Influence of the angle between two crown ether moieties on supramolecular copolymerization of bis(crown ether)s and bisparaquat homoditopic monomers

Bis(crown ether) homoditopic monomers containing two bis(p-phenylene)-34-crown-10 moieties with different angles (180° for monomer 3, 120° for monomer 4, and 60° for monomer 5) and a complementary bisparaquat homoditopic monomer (7) were designed and synthesized. The three bis(crown ether) monomers could organize into linear supramolecular polymers in concentrated solutions in CHCl3/CH3CN with the bisparaquat monomer 7, as demonstrated by 1H NMR and viscosity studies. The pseudorotaxanes or supramolecular polymers formed from 3+7 and 4+7 had larger values of Ka, p, n, slope 1, and slope 2 than those of 5+7. This result was attributed to the greater steric hindrance of compound 5 than that of 3 and 4, which resulted in less effective formation of linear supramolecular polymers from 5 with compound 7 than those from compounds 3 and 4 with compound 7, as also demonstrated by UV-vis method.