CRYSTALLINE HOST-GUEST COMPLEXES INVOLVING CARBOXYLIC-ACID HOSTS AND A DIMETHYL-SULFOXIDE GUEST - X-RAY CRYSTAL-STRUCTURES OF 2 INCLUSION SPECIES

The host compounds 2,2'-binaphthyl-3,3'-dicarboxylic acid (1) and 1,1' :3'-1''-terphenyl-2',4,4''-tricarboxylic acid (2) have been synthesize d, and crystal structures of their inclusion compounds with DMSO (1a [ 1 . DMSO(1:1)]; 2a [2 . DMSO (1:2)1) have been determined from single crystal X-ray diffraction data. The crystals show monoclinic symmetry with Z = 4 (P2(1)/n for la and P2(1)/c for 2a), with the unit cell dim ensions a = 11.567(1), b = 10.206(1), c = 17.579(1) Angstrom, beta = 1 00.50(1)degrees for 1a, and a = 14.910(1), b = 6.732(1), c = 26.084(1) Angstrom, beta = 100.41(1)degrees for 2a. The structural models were refined to R = 0.032 with 3127 reflections for 1a, and R = 0.035 with 3175 observations for 2a, collected at T = 173(1) K. Both structures c omprise a characteristic molecular recognition pattern for DMSO via st rong (CO)O-H ... O(=S) hydrogen bonds and possible C-H ... O contacts, the latter ones from the guest methyl groups to the carbonyl oxygen o f the host carboxyl groups. In the crystals H-bonded endless chains of alternating host and guest molecules are formed, which are held toget her by ordinary van der Waals' forces. Additionally, host 2 binds a se cond DMSO molecule by a single (CO)O-H ... O(=S)) bond.