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The quantum yield of photoluminescence and the photostability of perovskite cesium lead bromide nanocubes were improved by the formation of two-dimensional ordered arrays on a substrate.

Conductive polymers have been extensively studied as functional organic materials due to their broad range of applications. Conductive polymers, such as polypyrrole, polythiophene, and their derivatives, are typically obtained as coatings and precipitates in the solution phase. Nanoarchitectonics for conductive polymers requires new methods including syntheses and morphology control. For example, nanoarchitectonics is achieved by liquid-phase syntheses with the assistance of templates, such as macromolecules and porous materials. This minireview summarizes the other new synthetic methods using the solid and vapor phases for nanoarchitectonics. In general, the monomers and related species are supplied from the solution phase. Our group has studied polymerization of heteroaromatic monomers using the solid and vapor phases. The surface and inside of solid crystals were used for the polymerization with the diffusion of the heteroaromatic monomer vapor. Our nanoarchitectonics affords to form homogeneous coatings, hierarchical structures, composites, and copolymers for energy-related applications. The concepts using solid and vapor phases can be applied to nanoarchitectonics for not only conductive polymers but also other polymers toward a variety of applications.

Layered materials exhibit unique properties, such as intercalation and exfoliation, originating from the two-dimensional anisotropic nanostructures. A variety of inorganic and organic layered materials have been synthesized for design of functions. However, conventional host layers are static and rigid to induce dynamic functions originating from the structural flexibility. The present work shows a new dynamic and flexible host layer based on organic macrocycles. A macrocycle containing functional, flexible, and intercalating units, namely macrocyclic diacetylene (MCDA), was designed to form a self-assembled layered structure. After the guest molecules were intercalated in the interlayer space, the host MCDA layers were topochemically polymerized to obtain polydiacetylene. The layered macrocycles containing the π-conjugated main chain and interlayer guests showed gradual thermoresponsive color changes in a wide temperature range of −100 to 230 °C with variation of the effective conjugation length. The flexible host layer affords induction of the dynamic motion of the intrinsically rigid π-conjugated main chain in the wide temperature range. Moreover, the thermo-responsivity was tuned by the intercalated guests. The color-change properties enabled real-time temperature imaging for medical applications. Flexible layered macrocycles can be a new design strategy of soft materials with dynamic functions.

Spines projecting from a trochospiral test of a spinose planktonic foraminifer are a single-crystal-like calcite that has a nanogranular texture containing microstrain and an organic envelope.

Straightforward, interpretable, and modifiable linear-regression prediction models with appropriate accuracy are constructed by sparse modeling coupled with our chemical perspectives as researchers on small data, such as experimental data in laboratories.

Biomimetic strained SrSO4 crystals were produced through a nonclassical pathway involving fiber-by-fiber accumulation with poly(acrylic acid) in an aqueous solution system.

Hierarchical architectures consisting of iso-oriented fluorapatite microrods and nanograins are constructed via temporal control of the crystal growth mode by switching a physicochemical parameter.

Single-crystal fluorapatite rods elongated in the c direction are switched to iso-oriented nanorods by adding a specific carboxy compound (chemical approach) and to roughly arranged nanograins by increasing the supersaturation at the growth front (physicochemical approach).

Organic energy storage has attracted much interest enhance performances and save resource consumptions. If the performance predictors are prepared, the exploration of new compounds can be accelerated without consumptions of...

Weak friction forces in the range of 0.006–0.080 N locally applied on mm-to-cm scales are visualized and colorimetrically quantified by the cascading responses using a device combining a stimuli responsive capsule, a conjugated polymer, and a substrate.

Application of data-scientific approach to conventional sciences, such as chemo-informatics, bio-informatics, and materials informatics (MI), has attracted much interest toward data-driven research...

The adequate manipulation of nanometer-scale building blocks using dispersion systems is regarded as a fundamental technique to fabricate elaborate microstructures. Although a liquid flow with evaporation is generally regarded as an essential factor for the self-assembly of floating blocks, experimental evidence has not been sufficient to clarify the importance of the flow in the dispersion systems. In the present study, 2D nematic layers of sterically stabilized nanoscale calcite rods were achieved in a millimeter-scale region on a solid substrate via the very slow recession of an organic dispersion with evaporation. 2D random arrays of the nanorods were obtained via recession of the liquid in the same system without evaporation. When the nanorods were not sterically stabilized, 3D random arrays were formed even with evaporation. We demonstrated that the evaporation-driven flow of sterically stabilized nanorods to a confined space at the air-liquid-solid interface is essential for the formation of 2D nematic structures on a substrate.

