岸川 圭希

The structural color of Rock Pigeon feathers is produced by thin-layer interference, which occurs in the cortex layer of the barbule. Furthermore, melanin granules, which exist below the cortex layer, absorb scattered light to reduce the background reflection. In this paper, we describe the preparation of structural color materials from combined use of polydopamine-inorganic thin films (PDA/GOPTS thin film) and black particles (PDA/GOPTS particles) that mimic the coloration mechanism of Rock Pigeon feathers. A hierarchical structure of thin films and particles was created to endure the polymerization solution of DA and DA-GOPTS. The obtained materials showed beautiful structural colors and the colors were controlled by film thicknesses.

We describe a facile and simple method to prepare colloidal architectures by the in situ assembly of amphiphilic diblock copolymers onto submicron-sized core particles. Polystyrene-b-poly(acrylic acid) diblock copolymers (PSt(m)PAA(n)) were directly assembled onto hydrophobic silica (SiO2) core particles,. forming spherical core-shell particles. By varying the surface hydrophobicity of the core particles and the compositions of the diblock copolymers, core-shell particles with tailored shell thickness were observed. Furthermore, we demonstrated the preparation of ellipsoidal particles, which containing two core particles, based on this strategy. (C) 2016 Elsevier B.V. All rights reserved.

Novel C-2-symmetric chiral dopant derivatives, namely, N-substituted (2R, 3R)-2,3-bis(4-(4-octyloxyphenyl)benzoyloxy)succinimides1a-h, were synthesised, and the effects of the N-substituent and imide-carbonyl groups on the helical twisting powers (HTPs) were investigated in two nematic liquid crystalline compounds, 4-n-pentyl-4'-cyanobiphenyl (5CB) and N-(4-ethoxybenzylidene)-4-n-butylaniline (EBBA). As a result, it was clarified that the bulkiness of the N-substituents has a significant correlation with the HTPs, and the imide-carbonyl group interacts strongly with the cyano group of 5CB to give high HTPs in the nematic phases. However, it is assumed that the imide-carbonyl groups of the dopants do not have strong electrostatic attractive interactions with EBBA molecules in the nematic phase to afford the moderate HTPs. [GRAPHICS] .

Blue phases (BPs) obtained by doping a commercially available liquid crystalline compound (4-butyl-N-(4-ethoxybenzylidene)aniline (EBBA)) with (2R,3R)-2,3-bis(4-octyloxyphenylbenzoyloxy)-N-(hydroxydecyl)succinimide (1) were highly stabilised by the addition of a small amount of alkane diols. Especially, addition of only 0.5mol% of octane-1,8-diol increased the BP-Iso transition temperature by 10K and widened the BP temperature range up to 35K. A model stabilisation mechanism based on the construction of a hydrogen bond network in each disclination zone in BPs was proposed. [GRAPHICS] .

The beautiful structural colors in bird feathers are some of the brightest colors in nature, and some of these colors are created by arrays of melanin granules that act as both structural colors and scattering absorbers. Inspired by the color of bird feathers, high-visibility structural colors have been created by altering four variables: size, blackness, refractive index, and arrangement of the nano-elements. To control these four variables, we developed a facile method for the preparation of biomimetic core-shell particles with melanin-like polydopamine (PDA) shell layers. The size of the core-shell particles was controlled by adjusting the core polystyrene (PSt) particles' diameter and the PDA shell thicknesses. The blackness and refractive index of the colloidal particles could be adjusted by controlling the thickness of the PDA shell. The arrangement of the particles was controlled by adjusting the surface roughness of the core-shell particles. This method enabled the production of both iridescent and non-iridescent structural colors from only one component. This simple and novel process of using core-shell particles containing PDA shell layers can be used in basic research on structural colors in nature and their practical applications.

