An unprecedented porphyrin-pillar[5]arene hybrid ditopic receptor

Abstract

A novel porphyrin-pillar[5]arene host compound ZnPor-P5 was designed and prepared for the first time. A 1 : 1 supramolecular complex (ZnPor-P5)·C4 was formed with the neutral guest 1,4-bis(imidazol-1-yl)butane (C4) depending on the cooperative interactions between the coordination of the zinc ion locating at the center of the porphyrin moiety and the inclusion complexation of the pillar[5]arene cavity with the guest molecule according to a range of NMR, mass, electronic absorption, and fluorescence spectroscopic results in addition to ITC, demonstrating the ditopic receptor nature of this porphyrin-pillar[5]arene hybrid compound. The addition of CdI₂ into (ZnPor-P5)·C4 in chloroform induced the dissociation of the guest molecule from the zinc ion locating at the center of the porphyrin moiety due to the stronger coordination of imidazole with Cd²⁺ than with the zinc ion, yielding a new supramolecular system ZnPor-(P5)·C4·Cd with a different conformation.