Columnar Liquid Crystals from a Giant Macrocycle Mesogen

Abstract

Columnar liquid crystals composed of a giant macrocyclic mesogen were prepared. The giant macrocyclic mesogen has a square hollow with a 2.5 nm diagonal, which was bounded by diindolo[3,2-b:2',3'-h]carbazole (diindolocarbazole) moieties as the edges and bis(salicylidene)-o-phenylenediamine (salphen) moieties as the corners. The shape and size of the macrocycle were directly observed by scanning tunneling microscopy (STM). Each side of the bright square in the STM image corresponds to a diindolocarbazole moiety, and the length of the sides was consistent with the result of the single crystal analysis of diindolocarbazole. Finally, we successfully obtained a giant macrocycle with long and branched side chains, which exhibited a rectangular columnar LC phase over a wide temperature range. To the best of our knowledge, it contained the largest discrete inner space of any thermotropic columnar liquid crystal composed of macrocyclic mesogens.

Liquid‐crystalline Metallomacrocycles Composed of Bis(hydroxypyridono)toluene Ligand and Cu2+ Ions

“…Three kinds of branched alkyl chains were introduced to the nitrogen of bis(hydroxypyridono)toluene in order to impart solubility and LC properties. Thermal properties of thermotropic LC molecules are strongly dependent upon structure and density of side chains . Thereby, we have prepared three ligands, each having a different number of branched alkyl chains.…”

“…Thermal properties of thermotropic LC molecules are strongly dependent upon structure and density of side chains. [19,20,26] Thereby,w eh ave preparedt hree ligands,e ach having ad ifferent number of branched alkyl chains. As shown in Figure 1, L1 has two n-octyl groups in each of the hydroxypyridone moieties, three triethylene glycol monododecyl ether molecules are introduced in that of L2, and four triethylene glycol monohexyl ether molecules are introduced in that of L3.…”

“…Columnar liquid crystals, composed of ao ne-dimensional assembly of shape-persistent macrocycles, have been studied in recent times from the standpoint of construction of discrete nanospace in fluid materials. [17][18][19][20][21][22][23][24][25][26][27] Therein, chemical environmentso ft he interiors of the nanospaces in liquid crystals can be elaborately fabricated using an optimum choice of building blockso ft he liquid-crystalline (LC) macrocycles. Previously,w e reported discrete metallomacrocycles consistingo fn aphthalenedihydroxamate andC u 2 + ions that exhibit thermotropic LC properties.…”

A Constrained and “Inverted” [3+3] Salphen Macrocycle with an ortho‐Phenylethynyl Substitution Pattern

“…The cooperative metal-binding effect owing to their N 2 O 2 pocket makes them powerful ligandsf or metal complexation. [7][8][9][10][19][20][21] In particular,t he aggregation behavior of multinuclear Zn II salphen complexes is strongly enhanced owing to their unusual oligomeric (ZnÀO) n coordination motifs, ap eculiar property that has been exploited for the construction of self-assembled nanostructures of very high stability. Mononuclear Zn II Schiff-base complexes are known to form dimeric structuresh aving at ypical Zn 2 O 2 central unit, mediated by strong intermolecularZ n ÀOc oordinative interactions (through m 2 -phenoxob ridging).…”

“…[7][8][9][10][19][20][21] In particular,t he aggregation behavior of multinuclear Zn II salphen complexes is strongly enhanced owing to their unusual oligomeric (ZnÀO) n coordination motifs, ap eculiar property that has been exploited for the construction of self-assembled nanostructures of very high stability. [41] By changing the geometry (length, curvature) and/or nature of the diformyl-substituted aromatic precursor, several macrocycles of different size and shape could be prepared in high yields by following as imilar strategy: [41][42][43][44][45] [4+ +4], [7][8][9] and [6+ +6]. [33][34][35][36][37][38] Oneo ft he main synthetic challenges is to obtain selectively one type of macrocycle of ag iven size in good yield.…”