Synthesis and application of a novel turn-on fluorescent probe for the determination of sulfur ions in real samples

A novel and highly selective reactive sulfur ions (S2-) probe, 4′-(benzo[d]thiazol-2-yl)-3′-((7-nitrobenzo[c][1,2,5] oxadiazol-4-yl) oxy)-N, N-diphenyl-[1,1′-biphenyl]-4-amine (DBA), has been synthesized through covalent bonding of a 4-chloro-7-nitro-1,2,3-benzoxadiazole (NBD-Cl) unit with 4-(benzo[d]thiazol-2-yl)-4′-(diphenylamino)-3-phenylphenol (BO-OH). The structure was meticulously characterized using a combination of IR, NMR, HRMS, and LC-MS techniques. Notably, upon the addition of S2-, the fluorescence of the probe DBA solution underwent a marked enhancement, transitioning from nearly colorless to brilliant yellow-green luminescence. The Ultraviolet–visible absorption spectrum and fluorescence emission were utilized to assess the probe DBA efficacy in detecting and identifying S2-. It exhibited a substantial fluorescence amplification, enabling quantitative detection within a concentration range of 0 to 17.1 μM, and possessed a low detection limit of 66.89 nM. Moreover, this method boasts a high recovery rate, excellent accuracy, and usefulness for analysis when tracking S2- in real samples.