Benzimidazole-acid hydrazide Schiff–Mannich combo ligands enable the nano-molar detection of Zn 2+ in semi-aqueous media, HuH-7 cells, and plants via a fluorescence turn-on mode

• Published in: New journal of chemistry 2022-08, Vol.46 (33), p.16161-16171
• Main Authors: Bag, Riya, Sikdar, Yeasin, Sahu, Sutapa, Islam, Md Majharul, Mandal, Sukhendu, Goswami, Sanchita
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/D2NJ02875A

In this study, we synthesized two unsymmetrical and dipodal Schiff–Mannich combo ligands, namely benzoic acid (3-benzoimidazol-1-ylmethyl-2-hydroxy-5-methyl-benzylidene)-hydrazide (H2BBH) and the hydroxyl analogue 2-hydroxy-benzoic acid (3-benzoimidazol-1-ylmethyl-2-hydroxy-5-methyl-benzylidene)-hydrazide (H3BSH), for the selective detection of Zn 2+ in semi-aqueous media. Both the probes selectively depict a turn-on response to Zn 2+ as a result of the combined effect of chelation-induced enhanced fluorescence (CHEF) and photo-induced electron transfer (PET). Detailed experimental studies reveal that H2BBH and H3BSH can detect Zn 2+ in solutions with limit of detections of 27 nM and 46 nM, respectively. The structures of probe-Zn 2+ ensembles were proposed as [(HBBH) 2 Zn] and [(H 2 BSH) 2 Zn] by ESI-MS, FT-IR spectroscopy, 1 H NMR titration and DFT/TD-DFT methods. Moreover, both the probes were successfully employed in the detection of Zn 2+ in HuH-7 cells, seedlings of chickpea and mung beans, and paper strips.