Synthesis and photophysics of benzazole based triazoles with amino acid-derived pendant units. Multiparametric optical sensors for BSA and CT-DNA in solution

Herein we report the synthesis of a series of amino acid-derived triazoles by an organocatalytic cycloaddition reaction between azides and carbonyl compounds, catalyzed by a simple amine.These compounds present absorption maxima located in the UV-B ascribed to fully spin and symmetry allowed electronic transitions and a main fluorescence emission in the UV-A (similar to 380 nm) with a relatively large Stokes shift (5700 cm(-1)). No significant solvatochromism was observed in both ground and excited states. Unexpectedly, the benzoxazole derivatives presented much higher fluorescence quantum yield values (40-80%) of compared to the sulfur analogues (3-6%). In addition, the DNA binding assays indicated that these compounds presented strong interaction with CT-DNA, which could be attributed to pi-stacking and intermolecular hydrogen-bonding. The interaction of the benzazoles with bovine serum albumin (BSA) was also investigated, where a suppression mechanism was observed. In each case, docking was performed to better understand the observed interactions. (C) 2020 Elsevier B.V. All rights reserved.