Branching and guanidinylation of side chains of cyclophanes bearing fluorescent pyrene as a water-soluble host

Abstract Branched and guanidinylated cyclophanes (N6 and G3, respectively) were successfully synthesized from pyrene-appended water-soluble azacyclophane (N3) which was constructed with a tetraaza[6.1.6.1]paracyclophane, 3 hydrophilic side chains having a terminal ammonium group, and a hydrophobic pyrene side chain. By branching the side chain of N3 or introducing a guanidino groups on N3, we succeeded in improving water solubility of N6 and G3, even in an aqueous carbonate buffer (pH 10). In addition, the electrostatic interaction between G3 and hydrophobic anionic guest TNS was strengthened, and the guest-binding ability of G3 with TNS was also successfully improved.