Coatable Negative Dispersion Retarder: Kinetically Controlled Self-Assembly Pathway of Butterfly-Shaped Molecular Building Blocks for the Construction of Nanocolumns.

Disc-shaped building blocks with columnar phases have attracted attention for their potential in optical applications, including a retarder. However, to achieve coatable high-performance optical films, it is essential to understand a subtle interaction balance between building blocks and relevant self-assembled behaviors during material processing. Herein, we studied a self-assembled nanocolumn evaluation of linear butterfly-shaped dendrons (T-A3D) consisting of thiophene-based conjugated core and flexible alkyl dendron. X-ray diffraction provided insight into the unique hexagonal columnar liquid crystal phase of T-A3D, driven by intermolecular hydrogen bonding and coplanarity of the thiophene-based conjugated core. The formation of a self-assembled nanocolumn with high mobility enabled the uniaxial orientation of butterfly-shaped T-A3D on the aligned rod-shaped nematic reactive mesogens, resulting in a transparent and colorless two-layered negative retarder. The self-assembled nanocolumn consisting of butterfly-shaped molecule would break a new ground for developing advanced optical thin films.

Imidazolium-Functionalized Diacetylene Amphiphiles: Strike a Lighter and Wear Polaroid Glasses to Decipher the Secret Code.

The development of smart inks that change color and transparency in response to external stimuli is very important for various fields, from modern art to safety and anticounterfeiting technology. A uniaxially oriented diacetylene thin film on a macroscopic area is obtained by coating, self-assembling and topochemical photopolymerizing of imidazolium-functionalized diacetylenes (M-DA and T-DA) and 4,6-decadiyne ink (70 wt%:20 wt%:10 wt%) exhibiting a lyotropic smectic A liquid-crystalline phase at room temperature. The color and transparency of letters and symbols written with the DA-based secret inks change reversibly from blue to red as well as from colorless transparent to black opaque depending on the temperature and polarization axis. A secret code written with thermoresponsive and polarization-dependent secret inks consisting of imidazolium-functionalized diacetylenes is successfully deciphered by wearing polaroid glasses and holding a burning torch.

Diacetylene-Functionalized Dendrons: Self-Assembled and Photopolymerized Three-Dimensional Networks for Advanced Self-Healing and Wringing Soft Materials.

The physical properties of supramolecular soft materials strongly depend on the molecular packing structures constructed by thermodynamically and kinetically controlled molecular self-assembly. To investigate the relationship between molecular function and self-assembled molecular packing structure, a series of diacetylene (DA)-based supramolecules was synthesized by chemically connecting flexible dendrons to DA with amide (aDA-D) or ester (eDA-D) functions. The three-dimensional (3D) organogel network of amide-functionalized aDA-D was prepared in both polar and nonpolar solvents due to the intermolecular hydrogen bonding. 3D networks of aDA-D can be further stabilized by topochemical photopolymerization. The self-healing behavior of aDA-D was observed in the sheet-like structure formed in n-dodecane by the hydrophobic interaction between the gelator and solvent. The wringing behavior of aDA-D was also demonstrated using the dynamic interaction of amide function with n-butanol solvent. Kinetically controlled and photostabilized 3D networks can be a key component from biomedical devices to soft robotic applications.

Coatable Compensator for Flexible Display: Single-Layered Negative Dispersion Retarder Fabricated by Coating, Self-Assembling, and Polymerizing Host-Guest Reactive Mesogens.

Antireflective films for flexible display devices should be made by a coating process rather than a stretching process. Additionally, the compensator, which is the core of the antireflective film, must exhibit a wavelength-independent phase retardation in the visible-light region to act as an ideal retarder. To satisfy all of these requirements, we intend to make a single-layered negative dispersion retarder (SNDR) with a single coating process followed by polymer stabilization. To achieve this goal, X-shaped reactive mesogen (X2RM) is newly synthesized as a guest RM and mixed into a host RM that exhibits a smectic A mesophase. Based on the thermal, spectroscopic, microscopic, and scattering analyses combined with computer simulation, the content of X2RM in the HCM026 molecule is optimized to be 40 wt %. The SNDR thin film is fabricated by coating the optimized H-G mixture on the rubbed alignment substrate and subsequent heat treatment. The trans-to-cis photoisomerization of imine bond can help X2RM to be located in the smectic interlayer of the HCM026. The molecular long axis of HCM026 is parallel to the rubbing direction of the alignment layer and the conjugated benzene rings of X2RM aligned perpendicular to the molecular long axis of smectic RM, which is the ideal molecular arrangement of negative dispersion retarder. Additionally, polarized UV polymerization improves the mechanical and chemical stability as well as the molecular orientation of SNDR.