Dynamic properties are derived from the structural flexibility of 2D polymers. Softening layered structures has the potential for tuning and enhancing the dynamic properties. In the present work, the flexibility of layered polydiacetylene (PDA) is tuned by the interlayer polymeric guests with different branching structures. PDA shows thermoresponsive color-change properties through shortening the effective conjugation length with molecular motion. Whereas the blue-to-red color transition is observed at certain threshold temperatures for the layered PDA without the interlayer guest, the intercalation of the bulky polymer guests lowers the starting temperature and widens the temperature range for the thermoresponsive color changes. The resultant layered composite of PDA and bulky polymer affords the homogeneous coating on substrates on the centimeter scale. The thermoresponsive color-change coating is applied to temperature-distribution imaging. The specific heat of liquids is colorimetrically estimated using the coating on the bottle. The coating on a silk cloth visualizes the temperature distribution on a simulated tissue during surgical operation using an ultrasonic coagulation cutting device. The coating can be applied to thermal imaging in a variety of fields. Moreover, the softening strategy contributes to explore dynamic properties of soft 2D materials.

Exfoliation of layered materials provides nanosheets, such as monolayers and few-layers. In recent years, nanosheets have attracted much interest as two-dimensional (2D) materials for their diverse...

Pure and carbonated hydroxyapatite (HA) nanocrystals are regarded as capital biocompatible materials. However, the formation process for faceted nanorods of HA has not been sufficiently clarified in supersaturated aqueous solution systems. Here, we monitored morphological evolution of carbonated HA to faceted crystals on the conversion of a parent calcite nanocrystal under hydrothermal conditions. In the initial stage, low-crystalline carbonated HA nanosheets ∼5 nm thick are formed as metastable intermediates. In the progressive stage, faceted nanorods ∼50 nm wide and ∼200 nm long grow as a relatively stable form of HA through the intermediates. The morphological evolution is ascribed to a stabilizing process of HA for improvement of the crystallinity and a decrease in the specific surface area and carbonate content.

Silica membranes having macrochannels with mesoporous walls were spontaneously fabricated using a self-organized process with rapid gelation of concentrated silicate and surfactant precursor solutions. The specific hierarchical porous framework consisting of straight macrochannels ca. 1 μm in diameter is similar to that of a biological silica frustule of diatoms. We applied the diatom-mimetic channeled mesoporous silica membranes to high-permeability-rate filtration and enhanced photocatalytic systems. The presence of macrochannels was found to improve the performance of the mesoporous silica membranes in filtration and as a photocatalyst carrier.

Calcareous skeletons of stony corals are composed of a low-crystalline core (center of calcification: COC) and surrounding fibrous crystals. We characterized the overall framework of juvenile Acropora digitifera corals to clarify the entire calcic architecture and the contribution of abiotic processes. Skeletal and tubular frameworks contain string and sheet COCs, respectively, consisting of strained aragonite nanograins. Parallel and curved structures of fibrous aragonite develop around the COC cores through geometric selection and a gradual change in the growth direction of the c-direction-elongated nanorods. Based on a study of the nanoscale morphology of the coral frameworks by comparing them to fibrous crystals grown in artificial systems, it appears that subsequent precipitation of the fibrous aragonite on the COC is primarily regulated by environmental abiotic parameters. The architecture of the COC network is deduced to be designed biologically and then thickened by the fibrous crystals that are produced with morphology formation through physicochemical processes although the vital activity controls the total mineralization.

Band engineering with a quantum size effect is proposed to be utilized to design photocatalytic activity for the conversion of organic compounds. Subnanometer WO3 quantum dots (QDs) are spontaneously produced with the enhancement of the photocatalytic activity in a mesoporous silica matrix by preliminary photochemical dissolution. An appropriate upshift of the conduction band of subnanometer WO3 QDs stabilized by the coverage with the surface WO bonds promotes the efficient conversion of benzene to phenol without decomposition of the product into CO2 under ultraviolet illumination.

