Chiral Optoelectronic Functionalities DNA-Organic Semiconductor Complex.

We fabricate the bio-organic field-effect transistor (BOFET) with the DNA-perylene diimide (PDI) complex, which shows unusual chiroptical and electrical functionalities. DNA is used as the chirality-inducing scaffold and the charge-injection layer. The shear-oriented film of the DNA-PDI complex shows how the large-area periodic molecular orientation and the charge transport are related, generating drastically different optoelectronic properties at each DNA/PDI concentration.

Supramolecular Nanopumps with Chiral Recognition for Moving Organic Pollutants from Water.

Since organic pollutants in water resources have raised concerns on aquatic ecosystems and human health, mechanical machines such as a nanopump for rapid and efficient removal of pollutants from water with regeneration properties remains a challenge. Here, a pH-responsive artificial pump from left-handed porous tubules into right-handed solid fibers was presented by the self-assembly of bent-shaped aromatic amphiphiles. The bent-shaped amphiphile with a pH-sensitive segment was demonstrated in aromatic hexameric macrocycles, which could contract into dimeric disks.

Mosaics of topological defects in micropatterned liquid crystal textures.

Topological defects in the orientational order that appear in thin slabs of a nematic liquid crystal, as seen in the standard schlieren texture, behave as a random quasi-two-dimensional system with strong optical birefringence. We present an approach to creating and controlling the defects using air pillars, trapped by micropatterned holes in the silicon substrate. The defects are stabilized and positioned by the arrayed air pillars into regular two-dimensional lattices.

Directed Self-Assembly of Topological Defects of Liquid Crystals.

One of the alluring aspects of liquid crystals (LCs) is their readily controllable self-assembly behavior, leading to comprehension of complex topological structures and practical patterning applications. Here, we report on manipulating various kinds of topological defects by adopting an imprinted polymer-based soft microchannel that simultaneously imposes adjustable surface anchoring, confinement, and uniaxial alignment. Distinctive molecular orientation could be achieved by varying the surface anchoring conditions at the sidewall polymer and the rubbing directions on the bottom layer.

Supramolecular Nanotubules as a Catalytic Regulator for Palladium Cations: Applications in Selective Catalysis.

Despite the recent development of highly efficient and stable metal catalysts, conferral of regulatory characteristics to the catalytic reaction in heterogeneous systems remains a challenge. Novel supramolecular nanotubules were prepared by alternative stacking from trimeric macrocycles, which was found to be able to coordinate with Pd cations. The Pd complexes exhibited a high catalytic performance for C-C coupling reaction.

Switchable Plasmonic Film Using Nanoconfined Liquid Crystals.

Structural coloration using plasmonic particles has received substantial attention due to its robust, permanent, and scalable characteristics across the full color range. In this study, a plasmonic structure based on a porous anodic aluminum oxide (AAO) film coated with a metallic film was fabricated. Colors were varied by changing the refractive index, which was achieved with a convolution with nanopores of AAO film and an infiltrated liquid crystal (LC) material.

Morphogenesis of liquid crystal topological defects during the nematic-smectic A phase transition.

The liquid crystalline phases of matter each possess distinct types of defects that have drawn great interest in areas such as topology, self-assembly and material micropatterning. However, relatively little is known about how defects in one liquid crystalline phase arise from defects or deformations in another phase upon crossing a phase transition. Here, we directly examine defects in the in situ thermal phase transition from nematic to smectic A in hybrid-aligned liquid crystal droplets on water substrates, using experimental, theoretical and numerical analyses.

Orthogonal Liquid Crystal Alignment Layer: Templating Speed-Dependent Orientation of Chromonic Liquid Crystals.

Lyotropic chromonic liquid crystals (LCLCs) have been extensively studied because of the interesting structural characteristics of the linear aggregation of their plank-shaped molecules in aqueous solvents. We report a simple method to control the orientation of LCLCs such as Sunset Yellow (SSY), disodium cromoglycate (DSCG), and DNA by varying pulling speed of the top substrate and temperatures during shear flow induced experiment. Crystallized columns of LCLCs are aligned parallel and perpendicular to the shear direction, at fast and slow pulling speeds of the top substrate, respectively.

Arrangement and SERS Applications of Nanoparticle Clusters Using Liquid Crystalline Template.