Interesting phase behaviors and ion-conducting properties of dicationic N-alkylimidazolium tetrafluoroborate salts.

A series of dicationic imidazolium bis(tetrafluoroborate) salts were newly synthesized, and their phase transition behaviors were correlated with thermal, scattering, optical and conductivity results. The bis-imidazolium salts having side-chain lengths of C6-C10 showed plastic crystal mesophases, while a liquid crystal mesophase was formed in the bis-imidazolium salts with long side-chains (C11 and C12). Soft plastic and liquid crystalline phases were also confirmed by wide-angle X-ray diffraction. For the bis-imidazolium salts exhibiting a plastic crystal mesophase, the ionic conductivity suddenly increased at the melting temperature. However, the bis-imidazolium salts with long side-chains showed a slope increase during the liquid crystal-liquid crystal transition.

Programmed Hierarchical Hybrid Nanostructures from Fullerene-Dendrons and Pyrene-Dendrons.

The construction of fullerene (C60 ) hierarchical nanostructures with the help of amphiphilic molecules remains a challenging task in nanoscience and nanotechnology. Utilizing the host-guest complex concept, sub-10 nm layered superstructures are constructed from a monofunctionalized C60 dendron (C60 D, guest) and tweezer-like pyrene dendron (PD, host). Since C60 D and PD are asymmetric shape amphiphiles having liquid crystal (LC) dendrons, both C60 D and PD construct head-to-head bilayer superstructures by themselves. From fluorescence titration experiments, it is realized that the host-guest complex shows 1:1 stoichiometric binding with a binding constant (Ksv = 2.45 × 105 m-1 ). Based on the morphological observations and scattering analyses, it is found that buckle-like asymmetric building blocks (C60 D·PD) are self-assembled by the host-guest complex and construct multilayer hybrid nanostructures. The hierarchical hybrid nanostructures consist of the self-assembled C60 D·PD bilayer with a 2D C60 ·P nanoarray sandwiched between LC dendrons. This advanced strategy is expected to be a practicable and rational guideline for the fabrication of programmed hierarchical hybrid nanostructures.

Kinetically Controlled Polymorphic Superstructures of Pyrene-Based Asymmetric Liquid Crystal Dendron: Relationship Between Hierarchical Superstructures and Photophysical Properties.

To understand the relationship between kinetically controlled hierarchical superstructures and photophysical properties, pyrene-based asymmetric liquid crystal (LC) dendrons (abbreviated as PD) were newly synthesized by covalently attaching a pyrene moiety (P) at a biphenyl-based LC dendritic group (D). The phase transition behavior of PD has been systematically studied with a combined technique of thermal analysis, microscopy, spectroscopy, and scattering analysis. PD formed two different crystalline structures depending on the cooling rate: a stable crystalline phase (Ks , slow cooling) and a metastable crystalline phase (Kms , quenching). The kinetically controlled molecular packing structures of PD depend on the competition and cooperation of intermolecular physical interactions with nanophase separation. Upon slow cooling, the PD dimer formed by intermoelcular H-bonding constructed a layered hierarchical structure with the help of nanophase separation. Owing to the strong π-π stacking (J-aggregation) with weak H-bondings, the PD dimer in the layer was slightly tilted to give a monoclinic layered structure with a periodic layer d-spacing of 6.6 nm. In contrast, the metastable Kms phase formed by the quenching process showed a significant tilt of the PD dimer in the layer (d-spacing=4.4 nm) due to the weak π-π stacking (H-aggregation) and the strong H-bondings.

Azobenzene Molecular Machine: Light-Induced Wringing Gel Fabricated from Asymmetric Macrogelator.

To develop light-triggered wringing gels, an asymmetric macrogelator (1AZ3BP) was newly synthesized by the chemically bridging a photoisomerizable azobenzene (1AZ) molecular machine and a biphenyl-based (3BP) dendron with a 1,4-phenylenediformamide connector. 1AZ3BP was self-assembled into a layered superstructure in the bulk state, but 1AZ3BP formed a three-dimensional (3D) network organogel in solution. Upon irradiating UV light onto the 3D network organogel, the solvent of the organogel was squeezed and the 3D network was converted to the layered morphology. It was realized that the metastable 3D network organogels were fabricated mainly due to the nanophase separation in solution. UV isomerization of 1AZ3BP provided sufficient molecular mobility to form strong hydrogen bonds for the construction of the stable layered superstructure. The light-triggered wringing gels can be smartly applied in remote-controlled generators, liquid storages, and sensors.

