A novel pyridine-pyrazole based selective 'turn-off' fluorescent chemosensor for Fe(III) ions

摘要

A novel pyridine-pyrazole based "turn-off" fluorescent chemosensor namely, 5-N-(pyridine-2-yl)-3-(pyridine-4yl)-1H-pyrazole-5-carboxamide (PPPC) was designed, synthesized and well characterized by NMR, ESI-MS and FT-IR spectroscopic techniques. UV-vis absorption and fluorescence spectroscopic studies show that PPPC exhibits high selectivity and sensitivity towards Fe3+ ion in DMSO/H2O solution (9:1, v/v) over other metal ions. The binding constant (K) of PPPC with Fe3+ was calculated to be 5.1 x 10(-2) M and 6.1 x 10(-2) M from Benesi-Hildebrand plot using UV-vis and fluorescence spectrophotometer respectively. The detection limit of PPPC for Fe3+ was further determined as 57 nM and 88 nM by UV-vis and fluorescence titrations. Moreover, the binding mechanism of Fe3+ with PPPC was confirmed by DFT study.