Synthesis and photophysical behavior of fluorescent benzazole dyes and fluorescent microparticles: Their use as fingerprint developer

Novel benzazole derivatives were synthesized and their photophysical properties were determined experimentally in different types of solvents also by theoretical calculations using Density Functional Theory (DFT). The results of the theoretical computational studies were well consistent with those observed experimentally, evidencing the type of electronic transitions that occurs between the frontiers orbitals. All synthesized derivatives are highly fluorescent in the violet-green region (363-536 nm) under ultraviolet light of 365 nm with large Stokes shift due to excited state intramolecular proton transfer (ESIPT) mechanism. Furthermore, the thermogravimetric and differential thermogravimetric analysis showed their good thermal stability, with decomposition temperature up to 250 degrees C. The fluorescent benzazole derivative was successfully entrapped into starch-based microparticles and applied for visualization of latent fingerprints on different types of surfaces common to forensic cases (metal, plastic, paper, wood, and ceramic).