The cyclophane tetramethyl 3,8,13,18a,2l,26,31,36aoctahydro-
4,6:9,12:22,24:27,30-tetraetheno-l5,18,21:-33,36,39-diethenylylidenedibenzo[k,ɑl][1,8,17,24]tetraoxacyclodotriacontene-1,2,19,20-tetracarboxylate acetonitrile solvate, C_(56)H_(44)O_(12).CH_3C=N, contains a large cavity and forms host-guest complexes in solution with a variety of quaternary nitrogen compounds. Crystallization from an acetonitrile solution that contained damantyltrimethylammonium iodide led, though, to crystals of the uncomplexed cyclophane (but containing one molecule of acetonitrile of crystallization). The cavity, about 7.6
x 4.0 Å and roughly rectangular in cross section, is occupied by ester groupings from two adjacent cyclophanes,
entering from opposite sides. Crystal data: orthorhombic, P2_12_12_1, with a= 11.741 (6), b = 16.155 (5), c = 25.895 (7) Å, v = 4912 Å^3, T = 296 K, Z = 4, M_r= 950.01, D_x = 1.28 g cm^(-3), F(000) = 1992, Mo Kɑ, λ = 0.7107 Å, μ = 0.84 cm^(-1), R = 0.0538 for 2410 independent reflections with I> 0, S = 2.29 for 2610 total reflections