Construction of Polymer-Stabilized Automatic MultiDomain Vertical Molecular Alignment Layers with Pretilt Angles by Photopolymerizing Dendritic Monomers under Electric Fields.

The synthesized itaconic acid-based dendritic amphiphile (Ita3C12) monomers and the methacryl polyhedral oligomeric silsesquioxane (MAPOSS) cross-linkers were directly introduced for the construction of automatic vertical alignment (auto-VA) layers in the host nematic liquid crystal (NLC) medium. The auto-VA layer can be stabilized by irradiating UV light. For the automatic fabrication of a polymer-stabilized multidomain VA (PS auto-MDVA) layer with a pretilt angle, Ita3C12 and MAPOSS were photopolymerized under the electric field by irradiating UV light on the multidomain electrode cell. Mainly because of the pretilted NLC at zero voltage, the electro-optic properties of the PS auto-MDVA cell were dramatically improved. From the morphological observations combined with surface chemical analyses, it was found that various sizes of protrusions on the solid substrates were automatically constructed by the two-step mechanisms. We demonstrated the PS auto-MDVA cell with the enhancement of electro-optic properties as a single-step process and investigated how the protrusions were automatically developed during the polymer stabilization.

Multifunctional Optical Thin Films Fabricated by the Photopolymerization of Uniaxially Oriented Lyotropic Liquid Crystal Monomers for Electro-Optical Devices.

A multifunctional optical thin film (MOTF) is fabricated by coating the newly synthesized perylene-based reactive mesogen (PBRM) and stabilized by the subsequent photopolymerization. Based on the spectroscopic results combined with morphological observations, it is found that nematic liquid crystal (NLC) is aligned parallel to the molecular long axis of PBRM not only due to the long-range physical anchoring effect but also due to the short-range molecular physical interactions between alignment layer and NLC molecules. From the electro-optical properties of LC test cells fabricated with the PBRM MOTF, it is clearly demonstrated that the PBRM MOTF can work as the planar LC alignment layer as well as the in-cell coatable polarizer. The coatable PBRM MOTF from lyotropic chromonic reactive mesogens can pave a new way for the flexible optoelectronic devices.

Phytochemical Compositions of Immature Wheat Bran, and Its Antioxidant Capacity, Cell Growth Inhibition, and Apoptosis Induction through Tumor Suppressor Gene.

The purpose of this study was to investigate the phytochemical compositions and antioxidant capacity, cell growth inhibition, and apoptosis induction in extracts of immature wheat bran. Immature wheat bran (IWB) was obtained from immature wheat harvested 10 days earlier than mature wheat. The phytochemical compositions of bran extract samples were analyzed by ultra-high performance liquid chromatography. The total ferulic acid (3.09 mg/g) and p-coumaric acid (75 µg/g) in IWB were significantly higher than in mature wheat bran (MWB, ferulic acid: 1.79 mg/g; p-coumaric acid: 55 µg/g). The oxygen radical absorbance capacity (ORAC: 327 µM Trolox equivalents (TE)/g) and cellular antioxidant activity (CAA: 4.59 µM Quercetin equivalents (QE)/g) of the IWB were higher than those of the MWB (ORAC: 281 µM TE/g; CAA: 0.63 µM QE/g). When assessing cell proliferation, the IWB extracts resulted in the lowest EC50 values against HT-29 (18.9 mg/mL), Caco-2 (7.74 mg/mL), and HeLa cells (8.17 mg/mL) among bran extract samples. Additionally, the IWB extracts increased the gene expression of p53 and PTEN (tumor suppressor genes) in HT-29 cells, indicating inhibited cell growth and induced apoptosis through tumor suppressor genes.

Self-Assembled Hierarchical Superstructures from the Benzene-1,3,5-Tricarboxamide Supramolecules for the Fabrication of Remote-Controllable Actuating and Rewritable Films.

