Bistriazine-based streptocyanines. Preparation, structural determination and optoelectronic properties

• The preparation of streptocyanine based bistriazines is described.
• The structure of bistriazines has been studied by NMR, UV–vis and fluorescence.
• Computational calculations were employed to account for the reactivity patterns and UV absorption.
• These compounds are blue-emitters with large Stokes shifts.

A series of bistriazine-based streptocyanines has been selectively prepared. A variety of substituents has been introduced into the triazine ring with p-phenylenediamine as a conjugated spacer between the triazine and the streptocyanine moieties. Fukui indices have been used to explain the different sequential reactivity of the chlorine atoms in the triazine ring. 1D- and 2D-DNMR spectroscopy and computational calculations have been carried out to explain the dynamic behavior of these complex systems, which can be explained by the presence of a Cl … H bond. This method was used to build conjugated systems and to show the interaction between the triazine part, the spacer, and the streptocyanine moiety. A study of the optoelectronic properties has been performed by UV–vis and fluorescence spectroscopy. Streptocyanine-based bistriazines are violet-blue emitters and large Stokes shifts of more than 6000 cm−1 were observed. The title compounds showed interesting properties which have potential for use in optoelectronic devices.

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