We design a new naphthalenediimide (NDI) pi-system, NDI-Fc-NDI, having a ferrocene linker as a hinge unit and long alkyl chains as supramolecular assembling units. The NDI units are "directionally flexible" in concert with the pivoting motion of the ferrocene unit with a small rotational barrier. The NDI units rotate around the ferrocene unit faster than the NMR time scale in solution at room temperature. UV-vis absorption, synchrotron X-ray diffraction, and atomic force microscope studies reveal that NDI-Fc-NDI forms a fibrous supramolecular assembly in solution (methylcyclohexane and highly concentrated chloroform) and film states, wherein the NDI units are in the slipped-stack conformation. The NDI-Fc-NDI supramolecular assembly in the film state exhibits multiple phase transitions associated with conformational changes at different temperatures, which are confirmed by differential scanning calorimetry, polarized optical microscopy, and temperature-dependent X-ray diffraction. Such thermal transitions of NDI-Fc-NDI films also induce changes in the optical and electronic properties as revealed by UV vis absorption and photoelectron yield spectroscopies, respectively. The thermal behaviors of NDI-Fc-NDI, realized by the unique molecular design, are considerably different from the reference compounds such as an NDI dimer connected with a flexible 1,4-butylene linker. These results provide us with a plausible strategy to propagate the molecular dynamics of the pi-system into macroscopic properties in film states; the key factors are (i) the supramolecular alignment of molecular switching units and (ii) the directional motion of the switching units perpendicular to the supramolecular axis.

Luminescent particles have been attracting significant attention because they can be used in biochemical applications, such as detecting and imaging biomolecules. In this study, luminescent polystyrene latex particles were prepared through miniemulsion polymerization of styrene with dissolved europium complexes in the presence of bovine serum albumin (BSA) and poly(ethylene glycol) monomethoxy methacrylate as surfactants. The solubility of the europium complex in styrene has a strong effect on the yield of the particle. Europium tris(2-thenoyl trifluoroacetonate) di(tri-n-octyl phosphine oxide), which has a high solubility in styrene, was sufficiently incorporated into the polystyrene particles compared to europium tris(2-thenoyl trifluoroacetonate), which has a low solubility in styrene. The luminescence property of the europium complex could remain intact even after its incorporation through the miniemulsion polymerization. In the aqueous dispersion, the resulting particles could emit strong luminescence, which is a characteristic of the europium complex. The antibody fragments were covalently attached to BSA-covered particles after a reaction with a bifunctional linker, N-(6-maleimidocaproyloxy)succinimide. The time-resolved fluoroimmunoassay technique showed that 3.3 pg/mL of human ct-fetoproteins (AFP) can be detected by using the resulting luminescent particles. An immunochromatographic assay using the resulting particles was also performed as a convenient method to qualitatively detect biomolecules. The detection limit of AFP measured by the immunochromatographic assay was determined to be 2000 pg/mL. These results revealed that the luminescent particles obtained in this study can be utilized for the highly sensitive detection of biomolecules and in vitro biochemical diagnosis. (C) 2016 Elsevier B.V. All rights reserved.

We present a method for fabricating photonic crystals (PCs) by polymerization-induced microphase separation of block copolymers (BCPs). Molecular weight of BCP for PCs is so large that it has been difficult for conventional solution casting and annealing methods to complete the microphase separation to form periodically ordered submicron structures. Our method overcomes the difficulty by inducing the microphase separation and transitions during the polymerization, when the molecular weight of the BCPs is small enough for the microphase separation and transitions. The microphase-separated structure is then enlarged while maintaining the self-similarity. We succeeded in fabricating PCs with reflection wavelength lambda(m) approximate to 1000 nm and a full width at half-maximum Delta lambda = 0.05 lambda(m) by living-radical bulk block copolymerization of poly(methyl methacrylate)-block-polystyrene.

<p>This article describes a simple procedure to fabricate magnetically-responsive particles from as-prepared particles. Firstly, a magnetically-responsive, holmium-containing surfactant (DDAH) was prepared by mixing a commercially available surfactant and holmium(III) chloride hexahydrate. Subsequently, polydopamine (PDA) particles, which exhibit beautiful structural colors, were modified using the DDAH to afford PDA/DDAH particles. The magnetic behavior of the obtained PDA/DDAH particles was investigated. Furthermore, structural color changes of the materials prepared by PDA/DDAH particles under magnetic fields were also investigated.</p>

