The electronic structures, solvatochromism, and LSER (Linear Solvation Energy Relationship) properties of thiosemicarbazone derivatives having five different π-conjuged systems have been investigated. UV–Vis absorption spectra of TSC (Thiosemicarbazone) derivatives have been measured in 18 solvent media with different polarities. The global electronic transition in these compounds is described as π−π* electronic transition resulting from the resonance in the thiosemicarbazone group. The other lower wavelength maxima are denoted to the π−π* electronic transition in the indole ring and the n−π* electronic transition in the carboxyl group. To determine as analytical solvent–solute interactions of global electronic transitions has been studied with using LSERs with using Kamlet–Taft and Catalán parameters. The solvatochromic models between electronic transition wavenumbers with Reichardt parameter, and Marcus solvent function have been generated. Optoelectronic properties have been investigated using the Moss, Ravindra, Herve-Vándamme, Kumar, Singh, and Reddy relationships. According to E_g (molecular energy gap) values, the investigated compounds can be considered organic semiconductor materials.

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