Effect of Symmetry and Increasing Hydrophobicity on the Self-Assembly and Function of Benzoylurea Derivatives

A novel series of benzoylurea derivatives containing benzoic acid, m-dibenzoic acid, and benzene 1,3,5-tricarboxylic acid were designed with increasing hydrophobicity. The aggregation behavior of the derivatives was studied by several spectroscopic methods. The porous morphology of the resulting aggregates was examined by polar optical microscopy and field emission scanning electron microscopy. From X-ray single-crystal analysis, it is observed that N,N'-dicyclohexylurea containing compound 3 lost C₃ symmetry and adopted a "bowl"-shaped conformation and self-assembles to form a supramolecular honeycomb-like framework that is stabilized by multiple intermolecular hydrogen bonds. However, compound 2 with C₂ symmetry had a kink-like conformation and self-assembled to form a sheet-like structure. Discotic compound 3 coated paper, cloth, or glass surfaces, repealed water, and behaved like a self-cleaning material. Discotic compound 3 is also able to separate the oil and water from oil-water emulsion.