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

Abstract

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 × 10²M^–1, 1.1 × 10¹³M^–1, and 2.2 × 10²M^–1, respectively.