Push–pull molecular structures based on angular benzobisthiazolium acceptor: synthesis, photophysical properties and theoretical studies

A series of eight conjugated donor-π-acceptor (D-π-A) molecules based on an angular benzobisthiazolium acceptor core was designed, synthesized and fully characterized. The physical and optical properties of the prepared compounds were tuned by variations of amino substituents at the donor part of the structures. Negative solvatochromism is a typical property of these derivatives. Quantum chemical DFT calculations with full geometry optimization were performed and energy indices including energies of frontier orbitals were calculated. Fluorescence characteristics were measured and the singlet oxygen production was assayed for the compounds with very low emission. A comparison of selected spectral and non-linear optical properties of the prepared compounds with various thiazole based push–pull compounds was carried out. [Display omitted]