Supramolecular stereoisomer - the conformational isomer of 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol in the different inclusion compounds

The host 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol (1) exhibits different conformational isomers in inclusion compounds with 1,3,3-trimethyl-2-oxabicyclo[2,2,2]octane (2) and trans p-propenylanisole (3). The molar ratios of hosts and guests in an asymmetric unit of complexes (1) + (2) and (1) + (3) are 1 : 2 and 2: 1, respectively. In the complex of (1) + (2), the host (1) is linked with (2) via hydrogen bonding and exhibits antiperiplanar conformation, whereas in the 2:1 host guest complex (1) + (3), hosts (1) are associated with each other by hydrogen bonding and the complex adopts a gauche conformation; guests contact with hosts by C-H...pi weak hydrogen bonding. The structures of the two complexes and conformational isomers of the host have been determined by X-ray crystallographic analysis.