Magnetic Supramolecular Spherical Arrays: Direct Formation of Micellar Cubic Mesophase by Lanthanide Metallomesogens with 7-Coordination Geometry.

Here, an unprecedented phenomenon in which 7-coordinate lanthanide metallomesogens, which align via hydrogen bonds mediated by coordinated HO molecules, form micellar cubic mesophases at room temperature, creating body-centered cubic (BCC)-type supramolecular spherical arrays, is reported. The results of experiments and molecular dynamics simulations reveal that spherical assemblies of three complexes surrounded by an amorphous alkyl domain spontaneously align in an energetically stable orientation to form the BCC structure. This phenomenon differs greatly from the conventional self-assembling behavior of 6-coordinated metallomesogens, which form columnar assemblies due to strong intermolecular interactions.

CO switchable adhesion of ionic polydimethylsiloxane elastomers.

We have developed ionic polydimethylsiloxane elastomers that rapidly and reversibly increase their adhesion upon exposure to carbon dioxide (CO) gas. The CO molecules dissolve quickly into the ionic aggregates, physically crosslinking the polymer chains and plasticizing them. The elastomer consequently becomes softer and more adhesive upon exposure to CO.

A Rapid and Dual Optical CO -responsive Polydimethylsiloxane Elastomer with a Fluorinated Cyanine Dye.

We found that our optically CO -responsive polydimethylsiloxane (PDMS) elastomer rapidly and reversibly underwent both visible and fluorescent color changes in the presence of CO gas. Unlike conventional optically CO -responsive polymeric materials, it functions in totally dry gaseous conditions. The visible color and fluorescence of the elastomer sheet change after only 1 min of exposure to CO , and the sheet exhibits excellent repeatability in terms of color switching that persists for at least 20 times.

Aggregation structure of chiral cubic liquid crystals revealed by X-ray diffraction utilizing a new algorithm.

Chiral aggregation structure spontaneously formed by achiral rodlike molecules, a long-time unsolved problem in liquid crystal science, has been clarified by applying a new crystallographic algorithm recently developed while utilizing aggregation characteristics of this type. Bicontinuously interwoven networks characterize it similarly to the neighboring Gyroid phase in a phase diagram against the alkyl chain length and temperature. However, the network connectivity is significantly different from the bicontinuous networks that have been either known for related compounds or assumed for this phase.

Design, Regioselective Synthesis, and Photophysical Properties of Perfluoronaphthalene-Based Donor-Acceptor-Donor Fluorescent Dyes.

A one-step route to a series of perfluoronaphthalene-based donor (D)-acceptor (A)-D fluorescent dyes with various electron-donating groups was developed. The perfluoronaphthalene moiety in the D-A-D dyes served as a good electron-accepting aromatic ring with excellent intramolecular charge transfer properties, as determined by density functional theory calculations and measurements of the fluorescence properties in solution, in poly(methyl methacrylate) (PMMA) films, and in crystal form. Notably, replacing the naphthalene ring with perfluoronaphthalene in the D-A-D dyes carrying the phenothiazine moiety not only stabilized the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels but also reduced the energy band gap to change the emission color from blue to yellow.

Repulsive segregation of fluoroalkyl side chains turns a cohesive polymer into a mechanically tough, ultrafast self-healable, nonsticky elastomer.

Dynamic crosslinking of flexible polymer chains via attractive and reversible interactions is widely employed to obtain autonomously self-healable elastomers. However, this design leads to a trade-off relationship between the strength and self-healing speed of the material, i.e.

Effect of alkali metal cations on network rearrangement in polyisoprene ionomers.

The effects of cations, Li, Na, and Cs, on the structure of ionic aggregates and network rearrangement in carboxylated polyisoprene (PI) ionomers were studied. We found that network rearrangement interaggregate hopping of metal carboxylates is improved with a decrease in cation size, even though density functional theory (DFT) calculation indicated the increase in the attractive interaction between metal carboxylates. At the same time, we also found that as the size of the cation decreases, the inclusion of the PI segment in the ionic aggregate increases.

