A highly efficient and selective turn-on fluorescent sensor for Cu2+ ion based on calix[4]arene bearing four iminoquinoline subunits on the upper rim.

A new fluorescent chemosensor based on calix[4]arene bearing four iminoquinoline subunits on the upper rim was conveniently synthesized, which showed a remarkable enhanced fluorescent intensity in the presence of Cu(2+) ion and a high selectivity toward Cu(2+) ion over a wide range of tested metal ions in acetonitrile.