High Selectivity of Enol-keto Tautomers Imine Derivative for the Recognition of Co²⁺

A new enol-keto tautomers imine derivative R was designed and synthesized. The recognition property of the receptor R for 18 kinds of cations was studied by ultraviolet absorption spectroscopy (UV-Vis) analysis and naked-eye detection. The results showed that the receptor R had significant recognition ability for Co2+ Fe2+ and Ni2+ through UV-Vis analysis, which found single colorimetric recognition of Co2+ by color changes. The Job s plot indicated that the formation of complex between receptor R and Co2+ was in 1 : 1 stoichiometric ratios , and the limit of lowest detection of receptor R for Co2+ was 4. 14 x10(-7) mol/L. Meanwhile , naked recognition paper of receptor R was prepared. The enol-keto tautomerism of receptor R was illustrated during recognition process through theoretical calculation and nuclear magnetic resonance titration.