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.

Protonation-Induced Self-Assembly of Flexible Macrocyclic Diacetylene for Constructing Stimuli-Responsive Polydiacetylene

“…Macrocycles are appealing chemical structures that offer a shape-persistent self-assembly. Macrocyclic molecular frame controls the self-assembly pattern and is thus considered a straightforward and versatile approach for the creation of regulated predefined morphology. − The macrocyclic structure features a confined cavity and self-stacks into the unidirectional columnar assembly for generating highly organized hollow tubular nanochannels. , Since the columnar assembly of macrocycles mainly relies on sequential noncovalent interactions, these structures lack stability upon exposure to unfavorable environment conditions. Accordingly, they are likely to lose tubular morphology due to weakening or collapse in noncovalent interactions.…”

Columnar Liquid-Crystalline Macrocycles Synthesized via Metal Ion-Assisted Self-Assembly

“…This synthesis strategy can be adapted to the introduction of a variety of branched side chains to adjust the phase and structural behavior of the LC assembly. [11][12][13]16 L1 with shorter alkyl chains was suitable for X-ray crystallography analysis to acquire structural information. As shown in Figure 2a, the anthracene moiety in L1 exists in a pseudoperpendicular arrangement with respect to the 9,10-arene groups.…”

“…All of the reagents and solvents were purchased at the highest commercial quality available (Wako, Kanto, TCI, and Aldrich) and used without any further purification, unless otherwise stated. 1 H and 13 C NMR spectra were recorded on JNM-ECS400 (400 MHz for 1 H; 100 MHz for 13 C) and JNM-ECA600 (600 MHz for 1 H; 150 MHz for 13 C) spectrometers at a constant temperature of 298 K. Tetramethylsilane (TMS) was used as an internal reference for 1 H and 13 C NMR measurements in CDCl 3 . ESI−TOF MS was performed with a Waters LCT-Premier XE spectrometer controlled by using Masslynx software.…”

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

“…Schiff‐base ligands have been widely explored for the preparation of stable and functional coordination complexes, and have raised interest in various fields of research, especially in catalysis and asymmetric catalysis, but also as colorimetric sensors triggered by metal–ligand coordination, crystalline porous materials, molecular magnets, liquid crystals, and energy materials including organic light‐emitting diodes and, more recently, dye‐sensitized solar cells . They are distinguished by their relative ease of synthesis (condensation between carbonyl and primary amine precursors), tunable denticity allowing multiple binding of several kinds of metal ions, and thus a large range of oxidation states and tunable optical, redox, and even magnetic properties of their metal complexes .…”

“…Mononuclear Zn II Schiff‐base complexes are known to form dimeric structures having a typical Zn 2 O 2 central unit, mediated by strong intermolecular Zn−O coordinative interactions (through μ 2 ‐phenoxo bridging) . Salphen‐type macrocycles have attracted a particular interest in the field of supramolecular chemistry, owing to their ability to self‐assemble into organized stacks . In particular, the aggregation behavior of multinuclear Zn II salphen complexes is strongly enhanced owing to their unusual oligomeric (Zn−O) n coordination motifs, a peculiar property that has been exploited for the construction of self‐assembled nanostructures of very high stability …”