Tunable optical properties of push-pull chromophores: End group effect

A series of A--D--A type symmetrical push-pull chromophores with various end groups (e.g., trifluoroacetone, indanone, dicyano, isoxazolone and pyrazolinone) linked through a symmetric -conjugated backbone (EDOT-phenylene vinylene-EDOT) was synthesized. The effect of end group tuning on optical properties was intensively investigated by UVvisible absorption, fluorescence spectroscopy and DFT calculations. A broad range of chromophores showing strong absorption was achieved with a fine alteration of the electron-accepting strength of the terminal acceptors. The optical investigation demonstrated that their low optical band gap (1.82.2 eV) combined with outstanding molar absorptivity (45,000 101,500 M-1 cm(1)) which would provide strong light-capturing capability. (C) 2020 Elsevier Ltd. All rights reserved.