Diarylpyrazine-based position isomers: A detailed study of optical properties and structure-property relationship

Abstract

A versatile and expeditious synthetic route to pyrazine-based symmetric and asymmetric chromophores decorated with donor-acceptor (D-A) has been designed to study their structural effects on optical properties. Suzuki-Miyaura coupling of dihalopyrazine with various aryl boronic acids was synthesized under microwave condition. Pyrazine functionalized at C-2, C-5 and C-6 serve as acceptor to construct linear and angular push-pull chromophores. The photophysical, electrochemical and thermal properties of all the target chromophores were systematically investigated and the results were correlated theoretically by density functional theory computations. The emission wavelength was significantly red-shifted by introduction of strong electron withdrawing group (CN). The permutation of terminal donor acceptor units tunes the optoelectronic properties in a predictable way, aiding in the rational design of small molecule for luminescent materials. These chromophores displayed multicolour change in different solvents, exhibiting good solvatochromism with a large Stokes shift.