In this study, we demonstrate that the plasmonic properties of gold nanorods (GNRs) electrostatically adsorbed on a DNA brush substrate are reversibly controlled by changes in NaCl concentration. This plasmonic change results from GNR assembly/disassembly in a DNA brush layer. In addition, we show that this active plasmonic system exhibits intense and switchable chiroptical properties.
An efficient thioxanthone synthesis from benzoic acid esters is disclosed. Various thioxanthones were prepared by iridium-catalyzed C–H borylation of benzoic acid esters followed by copper-catalyzed deborylthiolation and direct acid-mediated cyclization. We also achieved a synthesis of benzo-fused thioxanthones through a transformation of an aryne intermediate having an ester moiety.
More than 25 weight percent of lithium ions were accommodated in silsesquioxane-pillared carbon with very small interlayer expansion. It delivered reversible capacity of 1023 mAh/g with a relatively high first columbic efficiency of 67% and good cycling property as an anode of an all-solid-state lithium ion battery.
The palladium-catalyzed synthesis of diarylborinic acid derivatives by intermolecular cross-coupling between aryl iodides and (amino)dihydrideborane is reported. The key to success of the reaction is the use of a less bulky diethylaminoborane reagent, which facilitates the second B-arylation.
We developed an anthracene-appended benzoxaborole dimer 1 and established selective sensing of d-glucose (Glc) and d-galactose (Gal) via an exciton-coupled circular dichroism (CD) technique. Our analytical strategies of CD spectroscopy based on the experimental and theoretical approach effectively clarified the underlying mechanism of Glc and Gal recognition by benzoxaborole dimer 1.
Ferroelectric columnar liquid crystals have received much attention as energy-saving electronic materials. In this study, an N,N′-bis(3,4,5-tris((2-ethylhexyl)oxy)phenyl)urea was synthesized and characterized. As a result, the compound exhibited a ferroelectric columnar liquid crystal phase at low-temperature (63–103 °C), and succeeded in significantly lowering the temperature compared to conventional ferroelectric urea compounds (>105 °C). This is the first example where ferroelectricity is greatly affected by the temperature in a columnar liquid crystal phase.
Guanine (G)-rich sequences can form non-canonical four stranded structures known as G-quadruplexes (G4s). The G4 structure has been found in biologically significant regions of the genomic DNA, and many G4 ligands with a high specificity and affinity have been reported. In this review, we focus on the functional G4 ligands, which not only bind to the G4 structure but also have some function, especially with inducing G4 folding, chemical reactions, and alkylation by proximity.
Donor–acceptor–donor arrays based on an anthracene bisimide (ABI) skeleton appended with 6,13-diethynylpentacene and 9,10-diethynylanthracene units have been constructed by Sonogashira coupling followed by reductive aromatization. Their photophysical and electrochemical properties are compared with those of the corresponding mono-substituted analogs on the basis of theoretical calculations and cyclic voltammetry to evaluate the intramolecular electronic interactions between ABI as the acceptor unit and diethynylacene as the donor unit.
DNA methyl transferase1 (Dnmt1) preferentially methylates hemi-methylated DNA. Upon the methylation of DNA, a methyl group is provided by S-adenosyl-l-methionine (SAM), which becomes the product S-adenosyl-l-homocysteine (SAH). We performed molecular dynamics (MD) simulations to trace the dynamics of SAM and address SAH in inactivated Dnmt1 in mice. Our MD simulations found that SAM was more stable than SAH under the inactivated Dnmt1 environment, indicating that an exchange of cofactors might occur in the inactivation state before the next methylation process.
Hydrogen boride (HB) sheets have recently been synthesized as new two-dimensional materials composed of boron and hydrogen. This study reports a new role of HB sheets as reductants. Ultraviolet–visible spectroscopy was undertaken for a mixture of HB sheets with several metal ions in solution. The sheets had a redox potential between −0.277 and −0.257 V versus standard hydrogen electrode (SHE). We subsequently demonstrated the facile formation of HB sheet nanocomposites with metal nanoparticles using this reduction property.
We have found that an iridium-dinitrogen complex bearing an anionic benzene-based PCP-type pincer ligand works as an effective catalyst for the reduction of dinitrogen into tris(trimethylsilyl)amine under ambient reaction conditions. This result demonstrates the first successful example of the iridium-catalyzed transformation of dinitrogen under ambient reaction conditions.
