In the present study, we used rare earth oxides for the catalytic transfer hydrogenation of carbonyl compounds. Pre-treated La2O3 showed better catalytic performance than various rare earth oxides for the reduction of carbonyl compounds. Reaction conditions, precursors, and donor hydrogen sources were also investigated to optimize the hydrogen transfer to furfural in 2-propanol. La2O3 provided a conversion of different carbonyl compounds and selectivity to the corresponding alcohols up to 100% and 99%, respectively. We also investigated a plausible mechanism using in situ IR and found that furfural was adsorbed on the catalyst surface in a different adsorption mode. Meanwhile, La(OH)3, a hydroxide derivative of La2O3 formed during the reaction, was also catalytically active.
Titanium bis(diethylamido) complex 1, which contains a carbon-bridged bis(indolyl) ligand, was obtained in 69% yield from the reaction of Ti(NEt2)4 with the corresponding bis(indole) ligand. Its molecular structure in the crystal was unequivocally determined by a single-crystal X-ray diffraction analysis. Furthermore, we examined applications of 1 as a catalyst for the intermolecular hydroamination of alkynes. When using phenylacetylene or 1-hexyne as alkynes, the Markovnikov products were obtained selectively, while the reaction with 1-phenyl-1-propyne afforded an imine of phenylacetone.
Styrene was grafted onto the surface of polypropylene (PP)/polyethylene (PE) films through direct radical polymerization using diethyl(1,10-phenanthroline-N1, N10)zinc (Phen-DEZ) and oxygen molecules as the radical initiators. The grafting of styrene on the PP/PE surface was confirmed by FT-IR, Raman, UV-Vis, atomic force microscope (AFM) and thermogravimetric analysis (TGA).
We have investigated the quantitative detection of aminoglutethimide (AGI) based on its adsorption on a SERS-active screen-printed electrode employing Electrochemical Surface-Enhanced Raman Spectroscopy (EC-SERS) technology. EC-SERS spectra of AGI molecules exhibited different adsorption mode onto the substrate with different potentials applied. When the applied potential reaches −400 mV, the intensities of the EC-SERS peaks provided by both aniline moiety and glutarimide moiety were significantly enhanced, which suggests the bidentate interaction of AGI molecule with the substrate. The peak of 1147 cm−1 showed the strongest intensity among the wavenumbers, with peak intensity over 30 times stronger than that of the standard SERS signal. A linear dependence occurred in the range of 1 × 10−5 M to 2 × 10−7 M. The limit of detection (LOD) is 40 ng/mL and the R squared of the linear curve was 0.98. This work was completed on a coin-sized chip using low sample volume (30 µL) only. Trace detection of this drug using this technique would be useful for the deterrence and prevention of dopant usage and other point-of-care diagnostics (POCD).
A new determination is presented for the intermolecular partial pair correlation functions of liquid water at ambient temperature. Time-of-flight (TOF) neutron diffraction measurements with excellent statistical accuracies have been carried out for liquid H2O, HDO, and D2O at 25 °C employing a high performance total scattering spectrometer installed at a high-power pulsed spallation neutron source. The intermolecular partial pair correlation functions, gHHinter(r), gOHinter(r), and gOOinter(r), have successfully been deduced from direct Fourier transformation of observed intermolecular interference terms. The nearest neighbor intermolecular H•••H, O•••H, and O•••O distances are determined to be 2.44, 1.84, and 2.86 Å, respectively. These values are significantly longer than those predicted by molecular dynamics (MD) simulation studies employing classical water-water potentials. Evidence on the deviation of the electron distribution from the spherical one around atoms in the liquid water has been experimentally derived from the combination of the present partial structure functions and high precision X-ray data of water obtained from synchrotron radiation X-ray diffraction.
The interaction between a single-stranded DNA (ssDNA) and a binding protein (Sulfolobus solfataricus ssDNA binding protein, SSB) were investigated by the ab initio fragment molecular orbital (FMO) method in explicit solvent. The calculated overall energy change upon complexation suggested that the ssDNA/SSB association is not strong. Nonetheless, more detailed analysis of interfragment interaction energy (IFIE) and pair interaction energy decomposition analysis (PIEDA) indicated that the ssDNA/SSB association is based upon a minute balance of various contributions of local structural parts of the molecules. The most stabilizing contribution was that by the electrostatic interaction between the sugar–phosphate backbone of ssDNA and charged side chains of SSB, and the second was that by the stacking interaction between bases of ssDNA and aromatic side chains of SSB. Thus, though the overall association energy change was small, the local interactions were suggested to contribute to the association.
