Self-organization of 1,6-dialkyl-3a,6a-diphenylglycolurils in the crystalline state

Abstract

Peculiarities of self-organization of 1,6-dimethyl(diethyl)-3a,6a-diphenylglycolurils in crystals were studied. Glycolurils were synthesized and crystals of 16 solid forms (two pure substances and fourteen solvates) were obtained by crystallization from different solvents. The effect of solvent on the dimensionality of H-bonding architectures and crystal morphology was revealed. The most widespread experimentally observed H-bonding synthon is the chain based on the amide–amide R²₂(8) motif, and solvent molecules typically act as terminal groups toward these chains. This is in accordance with results of pairwise interaction energy calculation between glycolurils and glycoluril/solvent pairs. Parallel packing of these H-bonded chains in some cases results in crystal morphology facetted by hydrophobic alkyl and aryl moieties and provides materials with a superhydrophobic surface. It was proposed that bulk water is repelled due to the corrugation of surfaces formed by the alkyl and aryl groups.