A ratiometric fluorescent probe for zinc ions based on the quinoline fluorophore

A ratiometric fluorescent zinc probe 1 of carboxamidoquinoline with a carboxylic acid group was designed and synthesised. Probe 1 exhibits high selectivity for sensing Zn2+; about a 13-fold increase in fluorescence emission intensity and an 82nm red-shift of fluorescence emission are observed upon binding Zn2+ in EtOH/H2O (1 : 1, V/V) solution. The ratiometric fluorescence response is attributed to the 1 : 1 complex formation between probe 1 and Zn2+ which has been utilised as the basis for the selective detection of Zn2+. The analytical performance characteristics of the proposed Zn2+-sensitive probe were investigated. The linear response range covers a concentration range of Zn2+ from 2.0 x 10(-6) to 5.0 x 10(-5) mol L-1 and the detection limit is 2.7 x 10(-7) mol L-1. The determination of Zn2+ in both tap and river water samples shows satisfactory results.