Non-covalent Electrostatic Interactions between Calix[4]arenes and Porphyrins using UV-VIS Spectroscopy

Different calix[4]arenes and cationic porphyrins were synthesized under suitable conditions. Electrostatic interactions between these cationic and anionic species were investigated using ultraviolet-visible spectroscopy spectroscopic techniques. A high thermodynamic stability was found between non-covalent calix[4]arenes capped porphyrins and the stability of the system retained even after addition of the electrolyte. The Job's Plot revealed that the complex follows a 1:1 stoichiometry, giving the best binding interaction when the host calix[4]arene is non-substituted. The hexyloxy chain appended at the lower rim of the calix[4]arenes for stabilizing its cone confirmation results into less binding with cationic porphyrins.