Stabilization of Bicontinuous Cubic Phase and Its Two-Sided Nature Produced by Use of Siloxane Tails and Introduction of Molecular Nonsymmetry.

A recent intriguing finding that a helical network arrangement forms the bicontinuous cubic phase is attracting great attention for the possibility of new routes to asymmetric synthesis by achiral molecules. However, the design of the molecular structure for the cubic phase is still unrevealed. In this work, a nonsymmetric core molecule with larger naphthalene and smaller benzene moieties at each side of the central linkage and the same disiloxanyldecyloxy terminal at both terminals is shown to be the first example of molecule forming both single-layered and double-layered core assembly modes in the Ia3d phase as a single molecule system.

Molecular design of anti-spindle-like molecules by use of siloxanyl terminals for a thermotropic bicontinuous cubic phase.

Selecting 1,2-bis(aryloyl)hydrazine as a model molecular framework, this article examines how the combined modification of two molecular moieties, i.e., variation of the molecular core motif (benzene B or naphthalene N as two aromatic rings) and use of bulky and flexible siloxane segments (disiloxane Si2, trisiloxane Si3, or its branched type Si3) at the end of both chains, affects the phase behavior including the cubic (Cub) phases such as well-known achiral Ia3d or the so-called "Im3m" phase mostly recognized as a chiral one.

Toward strong self-healing polyisoprene elastomers with dynamic ionic crosslinks.

To compromise high mechanical strength and efficient self-healing capability in an elastomer with dynamic crosslinks, optimization of the molecular structure is crucial in addition to the tuning of the dynamic properties of the crosslinks. Herein, we studied the effects of molecular weight, content of carboxy groups, and neutralization level of ionically crosslinked polyisoprene (PI) elastomers on their morphology, network rearrangement behavior, and self-healing and mechanical properties. In this PI elastomer, nanosized sphere-shaped ionic aggregates are formed by both neutralized and non-neutralized carboxy groups that act as stickers.

Molecular packing in two bicontinuous Ia3[combining macron]d gyroid phases of calamitic cubic mesogens BABH(n): roles in structural stability and reentrant behavior.

1,2-Bis(4'-n-alkoxybenzoyl)hydrazine [BABH(n), n is the number of carbon atoms in the alkyl chain] exhibits two different Ia3[combining macron]d cubic phases depending on the chain length (5 ≤n≤ 13 and 15 ≤n≤ 22). The molecular packing modes, not only of molecular cores but also of alkyl chains, are investigated through a maximum entropy method (MEM) and an analysis of the chain-length dependence of the body diagonal of the unit cell. The analyses revealed the difference in molecular packing.

A gas-plastic elastomer that quickly self-heals damage with the aid of CO gas.

Self-healing materials are highly desirable because they allow products to maintain their performance. Typical stimuli used for self-healing are heat and light, despite being unsuitable for materials used in certain products as heat can damage other components, and light cannot reach materials located within a product or device. To address these issues, here we show a gas-plastic elastomer with an ionically crosslinked silicone network that quickly self-heals damage in the presence of CO gas at normal pressures and room temperature.

Aromatic Fluorine-Induced One-Pot Synthesis of Ring-Perfluorinated Trimethine Cyanine Dye and Its Remarkable Fluorescence Properties.

We have developed a novel aromatic fluorine-induced one-pot synthesis of ring-perfluorinated trimethine cyanine dye without the use of a pyridine by reacting hexafluorobenzoindolenine with 5 equiv of methyl trifluoromethanesulfonate in mixed solvents of dimethylformamide and toluene. The thus-obtained ring-perfluorinated trimethine cyanine dye shows much better fluorescence properties, including intensity, quantum yield, and lifetime, than the nonfluorinated dye, not only in CHCl solution and the poly(methyl methacrylate) film but also in the powder state. Furthermore, ring-perfluorinated trimethine cyanine dye 2a shows better photostability toward white light-emitting diode irradiation than nonfluorinated dye trimethine cyanine dye 2b.

