Benzimidazolium-based new simple ratiometric fluorescent sensor for selective detection of dihydrogenphosphate

Abstract

A series of pyridine-coupled benzimidazolium-based receptors 1, 2 and 3 have been designed and synthesised. In the series, only receptor 1 is structurally appealing in the selective recognition of H₂PO₄⁻  in CHCl₃ as well as in CH₃CN over a series of other anions. The ratiometric change in emission with a triplet band at 420 nm is the distinctive feature of selective recognition of H₂PO₄⁻  in CHCl₃. In CH₃CN, a ‘turn on’ response is selectively observed. Binding studies have been carried out using fluorescence, UV–vis, ¹H NMR and ³¹P NMR spectroscopic techniques. Experimental results have been correlated with the theoretical findings.

Abstract

Pyridine-coupled benzimidazolium-based receptor 1, selectively recognises H₂PO₄⁻  in CHCl₃ as well as in CH₃CN over a series of other anions. The ratiometric change in emission with a triplet band at 420 nm is the distinctive feature of selective recognition of H₂PO₄⁻  in CHCl₃. In CH₃CN, a ‘turn on’ response is selectively observed. Experimental results have been correlated with the theoretical findings.

Keywords::

• ratiometric sensor
• dihydrogenphosphate binding
• benzimidazolium
• triplet excimer
• DFT study

Acknowledgements

D.K. thanks CSIR, New Delhi, India, for a fellowship.