A Novel Colorimetric and Fluorescent Anion Chemosensor Based on the Flavone Quasi-crown Ether−Metal Complex

Abstract
The metal−ligand complex 1 ([Mg (L)] 2+) (or 2 ([Ca (L)] 2+)) was demonstrated to selectively bind HSO4- (or H2PO4-) over other anions by using UV−vis absorption and fluorescence spectroscopy. The studied complex exhibits the remarkable color change and fluorescence quenching upon introducing HSO4- (or H2PO4-) anion in acetonitrile. Both the mechanism and structure of the secondary complex of complex 1 with anion were proposed on the basis of theoretical computation.