Combination of an Aromatic Core and Aromatic Side Chains Which Constitutes Discotic Liquid Crystal and Organogel Supramolecular Assemblies

Abstract

This paper reports unique and unusual formations of columnar liquid crystals and organogels by self-assembling discotic molecules, which are composed of an aromatic hexaazatriphenylene (HAT) core and six flexible aromatic side chains. In HAT derivatives 3a, with 4'-(N,N-diphenylamino)biphenyl-4-yl chains, 3b, with 4'-[N-(2-naphthyl)-N-phenylamino]biphenyl-4-yl chains, and 3c, with 4'-phenoxybiphenyl-4-yl chains, the two-dimensional hexagonal packings can be created by their self-assembling in the liquid crystalline phase, which were characterized by polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction analysis. In certain solvents, HAT molecules 3a-c can form the viscoelastic fluid organogels, in which one-dimensional aggregates composed of the HAT molecules are self-assembled and entangled into three-dimensional network structures. The organogel structures were analyzed by scanning electron microscopy observation, (1)H NMR, UV-vis, and circular dichroism spectroscopy. In contrast to 3a-c, none of the liquid crystalline and organogel phases could be formed from 3d and 3e with short aromatic side chains including a phenylene spacer, and 3f (except a few specific solutions) and 3g without terminal diarylamino and phenoxy groups. In 3a-c, the aromatic side chains with terminal flexible groups make up soft regions that cooperatively stabilize the liquid crystalline and organogel supramolecular structures together with the hard regions of the hexaazatriphenylene core.

Relaxation dynamics in the columnar liquid crystal phase of hard platelets

“…Understanding their equilibrium and out-of-equilibrium aggregation behavior is also an interesting challenge for fundamental research on stacking phenomena. The most common and frequently investigated molecular CLCDs are formed by mesogens, such as triphenylenes [13][14][15] or hexabenzocoronenes, [16][17][18] with a rather rigid central aromatic core surrounded by flexible peripheral alkyl chains bonded to the edges. 11,19 Both the core and the side chains can be tailored to control and eventually to improve the functional properties of the material.…”

Star-Shaped Conjugated Systems

“…Hexaazatriphenylenes with six biphenyl arms and peripheral donor groups ( 132c :R = C 6 H 6 OC 6 H 5 ; 132b R = C 6 H 6 N(C 6 H 5 ) 2 ; 132j :R = C 6 H 6 N(C 6 H 5 )-2-C 10 H 7 ) were obtained from condensation of 135 and the substituted benzils 134f - g [361,362,363]. These compounds, though missing any flexible side chain, form liquid-cystalline phases at high temperatures [361].…”

Chiralitätsverstärkung in dynamischen supramolekularen Aggregaten

“…Somit kann das Lösungsmittel seine Chiralität auf die selbstorganisierten Stapel übertragen. [87] 5. Kooperative Stapelung in helikalen selbstorganisierten Ureidopyrimidon-und UreidotriazinPolymeren…”