Funct. Mater. 2025; 32 (3): 498-507.

In this study, efficient synthesis methods were developed for obtaining a systematic series of mono- and diphenyl-substituted coumarin-3-carboxylic acids and their ethyl esters. The UV absorption and fluorescence characteristics were determined in solvents of different polarity: nonpolar (cyclohexane) and polar aprotic (acetonitrile). The results showed that the position and number of phenyl substituents significantly affect the fluorescent properties of the obtained dyes. In addition, calculations based on the time-dependent density functional theory (TD-DFT) provided a detailed analysis of the electronic effects of phenyl substitution. Comparative spectral analysis and theoretical study of the structure-fluorescence relationship indicate that 7-phenyl-substituted coumarin-3-carboxylic acids among the studied derivatives are a promising platform for the development of innovative fluorescent materials, in particular for laser dyes, dye-sensitizers for solar cells, optoelectronics, and other fields.