“Bis phenol A Cyclophanes”

The synthesis and structural characterisation of three new macrocyclic bis-phenol A cyclophane ethers are described. The solid state structures of two of the cyclophanes were determined by single crystal X-ray diffraction. Cyclophane 3 crystallises in the orthorhombic space group Pbca with unit cell dimensions of a = 11.533(7), b = 29.383(8), c = 14.927(8) Å and cyclophane 4 in themonoclinic space group P21/n with cell dimensions of a = 11.585(4), b = 11.839(2), c = 18.866(2) Å, = 94.48(2).The X-ray crystal structures reveal distorted conformations, thus supporting the weak binding of quats in solution observed by the NMR studies. In the crystalline state both macrocycles were found to form self-complementary dimers held together by weak intermolecular - and CH- interactions. The binding behaviour towards a series of tetralkylammonium cations was determined by 1H NMR titration in CDCl3 solution. The interactions between the hosts and the quats were clearly detectable but too weak to be translated into meaningful equilibrium constants.