A Novel Cyclophane. Host–Guest Complexation and Selective Inclusion of Aromatic Guests from Nonaqueous Solution

A novel cyclophane, 2,2,20.20-tetramethyl-11,29-dinitro-7,15,25,33-tetraoxaheptacyclo-[32.2.2.2.2.2.1.1]hexatetraconta-3,5,9(44),10,12,16,18,21,23,27(39),28,30,34,36,37,40,42,45-octadecaene(l), was synthesized by the reaction of 3,5-bis(bromomethyl)nitrobenzene (2) with bisphenol A (3). Both stepwise 2:2 cyclization of 2 and 3 via U-shaped precursor 4 and direct 2:2 cyclization of 2 and 3 were performed under several reaction conditions. With the coexistence of benzene in the reaction solvent, relatively high yield of 1 was achieved even without operation under high dilution conditions. This can be explained in term of a “template” effect of benzene in the cyclization step. The cyclophane 1 formed a “column-type” cave and included aromatic guests in this cave. This was confirmed by X-ray crystal structure analysis of the complex with benzene. The stoichiometry and the stability of the various inclusion complexes at high temperatures and under reduced pressure were examined. The remarkable discrimination selectivity in the inclusion complex formation from mixtures of guests is reasonably explained by the “packing-size relationship”.