Systematic exploitation of thermotropic bicontinuous cubic phase families from 1,2-bis(aryloyl)hydrazine-based molecules.

Rational design of molecules that exhibit a thermotropic bicontinuous cubic (Cub) phase has been earnestly desired. In this work, we describe the suitable selection of a molecular motif that has enabled the systematic exploitation of eight new series of Cub-phase molecules with symmetric molecular cores, N-n (1), PB-n (2), S-n (3), and PEB-n (4), and unsymmetric cores, B-N-n (5), B-PB-n (6), B-S-n (7), and B-PEB-n (8). These eight series all originate from achiral chain-core-chain type rod-like molecules that exhibit two types of Cub phases, an achiral Ia3d phase, and a chiral phase.

Experimental and Theoretical Examination of the Radical Cations Obtained from the Chemical and Electrochemical Oxidation of 5-Aminothiazoles.

Chemical or electrochemical one-electron oxidation of 5--arylaminothiazoles was found to afford stable radical cations. For chemical oxidation, 1 equivalent of [(4-BrCH)N][SbCl] (Magic Blue, MB) was added to CHCl solutions of the thiazoles, and the thus-obtained radicals showed light absorption in the near-infrared region. Electrochemical oxidation also led to bathochromic shifts in the absorption bands, and the obtained spectra were similar to those derived from the chemically oxidized species.

Mirror symmetry breaking by mixing of equimolar amounts of two gyroid phase-forming achiral molecules.

Mirror symmetry breaking was observed by mixing of equimolar amounts of two gyroid phase-forming achiral molecules, one having a short and the other with a long tail. This fact indicates the importance of a critical chain length for the appearance of the chiral bicontinuous cubic (Cubbi) phase. It also demonstrates that the molecular-level mobility is closely connected to the formation and stabilisation of those Cubbi phases.

Stabilization of the bicontinuous cubic phase in siloxane-terminated mesogens, 1,2-bis[4'-(n-(oligodimethylsiloxyl)alkoxy)benzoyl]hydrazine.

The introduction of oligodimethyl siloxane segments at the termini of the alkyl tails has been employed to stabilize the bicontinuous cubic (Cub(bi)) phase of a chain-core-chain type molecule having a 1,2-bis(benzoyl)hydrazine central core with two chains attached at the 4' position of each benzoyl moiety. In this study, three silylated molecules, bis-C10Si2, bis-C10Si3, and C10Si2-C8C=C, were synthesized, where "CnSim" represents the number of carbon and silicon atoms in the chain and "bis" indicates the two chains being the same, whereas the last one is asymmetric with respect to the core. The phase behaviors were examined by using polarized optical microscopy, differential scanning calorimetry, and X-ray diffraction techniques.

Photoresponsive Toroidal Nanostructure Formed by Self-Assembly of Azobenzene-Functionalized Tris(phenylisoxazolyl)benzene.

The self-assembly of tris(phenylisoxazolyl)benzene 1b with photochemically addressable azobenzene moieties produced toroidal nanostructures, the formation and dissociation of which were reversibly regulated upon photoirradiation. 1b displayed a mesogenic behavior. In the solution, the stacked assemblies along with their C3 axes were formed.

A structural model of the chiral "Im3m" cubic phase.

Assuming the twisted arrangement of rodlike molecules as the origin of the chirality as in the existing model, a new model of the molecular arrangement in the cubic "Im3m" phase is proposed. The adoption of a basic structure different from that assumed in the existing model resolves most difficulties of the model including the random placement of defects concerning the sense of twist.

5-N-Arylaminothiazoles as Highly Twisted Fluorescent Monocyclic Heterocycles: Synthesis and Characterization.

A series of 5-N-arylaminothiazoles was prepared by reacting thioamide dianions derived from secondary thioamides with thioformamides, followed by sequential oxidation with iodine. X-ray analyses demonstrated that they adopt structures that are highly twisted from planar conformations. Their orientations were tuned by the steric and/or electronic interactions of the substituents at their 2-, 4-, and 5-positions.