Manipulation of nanomaterials such as nanoparticles (NPs) and nanorods (NRs) to make clusters is of significant interest in material science and nanotechnology due to the unusual collective opto-electric properties in such structures that cannot be found in the individual NPs. This work demonstrates an effective way to arrange NP clusters (NPCs) to make the desired arrays based on removable and NP-guidable liquid crystalline template using sublimation and reconstruction phenomenon. The position of the NPCs is precisely controlled by the defect structure of the liquid crystal (LC), namely toric focal conic domains (TFCDs), during thermal annealing to construct the LC and corresponding NPC structures.

Switchable Photonic Crystals Using One-Dimensional Confined Liquid Crystals for Photonic Device Application.

Photonic crystals (PCs) have recently attracted considerable attention, with much effort devoted to photonic bandgap (PBG) control for varying the reflected color. Here, fabrication of a modulated one-dimensional (1D) anodic aluminum oxide (AAO) PC with a periodic porous structure is reported. The PBG of the fabricated PC can be reversibly changed by switching the ultraviolet (UV) light on/off.

Digital DNA detection based on a compact optofluidic laser with ultra-low sample consumption.

DNA lasers self-amplify optical signals from a DNA analyte as well as thermodynamic differences between sequences, allowing quasi-digital DNA detection. However, these systems have drawbacks, such as relatively large sample consumption and complicated dye labelling. Moreover, although the lasing signal can detect the target DNA, it is superimposed on an unintended fluorescence background, which persists for non-target DNA samples as well.

Control of Periodic Zigzag Structures of DNA by a Simple Shearing Method.

A periodic zigzag structure of DNA material is successfully fabricated by a simple shearing method. The periodicity of the pattern can be finely controlled by combining the mechanical shearing method with topographic patterns of microchannels. The resultant zigzag patterns can be used as a template to control the alignment of rod-like liquid crystals due to its highly regular periodicity.

Orientation Control of Smectic Liquid Crystals via a Combination Method of Topographic Patterning and In-Plane Electric Field Application for a Linearly Polarized Illuminator.

We dynamically controlled the configuration of layering structures built by smectic A liquid crystal molecules using the combination method of the microchannel confinement and the in-plane electric field to realize the linearly polarized illuminator and bistable structures. Once a mild in-plane electric field (∼30 V) is applied between polymeric walls, the layer configuration was changed from the toric focal conic domains to periodic zigzag patterns of alternatively packed focal conic domains. The transformed zigzag patterns maintained their structures even after turning off the applied electric fields, revealing the ability for use in a bistable memory device.

Airflow-aligned helical nanofilament (B4) phase in topographic confinement.

We investigated a controlled helical nanofilament (HNF: B4) phase under topographic confinement with airflow that can induce a shear force and temperature gradient on the sample. The resulting orientation and ordering of the B4 phase in this combinational effort was directly investigated using microscopy. The structural freedom of the complex B7 phase, which is a higher temperature phase than the B4 phase, can result in relatively complex microscopic arrangements of HNFs compared with the B4 phase generated from the simple layer structure of the B2 phase.

Molecular Orientation of Liquid Crystals on Topographic Nanopatterns.

Controlling the orientation of building blocks in soft matter on the substrate has been a big challenge in material sciences. We have controlled the molecular orientation of liquid crystal (LC) materials on the porous anodic aluminum oxide (AAO) film having hexagonal pore arrays on the top surface. In our method, anchoring conditions can be varied by changing the pore size (Dp) and the porosity (P).

Chiral nematic self-assembly of minimally surface damaged chitin nanofibrils and its load bearing functions.

Chitin is one of the most abundant biomaterials in nature, with 10(10) tons produced annually as hierarchically organized nanofibril fillers to reinforce the exoskeletons of arthropods. This green and cheap biomaterial has attracted great attention due to its potential application to reinforce biomedical materials. Despite that, its practical use is limited since the extraction of chitin nanofibrils requires surface modification involving harsh chemical treatments, leading to difficulties in reproducing their natural prototypal hierarchical structure, i.

Controlling Gaussian and mean curvatures at microscale by sublimation and condensation of smectic liquid crystals.

Soft materials with layered structure such as membranes, block copolymers and smectics exhibit intriguing morphologies with nontrivial curvatures. Here, we report restructuring the Gaussian and mean curvatures of smectic A films with free surface in the process of sintering, that is, reshaping at elevated temperatures. The pattern of alternating patches of negative, zero and positive mean curvature of the air-smectic interface has a profound effect on the rate of sublimation.

