3D Continuous Water Nanosheet as a Gyroid Minimal Surface Formed by Bicontinuous Cubic Liquid-Crystalline Zwitterions

Co-organization of amphiphilic zwitterions and bis­(trifluoromethanesulfonyl)­imide led to the formation of bicontinuous cubic liquid-crystalline structures having 3D continuous hydrophilic gyroid minimal surface. The gyroid surface, incorporating a small amount of water, provided extremely thin but macroscopically continuous water nanosheet with a thickness of approximately 5 Å. The water nanosheet functioned as alignment free proton conduction pathway

Novel V- and Y‑Shaped Light-Emitting Liquid Crystals with Pentafluorinated Bistolane-Based Luminophores

Herein, we describe the synthesis of novel light-emitting liquid-crystalline (LC) compounds bearing pentafluorinated bistolane-based luminophores with a V- or a Y-shaped molecular geometry and the evaluation of their LC and photophysical characteristics. The V- or Y-shaped compounds exhibited a unique LC phase and showed photoluminescence (PL) behavior under various circumstances, such as in dilute solution or in the solid state. Notably, PL characteristics were observed even under high-temperature conditions with a crystal (Cr) to LC phase transition, although the PL efficiency (ΦPL) was gradually reduced because of thermal molecular motion. Interestingly, ΦPL was found to be completely recovered through the LC → Cr phase transition during the cooling process; the PL characteristics of the V- or Y-shaped compounds were sensitively changed by external thermal stress, giving these compounds the ability to act as thermoresponsive PL sensing materials

Amphotropic liquid-crystalline behaviour of glycolipids in amino acid ionic liquids

We examined lyotropic liquid-crystalline behaviour of glycolipids (GLs) with a normal alkyl chain or a diacetylene-functionalised alkyl chain in several amino acid ionic liquids (AAILs). It was found that the mixtures of GL and AAIL form various nanosegregated liquid-crystalline phases, such as smectic, bicontinuous cubic and hexagonal columnar phases, depending on the two-component ratio and AAIL species. The observed liquid-crystalline behaviours were summarised as phase diagrams. It is noteworthy that the employment of amino acid anions with superior hydrogen-bonding ability, such as aspartic and glutamic acid anions, gives a phase diagram with a wide liquid-crystalline region. Comparing with a phase diagram obtained for the GL/water mixtures, we gained insights on the similarity/dissimilarity between water and AAILs as self-organisation media of amphiphiles. For the diacetylene-functionalised molecule, UV irradiation was carried out to progress polymerisation. It is of interest that the polymerisation reaction progressed when the glycolipid formed a smectic phase in an AAIL while a reaction progress was not found when it formed a bicontinuous cubic phase in another AAIL. We believe that AAILs have a great potential to be a liquid media not only for amphiphiles but for various functional materials, such as polymers and colloids, to form novel assemblies.</p

3D Interconnected Ionic Nano-Channels Formed in Polymer Films: Self-Organization and Polymerization of Thermotropic Bicontinuous Cubic Liquid Crystals

Thermotropic bicontinuous cubic (Cubbi) liquid-crystalline (LC) compounds based on a polymerizable ammonium moiety complexed with a lithium salt have been designed to obtain lithium ion-conductive all solid polymeric films having 3D interconnected ionic channels. The monomer shows a Cubbi phase from −5 to 19 °C on heating. The complexes retain the ability to form the Cubbi LC phase. They also form hexagonal columnar (Colh) LC phases at temperatures higher than those of the Cubbi phases. The complex of the monomer and LiBF4 at the molar ratio of 4: 1 exhibits the Cubbi and Colh phases between −6 to 19 °C and 19 to 56 °C, respectively, on heating. The Cubbi LC structure formed by the complex has been successfully preserved by in situ photopolymerization through UV irradiation in the presence of a photoinitiator. The resultant nanostructured film is optically transparent and free-standing. The X-ray analysis of the film confirms the preservation of the self-assembled nanostructure. The polymer film with the Cubbi LC nanostructure exhibits higher ionic conductivities than the polymer films obtained by photopolymerization of the complex in the Colh and isotropic phases. It is found that the 3D interconnected ionic channels derived from the Cubbi phase function as efficient ion-conductive pathways