Anthracene derivatives possessing a carbamate group and an ester group at their 9- and 10-positions, respectively, were prepared to furnish pairwise packing of anthracene fluorophores in their crystal structures. They were nonluminescent in ethanol solution and showed AIE (aggregation-induced emission) in aqueous ethanol solution and in solid state. Crystal structure analysis of them showed that the H-bonding networks involved in their crystal structures could be classified into four patterns, H-bonding between the carbamate and the ester carbonyl (motif A), H-bonding between the carbamate and the ester oxygen atom (motif B), H-bonded cyclic dimer of carbamate moieties (motif C), and H-bonded chain among carbamate moieties (motif D). Compounds with pairwisely packed anthracene fluorophores showed dimer emission with the longer fluorescence wavelength than others without the pair formation. Fluorescence maximum wavelengths and lifetimes become longer proportional to the degree of overlapping of two facing anthracene pi-planes.

Anthracene derivatives possessing a carbamate group and an ester group at their 9- and 10-positions, respectively, were prepared to furnish pairwise packing of anthracene fluorophores in their crystal structures. They were nonluminescent in ethanol solution and showed AIE (aggregation-induced emission) in aqueous ethanol solution and in solid state. Crystal structure analysis of them showed that the H-bonding networks involved in their crystal structures could be classified into four patterns, H-bonding between the carbamate and the ester carbonyl (motif A), H-bonding between the carbamate and the ester oxygen atom (motif B), H-bonded cyclic dimer of carbamate moieties (motif C), and H-bonded chain among carbamate moieties (motif D). Compounds with pairwisely packed anthracene fluorophores showed dimer emission with the longer fluorescence wavelength than others without the pair formation. Fluorescence maximum wavelengths and lifetimes become longer proportional to the degree of overlapping of two facing anthracene pi-planes.

Biaxial smectic A (SmA(b)) and biaxial nematic (N-b) liquid crystal (LC) phases using achiral straight-rod molecules were realized through perfluoroarene-arene (PFA-A) and CH/F interactions. Compounds 1a, 1b and 1c, 4,4'-bis(2,3,4-trifluorobenzoyloxy)biphenyl, 4,4'-bis(2,3-difluorobenzoyloxy)biphenyl and 4,4'-bis(2-fluorobenzoyloxy)biphenyl, were synthesized. The liquid crystallinity of these compounds was investigated using polarized light optical microscopy (POM) and differential scanning calorimetry (DSC). Furthermore, the ferroelectric switching behaviors of 1a in the nematic (N) and smectic A (SmA) LC phases and 1b in the N phase were confirmed by applying a triangular wave voltage in electro-optic experiments. Then, the values of spontaneous polarization (P-s) in the LC phases of 1a were investigated as functions of frequency, voltage, and temperature. It was strongly hypothesized that the semiperfluorinated phenyl (SFP) groups rotate around the molecular long axes and change pairs in the CH/F interacting sites, and this cooperative movement of the SFP groups is repeated during the switching process.

A novel approach for creating non-iridescent bright structural color materials from polydopamine (PDA) black particles is presented. Two biomimetic features, melanin granules and the amorphous structures found in nature, were incorporated into these materials, consisting of PDA black particles to develop a bright and non-iridescent structural color without using any additives.

A novel approach for creating non-iridescent bright structural color materials from polydopamine (PDA) black particles is presented. Two biomimetic features, melanin granules and the amorphous structures found in nature, were incorporated into these materials, consisting of PDA black particles to develop a bright and non-iridescent structural color without using any additives.

A simple chiral dopant molecule (R)-1 with both rod- and arch-like units was prepared, and extremely large helical twisting powers (+123 to +228 μm(-1)) in nematic liquid crystal phases were achieved. We have demonstrated that the introduction of an arch-like unit in addition to rod-like units is highly effective in controlling the helical molecular alignment. As an application of the dopant, induction of blue phases by addition of a small amount of it was achieved.

