A novel selective colorimetric chemosensor for cobalt ions in a near perfect aqueous solution

A novel chemosensor 1 (1 = 2-( N-( 2-hydroxybenzy1)-N-(( pyridin-2-y1)methyl)amino)-N-(2-hydroxyphenyl)acetamide) was synthesized and characterized. The receptor 1 showed a selective colorimetric sensing ability for cobalt ion by changing color from colorless to pale violet in a near perfect aqueous solution, facilitating naked eye detection of Co3+ through the oxidation of Co2+ to Co3+. This phenomenon could be possibly explained by ligand-to-metal charge-transfer. Moreover, the detection limit (1.8 mu M) of 1-Co complex is comparable to the environmental protection agency (EPA) guideline (1.7 mu M) in drinking water. Practically, 1 also functioned when supported by silica, indicating that receptor 1 had the potential for working as optical solid sensors. (C) 2015 Elsevier B.V. All rights reserved.