Crystal structures of the inclusion complexes of beta-cyclodextrin with aliphatic monoacids tridecanoic acid and (Z)-tetradec-7-enoic acid. Formationof [3]pseudorotaxanes

The structures of the inclusion complexes of beta cyclodextrin with the ali phatic mono-acids tridecanoic acid (1) and (Z)-tetradec-7-enoic acid (2) ha ve been determined at room temperature. Both compounds crystallise in P1, a = 15.654(6) Angstrom, b = 15.650(6) Angstrom, c = 15.937(6) Angstrom, alph a = 101.58(1)degrees, beta = 101.59(1)degrees, gamma = 103.58(1)degrees, Z = 1, for 1 and a = 15.6259(9) Angstrom, b = 15.623(1) Angstrom, c = 15.935( 1) Angstrom, alpha = 101.547(2)degrees, beta = 101.555(2)degrees, gamma = 1 03.642(2)degrees, Z = 1, for 2. One molecule of the monoacids threads throu gh two cyclodextrin macrocycles arranged in dimers thus forming [3]pseudoro taxanes. The host dimers are aligned along a channel in order to create a h ydrophobic environment for the terminal methyl group of the guest and isola te it from the aqueous environment that surrounds the cyclodextrin dimeric units. The guests exhibit disorder over two orientations resulting in hydro gen bonding between the carboxyl groups of adjacent guest molecules along t he channel and formation of carboxylic dimers. This crystal packing differs from that of beta-CD complexes of homologous dicarboxylic acids.