Photomodulated Supramolecular Chirality in Achiral Photoresponsive Rodlike Compounds Nanosegregated from the Helical Nanofilaments of Achiral Bent-Core Molecules.

We prepared a nonchiral mixture of achiral bent-core molecules and photoresponsive rodlike liquid crystalline (LC) molecules. With the help of the isothermal photochemical nematic (N)-isotropic (Iso) phase transition of the photoresponsive rodlike LC molecules, the corresponding phase transition from a dark conglomerate BX phase to another distinguishable dark conglomerate B4 phase took place in the mixture. A large circular dichroism (CD) signal originating from supramolecular chirality was detected in the initial BX phase.

Creation of liquid-crystal periodic zigzags by surface treatment and thermal annealing.

The orientation control of soft matter to create a large area single domain is one of the most exciting research topics in materials science. Recently, this effort has been extended to fabricate two- or three-dimensional structures for electro-optical applications. Here, we create periodic zigzag structures in liquid crystals (LCs) using a combination of surface treatment and thermal annealing.

Nucleation and growth of a helical nanofilament (B4) liquid-crystal phase confined in nanobowls.

The B4 helical nanofilament (HNF) liquid crystal (LC) phase is a three-dimensional (3D) helical structure composed of 2D smectic layers. Because of the complex shape of the HNF phase, it is difficult to understand the generation mechanism of HNFs in the bulk as well as in the thin-film condition. Here, we directly investigated the nucleation and growth of HNFs in nanobowls.

Multidimensional Helical Nanostructures in Multiscale Nanochannels.

We have investigated the various morphological changes of helical nanofilament (HNF; B4) phases in multiscale nanochannels made of porous anodic aluminum oxide (AAO) film. Single or multihelical structures could be manipulated depending on the AAO pore size and the higher-temperature phase of each molecule. Furthermore, the nanostructures of HNFs affected by the chemical affinity between the molecule and surface were drastically controlled in surface-modified nanochannels.

In-Plane Switching Mode for Liquid Crystal Displays Using a DNA Alignment Layer.

We successfully fabricated the in-plane switching mode (IPS) LC display (LCD) based on a double stranded DNA (dsDNA) alignment layer. As widely known, the DNA has the right-handed double helical structure that has naturally grown grooves with a very regular period, which can be used as an alignment layer to control the orientation of liquid crystal (LC) molecules. The LC molecules on this topographical layer of DNA material align obliquely at a specific angle with respect to the direction of DNA chains, providing an instant and convenient tool for the fabrication of the IPS display compared to the conventional ways such as rubbing and mechanical shearing methods.

Physico-chemical confinement of helical nanofilaments.

Helical nanofilaments (HNFs) have attracted much interest because of their unique optical properties, but there have been many hurdles to overcome in using them for the practical applications due to their structural complexity. Here we demonstrate that the molecular configuration and layer conformation of a modulated HNF (HNFs(mod)) can be studied using a physicochemical confinement system. The layer directions affected by the chemical affinity between the mesogen and surface were drastically controlled in surface-modified nanochannels.

Cybotactic behavior in the de Vries smectic-A* liquid-crystal structure formed by a silicon-containing molecule.

We have identified a metastable liquid-crystal (LC) structure in the de Vries smectic-A* phase (de Vries Sm-A*) formed by silicon-containing molecules under certain boundary conditions. The phase transition with the metastable structure was observed in a LC droplet placed on a planar aligned substrate and LCs confined in the groove of a silicon microchannel. During the rapid cooling step, a batonnet structure was generated as an intermediate and metastable state prior to the transition that yielded the thermodynamically stable toric focal conic domains.

Three-dimensional textures and defects of soft material layering revealed by thermal sublimation.

Layering is found and exploited in a variety of soft material systems, ranging from complex macromolecular self-assemblies to block copolymer and small-molecule liquid crystals. Because the control of layer structure is required for applications and characterization, and because defects reveal key features of the symmetries of layered phases, a variety of techniques have been developed for the study of soft-layer structure and defects, including X-ray diffraction and visualization using optical transmission and fluorescence confocal polarizing microscopy, atomic force microscopy, and SEM and transmission electron microscopy, including freeze-fracture transmission electron microscopy. Here, it is shown that thermal sublimation can be usefully combined with such techniques to enable visualization of the 3D structure of soft materials.