We prepared the novel fluorescent polymer latex particles which can change their fluorescence intensity in response to the increasing NaCl concentration in water. Core polymer latex particles were synthesized by emulsifier-free emulsion polymerization of styrene and 2-(2-chloroisobutyroyloxy)ethyl methacrylate. Hydrophilic polymer chains containing epoxy groups were grafted from the core particles by surface-initiated atom transfer radical copolymerization of methoxy polyethyleneglycol methacrylate (MEO(x)MA, x = 4 or 9) and glycidyl methacrylate in aqueous media. After azidation of epoxy groups in graft chains, a water-soluble fluorescent dansyl derivative was successfully coupled with the graft chains by copper-catalyzed azide-alkyne cycloaddition in aqueous media. The wavelength of maximum fluorescence intensity of polymer particles carrying graft chains with longer PEG side chains (x = 9) was slightly blue-shifted (7 nm) and the fluorescence intensity increased (1.35 times) with an increase in NaCl concentration as opposed to polymer particles with shorter PEG chains (x = 4). (C) 2014 Elsevier Ltd. All rights reserved.

Blue phases (BPs) have received considerable attention as light shutters in the next generation of liquid crystal (LC) displays. However, no simple and efficient chiral dopant for induction of BPs of commercially available rodlike LC compounds has been reported. In this study, both (R) and (S) forms of novel chiral dopants were synthesized, showed extremely high helical twisting power values in nematic LC compounds, and induced stable BPs with a small amount of our chiral dopants (3-5 mol %). In enantiomeric excess controlled experiments, we found novel phenomena in their physical properties, such as generation of a metastable chiral nematic phase between an isotropic state and a BP.

To investigate the effect of the number of chiral mesogenic units and their spatial arrangement in dopant molecules on the induction of blue phases (BPs), and widening the temperature ranges of these phases, six benzene derivatives possessing (cholesteryloxycarbonyl)pentyloxy groups (monosubstituted (1), 1,2-disubstituted (2), 1,3-disubstituted (3), 1,4-disubstituted (4), 1,2,3-trisubstituted (5) and 1,3,5-trisubstituted (6) compounds) were prepared. Their helical twisting powers (HTPs) in 4-cyano-4 '-pentylbiphenyl (5CB) were proportional to the number of the chiral mesogenic units in each molecule. Furthermore, the minimum amount of the chiral dopant necessary for the induction of BPs was almost inversely proportional to its HTP value in this series.

The facile preparation of nonspherical raspberry-like particles composed of a polystyrene (PSt) core and polydopamine (PDA) nodules was described. Various polymerization parameters influencing the PDA nodules were investigated in detail. It was found that raspberry-like particles were obtained in a 1:1 water/methanol solution in the presence of compounds with carboxylic acid groups, e.g., caffeic acid (CF). The raspberry-like particles obtained were characterized in terms of their size, morphology, and chemical composition using scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared (IR) spectroscopy, elemental analysis, and solid-state nuclear magnetic resonance (NMR) measurements. Finally, the formation mechanism was discussed. Because PDA may be used to cover a variety of particle surfaces, the present method has great potential for fabricating many types of raspberry-like particles. (C) 2014 Elsevier B.V. All rights reserved.

Phenylenediurea dibenzoic acid derivatives 1, 2, 3, and 5 and an amide derivative 4 were synthesized, and their molecular structures were elucidated to be an S-shape by single crystal X-ray analysis. Crystals of 1 were obtained as a DMF solvate, while those of 2 and 3 were not. Sheet and ladder structures were created in the crystal packing of 1 and 3, and 2, respectively. Unlike the para-substituted diureas 1-3 which possessed meso-conformation, the meta-substituted diurea 5 exhibited helical-conformation in its crystal structure. The way of crystal packing of 4 is analogous to that of the corresponding dicarboxylic acid derivative 2. A water cluster of a chair-shaped hexagonal array of water molecules was created in the crystal structure of 4. Diureas 1 and 2 gave cocrystals with melamine recrystallized from DMF/ethyl acetate and DMF/H2O, respectively. Unusual zigzag tapes of a H-bonding network of melamine were created in both cocrystals. The zigzag tapes were connected with S-shaped diureas by H-bonding to furnish an interpenetrated fishnet-type crystal structure.

We report the first synthesis of polymer nanoparticles employing the phase inversion temperature (PIT) method using a polymeric surfactant. Oil-in-water nanoemulsions were prepared by the PIT method using amphiphilic comb-like block polymer (polystyrene-b-poly[oligo(ethylene glycol) methyl ether methacrylate], PSt-b-POEGMA) as a polymeric surfactant, and subsequently St droplets were polymerized. PSt-b-POEGMA was synthesized by sequential atom transfer radical polymerization of St and OEGMA. The interfacial property of PSt-b-POEGMA in aqueous media was investigated by surface tension measurement and fluorescence probe technique. Monodisperse PSt nanoparticles with 50 nm in diameter were obtained by a free radical polymerization of St droplets initiated by the water-soluble initiator.

