Glass forming donor-substituted s-triazines: Photophysical and electrochemical properties

Triazine derived organic materials possessing various donor-chromophores at the periphery have been designed, synthesized and characterized. The synthesized compounds formed molecular glasses. Their glass transition temperatures ranged from 148 to 235 °C. The compounds demonstrated high thermal stability. The onset temperatures of their thermal decomposition exceeded 390 °C. The fluorenyl- and carbazolyl-substituted triazine derivatives were shown to be highly fluorescent in solutions and rigid polymer matrices with fluorescence quantum yields being in the range of 0.73–0.82. The phenothiazinyl-substituted triazine derivative showed moderate fluorescence quantum yields in dilute solution (η = 0.25) or polymer matrix (η = 0.50). Photophysical studies of phenothiazinyl-substituted triazine derivative in media of different rigidity and polarity revealed its twisted intramolecular charge transfer character. Neat films of the triazine compounds displayed significant fluorescence quenching accompanied by a non-exponential excited-state decay profile which was attributed to migration-assisted exciton quenching at non-radiative decay sites in disordered media. Differential pulse voltammetry studies of the synthesized materials showed that the nature of donor-substituents attached to the triazine core can influence their redox behaviour. Investigation by cyclic voltammetry revealed that the synthesized materials can be used as monomers to prepare high dimensional conjugated polymers by electro-oxidation. Spectroelectrochemical investigation of electro-oxidation products suggested the formation of charged species like polarons or bipolarons.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Suzuki reaction yielded donor-containing triazine core-centred compounds. ► Glass transition temperatures of the synthesized materials ranged from 148 to 235 °C. ► The materials exhibited high fluorescence quantum yields in dilute liquid/solid solutions. ► Phenothiazinyl derivative exhibited pronounced intramolecular charge transfer. ► The materials can be employed as monomers for oxidative electropolymerization.