This article focuses on the development of practical approaches to the preparation of benzo[1,2-d:4,3-d′]bis(thiazoles) using blue light-induced photochemical cyclization of N,N′-(1,4-aryl)dithioamides in the presence of p-chloranil as a mild oxidant. The proposed method allows to obtain benzo[1,2-d:4,3-d′]bis(thiazoles) containing donor substituents in the conjugated chain. Photophysical and (spectro)electrochemical properties of 2,6-di([2,2′-bithiophen]-5-yl)benzo[1,2-d:4,3-d′]bis(thiazole) and -benzo[1,2-d:4,5-d′]bis(thiazole) are studied in detail. The properties of the synthesized compounds suggest their potential applications for organic electronics.

Acylation of benzo[c][1,2,5]thiadiazole-4,7-diamine and 2-hexyl-2H-benzo[d][1,2,3]triazole-4,7-diamine with aromatic acid halides furnished the corresponding N,N′-diamides, which were converted into N,N′-dithioamides by reacting with Lawesson’s reagent. A method was developed for the preparation of previously unknown fused systems, dithiazolobenzo[1,2-c][1,2,5]thiadiazoles and dithiazolobenzo[1,2-d][1,2,3]triazoles, by oxidative photochemical cyclization of N,N′-dithioamides. The photophysical and (spectro)electrochemical properties of the obtained compounds and their polymer films electrochemically deposited on ITO were studied. The optical contrast and response time of the synthesized oligomers were determined. The results obtained allow us to consider these substances as promising candidates for electrochromic devices.