Herein, we describe a general and versatile procedure to fabricate hierarchically structured coatings onto material surfaces using colorless polydopamine (PDA) thin layer and polymer brush layer. Firstly, atom transfer radical polymerization (ATRP) initiator-containing colorless PDA layer was coated onto various types of material surfaces. Then, surface-initiated ATRP was conducted to produce functional polymer brush layer. This methodology will be applied to a broad range of materials to modification of surface properties. Furthermore, one-step hierarchically structured coatings of materials surface were also investigated.

Herein, we describe a facile and green method to prepare fluorescent polymer particles by combined use of enzymatic miniemulsion polymerization and click reaction. Firstly, alkyne-bearing polymer particles were prepared by HRP-mediated miniemulsion polymerization of styrene with clickable surfmer (surfactant + monomer) 1. Then, azide-bearing fluorescence compound, i.e., dansyl azide compound 2, was introduced to polymer particles surface via click reaction using Cu(I) catalyst. This methodology will be applied to a broad range of azide-bearing compounds to generate functional polymer particles. Since both enzymatic miniemulsion polymerization and click reaction are conducted at room temperature in water, present method offers a practical and environmental friendly method for preparation of functional polymer particles.

We developed a novel fluorescence labeling technique for quantification of surface densities of atom transfer radical polymerization (ATRP) initiators on polymer particles. The cationic P(St-CPEM-C(4)DMAEMA) and anionic P(St-CPEM) polymer latex particles carrying ATRP-initiating chlorine groups were prepared by emulsifier-free emulsion polymerization of styrene (St), 2-(2-chloropropionyloxy)ethyl methacrylate (CPEM), and N-n-butyl-N,N-dimethyl-N-(2-methacryloyloxy)ethylammonium bromide (C(4)DMAEMA). ATRP initiators on the surface of polymer particles were converted into azide groups by sodium azide, followed by fluorescent labeling with 5-(N,N-dimethylamino)-N-(prop-2-yn-1-yl)naphthalene-1-sulfonamide (Dansyl-alkyne) by copper-catalyzed azide-alkyne cycloaddition (CuAAC). The reaction time required for both azidation of ATRP-initiating groups and successive fluorescence labeling of azide groups with Dansyl-alkyne by CuAAC were investigated in detail by FTIR and fluorescence spectral measurement, respectively. The ATRP initiator densities on the cationic P(St-CPEM-C(4)DMAEMA) and anionic P(St-CPEM) particle surfaces were estimated to be 0.21 and 0.15 molecules nm(-2), respectively, which gave close agreement with values previously determined by a conductometric titration method. The fluorescence labeling through click chemistry proposed herein is a versatile technique to quantify the surface ATRP initiator density both on anionic and cationic polymer particles. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4042-4051

A free-standing polymer brush film with tailored thicknesses based on a colorless polydopamine (PDA) thin layer is prepared and characterized. The surface-initiated atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate (HEMA) is performed on a PDA layer with thickness of ca. 6 nm, which generated an optically transparent and colorless free-standing PHEMA brush film (1.5 cm x 1.5 cm). Because the cross-linked PDA layer is used as the base for the polymer brushes, the reported method does not require cross-linking the polymer brushes. The free-standing film thicknesses of approximate to 16-75 nm are controlled by simply changing the ATRP reaction time. The results show that the free-standing PHEMA brush film transferred onto a plate exhibits a relatively smooth surface and is stable in any solvent.

Crystal structures of U-shaped aromatic ureadicarboxylic acid possessing two carboxy moieties at meta-positions of phenyl rings were investigated. It afforded cocrystals with dipyridyl derivatives. In addition to the U-shaped conformation obtained by recrystallization from methanol, another three types of U-shaped conformations were found in the crystal structure of the cocrystals. The direction of H-bonding was fixed based on the relative geometry of two carboxy moieties in the resulting conformations. Depending on these conformations, triple helices with one-dimensional water channels, infinite cross-belt, and step-like structures were generated via H-bonding between the carboxy and the pyridyl moieties. Methanol solvate was obtained for the cocrystal with 1,4-di(pyridine-4-yl)benzene which showed different U-shaped conformation of urea dicarboxylic acid from that involved in the cocrystal free of methanol.

