The CH•••π interaction as an important factor in the crystal packing and in determining the structure of clathrates

Crystal structures in the Cambridge Structural Database (CSD) were examined to investigate the role of the CH...pi interaction in the crystal packing and the structure of clathrates. More than 77% of organic crystals have been found to bear CH...pi interatomic distances shorter than 3.05 Angstrom. Database subsets were edited by monitoring the entire CSD with the structure of included solvents (CHCl3, CH2Cl2, MeNO2, MeCN, MeOH, Me2CO, DMSO, DMF, 1,4-dioxane, benzene, toluene and p-xylene). A great many of the examined compounds have been shown to bear short CH...pi distances among themselves and between supramolecular components. A variety of different solvents (protic, dipolar aprotic as well as non-polar) has been found to be included by CH...pi interactions. The crystal structures were retrieved and examined in detail for clathrates of 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol and 1,1'-binaphthyl-2,2'-dicarboxylic acid in complexation with their specific guests. The results are discussed in the context of the CH... pi interaction in controlling the specific structure of supramolecular aggregates.