Self-Assembled Molecular Fibers Aligned by Compression in Water.

Molecular self-assembly has attracted much attention as a potential approach for fabricating nanostructured functional materials. To date, energy-efficient fabrication of nano-objects such as nanofibers, nanorings, and nanotubes is achieved using well-designed self-assembling molecules. However, the application of molecular self-assembly to industrial manufacturing processes remains challenging because regulating the positions and directions of self-assembled products is difficult.

Perfluoroalkyl Group-Covered Organosilica Films for the Sensitive Detection of Sulfonylurea Herbicides in Laser Desorption/Ionization Mass Spectrometry.

Simple and rapid screening of agrochemicals greatly contributes to food and environmental safety. Matrix-free laser desorption/ionization mass spectrometry (LDI-MS) is an effective tool for high-throughput analysis of low-molecular-weight compounds. In this study, we report a UV-laser-absorbing organosilica film for the sensitive detection of various sulfonylurea herbicides using LDI-MS.

Self-assembled single-crystal bimodal porous GaN exhibiting a petal effect: application as a sensing platform and substrate for optical devices.

This paper investigates the petal effect (hydrophobicity and strong adhesion) observed on single-crystal bimodal porous GaN (porous GaN), which has almost the same electrical properties as bulk GaN. The water contact angles of porous GaN were 100°-135° despite the intrinsic hydrophilic nature of GaN. Moreover, it was demonstrated that the petal effect of porous GaN leads to the uniform attachment of water solutions, enabling highly uniform and aggregation-free attachment of chemicals and quantum dots.

Nanoporous Substrates with Molecular-Level Perfluoroalkyl/Alkylamide Surface for Laser Desorption/Ionization Mass Spectrometry of Small Proteins.

The rapid detection of biomolecules greatly contributes to health management, clinical diagnosis, and prevention of diseases. Mass spectrometry (MS) is effective for detecting and analyzing various molecules at high throughput. However, there are problems with the MS analysis of biological samples, including complicated separation operations and essential pretreatments.

TiN nanopillar-enhanced laser desorption and ionization of various analytes.

The present paper reports on the use of TiN nanopillars as a robust analytical substrate for laser desorption/ionization mass spectrometry (LDI-MS). TiN nanopillars were fabricated on silicon wafers through the dynamic oblique deposition of titanium, followed by thermal treatment in an ammonia atmosphere. The TiN nanopillars were readily applicable to a simple "dried-droplet" method in the LDI-MS without surface modification or pre-treatment.

Hybrid Surface Design of Organosilica Films for Laser Desorption/Ionization Mass Spectrometry: Low Free Energy Surface with Interactive Sites.

Laser desorption/ionization mass spectrometry (LDI-MS) assisted by solid substrates is useful for the facile and rapid analysis of low-molecular-weight compounds. The LDI performance of solid substrates depends on not only a surface morphology but also the surface functionalities dominating the surface-analyte interactions. In this study, we propose a hybrid surface design for LDI substrates, realizing both weak surface-analyte interaction and homogeneous distribution of analytes.

Direct nanoimprinting of nanoporous organosilica films consisting of covalently crosslinked photofunctional frameworks.

Nanoimprinting methods have been used widely to prepare various patterned or nanostructured thin films from inorganic or organic components. However, the accumulation of large functional aromatic groups in covalently crosslinked nanoimprints is challenging, due to the difficulty in controlling the fluidity and reactivity of the precursor films. In this work, nanoimprinting of naphthalimide-silica sol-gel films results in vertically oriented nanoporous structures consisting of covalently crosslinked UV-absorbing frameworks.

Charge Separation in a Multifunctionalized Framework of Hydrogen-Bonded Periodic Mesoporous Organosilica.

Integration of functional molecular parts into nanoporous materials in a state that allows intermolecular charge or energy transfer is one of the key approaches to the development of photofunctional and electroactive materials. Herein, we report charge separation in a functionalized framework of a periodic mesoporous organosilica (PMO) self-assembled by hydrogen bonds. Electroactive π-conjugated organic species with different electron-donating and electron-accepting properties were selectively fixed onto the external surface of a nanoparticulate PMO, within the pore wall, and onto the surface of the internal mesopore.

Amphiphilic Polymer Mediators Promoting Electron Transfer on Bioanodes with PQQ-Dependent Glucose Dehydrogenase.

Redox-active phenazinium salts bonded to amphiphilic polymer backbones are demonstrated to function as high-performance electron-transfer mediators in enzymatic bioanodes applicable to biofuel cells. The redox-active moieties could be easily tethered to the electrodes by physical adsorption of the hydrophobic regions of the polymer backbones onto the electrode surface. On the other hand, long hydrophilic chains were essential to ensure high mobility of the redox-active moieties in aqueous solutions and to enhance their electron-transfer properties.

Versatile Antireflection Coating for Plastics: Partial Embedding of Mesoporous Silica Nanoparticles onto Substrate Surface.

Antireflection (AR) coating for transparent plastic substrates is constructed by partially embedding mesoporous silica nanoparticles (MSNs) onto the surface of the substrates. Simulation of optical properties of polymer substrates coated with a single-particle MSN layer indicates that the surface has a low and graded refractive index in the direction of the thickness and effectively decreases the reflectance of visible light. The MSN-coated surfaces can be prepared by exposure of the MSN-painted substrates to a solvent vapor, irrespective of the shape of the polymer substrates.

Periodic mesoporous organosilica with molecular-scale ordering self-assembled by hydrogen bonds.

Nanoporous materials with functional frameworks have attracted attention because of their potential for various applications. Silica-based mesoporous materials generally consist of amorphous frameworks, whereas a molecular-scale lamellar ordering within the pore wall has been found for periodic mesoporous organosilicas (PMOs) prepared from bridged organosilane precursors. Formation of a "crystal-like" framework has been expected to significantly change the physical and chemical properties of PMOs.

