Comparative studies on the electrochemical and optical properties of representative benzo[1,2-c;4,5-c′]bis[1,2,5]thiadiazole, [1,2,5]-thiadiazolo[3,4-g]quinoxaline and pyrazino[2,3-g]quinoxaline derivatives

We report the synthesis and characterization of a series of structurally correlated benzo[1,2-c;4,5-c′]bis[1,2,5]thiadiazole, [1,2,5]- thiadiazolo[3,4-g]quinoxaline and pyrazino[2,3-g]quinoxaline derivatives using our previously published improved synthetic methods, in order to better understand the effect of different substituents and core structures on their electrochemical and optical properties with the detailed analysis with density functional theory. Depending upon the interplay between the quinoid character, cross-conjugation, and the aromaticity of the core, these compounds exhibit tunable electronic structures, with energy gaps varying from 1.3 eV to 2.4 eV. This work marks a forward step towards the rational design of new materials for electronic and optical applications.