MOLECULAR INCLUSION IN CALIXARENES .18. CRYSTAL AND MOLECULAR-STRUCTURE OF THE P-TERT-BUTYLCALIX[7]ARENE 1-3 PYRIDINE COMPLEX CLATHRATE

The structure of the p-tert-butylcalix[7]arene 1:3 pyridine complex/clathrate (C77H98O7. 3C5H5N) has been determined by X-ray crystallography. The crystal data are as follows: monoclinic, space group P2(1)/c, a = 37.790(4), b = 9.423(2), c = 29.075(4) angstrom; beta = 112.74(2)-degrees; V = 8285(3) angstrom3; Z = 4; D(calc) = 1.10 g.cm-3. The host p-tert-butylcalix[7]arene links one pyridine molecule through a hydrogen bond between one of the seven hydroxy groups and the nitrogen of the pyridine. Two other guest molecules have been found in the crystal lattice, so the title compound may be defined as a complex/clathrate hybrid. The unambiguous conformation of the macrocycle is described by an alternative method, which avoids the use of dihedral angles (and the ambiguities in their values).