Synthesis of New Efficient Fluorophores of Thieno[2,3-b]pyridine Series

• Published in: Russian journal of general chemistry 2023-08, Vol.93 (8), p.1980-1988
• Main Authors: Alekseeva, A. U., Ievlev, M. Yu, Zinovieva, E. G., Ershov, O. V., Ershova, A. I., Bardasov, I. N.
• Format: Article
• Language: English
• Subjects: Absorption spectra; Chemical compounds; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Emission; Ethyl esters; Fluorescence; Photoluminescence; Pyridine; Pyridines; Quantum chemistry
• ISSN: 1070-3632; 1608-3350
• DOI: 10.1134/S1070363223080066

The reaction of 4-amino-6-aryl-2-halopyridine-3,5-dicarbonitriles with thioglycolic acid ethyl ester was used to synthesize a series of new efficient fluorophores of thieno[2,3- b ]pyridine series. The long-wavelength absorption bands of DMSO solutions of the prepared compounds are at the boundary of the UV and visible regions of the spectrum (λ abs 375–388 nm) and show an ambiguous influence of the substituent electronic effect, that was explained by quantum chemical calculations. The emission maxima are in the yellow-green region (λ em 490– 510 nm) and they are blue-shifted in the presence of electron donor groups with slightly increasing intensity (Φ em 37.8–60.6%). It was found that the nitro group presence causes a complete photoluminescence quenching both in solution and in the solid state. In addition, the position of the emission maximum (λ em 473–505 nm) and its intensity (Φ em 3.6–72.7%) strongly depend on the polarity and the basic properties of the medium, that was established using the Catalan empirical model.