Robust Angular Anisotropy of Circularly Polarized Luminescence from a Single Twisted-Bipolar Polymeric Microsphere.

It has long been surmised that the circular polarization of luminescence (CPL) emitted by a chiral molecule or a molecular assembly should vary with the direction in which the photon is emitted. Despite its potential utility, this anisotropic CPL has not yet been demonstrated at the level of single molecules or supramolecular assemblies. Here we show that conjugated polymers bearing chiral side chains self-assemble into solid microspheres with a twisted bipolar interior, which are formed via liquid-liquid phase separation and subsequent condensation into a cholesteric lyotropic liquid crystalline mesophase.

Disila- and digermabenzenes.

Reactions of isolable disilynes and digermynes with alkynes can result in the formation of the corresponding disila- (DSBs) and digermabenzenes (DGBs), wherein two carbon atoms of the benzene ring are replaced by silicon or germanium atoms. Detailed structural and spectroscopic analyses of these DSBs and DGBs have revealed that they exhibit considerable aromaticity, comparable to that of benzene. However, in contrast to the all-carbon system benzene, these DSBs and DGBs are highly reactive toward small molecules such as oxygen, hydrogen, 1,3-dienes, and water.

One-Pot Synthesis of Triazatriphenylene Using the Povarov Reaction.

The Povarov reaction combines aromatic amines, aldehydes, and alkynes in a single step and is regarded as an annulative π-extension reaction of aromatic amines. In this study, the Povarov reaction was investigated as an efficient tool for the synthesis of aza-polycyclic aromatic hydrocarbons via multiple π-extensions. The double Povarov reaction of 1,4-diaminobenzene yielded the 4,7-phenanthroline derivative as the major product, regardless of the steric repulsion in the product.

Atomic-Scale Visualization of Ultrafast Bond Breaking in X-Ray-Excited Diamond.

Ultrafast changes of charge density distribution in diamond after irradiation with an intense x-ray pulse (photon energy, 7.8 keV; pulse duration, 6 fs; intensity, 3×10^{19}  W/cm^{2}) have been visualized with the x-ray pump-x-ray probe technique. The measurement reveals that covalent bonds in diamond are broken and the electron distribution around each atom becomes almost isotropic within ∼5  fs after the intensity maximum of the x-ray pump pulse.

In situ IR spectroscopy during oxidation process of cobalt Prussian blue analogues.

Cobalt Prussian blue analogues (Co-PBA; NaCo[Fe(CN)]), consisting of cyano-bridged transition metal network, -Fe-CN-Co-NC-Fe-, are promising cathode materials for Na-ion secondary batteries. In the oxidation process, oxidization of Fe and/or Co are compensated by Na deintercalation. Here, we investigated the oxidization process of three Co-PBAs by means of in situ infrared absorption (IR) spectroscopy.

Exclusive formation of a meridional complex of a tripodand and perfect suppression of guest recognition.

Tripodal ligands have been utilized for complexation-induced structural change, but all the tripodal complexes reported so far are facial isomers, which do not completely reduce the recognition ability by closing the binding pocket. We now report the first example of the selective synthesis of a meridional tripodal complex. The tripodal ligand with a 1,3,5-triethyl-2,4,6-tris(methylene)benzene pivot possessing 2,2'-bipyridine on each arm exclusively formed a mononuclear complex with the mer-[Fe(bpy)]2+ unit.

Long-wavelength visible to near infrared photoluminescence from carbon-bridged styrylstilbene and thiadiazole conjugates in organic and aqueous media.

Donor-acceptor-donor conjugates composed of electron-donating carbon-bridged styrylstilbene (COPV2) and electron-accepting thiadiazole derivatives equipped with carbazolyl (Cz) terminators, Cz-COPV2-A-COPV2-Cz (A = benzothiadiazole (BTz), naphthobis(thiadiazole) (NTz), or benzobis(thiadiazole) (BBTz)), were newly synthesized and found to serve as efficient and stable long-wavelength photoluminescent dyes in organic and aqueous media. In particular, Cz-COPV2-BBTz-COPV2-Cz showed photoluminescence in the near infrared region (895-927 nm) with a photoluminescence quantum yield (PLQY) of up to 0.19 in cyclohexane and of 0.

Fluorescence Switchable Conjugated Polymer Microdisk Arrays by Cosolvent Vapor Annealing.

Depositing minute light emitters into a regular array is a basic but essential technique in display technology. However, conventional lithographic methodologies involve multistep and energy-consuming processes. Here, we develop a facile method in which organic and polymeric fluorescent dyes spontaneously aggregate to form a patterned microarray.

