A Highly Selective Fluorescent Sensor for Distinguishing Cadmium from Zinc Ions Based on a Quinoline Platform

A fluorescent sensor, N-(quinolin-8-yl)-2-(quinolin-8-yloxy)­acetamide (HL), based on 8-aminoquinoline and 8-hydroxyquinoline platforms has been synthesized. This sensor displays high selectivity and sensitive fluorescence enhancement to Cd2+ in ethanol. Moreover, sensor HL can distinguish Cd2+ from Zn2+ via two different sensing mechanisms (photoinduced electron transfer for Cd2+; internal charge transfer for Zn2+). The composition of the complex Cd2+/HL or Zn2+/L– has been found to be 1:1, based on the fluorescence/absorption titration and further confirmed by X-ray crystallography.