Novel Carbazole–Thiazole Conjugates: Synthesis and Biophysical Characterization

This presented study depicts the synthesis of three novel carbazole–thiazole conjugates, thoroughly investigating their spectroscopic properties as well as evaluating their biological activity as tyrosinase inhibitors. Additionally, we investigated the possibility of using Concanavalin A (ConA) complexes with dyes from a theoretical point of view, developing a promising protein-based strategy of delivery of dyes to the target cells. The tyrosinase inhibition assay showed that compounds K1 and K3 demonstrated higher activity than the kojic acid with IC₅₀ values of 46 and 59 mM, respectively. Among the tested compounds, carbazole K3 exhibits the most pronounced nonlinear optical response due to its high electronic flexibility, strong solvatochromism, large excited-state dipole moments, and efficient intramolecular charge transfer. Additionally, all investigated carbazoles demonstrate high ability to form stable supramolecular complexes with ConA, which was confirmed using molecular docking studies. It was found experimentally and theoretically that the compound K3 has the best biophysical parameters, making it a promising candidate for potential diagnostic applications.