Structural and functional characterization of complexes between heme and dimeric parallel G-quadruplex DNAs.

Heme has been receiving considerable interest as a prosthetic group of ribozymes and deoxyribozymes, because heme-bound nucleic acids exhibit peroxidase-like catalytic activities (Travascio, P., Li, Y., and Sen, D.

Anionic Fluorinated Zn-porphyrin Combined with Cationic Endohedral Li-fullerene for Long-Lived Photoinduced Charge Separation with Low Energy Loss.

Here we report an anionic -tetrakis(4-carboxymethylthio-2,3,5,6-tetrafluorophenyl) zinc porphyrin (ZnTFPPTC) to form a supramolecular complex with a cationic lithium endohedral [60]fullerene (Li@C). The supramolecular ZnTFPPTC/Li@C complex formed by strong electrostatic attraction with a large binding constant generates a long-lived charge-separated (CS) state with low energy loss by photoinduced electron transfer from ZnTFPPTC to Li@C. The anionic fluorinated zinc porphyrin with high oxidation potential reduces the energy loss associated with the charge separation and enhances the energy level of the CS state.

Effect of the Electron Density of the Heme Fe Atom on the Nature of Fe-O Bonding in Oxy Myoglobin.

Mössbauer spectroscopy has been used to characterize oxygenated myoglobins (oxy Mbs) reconstituted with native and chemically modified Fe-enriched heme cofactors with different electron densities of the heme Fe atom (ρ) and to elucidate the effect of a change in the ρ on the nature of the bond between heme Fe and oxygen (O), i.e., the Fe-O bond, in the protein.

Exploring Structures and Dynamics of Molecular Assemblies: Ultrafast Time-Resolved Electron Diffraction Measurements.

ConspectusMolecular assemblies have been widely applied to functional soft materials in a variety of fields. Liquid crystal is one of the representative molecular soft materials in which weak intermolecular interactions induce its dynamic molecular behavior under external stimuli, such as electric and magnetic fields, photoirradiation, and thermal treatment. It is important to understand molecular behavior and motion in the liquid-crystalline (LC) states at the picosecond level for further functionalization of liquid crystals and molecular assembled materials.

Fast Response Organic Supramolecular Transistors Utilizing In-Situ π-Ion Gels.

Despite their remarkable charge carrier mobility when forming well-ordered fibers, supramolecular transistors often suffer from poor processability that hinders device integration, resulting in disappointing transconductance and output currents. Here, a new class of supramolecular transistors, π-ion gel transistors (PIGTs), is presented. An in situ π-ion gel, which is an unprecedented composite of semiconducting nanofibers and an enclosed ionic liquid, is directly employed as an active material and internal capacitor.

Step-Economical Synthesis of Conjugated Polymer Materials Composed of Three Components: Donor, Acceptor, and π Units.

Conjugated polymers have immense potential for their use as semiconducting materials in organic optoelectronic devices. The improvement of synthetic methods for conjugated polymers is important for the practical application of conjugated polymers. For mass production, synthetic methods must be developed by considering the concerns regarding cost and environment.

Structure, metabolism and biological functions of steryl glycosides in mammals.

Steryl glycosides (SGs) are sterols glycosylated at their 3β-hydroxy group. They are widely distributed in plants, algae, and fungi, but are relatively rare in bacteria and animals. Glycosylation of sterols, resulting in important components of the cell membrane SGs, alters their biophysical properties and confers resistance against stress by freezing or heat shock to cells.

Operando direct observation of spin-states and charge-trappings of blue light-emitting-diode materials in thin-film devices.

Spin-states and charge-trappings in blue organic light-emitting diodes (OLEDs) are important issues for developing high-device-performance application such as full-color displays and white illumination. However, they have not yet been completely clarified because of the lack of a study from a microscopic viewpoint. Here, we report operando electron spin resonance (ESR) spectroscopy to investigate the spin-states and charge-trappings in organic semiconductor materials used for blue OLEDs such as a blue light-emitting material 1-bis(2-naphthyl)anthracene (ADN) using metal-insulator-semiconductor (MIS) diodes, hole or electron only devices, and blue OLEDs from the microscopic viewpoint.

Synthesis of Single Isomeric Complexes with Dissymmetric Structures Using Macrocyclic Homooligomers.

Bottom-up chemical synthesis to construct intricate molecules has been a profound challenge. An effective approach is to utilize organic ligands and metal ions, but the formation of a single product among other possible candidates has proven difficult for dissymmetric structures. We now report the synthesis of single isomeric complexes with dissymmetric structures using the mismatch in the coordination valences of macrocyclic homooligomers and metal ions.