Parallel cascade selection molecular dynamics (PaCS-MD) is a rare event sampling method. PaCS-MD repeats cycles of resampling from important initial structures based on short-time MD simulations. When restarting the short-time MD simulations, regenerations of the initial velocities play an essential role in creating perturbations to promote conformational transitions. Therefore, we addressed the conformational sampling efficiencies of PaCS-MDs with and without the regenerations of initial velocities by modeling the folding of a mini-protein (Chignolin) in explicit water. In the present letter, we confirmed that the regenerations of initial velocities increased the conformational sampling efficiency of PaCS-MD.
We synthesized directly linked diphenylalanine and dibenzoylmethanatoboron difluoride (DPA-BF2DBMb) and investigated the assembling structure. The aggregation forms and fluorescence of precipitated DPA-BF2DBMb depended on the solvent. Based on this result, the aggregation process of DPA can be controlled and new luminescent materials that show environment-induced color changes can be developed.
Plasmonic chemical reactions triggered by the excitation of a localized surface plasmon show unique reactivity in a highly localized electric field. In this study, visible light driven hydrogen evolution reactions have been successfully induced by the combination of plasmonic Ag nanostructures with a p-type GaP semiconductor electrode. Through photoelectrochemical measurements, the unique reactivity of the plasmon-induced electron transfer reaction, especially under neutral conditions, has been confirmed.
A facile synthesis of diverse N-arylphenylalanine derivatives is described. We have developed an efficient method for preparing diverse N-arylphenylalanine ester-type platforms containing an aryne generating moiety and a halogen via oxidative cross-coupling. A wide variety of N-arylphenylalanine esters were convergently synthesized using the platforms by a range of aryne reactions and following cross-coupling reactions.
An efficient method to synthesize allyl sulfides from sulfinate esters and allylsilanes is described. Based on the reactivity of isolated allyl(methoxy)phenyl sulfonium triflate, we have developed a simple one-pot method for the allyl sulfide synthesis by S-allylation of sulfinate esters and subsequent reduction with sodium borohydride. A number of allyl sulfides were prepared by this method leaving various functional groups unreacted.
Therapies such as photodynamic therapy and radiotherapy, are highly dependent on oxygen to generate reactive oxygen species to kill cancer cells. However, the hypoxic environment in the tumor significantly reduces the therapeutic efficacy. Here, thermosensitive lipid nanoparticles are fabricated to deliver a polymerization initiator, which can generate free radicals in an oxygen-independent manner. Indocyanine green is co-encapsulated in the nanoparticles to generate heat upon laser irradiation. Once the temperature is over the melting point of the lipid nanoparticles, the initiator will be released and decomposed to generate free radicals. The free radicals produced in this way demonstrate pronounced anticancer effects in both normoxic and hypoxic environment, holding a great potential to increase the therapeutic effect in clinic.
Reductive dehalogenation of aryl halides, bromobenzonitrile and iodobenzonitrile by the photo-excited B12 complex with the labile Co(I) oxidation state under anaerobic conditions was reported for the first time. A sub-pico second time-resolved spectroscopic analysis showed that the excited state of the B12 complex, *Co(I), has a 280 ps lifetime and the rate constants of electron transfer to the reactants (kET) are 3.6 × 109, 3.3 × 109, and 1.4 × 109 M−1s−1 for iodobenzonitrile, bromobenzonitrile, and chlorobenzonitrile, respectively.
The nanostructure of oleyl acid phosphate (OLAP) in lubricant, which is an essential factor for understanding lubrication properties, was investigated using small-angle X-ray scattering (SAXS). SAXS profiles were observed for OLAP with concentrations of 1, 3, 5, and 10 mass % in poly-α-olefin (PAO). The SAXS results demonstrated that OLAP forms reverse-micellar-like aggregates in PAO. This nanostructural information from SAXS will drive further development of advanced lubricants.
When performing a conformation search for a macromolecule, we propose the use of a new selection process for choosing reaction center atoms by applying the microiteration method. Conformation searches of glycine were performed by using this new selection process with the μ-ADDF method. These searches found seven conformers, including the most stable conformer.
Performances of direct ascorbic acid fuel cells using anodes of nano carbons (SWCNT, graphene, C60) and their composites with conducting polymers were studied. The output power using polyaniline@SWCNT composite was 8.7 mW cm−2 for Nafion separator and Pt cathode. Cells using PEDOT*PSS@SWCNT composite and filter paper for separator exhibited power >2 mW cm−2. The facts are explained by the idea that PEDOT*PSS plays the role of cation exchange membrane.