Herein, we describe a facile method to prepare a colorless functional polydopamine (PDA) thin layer by the in situ oxidative copolymerization of dopamine (DA) and ATRP initiator-bearing DA (DA-BiBB) onto polystyrene (PSt) core particles: PSt@PDA/BiBB2. Surface-initiated ATRP of 2-hydroxyethyl methacrylate (HEMA) was performed on PSt@PDA/BiBB2 particles, followed by the removal of the template particles, which generated PHEMA capsules that were based on a colorless PDA thin layer and have tailored hollow core sizes and capsule wall thicknesses. The PDA thin layer is used as a basis for polymer brushes. The present method does not require cross-linking the polymer brushes. Furthermore, subsequent preparation of functional PHEMA capsules by post-functionalization of hydroxy groups of PHEMA chains was successful.

Nematic liquid-crystal phases doped with the novel dopant compounds 1 (C6F5COO(CH)(n)OCOC6F5, n = 1-7) and 2 (C6H5COO(CH)(n)OCOC6H5, n = 1-7) showed an "opposite odd-even effect" on clearing temperatures. The tendency was exactly opposite to that reported for liquid-crystal dimers. A mechanism is postulated on the basis of the difference in the formation of molecular aggregations of even- and odd-number-dopant molecules in the host liquid-crystal molecules.

Utilization of the perfluoroarene-arene interaction for stabilization of liquid crystal phases is reviewed. This interaction is strong (3.7-5.6 kcal/mol), but it is difficult to generate stable liquid crystal phases by using it. From the examples in this review, it is strongly suggested that flatness of the mesogenic units is important for obtaining stable liquid crystal phases. Introduction of a perfluorinated benzene ring to a rodlike molecule is effective in generating local biaxiality in the nematic and smectic A phases. Furthermore, the absence of an odd-even effect and the presence of a "trans-gauche-gauche" effect in the liquid crystal phases of monoalkylated rodlike molecules possessing a pentafluorophenyl group are explained by suppression of the molecular spin movements.

Single crystal X-ray structures of cocrystals, 1.2 and 1.3, derived from U-shaped ureadicarboxylic acid (1) with 2-aminopyrimidine (2) and melamine (3), respectively, were examined. Cocrystals were obtained as a 1:1 mixture of 1 and the corresponding base. Two molecules of 1 and two molecules of the base were combined together via intermolecular H-bonding creating a supramolecularly assembled cyclic heterotetramer motif of rhombus shape. In the case of cocrystal 1.3, the cyclic heterotetramers were connected via H-bonding by utilizing a remaining amino group of melamine resulting in the formation of a tape of cyclic heterotetramer. (C) 2012 Elsevier Ltd. All rights reserved.

Crystal structures of three zwitterionic bisimidazolium salts 1-3 in which imidazolium sulfonate moieties were connected with aromatic linkers, p-xylylene, 4,4'-dimethylenebiphenyl, and phenylene, respectively, were examined. The latter two were obtained as hydrates. An S-shaped molecular structure in which the sulfonate moiety was placed on the imidazolium ring was observed for 1. A helical array of hydrated water molecules was obtained for 2 while a linear array of hydrated water molecules was observed for 3. (C) 2012 Elsevier B.V. All rights reserved.

As novel rodlike liquid crystalline ester compounds exhibiting blue phases (BPs), chiral 4-(4'-alkoxyphenyl) phenyl 4-(4'-alkoxyphenyl)benzoate derivatives (R-C6H4-C6H4-OCO-C6H4-C6H4-R'), 1 (R = R' (R)-1-methylheptyloxy, BP range: 1.6 K on heating), 2 (R = (R)-1-methylheptyloxy, R' = n-octyloxy, BP range: 0.8 K on heating), 4 (R (R)-1-methylheptyloxy, R' = H, BP range: 1.0 K on heating), were synthesized and their phase behaviors were investigated. Further, the BP of 1 was stabilized by addition of its achiral homologue ester compound 3 (R = R' n-octyloxy). In the range of the composite ratio of 1 : 3 from 10 : 0 to 0 : 10, the BP temperature range became wider with increase of the content of 3 in the mixture. At the ratio of 6 : 4, the BP indicated the widest temperature range in the mixing experiment (5.0 K on heating and 6.0 K on cooling).

