Pseudopolymorphism in the p-tert-butylcalix[4]arene--n-butylamine system: directing the structural motifs.
p-tert-Butylcalix[4]arene forms three compounds with n-butylamine, two weakly interacting guest-host compounds of 1:1 and 1:2 stoichiometry, as well as a hydrogen-bonded 3:1 compound containing some n-butylamine molecules not coordinated to the host.