The well-defined hierarchical superstructures constructed by the self-assembly of programmed supramolecules can be organized for the fabrication of remote-controllable actuating and rewritable films. To realize this concept, we newly designed and synthesized a benzene-1,3,5-tricarboxamide (BTA) derivative (abbreviated as BTA-3AZO) containing photoresponsive azobenzene (AZO) mesogens on the periphery of the BTA core. BTA-3AZO was first self-assembled to nanocolumns mainly driven by the intermolecular hydrogen-bonds between BTA cores, and these self-assembled nanocolumns were further self-organized laterally to form the low-ordered hexagonal columnar liquid crystal (LC) phase below the isotropization temperature. Upon cooling, a lamello-columnar crystal phase emerged at room temperature via a highly ordered lamello-columnar LC phase. The three-dimensional (3D) organogel networks consisted of fibrous and lamellar superstructures were fabricated in the BTA-3AZO cyclohexane-methanol solutions. By tuning the wavelength of light, the shape and color of the 3D networked thin films were remote-controlled by the conformational changes of azobenzene moieties in the BTA-3AZO. The demonstrations of remote-controllable 3D actuating and rewritable films with the self-assembled hierarchical BTA-3AZO thin films can be stepping stones for the advanced flexible optoelectronic devices.

Flexible and Patterned Thin Film Polarizer: Photopolymerization of Perylene-based Lyotropic Chromonic Reactive Mesogens.

A perylene-based reactive mesogen (DAPDI) forming a lyotropic chromonic liquid crystal (LCLC) phase was newly designed and synthesized for the fabrication of macroscopically oriented and patterned thin film polarizer (TFP) on the flexible polymer substrates. The anisotropic optical property and molecular self-assembly of DAPDI were investigated by the combination of microscopic, scattering and spectroscopic techniques. The main driving forces of molecular self-assembly were the face-to-face π-π intermolecular interaction among aromatic cores and the nanophase separation between hydrophilic ionic groups and hydrophobic aromatic cores. Degree of polarization for the macroscopically oriented and photopolymerized DAPDI TFP was estimated to be 99.81% at the λmax = 491 nm. After mechanically shearing the DAPDI LCLC aqueous solution on the flexible polymer substrates, we successfully fabricated the patterned DAPDI TFP by etching the unpolymerized regions selectively blocked by a photomask during the photopolymerization process. Chemical and mechanical stabilities were confirmed by the solvent and pencil hardness tests, and its surface morphology was further investigated by optical microscopy, atomic force microscopy, and three-dimensional surface nanoprofiler. The flexible and patterned DAPDI TFP with robust chemical and mechanical stabilities can be a stepping stone for the advanced flexible optoelectronic devices.

The simple determination method for anthocyanidin aglycones in fruits using ultra-high-performance liquid chromatography.

The simple determination method for anthocyanidin aglycones in fruits using ultra-high-performance liquid chromatography (UHPLC) coupled with the heating-block acidic hydrolysis method was validated through the precision, accuracy and linearity. The UHPLC separation was performed on a reversed-phase C18 column (particle size 2 µm, i.d. 2 mm, length 100 mm) with a photodiode-array detector. The limits of detection and quantification of the UHPLC analyses were 0.09 and 0.29 mg/kg for delphinidin, 0.08 and 0.24 mg/kg for cyanidin, 0.09 and 0.26 mg/kg for petunidin, 0.14 and 0.42 mg/kg for pelargonidin, 0.16 and 0.48 mg/kg for peonidin and 0.30 and 0.91 mg/kg for malvidin, respectively. The intra- and inter-day precisions of individual anthocyanidin aglycones were <10.3%. All calibration curves exhibited good linearity (r = 0.999) within the tested ranges. The total run time of UHPLC was 8 min. The simple preparation method with UHPLC detection in this study presented herein significantly improved the speed and the simplicity for preparation step of delphinidin, cyanidin, petunidin, pelargonidin, peonidin and malvidin in fruits. Especially, the UHPLC detection exhibited good resolution in spite of shorter run time about four times than conventional HPLC detection.

Rapid method for the determination of 14 isoflavones in food using UHPLC coupled to photo diode array detection.

A rapid method for the determination of 14 types of isoflavones in food using ultra-high performance liquid chromatography (UHPLC) was validated in terms of precision, accuracy, sensitivity and linearity. The UHPLC separation was performed on a reverse-phase C18 column (particle size 2 µm, i.d. 2 mm, length 100 mm) using a photo diode array detector that was fixed to 260 nm. The limits of detection and quantification of the UHPLC analyses ranged from 0.03 to 0.33 mg kg(-1). The intra-day and inter-day precision of the individual isoflavones were less than 11.77% and calibration curves exhibited good linearity (r(2) = 0.99) within the tested ranges. These results suggest that the rapid method used in this study could be available to determine of 14 types of isoflavones in a variety of food such as soy bean, black bean, red bean and soybean paste.