Guest Vapor-Induced State Change of Structural Liquid Pillar[6]arene

State change is a key phenomenon in materials science. We report the first observation of vapor-responsive reversible structural liquid-to-solid and solid-to-structural liquid state changes. We observed that a macrocyclic compound, a pillar[6]­arene derivative bearing 12 n-hexyl substituents, is a room temperature structural liquid with unique properties. Formation of a host–guest complex between the pillar[6]­arene cavity and the n-hexyl substituent results in a structural liquid with nanoscale structural heterogeneities. The structural liquid solidifies when exposed to competitive cyclohexane guest vapor, whereupon cyclohexane replaces the n-hexyl substituents in the pillar[6]­arene cavity and the n-hexyl substituents located outside of the cavity crystallize into distinct nanolayer assemblies. The solid reverts back to the structural liquid when the cyclohexane guest is removed through heating under reduced pressure because of rethreading of the n-hexyl substituents into the cavity. The structural liquid-to-solid and solid-to-structural liquid changes are reversible through the uptake and release of cyclohexane guest vapor

Self-Organization of Room-Temperature Ionic Liquids Exhibiting Liquid-Crystalline Bicontinuous Cubic Phases: Formation of Nano-Ion Channel Networks

Three-dimensionally interconnected nano-ion channel networks are formed by room-temperature ionic liquids exhibiting thermotropic liquid-crystalline (LC) bicontinuous cubic phases. These LC ionic liquids are a new family of ion-conductive materials with self-organized nanostructures. The ionic liquids have fan-shaped block molecular structures composed of two immiscible molecular parts:  the ammonium moiety at the focal point and the lipophilic tris(alkyloxy)phenyl part. We demonstrate that the ionic conductivities of the materials that are alignment free in the LC bicontinuous cubic phases are higher than those observed in the LC columnar phases

Ionic Switch Induced by a Rectangular–Hexagonal Phase Transition in Benzenammonium Columnar Liquid Crystals

We demonstrate switching of ionic conductivities in wedge-shaped liquid-crystalline (LC) ammonium salts. A thermoreversible phase transition between the rectangular columnar (Col_r) and hexagonal columnar (Col_h) phases is used for the switch. The ionic conductivities in the Col_h phase are about four orders of magnitude higher than those in the Col_r phase. The switching behavior of conductivity can be ascribed to the structural change of assembled ionic channels. X-ray experiments reveal a highly ordered packing of the ions in the Col_r phase, which prevents the ion transport

3D Anhydrous Proton-Transporting Nanochannels Formed by Self-Assembly of Liquid Crystals Composed of a Sulfobetaine and a Sulfonic Acid

Herein we describe anhydrous proton transportation through 3D interconnected pathways formed by self-assembled molecular complexes. A thermotropic bicontinuous cubic (Cub_bi) phase has been successfully obtained by mixing a wedge-shaped sulfobetaine with benzenesulfonic acid in different ratios. These ionic complexes exhibit the Cub_bi phase in a wide range of temperatures, while the single zwitterionic compound shows only a columnar hexagonal phase, and benzenesulfonic acid is nonmesomorphic. Anhydrous proton conduction on the order of 10^–4 S cm^–1 has been achieved for the mixture in the Cub_bi phase over 100 °C, which can be useful for the development of new electrolytes for the next generation of fuel cells

Oligothiophene–Indandione-Linked Narrow-Band Gap Molecules: Impact of π‑Conjugated Chain Length on Photovoltaic Performance

Solution-processed organic solar cells (OSCs) based on narrow-band gap small molecules hold great promise as next-generation energy-converting devices. In this paper, we focus on a family of A−π–D−π–A-type small molecules, namely, BDT-<i>n</i>T-ID (<i>n</i> = 1–4) oligomers, consisting of benzo­[1,2-<i>b</i>:4,5-<i>b</i>′]­dithiophene (BDT) as the central electron-donating (D) core, 1,3-indandione (ID) as the terminal electron-accepting (A) units, and two regioregular oligo­(3-hexylthiophene)­s (<i>n</i>T) with different numbers of thiophene rings as the π-bridging units, and elucidate their structure–property–function relationships. The effects of the length of the π-bridging <i>n</i>T units on the optical absorption, thermal behavior, morphology, hole mobility, and OSC performance were systematically investigated. All oligomers exhibited broad and intense visible photoabsorption in the 400–700 nm range. The photovoltaic performances of bulk heterojunction OSCs based on BDT-<i>n</i>T-IDs as donors and a fullerene derivative as an acceptor were studied. Among these oligomers, BDT-2T-ID, incorporating bithiophene as the π-bridging units, showed better photovoltaic performance with a maximum power conversion efficiency as high as 6.9% under AM 1.5G illumination without using solvent additives or postdeposition treatments. These favorable properties originated from the well-developed interpenetrating network morphology of BDT-2T-ID, with larger domain sizes in the photoactive layer. Even though all oligomers have the same A–D–A main backbone, structural modulation of the π-bridging <i>n</i>T length was found to impact their self-organization and nanostructure formation in the solid state, as well as the corresponding OSC device performance