Photo-physical and complexation properties of chromogenic azo-calix[4]arene: Application to the detection of Eu3+

A studies of a tetrakis(phenylazo)calix[4]arene derivative have been developed for cation recognition. The complexation properties of this ligand towards transition metal ions have been investigated by UV–Visible and fluorescence spectroscopies. It has been found that the ligand has remarkable complexation ability for transition metal Ni2+, Co2+, Hg2+, heavy metal ions Al3+ and Pb2+ with an exceptional high affinity for the lanthanide Eu3+ ion. The stoichiometric ratio of the complexation between the ionophore and Eu3+ ions in acetonitrile solution has been determined by applying the molar ratio method. The complexes formed are ML2 and ML in neutral and in basic medium respectively. The recognition properties between the thin film and the ions have also been studied. The complexation properties of the ligand with Eu3+ ion has been confirmed by fluorescence spectroscopy.

► Good affinity of azo-calix[4]arene derivative towards Eu3+ has been obtained.
► Change in complexation properties in basic medium.
► The detection process of Eu3+ has been obtained by “switch off” mode.