Azacalix[3]arene-carbazole conjugated polymer network ultrathin films for specific cation sensing

Developing highly selective and sensitive chemical sensors is a challenge with respect to new materials for chemical recognition. In this study, a new conjugated polymer network precursor, hexahomotriazacalix[3]arene-carbazole has been synthesized and electrochemically cross-linked to form ultrathin films using cyclic voltammetry. The incorporation of hexahomotriazacalix[3]arene moiety as a neutral cation-binding receptor into a conjugated polycarbazole network facilitates high selectivity and sensitivity for Zn²⁺. The ultrathin films were characterized spectroscopically using UV-vis absorption and fluorescence spectroscopy. Surface morphology properties were examined by atomic force microscopy. Electrochemical deposition parameters and sensor transduction was studied by an electrochemical quartz crystal microbalance, surface plasmon resonance spectroscopy, and open-circuit potentiometry techniques. The results indicate that the high selectivity and sensitivity for Zn²⁺ compared to those of other cations is due to the combined size and dipole specificity of the azacalixarene unit and nonspecific ionic interaction with the redox couple of the conjugated polycarbazole units.