A new urea gelator: incorporation of intra- and intermolecular hydrogen bonding for stable 1D self-assembly

A new bisurea gelator derived from 2,6-diaminopyridine has been developed. It efficiently gelates common organic and liquid crystalline (LC) solvents by forming elongated self-assembled fibres in solvents. X-Ray crystallography and 1H NMR measurements reveal that two urea groups in pyridine-based bisurea compounds form different hydrogen bonding patterns. One of two urea units is involved in intramolecular hydrogen bonding with the pyridyl nitrogen, while the other urea unit forms bifurcated intermolecular hydrogen bonding. This hydrogen-bonded structure is key for the fibrous self-assembly along with the efficient gelation. In addition, LC gels based on the pyridine-based gelator exhibit good electrooptic properties. These results indicate that the pyridine-based bisurea compound is a good gelator not only effective in gelation but also useful as a component of functional soft materials.