A hydroxypropiophenone based fluorescent probe for selective determination of Al3+ ions in aqueous ethanol

Abstract

Abstract In this work, we had synthesized a novel dihydrazone-based fluorescent probe N'1,N'2-bis{1-(2-hydroxyphenyl)propylidene}oxalohydrazide for Al3+ by simple condensation reaction. The prepared organic probe has been characterized by different physicochemical and spectroscopic techniques. The single-crystal structure of the receptor has also been reported. Aqueous ethanolic solution of probe shows an enhanced fluorescence in the presence of Al3+ ions whereas no appreciable change in spectral pattern is observed in presence of other cations viz. Na+, K+, Ca2+, Ba2+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cr3+, Cd2+ and Hg2+. The binding mode of the receptor with Al3+ was studied by various spectral titration techniques such as UV-visible, fluorescence and 1H NMR. The receptor acts as a dibasic hexadentate ligand and interacts with two Al3+ ions with a high binding constant KB = 8.99 × 1010 M− 1. The lowest detection limit for the Al3+ complex of H2hpoh was determined to be 7.8 × 10− 5 M. With the help of DFT calculation, the mechanism of fluorescence enhancement has been explained.