In order to examine versatility of ureadicarboxylic acids as U-shaped building blocks for crystal engineering, their crystal structures and cocrystals with pyridine derivatives were investigated. H-bonding networks created by a sequential linking of H-bonded carboxylic acid dimers resulted in the formation of ladder-type networks in the crystals of N,N-diethyl-N,N'-diphenylureadicarboxylic acid (2) and N,N'-diallyl-N,N'-diphenylureadicarboxylic acid (3). A zigzag type H-bonding network with wedging of water molecules into carboxy carboxy H-bonding was observed for N,N'-dibenzyl-N,N'-diphenylureadicarboxylic acid (4). Cocrystals of N,N'-dimethyl-N,N'-diphenylureadicarboxylic acid (1) with 2,S-di(pyridine-4-yl)thiazolo[5,4-d]thiazole (5) and 2 with 4,4'-dipyridyl (6) afforded zigzag-type assembled structures. Two types of channel structures were created in the cocrystals of! and dipyridylurea (7) by inclusion of water molecules together with either methanol or ethanol. The former afforded a straight-type one-dimensional channel, while the latter afforded a fishnet-type two-dimensional channel.

Organic crystals containing several types of water channels are generated by clipping water molecules with biszwitterionic imidazolium carboxylates as hydrogen-bonding acceptors. The types of water channels to be generated depend on the size and the shape of the aromatic spacers tethered with two imidazolium carboxylates moieties. Clusters of water tetramers and dimers were obtained from imidazolium carboxylates with phenylene (1) and naphthalene (2) linkers, respectively. The latter showed pseudopolymorphism, affording layers of water hexamers. Imidazolium carboxylate possessing biphenylene linker (3) afforded channels of discrete water tetramers.

U-shaped N,N&apos;-dimethyl-N,N&apos;-diphenylureadicarboxylic acid was developed as a folding unit to fabricate an H-bonding aromatic zigzag array. Recrystallization of it with dipyridyl derivatives gave cocrystals. Zigzag-type strands were formed by pinching dipyridyl derivatives via H-bonding with two carboxy moieties. Two types of H-bonding networks, helix and zigzag, were obtained depending on the structure of dipyridyl derivatives to be included. The former afforded a triple helix and the latter gave a twisted zigzag tape with chirality.

In order to realize biaxial mesophases of straight rod-like molecules by introduction of lateral perfluoroarene-arene interactions, non-alkylated rod-like liquid crystalline compounds C6X5-COO-C(6)Z(4)-C(6)Z(4)-OOC-C6Y5, F-BB-F (X = Y = F, Z = H), F-BB-B (X = F, Y = Z = H), B-BB-B (X = Y = Z = H), B-FF-B (X = Y = H, Z = F), F-FF-B (X = F, Y = H, Z = F), and F-FF-F (X = Y = Z = F) were prepared, and their phase transition behaviors were investigated by polarized light optical microscopy (POM) and differential scanning calorimetery (DSC). From the one-and two-dimensional X-ray diffraction (1D- and 2D-XRD) studies of the nematic and smectic A phases of F-BB-F, it was clarified that the smectic A phase had a lateral directional order in the layer and the nematic phase had a cybotactic smectic A structure.

Utilizing hydrogen bonding between pyridine and benzoic acids, hydrogen-bonded ionic liquid crystals were prepared from pyridinylmethylimidazolium and alkoxy-substituted benzoic acids. Depending on the number of alkoxy substituents, smectic C (SmC), rectangular columnar (Col(r)), and cubic (Cub) phases were obtained from mono-, di-, and tri-substituted benzoic acids, respectively. These phases were investigated with X-ray diffraction, differential scanning calorimeter, and polarized optical microscopy. (C) 2010 Elsevier Ltd. All rights reserved.