Multicopper(II) complexes were synthesized using bis-benzimidazole ligands expressed as B–CH2–C6R4–CH2–B (B = benzimidazole, R = Me (bbitrb), OMe (bbitrmob)). For the reactions with Cu(ClO4)2·6H2O and CuSO4·5H2O, bbitrb gave M2L4 cage complexes, while bbitrmob gave a M2L4 cage complex and a new 1D coordination polymer. The substituent-controlled syntheses of the Cu(II) complexes are described.
A dearomative C4-allylation of benzyl ammoniums with allyltributylstannane by a palladium catalysis is described. A triarylphosphine-ligated palladium catalyst, which is capable of cleaving benzylic C–N bonds, realized facile dearomative reactions with C4 selectivity. Combined with precedented C2- and C3-selective functionalizations of benzyl amine derivatives, the present reaction can provide a new synthetic option for the synthesis of multi-substituted alicyclic compounds as well as aromatic compounds.
We have designed novel multinuclear metal-binding sites by introducing 96 Cys residues at the 2-fold symmetric interfaces in the protein cage of ferritin. X-ray crystal structure analysis showed that the introduced Cys coordinates to Au ions, forming a multinuclear gold-binding site. This study revealed that the robust cage structure contributes to fix the Cys residues introduced at the desired position and the ferritin subunit interface is a suitable site for constructing multinuclear metal-binding architectures.
Luminescent lanthanide (Ln) complexes based on chelate effects will be introduced using a series of hexadentate bipyridine derivatives as their ligand moieties. The molecules form a single helicate molecular structure with a Ln-coordination. Molecular distortion and various derivations induce the intended luminescence and characteristic molecular conformation, which depend on atmosphere or media. It would be a supportive case to design novel units of Ln components for emission.
A simple and efficient molecularly imprinted (MIP) electrochemiluminescence (ECL) sensor with graphitic carbon nitride nanosheets (g-C3N4 NSs) as emitter was developed for sensitive and selective determination of hydroquinone (HQE). The resulting MIP-ECL sensor exhibits not only high sensitivity and selectivity to HQE, but also excellent reproducibility and stability, and was successfully applied to detect HQE in water samples with satisfactory results. Owing to easy preparation and low cost, this MIP-ECL sensor has a great potential for development and application.
Photocatalytic nitrogen oxides (NOx) trapping is a new approach to reduce NOx emission from automobiles. The modification of TiO2 with Ba (Ba-TiO2) improves the NOx storage capacity (NSC) of TiO2. X-ray absorption spectroscopy shows that Ba-TiO2 consists of isolated Ba species and bulky Ba(NO3)2. Diffused reflectance infrared Fourier transform spectroscopy reveals that isolated Ba species affect the NOx trapping ability on neighboring Ti sites and enhance the photocatalytic NSC on Ba-TiO2.
The chemical energy from the Belousov-Zhabotinsky (BZ) reaction powers autonomous mechanical oscillations in BZ gels. One drawback is that the process produces carbon dioxide bubbles, making lengthy experiments and practical applications difficult. Herein we synthesize a microphase-separated BZ gel and determine mechanical oscillation conditions that do not generate bubbles. Investigations of the thermodynamic mechanism of the CHD-BZ gel using 1,4-cyclohexanedione (CHD) reveals that the Flory interaction parameter χ is altered by the redox changes to the metal ion incorporated in a microphase-separated CHD-BZ gel. This microphase-separated structure leads to alterations in χ as well as the entropy when redox changes occur in a microphase-separated CHD-BZ gel.
Substituted chiral hydrindanes were synthesized as single isomers in almost enantiopure forms through a one-pot process that proceeds via the diphenylprolinol silyl ether mediated-domino Michael/Michael reaction of α,β-unsaturated aldehydes and 3-hexene-2,5-dione, and a subsequent intramolecular aldol condensation of the generated cyclopentanone intermediate.
Ambipolar transistor properties are observed in Schiff-base complexes derived from 2-aminobenzenethiol and 2-mercapto benzaldehyde, where a nickel atom is coordinated by two sulfur and two nitrogen atoms. The former complexes have extremely small energy gaps of 0.5∼0.6 eV, where air-stable ambipolar characteristics with small off region are observed.