FT-IR Study on Liquid Crystal Phase Transitions of Thermotropic Hydrogen-Bonded Cubic Mesogenes, 1,2-Bis(4'-n-alkoxybenzoyl)hydrazines (BABH-n) and 4'-n-Alkoxy-3'-nitrobiphenyl-4-carboxlic acid (ANBC-n): Spectroscopic Evidence for Quasibinary Picture Model.

Changes in intermolecular interactions and molecular geometry for two kinds of thermotropic cubic mesogenes, 4'-n-alkoxy-3'-nitrobiphenyl-4-carboxlic acid (denoted as ANBC-n, where n represents the number of carbon atoms in the alkoxy group) and 1,2-bis(4'-n-alkoxybenzoyl)hydrazines (BABH-n), at liquid crystal (LC) phase transitions were revealed utilizing the frequency shifts in Fourier transform infrared (FT-IR) bands as a guide. The ANBC-n and BABH-n form two kinds of bicontinuous cubic (Cub(bi)), Ia3d and Im3m types, and smectic LC phases depending on the length of the alkyl chain and temperature. In the present work, two kinds of phase transitions, i.

Phase structure and phase transition mechanism for light-induced Ia3d cubic phase in 4'-n-docosyloxy-3'-nitrobiphenyl-4-carboxlic acid/ethyl 4-(4'-n-docosyloxyphenylazo)benzoate binary mixture.

The light-induced smectic C (SmC) to bicontinuous cubic (Cub(bi)) phase transition was investigated using grazing-incidence X-ray diffraction (GI-XRD) and Fourier transform infrared (FT-IR) spectroscopy to elucidate the mechanism at the molecular level. The sample was a binary mixture of 4'-n-docosyloxy-3'-nitrobiphenyl-4-carboxylic acid with an azobenzene derivative having a similar structure. The GI-XRD analysis revealed that the lattice size of the light-induced Cub(bi) phase almost coincides with the extrapolated value of the thermally induced one to the irradiation temperature.

Rapid Stretching Vibration at the Polymer Chain End.

Stretching vibrations of aliphatic C-D bonds at the chain end and midchain site of partially deuterated polystyrene (PS) were determined by Fourier transform infrared (FT-IR) spectroscopy. It was first found that the stretching vibration at the chain end is more rapid compared to that at the midchain site in the glassy bulk state. The difference in the frequencies of the stretching vibrations at the chain end and midchain site changed little even when the PS was dissolved in toluene.

The pressure effect on thermotropic cubic phases of 1,2-bis(4'-n-alkoxybenzoyl)hydrazines.

The effect of pressure on the nanostructure of a thermotropic cubic (Cub) mesogen 1,2-bis(4'-n-alkoxybenzoyl)hydrazine (BABH-n; n is the number of carbon atoms in the alkyl chain) was investigated under elevated pressures up to 140 MPa by an X-ray diffraction (XRD) technique. Four compounds, BABH-12, -14, -16 and -18, were examined and the type of Cub mesophase formed at ambient pressure is Ia3d for BABH-12 and -18, Im3m for BABH-14, and both for BABH-16. The high-pressure XRD enabled the discrimination of the Cub phase type in the low-pressure Cub phase regions of BABH-14 and BABH-16 and the revision of the phase diagrams reported previously.

Light-driven phase transition in a cubic-phase-forming binary system composed of 4'-n-docosyloxy-3'-nitrobiphenyl-4-carboxylic acid and an azobenzene derivative.

Binary mixtures were prepared from an azobenzene derivative and a liquid-crystal (LC) compound that exhibits smectic C (SmC) and bicontinuous cubic (Cub(bi)) LC phases. Reversible switching between the two phases in response to UV-light irradiation was observed. This light-driven SmC-to-Cub(bi) transition is the first example showing the increased dimensionality of molecular ordering with isomerization of azobenzenes (see figure).