Bridged di(alkyl- and 4,4,4-trifluorobutylimidazolium) quaternary salts based on p-tert-butylcalix[4]arene

Di(alkyl- and 4,4,4-trifluorobutylimidazolium) quaternary halides of p-tert-butylcalix4]arene, 5a-8a and 11a, were prepared and characterized. Metathetical reactions of these compounds with LiN(SO(2)CF(3))(2) and KPF(6) in methanol and water gave the corresponding new quaternary salts 5b-8b and 11b and 5c-8c and 11c, respectively, with high thermal stabilities. Compounds 5a-d, 6b, and 11a-c exhibit melting points <100 degrees C. On the basis of (1)H NMR and (13)C NMR spectral measurements, all of the new quaternary calix4]arene salts were found to exist in a cone conformation. (1)H NMR titration experiments and electrospray MS spectra support the encapsulation of K(+) in the ionophoric cavity of 11c.