Facile synthesis and photo-physical properties of cyano-substituted styryl derivatives based on carbazole/phenothiazine

Four new cyano-substituted styryl derivatives based on carbazole and phenothiazine were facilely synthesized by conventional Knoevenagel condensation and well characterized. The UV–vis spectra of these dyes showed the lowest-energy absorption bands were mainly caused by the HOMO–LUMO one-electron promotion as conformed by TD-DFT calculations. The thermogravimetric analysis showed these dyes were thermally stable up to 350 °C. The UV–vis absorption and fluorescence emission spectra were also studied in solvents of different polarity, these dyes exhibited unusual large Stokes shift.

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► Four cyano-substituted styryl derivatives based on carbazole and phenothiazine were synthesized.
► The TGA results show these derivatives are thermally stable.
► These derivatives exhibited unusual large Stokes shifts.