Water-soluble macrocyclic paddlanes and propellane as a new class of host molecules

A new class of water-soluble macrocyclic polyamine host molecules containing bicyclo[2.2.2]octane or bicyclo[4.4.0]decane subcyclic units, tetra-azabispaddlane (2a), hexa-azatrispaddlane (3a), and tetra-azabispropellane (4a), have been synthesized. While trispaddlane (3a) and bispropellane (4a) showed only line broadening of the n.m.r. spectra at -59 °C, bispaddlane (2a) exhibited coalescence behaviour at -31 °C, (benzyl protons), -35 °C (N-methylene protons adjacent to the bicyclo-octane unit), and -50 °C (ArH). The association constants of (2a)-(4a) and the fluorescent hydrophobic guest, 1-anilinonaphthalene-8-sulphonate, were determined in KCl-HCl buffer of pH 1.68 to be 2.7 × 10² M^-1, 1.1 × 10 ³ M^-1, and 2.2 × 10² M^-1, respectively.