Crystalline host-guest complexes involving carboxylic acid hosts and a dimethyl sulphoxide guest. X-ray crystal structures of two inclusion species

Abstract

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 synthesized, and crystal structures of their inclusion compounds with DMSO {1a [1·DMSO(1∶1)];2a [2·DMSO (1∶2)]} have been determined from single crystal X-ray diffraction data. The crystals show monoclinic symmetry withZ=4 (P21/n for1a andP21/c for2a), with the unit cell dimensionsa=11.567(1),b=10.206(1),c=17.579(1) A,β=100.50(1)° for1a, anda=14.910(1),b=6.732(1),c=26.084(1) A,β=100.41(1)° for2a. The structural models were refined toR=0.032 with 3127 reflections for1a, andR=0.035 with 3175 observations for2a, collected atT=173(1) K. Both structures comprise a characteristic molecular recognition pattern for DMSO via strong (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 of the host carboxyl groups. In the crystals H-bonded endless chains of alternating host and guest molecules are formed, which are held together by ordinary van der Waals' forces. Additionally, host2 binds a second DMSO molecule by a single (CO)O−H⋯O(=S) bond.