Proton-Transfer-Based Azides with Fluorescence Off–On Response for Detection of Hydrogen Sulfide: An Experimental, Theoretical, and Bioimaging Study

Abstract

This work describes the synthesis of photoactive proton transfer compounds based on the benzazolic core containing the azide group. The compounds present absorption in the UV region and fluorescence emission in the visible region of the spectra with large Stokes shift due to a phototautomerism in the excited state (ESIPT). The azide location on the benzazolic structure presented a noteworthy role on their photophysics, leading to fluorescence quenching. A photophysical study was performed in the presence of NaHS to evaluate their application as an H 2 S sensor. The methodology employed was the reduction of azides to amines using NaHS to mimic H 2 S, resulting in an off−on response fluorescence mechanism. The observed photophysical features were successfully used to explore the azides as fluorescent probes in biological media. In addition, DFT and TD-DFT calculations with the CAM-B3LYP/cc-pVDZ and CAM-B3LYP/jun-cc-pVTZ level, respectively, were performed in order to understand the photophysics features of azide derivatives, where the main interest was to investigate the fluorescence quenching experimentally observed in the azide derivatives.

Reaction-Based Luminescent Probes for Reactive Sulfur, Oxygen, and Nitrogen Species: Analytical Techniques and Recent Progress

“…Hydrogen sulfide has sparked vast creativity in the design of reaction-based triggers for this reactive analyte, and these can be generally categorized into reduction-based triggers, electrophilic triggers, copper-based triggers, and a few other interesting developments, including triggers incorporating molecular recognition (Figures – ). Reduction-based triggers include azides, − sulfonyl azides, , nitro groups, − nitroso groups, and quinones . A wide variety of electrophilic triggers that operate via hydrogen sulfide’s nucleophilicity have been developed including aldehyde-assisted ester cleavage, aldehyde-assisted conjugate addition, aldehyde-assisted dinitrophenyl cleavage, nucleophilic aromatic substitution, , nucleophilic addition to an imine, , nitrobenzoxadiazole with amine ,− or alcohol , leaving groups, vinyl chloride substitution alone or followed by cyclization, an aryl cyanate, disulfide-assisted ester cleavage, − diselenide-assisted ester cleavage,…”

Photocontrolled Single-/Dual-Site Alternative Fluorescence Probes Distinguishing Detection of H2S/SO2 in Vivo

“…Studies suggest that the aryl azide group shows high selectivity with hydrogen sulfide. 26,27 Therefore, we speculate that azide derivative seems to be an ideal probe for H 2 S detection. Spiropyran, as a typical photoswitchable molecule, 28−30 was a latent fluorophore that can be reversibly tuned to merocyanine, which shows high selectivity for SO 2 detection.…”

“…The design of a single fluorescent probe which displays a highly selective and distinctive response for H 2 S and SO 2 simultaneously is highly desirable but even more challenging. Studies suggest that the aryl azide group shows high selectivity with hydrogen sulfide. , Therefore, we speculate that azide derivative seems to be an ideal probe for H 2 S detection. Spiropyran, as a typical photoswitchable molecule, − was a latent fluorophore that can be reversibly tuned to merocyanine, which shows high selectivity for SO 2 detection .…”

Interaction Study between ESIPT Fluorescent Lipophile-Based Benzazoles and BSA

“…10000 cm −1 ) [14,15]. These photophysical features allow these compounds to be applied as pH sensors [16][17][18][19], WOLEDs [20][21][22][23][24][25], optical sensors [26][27][28], bioimaging [29][30][31][32][33][34][35], and lipid probes [36][37][38][39][40].…”