The proposed research would provide a starting point for studying a series of new biologically active fluorescent ligands based on heterocyclic compounds (triazoles, thiazoles, pyrazolines, uracils, coumarins etc.) bearing special functionality/functionalities (COOH, CONHR, OH etc.) and their Ga(III), Ce(III), La(III), Nd(III), Sm(III), Gd(III), Dy(III), Pr(III), Ho(III), Er(III) coordination compounds that have not been synthesized and tested before for their potential optical properties, their sensitivities to the biological or natural compounds, specific receptors, cell organelles, and their targeted antioxidant activity. Realizing the project would lead to the first known synthesis and characterization of new types of unique luminophores with pronounced photophysical characteristics, as well as physicochemical, chemical, and biological properties and photostability to make it possible to recommend them for biological or medical applications. Theoretical characterization of biologically active ligands and their metal complexes will be performed, which includes DFT calculations with geometry optimization, molecular interactions, hydration effect, vibrational assignment, NMR and fluorescence. This research may contribute to the development of new radical-scavenging, cancer-treatment drugs and would be beneficial to members of the broader scientific community who work in the area of antioxidant and anticancer drug development.