Hierarchical Nanoporous Silica Films for Wear Resistant Antireflection Coatings.

High-performance antireflection (AR) layers were prepared by depositing hierarchical nanoporous silica films on glass substrates. We designed a composite layer consisting of mesoporous silica nanoparticles (MSNs) and a mesoporous silica matrix. The introduction of bimodal nanoporous structures, i.

A solid chelating ligand: periodic mesoporous organosilica containing 2,2'-bipyridine within the pore walls.

Synthesis of a solid chelating ligand for the formation of efficient heterogeneous catalysts is highly desired in the fields of organic transformation and solar energy conversion. Here, we report the surfactant-directed self-assembly of a novel periodic mesoporous organosilica (PMO) containing 2,2'-bipyridine (bpy) ligands within the framework (BPy-PMO) from a newly synthesized organosilane precursor [(i-PrO)3Si-C10H6N2-Si(Oi-Pr)3] without addition of any other silane precursors. BPy-PMO had a unique pore-wall structure in which bipyridine groups were densely and regularly packed and exposed on the surface.

Facile preparation of oriented nanoporous silica films from solvent-free liquid-crystalline mixtures.

Mixtures of an amphiphilic perylene bisimide derivative and tetramethoxysilane in the absence of solvents have been found to exhibit stable columnar liquid-crystalline phases which transform into macroscopically oriented nanoporous silica films as a result of simple mechanical shearing.

Isothermally reversible fluorescence switching of a mechanochromic perylene bisimide dye.

Isothermally rewritable fluorescence mechanochromism has been realized for a perylene bisimide dye with bulky and flexible substituents. Fluorescent patterns drawn by mechanical stimuli can be erased by thermal stimuli, treatment with solvent vapors, or spontaneous structural transition from orange-fluorescent to green-fluorescent states. The isothermal fluorescence switching of solid dye films is applicable to displays and sensory materials.

Energy and electron transfer from fluorescent mesostructured organosilica framework to guest dyes.

Energy and electron transfer from frameworks of nanoporous or mesostructured materials to guest species in the nanochannels have been attracting much attention because of their increasing availability for the design and construction of solid photofunctional systems, such as luminescent materials, photovoltaic devices, and photocatalysts. In the present study, energy and electron-transfer behavior of dye-doped periodic mesostructured organosilica films with different host-guest arrangements were systematically examined. Fluorescent tetraphenylpyrene (TPPy)-silica mesostructured films were used as a host donor.

Enhanced fluorescence detection of metal ions using light-harvesting mesoporous organosilica.

Enhanced fluorescence detection of metal ions was realized in a system consisting of a fluorescent 2,2'-bipyridine (BPy) receptor and light-harvesting periodic mesoporous organosilica (PMO). The fluorescent BPy receptor with two silyl groups was synthesized and covalently attached to the pore walls of biphenyl (Bp)-bridged PMO powder. The fluorescence intensity from the BPy receptor was significantly enhanced by the light-harvesting property of Bp-PMO, that is, the energy funneling into the BPy receptor from a large number of Bp groups in the PMO framework which absorbed UV light effectively.

Synthesis of a spirobifluorene-bridged allylsilane precursor for periodic mesoporous organosilica.

A novel spirobifluorene-bridged allylsilane precursor, which can be easily purified by silica gel chromatography, was prepared by using a new molecular building block for allylsilane sol-gel precursors (MBAS) and successfully converted into a highly fluorescent periodic mesoporous organosilica film.

Syntheses, properties and applications of periodic mesoporous organosilicas prepared from bridged organosilane precursors.

Periodic mesoporous organosilicas (PMOs) prepared by surfactant-directed polycondensation of bridged organosilane precursors are promising for a variety of next-generation functional materials, because their large surface areas, well-defined nanoporous structures and the structural diversity of organosilica frameworks are advantageous for functionalization. This critical review highlights the unique structural features of PMOs and their expanding potential applications. Since the early reports of PMOs in 1999, various synthetic approaches, including the selection of hydrolytic reaction conditions, development of new precursor compounds, design of templates and the use of co-condensation or grafting techniques, have enabled the hierarchical structural control of PMOs from molecular- and meso-scale structures to macroscopic morphology.

Mesostructured organosilica with a 9-mesityl-10-methylacridinium bridging unit: photoinduced charge separation in the organosilica framework.

Polycondensation of 9-mesityl-10-methylacridinium-bridged organosilane in the presence of a nonionic surfactant yielded a mesostructured organosilica solid with a functional framework that exhibited long-lived photoinduced charge separation.

Crystal-like periodic mesoporous organosilica bearing pyridine units within the framework.

Periodic mesoporous organosilica with densely packed pyridine units within the framework and crystal-like molecular-scale periodicity was synthesized. The framework pyridines were chemically active and fully accessible for protonation and Cu(2+) adsorption.

Theoretical studies on Si-C bond cleavage in organosilane precursors during polycondensation to organosilica hybrids.

Molecular orbital theory calculations were carried out to predict the occurrence of Si-C bond cleavage in various organosilane precursors during polycondensation to organosilica hybrids under acidic and basic conditions. On the basis of proposed mechanisms for cleavage of the Si-C bonds, the proton affinity (PA) of the carbon atom at the ipso-position and the PA of the carbanion generated after Si-C cleavage were chosen as indices for Si-C bond stability under acidic and basic conditions, respectively. The indices were calculated using a density functional theory (DFT) method for model compounds of organosilane precursors (R-Si(OH)(3)) having organic groups (R) of benzene (Ph), biphenyl (Bp), terphenyl (Tph), naphthalene (Nph), N-methylcarbazole (MCz), and anthracene (Ant).