Room-temperature operations of rechargeable Mg coin-cell batteries have been achieved using a Mg alloy negative electrode and a spinel MgMn2O4 (MMO)-positive electrode. The present work focuses on clarifying the effects of the physiochemical properties of the MMO powder including the specific surface area (SBET) and porosity of the positive electrode on Mg battery performances in practical applications. Finally, optimal specific surface area and porosity parameters were obtained that ensured excellent battery performances as a standard coin-cell at room temperature. A typical MMO powder synthesized using a modified sol–gel method with propylene oxide-driven complex polymerization had a large SBET > 200 m2 g−1, and more than 90% porosity with a triple-tiered 3D open-channel network. Here we evaluated the discharge capacity and the cyclability for room-temperature operation as a function of SBET in a full cell with a Mg negative electrode as well as half cells with a carbon graphite electrode. Irrespective of whether half cells or a full cell was used, the initial discharge capacity was found to depend linearly on the SBET of the porous MMO powder in a Mg tetrakis(hexafluoroisopropyl)borate/triglyme electrolyte with a wide potential window, ΔE > 3.6 V. Eventually, the maximum discharge capacity of 220 mA h g−1 was realized at 25 °C in the full cell using the 3D open-channel nanostructure with SBET = 236 m2 g−1. The cyclability in the full cell with the Mg alloy negative electrode, however, degraded with the increasing SBET, while no cyclability degradation was observed in the half cell with the carbon electrode. A possible mechanism is discussed regarding passivation of the Mg alloy electrode in discharge/charge cycles.

Spinel-type MgMn2O4 nanoplates ~10 nm thick were prepared as a positive electrode for magnesium rechargeable batteries by transformation of metal hydroxide nanoplates. Homogeneous coating with a va...

Silica frustules of most planktonic diatoms have many shallow holes in which the length (L) is smaller than the width (W). The present study focuses on a silicic ultrastructure of the setae of a planktonic diatom having deep (L/W > 1) holes. Here, we characterized nanoholes on the silica walls of hollow setae of a colony of Chaetoceros coarctatus. Basically, tetragonal poroid arrangements with and without a costa pattern are observed on the inner and outer surfaces, respectively, for three kinds of curving hollow setae. Deep nanoholes ∼90 nm wide are elongated from 150 to 1500 nm (L/W ∼17) with an increase in the wall thickness of the polygonal tubes of the setae. The inside poroid array, with a period of 190 nm in the extension direction of setae, is lined by parallel plates of the costae. However, the poroid arrangement on the outer surface is disordered, with several holes obstructed with increasing wall thickness of the posterior terminal setae. According to the movement of a colony in a fluid microchannel, the thick curving terminal setae is suggested to involve attitude control and mechanical protection. Using an optical simulation, the patterned deep through-holes on the intercalary setae were inferred to contribute anti-reflection of blue light for the promotion of photosynthesis in seawater.

We clarified the specific micrometric arrangement and nanometric structure of the radiolarian crystalline spines that are not a simple single crystal. A body of the celestite (SrSO4) skeleton of acantharian Acanthometra cf. multispina (Acanthometridae) composed of 20 radial spines having four blades was characterized using microfocus X-ray computed tomography. The regular arrangement of three types of spines was clarified with the connection of the blades around the root of each spine. The surface of the spines was covered with a chitin-based organic membrane to prevent from dissolution in seawater. In the nanometric scale, the mesocrystalline structure that consists of nanoscale grains having distorted single-crystal nature was revealed using scanning- and transmission electron microscopies, electron diffraction, and Raman spectroscopy. The acantharian skeletons have a crystallographically controlled architecture that is covered with a protective organic membrane. These facts are important for penetrating the nature of biogenic minerals.

Most biominerals are composed of mesocrystals, in which individual nanoparticle building units have a defined long-range order on the atomic scale in at least one direction. Although the crystal size and orientation of the mesostructures are spatially designed in biological architectures, it has been difficult to achieve adequate control of the crystal growth to produce modulated mesostructures in artificial aqueous systems. Here, we propose a simple physicochemical approach for the spatial design of nanostructures using an aqueous solution system. The ordered arrays of oriented fluorapatite (FA) rods similar to tooth enamel are produced on a polymer substrate in a supersaturated solution. We succeeded in reversible switching of the growth mode of FA between single-crystalline rods and mesocrystalline grains through the disturbance of the solution. The primary crystal size was tuned between micrometric rods ∼0.5 μm wide and5 μm long and nanoscale grains ∼10 nm wide and 50 nm long without a drastic change in the

The micrometric morphology of anhydrous β-guanine crystals is adequately designed by various organisms for their specific optical properties. We successfully controlled the morphology of an anhydro...

