Azobenzene coupled chromogenic receptors for the selective detection of copper(II) and its application as a chemosensor kit

Azobenzene-based receptors 1–4 as colorimetric sensing materials were synthesized and their sensing properties were examined. In solution, the proposed sensing materials give rise to a large cation-induced hypochromic shift for Cu2+ resulting in a change from red to pale-yellow, whereas no significant color change was observed upon addition of other selected metal ions. The use of the silica gel plate modified with immobilization of receptor 4 to detect Cu2+ was also reported.