Similarities and Differences between Crystal and Enzyme Environmental Effects on the Electron Density of Drug Molecules.

The crystal interaction density is generally assumed to be a suitable measure of the polarization of a low-molecular weight ligand inside an enzyme, but this approximation has seldomly been tested and has never been quantified before. In this study, we compare the crystal interaction density and the interaction electrostatic potential for a model compound of loxistatin acid (E64c) with those inside cathepsin B, in solution, and in vacuum. We apply QM/MM calculations and experimental quantum crystallography to show that the crystal interaction density is indeed very similar to the enzyme interaction density.

Thermal-rectification coefficients in solid-state thermal rectifiers.

The thermal rectifier is an analog of the electrical rectifier, in which heat flux in a forward direction is larger than that in the reverse direction. Owing to the controllability of the heat flux, the solid-state thermal rectifier is promising from both theoretical and applicational points of view. In this paper, we examine analytical expressions of thermal-rectification coefficients R for thermal rectifiers with typical linear and nonlinear model functions as nonuniform thermal conductivities against temperature T.

Stepwise binding of a cationic phthalocyanine derivative to an all parallel-stranded tetrameric G-quadruplex DNA.

Interaction between an Ga(III) phthalocyanine (Pc) derivative bearing eight N-methylpyridinium groups at peripheral β-positions (2,3,6,7,10,11,14,15-octakis-[N-methyl-(4-methylpyridinium-3-yloxy)phthalocyaninato] chloro gallium(III) iodide (GaPc)) and an all parallel-stranded tetrameric G-quadruplex formed from a heptanucleotide d(TTAGGGT) ([d(TTAGGGT)]) has been investigated to elucidate the molecular recognition of G-quadruplex DNA by the Pc derivative, which provides a useful insight as to the design of G-quadruplex ligands suitable for various in vitro and in vivo applications. We found that GaPc binds to the A3G4 and G6T7 steps of [d(TTAGGGT)], with binding constants of (21 ± 2) × 10 and (0.09 ± 0.

Kinetic and Thermodynamic Behaviors of Pseudorotaxane Formation with Macrocyclic BODIPY Trimers and the Remarkable Substituent Effect on Ring-Face Selectivity.

The thermodynamic and kinetic behaviors of the pseudorotaxane formation between the macrocyclic BODIPY trimers and unsymmetrical secondary ammonium guests are investigated. We find a remarkable substituent effect of the BODIPY trimer on the ring-face selectivity during the threading. The difference in the small substituents (H or CH) in the macrocyclic host molecules significantly modulated the thermodynamic and kinetic selectivity of the threading direction of the unsymmetrical ammonium ions.

Air-stable Pd(0) catalyst bearing dual phosphine ligands: a detailed evaluation of air stability and catalytic property in cross-coupling reactions.

We have synthesised an air-stable Pd(0) catalyst bearing donor and acceptor phosphine ligands (Complex 1). This study revealed the long-term air stability and catalytic property of Complex 1 as a catalyst for cross-coupling reactions, where it was stable in air for eight months. DFT calculations revealed that the acceptor ligands in Complex 1 decreased the HOMO energy level, which provided the observed air stability.

Sigmoidally hydrochromic molecular porous crystal with rotatable dendrons.

Vapochromic behaviour of porous crystals is beneficial for facile and rapid detection of gaseous molecules without electricity. Toward this end, tailored molecular designs have been established for metal-organic, covalent-bonded and hydrogen-bonded frameworks. Here, we explore the hydrochromic chemistry of a van der Waals (VDW) porous crystal.

Diborane Concatenation Leads to New Planar Boron Chemistry.

Diborane has long been realized to be analogous to ethylene in terms of its bonding MOs, both as to symmetries and splitting patterns. This naturally suggests an investigation to see whether other similar conjugated hydrocarbons manifest a similar boron-substituted and H supplemented borane. That is, for a conjugated hydrocarbon structure with a neighbor-paired resonance pattern, we propose to look at boranes where each carbon atom is replaced by a boron atom, and an H-atom pair is added to each double bond of the resonance structure, with one H above the molecular plane and one below.

Aggregation tendency of guest Fe in NaCoFeO (x < 0.1) as investigated by systematic EXAFS analysis.

In transition metal (M) compounds, the partial substitution of the host transition metal (M) to guest one (M) is effective to improve the functionality. To microscopically comprehend the substitution effect, degree of distribution of M is crucial. Here, we propose that a systematic EXAFS analysis against the M concentration can reveal the spatial distribution of M.