Crystal structure of a calix[4]crown ether-ester and molecular recognitionof alkyl- and arylalkylamines

The crystal and molecular structure of 3 has been determined by X-ray analy sis. The crystal data are: triclinic, space group P (1) over bar, a = 12.99 9(2), b = 14.114(3), c = 16.132(3) Angstrom, alpha = 91.62(2), beta = 97.71 (1), gamma = 91.38(2)degrees, V = 2930.6(9) Angstrom(3), Z = 2, D-m = 1.046 g cm(-3). Rotational disorder has been seen in the t-butyl groups which we re refined isotropically. Least-squares refinement based on F-2, using 4827 observed reflections with I > 2 sigma(I) and 18 restraints, led to R = 0.1 23. The calix is found in a cone conformation. The crown ether part of the molecule is not in a fully extended conformation but has folds in the chain . The calix[4]crown ether-ester exhibits molecular recognition properties t oward alkylamines.