Geometry 1,3,5-trimesic acid

Examples of crystalline associates where dimethyl sulfoxide is involved as one of the heteromolecular constituents are known in an appreciable number1. Certainly the associate between dimethyl sulfoxide and trimesic acid 84 (cf. Chapter 5 in Vol. 140 of this series) is one of the important individual cases. Characteristic modes of association between the carboxylic hosts discussed here and dimethyl sulfoxide are illustrated in Fig. 24. Pertinent geometry data are listed in Tables 17 and 18. One may realize from Fig. 24 that the fundamental mode of association of the host acids 20, 26, 37, and 41 is the formation of discrete H-bonded islands of host and (usually) one guest molecule. 

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