Crystal engineering with supramolecular chirons based on enantiodifferentiating self-assembly between amines and alcohols (Supraminols)

Homochiral pairs of vicinal diamines and vicinal diols form well-defined cryst. supramol. assemblies (supraminols) as a result of mutual recognition. X-ray crystallog. anal. shows extensive hydrogen bonding between amine and alc. groups that results in a hydrophilic inner core and hydrophobic outer peripheral units. The inner core consists of partially or fully hydrogen-bonded amine-alc. interactions that lead to a pleated-sheet-or ribbonlike secondary structure. The outer periphery consists of left- or right-handed helical strands of alternating diamine-diol units, depending on the sense of chirality of the diamine and the diol. High enantiomeric enrichment is possible when an enantiopure diamine and a racemic diol are allowed to interact resulting in a matched homochiral cryst. adduct. In one instance, the occlusion of a mol. of benzene within the assembly was obsd. On the basis of competition expts., some predictions can be made regarding the best matched pairs of diamines and diols, which we have termed supramol. chirons.