Benzimidazole based ESIPT active chemosensors enable nano-molar detection of Cu2+ in 90% aqueous solution, MCF-7 cells, and plants

Herein, two new ESIPT active chemosensors, 2-(1H-benzoimidazol-2-yl)-6-(3,5-dimethyl-pyrazol-1-ylm ethyl)-4-methyl-phenol (HPBI) and 2-(1H-benzoimidazol-2-yl)-6-imidazol-1-ylmethyl-4-methyl-phenol (HIBI), have been fabricated that can be successfully utilized for selective nano-molar (28.5 nM for HPBI and 4.22 nM for HIBI) detection of Cu2+ from 90% aqueous solution. The crystal structure of HPBI-Cu2+ entity has been successfully worked out by single crystal X-ray diffraction studies as [(PBI)(2)Cu-2](ClO4)(2). A series of four probable keto-enol tautomers/rotamers have been theoretically investigated using DFT/TD-DFT calculations and it hinted enol form as the most stable one. Both HPBI and HIBI are able to sense Cu2+ in MCF-7 cell lines and plants (chickpea and Mung bean). Moreover, both the sensors have been applied for real sample analysis. Thus, the reported chemosensors will be able to address the problem of detection of excess Cu2+ efficiently from ground water samples and biological cell lines.