Exchange-Storage of a Guest Molecule in an Inclusion Crystal of 2,11,20,29-Tetramethyl-2,11,20,29-tetraaza [3.3.3.3]paracyclophane

The CHCl3 guest molecules of the 2,11,20,29-Tetramethyl-2,11,20,29-tetraaza[3.3.3.3]paracyclophane (1) inclusion complex were completely replaced by CH2BrCl when [1·CHCl3] powder simply made contact with gaseous CH2BrCl molecules. This guest exchange in the crystalline phase was confirmed by 1H NMR, GLPC, and X-ray analysis. The guest exchange was found to proceed in a biphasic manner, viz., (a) a “slow” exchange approaching a guest composition of 65% CHCl3 / 35% CH2BrCl followed by (b) a “rapid” exchange. The latter abrupt increase of the exchange rate was most reasonably attributed to a change of in crystal structure, based on the X-ray diffraction pattern of a fully guest-exchanged crystal (Type I) which was found to be very similar to that of a Type II crystal of [1·CH2BrCl].