Ternary organic crystals consisting of an L-tartaric acid-derived dicarboxylic acid, a commercially available achiral diamine, and a chiral secondary alcohol have been developed and characterized by X-ray crystallography. 1D, 2D, and 3D hydrogen-bonded supramolecular networks were constructed, depending on the structure of the diamine used. Benzylic and aliphatic secondary alcohols were enantioselectively incorporated into the crystal and were successfully enantioseparated with up to 86 and 79% enantiomeric excess (ee), respectively. Selective incorporation of one enantiomer of 2-butanol, which is a small chiral aliphatic alcohol, was achieved by the cooperative effects of hydrogen bonds, CH···π interactions, and van der Waals interactions between the guest and host molecules, with the aid of two water molecules. The high host potential of the binary supramolecular system is mainly attributed to the skewed conformation of two rigid aromatic groups of tartaric acid derivatives, which prevents dense packing of the molecules and enhances the formation of multicomponent inclusion crystals.

A supramolecular chiral host consisting of N-(2-naphthoyl)-L-aspartic acid (L-1) and meso-1,2-diphenylethylenediamine (2) is effective in enantioseparation of 1-arylethanols (up to 96% ee with 100% inclusion ratio). Here we report three different methods to prepare the inclusion crystals and discuss the chiral recognition mechanism on the basis of X-ray crystallography results.

The structure and inclusion ability of eight types of salts prepared from a combination of four tartaric acid derivatives (dibenzoyl-and three positional isomers of ditoluoyl-L-tartaric acid) and two V-shaped dianilines were investigated. They afforded 1 : 1 or 2 : 1 stoichiometric salts and the hydrogen-bonding networks changed from three-dimensional to two-and one-dimensional networks as the distance between the methyl and carboxyl groups on the tartaric acid increased. When the methylene group of dianiline was changed to an oxygen atom, the molecular structure became thinner, forming a different hydrogenbonding network. Despite such diverse hydrogen-bonding networks, all the salts incorporated water and/ or 2-butanol molecules in their structure, affording ternary or quaternary inclusion crystals.