Detection of water content in alcohol solvents over Al3+ induced colorimetric and NIR-fluorescent sensor based on isophorone-phenylamine

Environment-sensitive fluorescent dyes become universal tools in fluorescence detection and imaging. They are particularly useful as polarity-responsive sensors without destruction. The present study reports a novel isophorone and phenylamine dye (IPA), its recognition ability for Al3+ and its solvatofluorchromic properties in several organic solvents. Structures of IPA was characterized using 1H NMR, 13C NMR, FT-ITR, TOF-MS spectra. Photophysical properties of IPA and its solvatochromic and solvatofluorchromic characteristics were examined using UV–vis and fluorescence spectroscopy. IPA displayed a remarkable “turn-on” NIR emissive and colorimetric response towards Al3+. A correlation between solvent polarity parameter dependent Stokes shifts was interpreted using the Lippert-Mataga model. The results were supported by theoretical calculations. Water content of commercial alcoholic solutions was successfully determined by IPA-Al3+ complex. Therefore, a highly selective and simple fluorescence analysis for Al3+ and trace water in alcohols or alcoholic mixtures was established on basis of intramolecular charge transfer mechanism.