Optical Thin Film Sensing of Metal Ions Based on a New Chromogenic Calix[4]arene Derivative

The development of sensors to detect transition metal ions is a matter of special attention because of their toxic impact on our environment. A new chromogenic calix[4]arene derivative has been investigated combining the high recognition properties of calixarenes functionalized by an ester group and the optical response of an azo-group. The complexing properties of the tetrakis-(phenylazo)calix[4]arene derivative thin films have been studied by UV-Vis spectrophotometry. The sensing properties of the calix[4]arene thin films have been characterized in a second step by fluorescence spectroscopy. Main changes in the absorption spectrum so as in the fluorescence response are shown upon complexation of metallic and lanthanide cations, providing an easy and sensitive tool to detect main pollutants.