigated. At the 5,5′ positions central bi/dithiophene units, molecules possess 1,4-phenylalkynyl groups that bear either electron-donating (NPh2) or electron-withdrawing (SO2CF3) groups. were experimentally studied modelled via quantum chemistry computations key configurations conformations. All compounds show good light harvesting efficiency due to their strong absorption in visible range. These fluorescent are also two-photon absorbers NIR range can photosensitize oxygen toluene. DFT calculations reveal mixtures conformers a solution similar properties. TD-DFT reproduce experimental spectroscopic data fairly well, including vibronic couplings fluorescence spectra. lowest excited state for corresponds S2 state. roles SO2CF3 NPh2 terminal on response analyzed possible bio-oriented applications, with showing most promising figures merit.