Dual-function thiourea-linked benzothiazole derivative: sensitive fluorescent detection of Hg ²⁺ and broad-spectrum antibacterial and antifungal activity

A novel thiourea-linked benzothiazole derivative <b>TH1</b> was synthesized and systematically characterized for its dual-functional application in sensing and antimicrobial activity. The compound exhibited excellent selectivity and sensitivity toward Hg²⁺ ions, with a clear fluorescence quenching ("turn-off") response upon binding due to formation of <b>TH1-Hg(II)</b> complex. The probe demonstrated a remarkably low detection limit of 0.019 ppm, making it suitable for trace-level mercury detection. Interference studies confirmed its high selectivity, and practical applicability was validated by testing blood serum and various real water samples including river, pond, lake, river and drinking water as well as soil sample with percent recovery rates ranging from 89.0 ± 0.54% to 102.0 ± 0.74%, confirming its reliability and accuracy in complex environmental matrices. Beyond its sensing capabilities, the benzothiazole-thiourea <b>TH1</b> and complex <b>TH1-Hg(II)</b> also showed promising broad-spectrum antimicrobial activity. Both ligand and its complex effectively inhibited the growth of bacterial and fungal strains, producing well-defined zones of inhibition. This dual-functionality, highly sensitive Hg²⁺ detection and notable antibacterial performance, positions the <b>TH1</b> as a strong candidate for multifunctional applications in environmental monitoring and biomedical fields.