Complexation of hydrogen bonding-driven preorganized di- and hexacationic bisporphyrin receptors for C60 in aqueous and DMSO media

This Letter reports the synthesis of three dicationic and two hexacationic receptors in which two porphyrin units are connected with an aryl amide linker. 1H NMR and X-ray crystal structure analysis for model compounds show that in aqueous or DMSO medium the receptors could adopt preorganized U-styled conformation due to intramolecular hydrogen bonding-induced rigidity of the amide linker. 1H NMR, UV–vis and fluorescent investigations revealed that the ionic receptors efficiently complex C60C ( CO 2 - ) 2 in aqueous medium with cooperative intermolecular electrostatic and donor–acceptor interactions as driving forces. A 1:1 binding stoichiometry has been established for the complexes and the related association constants have been evaluated.