Amorphous calcium carbonate (ACC) is regarded as an important precursor of biogenic crystal phases having specific shapes and mechanical properties. In the present work, calcite that was produced from ACC nanoparticles containing aspartic acid was characterized by Raman scattering spectroscopy and nanoindentation techniques. The tensile strain of the calcite lattice that was estimated from the vibrational spectroscopy varied with the organic content and the mild calcination condition of ACC nanoparticles. Calcite was found to be hardened by the presence of residual organic components inside the crystal lattice. On the other hand, the modulus of calcite decreased as the content of external organic components increased. Here, the mechanical properties of the calcite framework are successfully tuned by the crystallization of the specific amorphous phases containing organic molecules. The mechanical modulation of calcite can be associated with lattice expansion by using vibrational spectroscopy.

The organization states of functional molecules have a significant impact on the properties of materials. A variety of approaches have been studied to obtain well-organized molecular assemblies. The present work shows a new non-organized state of isolated and dispersed functional molecules in amorphous flexible covalent organic networks. Redox-active quinone molecules are embedded in the amorphous network polymers. Consecutive reactions between benzoquinone (BQ) and linker molecules generate random network structures through polymerization at different rates and in multiple directions. The low-crystalline stackings of the amorphous network polymers facilitate the formation of nanoflakes through exfoliation in dispersion media. Enhanced electrochemical performances, one of the highest specific capacities in recent studies, were achieved by efficient redox reactions of the quinone moiety. The present noncrystalline approach, low-crystalline stacking of designer amorphous covalent organic networks, can be applied to construct similar nanostructured polymer materials containing functional units.

Measurement of friction force is important for safety, security, and health. Excessive friction force causes degradation of materials and biological bodies. For example, tooth enamel and gums are damaged by strong toothbrushing force. However, friction force is not easily measured by conventional materials and devices. Here, we proposed design strategies of a paper-based device for measurement of friction force. Toothbrushing force, a model of weak friction force, is the measurement target in the present work. Soft layered composites of polydiacetylene (PDA) and interlayer guest macromolecules were designed and synthesized to achieve a visible color change in response to weak friction force. A data-scientific approach assisted in the selection of the interlayer guest molecule to control the stimuli responsivity of the layered PDA. The guest polyethyleneimine (PEI) formed soft layered composites exhibiting a color change in response to weak friction force. The paper-based device of the layered PDA/PEI composite showed a gradual color change from blue to red in response to the strength and number of the applied friction force. As a model case, toothbrushing force was measured using the paper-based device. The present work shows new design strategies of molecules and materials toward measurement of a wide variety of friction forces.

Layered materials, alternate stackings of two or more components, are found in a wide range of scales. Chemists can design and synthesize layered structures containing functional units. The soft-type layered materials exhibit characteristic dynamic functions originating from two-dimensional (2D) anisotropy and structure flexibility. This feature article focuses on "intercalation" and "flexibility" as two new perspectives for designing soft layered materials. Intercalation of guests is a characteristic approach for design of layered structures. Flexibility is an important factor to control the dynamic functions of the layered structures. As a model case, the intercalation-induced tunable stimuli-responsive color-change properties of layered polydiacetylene (PDA) are introduced to study the impact of the intercalation and flexibility on the dynamic functions. Recently, layered materials have drastically expanded the research area from conventional rigid inorganic compounds to new self-assembled nanostructures consisting of organic components, such as polymers, metal-organic frameworks, and covalent-organic frameworks. These new layered architectures have potentials for exhibiting dynamic functions originating from the structure flexibility beyond the static properties originating from classical intercalation and host-guest chemistries. Therefore, intercalation and flexibility chemistries of soft layered materials are regarded as new perspectives for design of advanced dynamic functional materials.

Fluorescent pyrone derivatives were extracted from the pyrolitic product of citric acid confined in supermicroporous silicas (SMPSs). We utilized the tiny spaces of SMPSs to produce fluorescent mol...

Uniformly sized building units are generally required to construct highly elaborate architectures over a wide range. Defined nanocubes of Co3O4 evolved from deformed precursor nanograins 2–5 nm in ...

A variety of organic and inorganic layered compounds are exfoliated into 2D nanomaterials in liquid phase. Improvement of exfoliation yield is a significant challenge for further applications of 2D...

Uniformly sized nanoparticles 3–5 nm in diameter of Y2O3-stabilized ZrO2 (YSZ) were fabricated by a water-toluene two-phase solvothermal method. The nanoparticles that were covered with oleic acid ...