INCLUSION-COMPOUNDS OF ALPHA-TRUXILLIC ACID - X-RAY CRYSTAL-STRUCTURES OF THE COORDINATOCLATHRATES WITH METHANOL (1-2) AND DIMETHYLACETAMIDE (1-2)

The crystal structures of the inclusion compounds of the 2c,4t-diphenylcyclobutane-1r,3t-dicarboxylic acid (alpha-truxillic acid) host (1) with methanol [MeOH] (1:2) and with dimethylacetamide [DMA] (1:2) have been determined by single crystal X-ray diffraction. The substantial difference between the effects of the protic (MeOH) and aprotic (DMA) guests on the molecular packing is discussed. Crystal data: 1.2MeOH: monoclinic (P2(1)/n), a = 12.528(4), b = 5.589(1), c = 13.715(4) angstrom, beta = 101.16(4)-degrees, Z = 2, R = 0.064 for 1300 reflections; 1.2DMA: monoclinic (P2(1)/c), a = 6.151(1), b = 26.586(2), c = 7.938(1) angstrom, beta = 105.32(6)-degrees, Z = 2, R = 0.056 for 1488 observations. In both clathrates, half of the rigid alpha-truxillic acid molecule occupies the asymmetric unit together with one guest molecule. The hydrogen bonds between the trans-positioned functional groups of the host acid and the guest molecules in 1.2MeOH give rise to infinite layers parallel with the crystallographic ac diagonal. In contrast, the only one-way hydrogen bond from host to guest in 1.2DMA leads to discrete 1:2 host-guest aggregates. In this latter case, the hosts and guests are stacked separately, along the c axis direction.