A novel colorimetric and fluorescent anion chemosensor based on the flavone quasi-crown ether-metal complex

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.