The lack of ROE cross peaks between the two different stoppers and the corresponding hexyl chains, or with protons of the wheel, precluded the existence of equivalent matching spacer—stopper groups. Nevertheless, the presence of only one signal for proton a at d = 5.24 ppm in the NMR spectrumof 8 enables it to be assumed that the diphenylacetyl stopper is positioned at the upper rim of the wheel, while the dicyclohexyl one points toward the lower rim of the calixarene