Complexes of p-t-butylcalix[4]arene derivatives with neutral molecules: Structures and stabilities

Complexation of p-tert-butylcalix[4]arene derivatives with a series of neutral guests in CCl4 solution was studied. The formation of inclusion-type complexes was determined. The solution structural data obtained were compared with solid state (X-ray) data and with the results of AMBER force field calculations for several compounds. Stability constants were measured by the conventional NMR titration technique. The relationship of the nature of the guest and substitution pattern in the calix[4]arene lower rim with the complex stabilities is discussed.