A new fluorescent chemosensor for copper(II) and molecular switch controlled by light

A novel fluorescent chemosensor with two 5-nitro-salicylaldehyde groups at the upper rim of calix[4]arene has been synthesized. The chemosensor can effectively recognize copper(II) ion. This system could be considered as a molecular switch. By alternating the light irradiation of mixed solution formed by the host and Cu2+, off-on-off fluorescent switching is carried out.