Selective detection of Zn2+ and Cd2+ ions in water using a host-guest complex between chromone and Q[7]

In this paper, the host-guest interaction of cucurbit[7]uril (Q[7]) and chromone (CMO) has been developed as a fluorescent probe for the highly selective detection of Zn2+ and Cd2+ in water based on a chelation-enhanced fluorescence (CHEF) mechanism. There was a good linear relationship between the fluorescence intensity of the CMO@Q[7] probe and the concentration of Zn2+ or Cd2+ in the range of 0-3.0 x 10(-5) mol/L and the detection limit for Zn(2+ )and Cd2+ was found to be 2.03 x 10(-6) mol/L and 1.89 x 10(-6) mol/L, respectively. The X-ray crystal structure indicated that different coordination fashions were triggered by Zn2+ and Cd2+ in the CMO@Q[7] complexes, respectively. However, both metal ions coordinated with the carbonyl oxygen of CMO, which was encapsulated in the cavity of Q[7], thus leading to the enhancement of recognition fluorescence emission of CMO. (C) 2021 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.

Automated summary

This paper developed a fluorescent probe based on a chelation-enhanced fluorescence mechanism for the highly selective detection of Zn2+ and Cd2+ in water, with low detection limits. Through X-ray crystal structure analysis, different coordination modes of metal ions in the complexes were observed.