A new metal ion probe 8-(1, 4, 7, 10-tetraoxa-13-azacyclopentadec-13-ylmethyl) quinolin-7- ol (1a) was synthesized via a modified Mannich reaction, in which the mechanism of recognition incorporates excited-state proton transfer reactions. The remarkable differentiation in spectral properties upon metal complexation makes 1a a highly sensitive fluorescence probe.
