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

Abstract

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.

Funktionelle flüssigkristalline Aggregate: selbstorganisierte weiche Materialien

“…[142-144, 147, 153-159] Beispielsweise werden Wasserstoffbrü-cken zwischen Amidgruppen für das Design von Gelbildnern genutzt, die in Lösung eindimensionale faserartige Aggregate aufbauen. [155][156][157][158] Darüber hinaus können auch Wasserstoffbrücken zwischen Harnstoffgruppen zu eindimensionaler Selbstorganisation führen. [147,[153][154][155] 2.1.5.…”

“…[155][156][157][158] Darüber hinaus können auch Wasserstoffbrücken zwischen Harnstoffgruppen zu eindimensionaler Selbstorganisation führen. [147,[153][154][155] 2.1.5. Zwei-und dreidimensionale offene Aggregate Netzwerke mit wasserstoffverbrückten Hydroxygruppen sind ein weiterer Typ offener Wasserstoffbrückenarchitektu-ren (Abbildung 4 D).…”

Tri- and Mono-Nuclear Zinc(II) Complexes Based on Half- and Mono-Salamo Chelating Ligands

“…In addition, the Cg3 (O 2 -C 1 -C 2 -C 3 -C 4 -C 9 ) of pyrone rings as acceptors forms one hydrogen bond with the protons (-C26H26B) of coordinated ethanol molecules. The space skeleton of complex 1 adopts a 3D supramolecular structure by the action of hydrogen bond and C-H···π stacking interactions [34,59,60]. …”

Gelation Process of Toluene-Based bis-Urea in Cyclohexane Studied with Magnetic Resonance Imaging

“…The toluene-based bis-urea belongs to a new class of low molecular weight gelators [1][2][3][4][5][6][7][8]. Such small organic molecules interact in solution (mostly in organic solvent, but also in water) with the other molecules in such a way that large supramolecular aggregates in a form of elongated fibers are created.…”