To address the global energy crisis, it is imperative to develop effective, renewable and clean energy carriers. As one of the most promising candidates, hydrogen has a high energy density and is environmentally friendly. However, the limitation of hydrogen storage hinders the realization of a hydrogen society. Generally, a high hydrogen capacity, fast reaction kinetics, low cost, and safety are required in a hydrogen storage system for practical applications. In this respect, liquid chemical hydrides, like aqueous ammonia borane, hydrous hydrazine, and formic acid, have received much attention which would satisfy the above requirements and have good compatibility with the infrastructure for liquid fuels. This account reviews detailed research progress in hydrogen generation from liquid chemical hydrides catalyzed by metal nanoparticles in our group. Finally, the challenges and prospects are discussed.
Parallel artificial membrane permeation assay (PAMPA) was performed for nine amine drugs and their permeability coefficient (log Ppampa) was determined at different pHs. The previously developed digital simulation method was successfully used to reproduce the sigmoid-like pH dependence of log Ppampa, and the distribution coefficient (log KD,M) to the lipid-containing dodecane membrane could be determined for all the amine drugs studied. The thus determined log KD,M values showed a linear free-energy relationship with the standard ion-transfer potential (ΔOWφ°; R2 = 0.754) and the distribution coefficient (log KD; R2 = 0.891), which were previously determined by ion-transfer voltammetry with the 1,2-dichloroethane|water interface. On the other side, we can predict ΔOWφ° very accurately by a previously proposed solvation model called the “non-Bornian” model. These findings suggest a possible strategy for perfect in silico prediction of the membrane permeability of drugs.
Efficiency of the isomer exploration of BCNOS was investigated by limited search techniques using the LADD and NRUN options of the Global Reaction Route Mapping (GRRM) program. LADD specifies the number of Anharmonic Downward Distortions (ADDs), which should be preferentially traced from the largest ADD, and NRUN specifies the number of randomly generated initial structures. When the value of NRUN was fixed and the value of LADD was varied, all relatively stable structures (with respect to the most stable structure) below 300 kJ/mol were explored for LADD=1–3. When the value of LADD was fixed and the value of NRUN was varied, most of the low energy structures were obtained for NRUN=1, and the higher energy structures were complemented for larger NRUN values.
In this study, we report synthesis of a new series of mixed-valence (MV) complexes having intervalence charge transfer (IVCT) energies variable from the first to the third telecommunication window. This wide-range modulation was achieved by variation of covalently-dimerized catecholato ligands, in combination with Pd(II) ions, which lowered the oxidation potentials and enabled access to MV states. Importantly, we found that regulation of the conjugation lengths enabled energy gap control and annulation of an additional benzene ring switched the nature of the IVCT transitions. These changes were accompanied by a cross-over from moderately delocalized Class II to delocalized Class III character according to the Robin-Day classification. Through accurate comparisons with well-known ferrocene counterparts and their hetero-conjugate, our non-innocent ligand-based approach is found to be effective for controlling IVCT parameters. These findings offer a new approach to materials design for electro-optic switching.
Herein we report the detection and differentiation of plasmonic and non-plasmonic nanoparticles simultaneously administered to A549 lung epithelium cells using dark-field microscopy and hyperspectral imaging. Reflectance spectra-based hyperspectral mapping and image analysis allows for the effective quasi-quantitative identification of nanomaterials in cultured human cells.
A specific chiral selective chemical reaction on flavin-wrapped single-walled carbon nanotubes (SWNTs) is recognized based on a unique assembled structure formation of the flavin when using a chlorinated solvent such as chloroform; namely, the self-assembled flavin onto the SWNT surface protected (8,6)SWNTs from the chlorine radical reaction.
Optical switching between one-dimensionally ordered layered smectic C (SmC) and three-dimensionally periodic bicontinuous cubic (Cubbi) liquid-crystalline (LC) phases is a fascinating challenge because of the dramatic changes of structural symmetries and orders as well as physical properties. In this work, we have developed a new light-driven Cubbi phase system consisting of 4′-n-hexadecyloxy-3′-cyanobiphenyl-4-carboxylic acid (ACBC-16) and a structurally analogous azo compound (Azo-2). The employment of the CN side-group in the host compound brought about outstanding responsiveness under ultraviolet (UV) light in the mixtures containing 11 and 19 mol % Azo-2, leading to a UV response time of ∼5 s and excellent repeatability of on-off switching for the conversion between the two LC phases. The modification also enabled us to quantitatively analyze the mechanism of the light-induced transformation between the two LC phases. The evaluation revealed that the presence of ∼4% of bent molecules in the system under UV light destabilizes the SmC layered structure originally constructed by rod-shaped molecules, causing formation of the Cubbi phase at temperatures 10–35 K below the temperature range of the thermally-stable Cubbi phase.
Certain concentrated mixtures of lithium salt and solvent (ligand) are no longer simple solutions, but categorized as solvate ionic liquids (SILs), where the solvent strongly coordinates to the cation to form a solvate, a negligible amount of free solvent remains, and thus the SIL consists of the solvate cation and the anion. Typical examples are mixtures of lithium bis(trifluoromethane sulfonyl)amide (Li[TFSA]) and certain glymes . The successful formation of a SIL greatly depends on both the ligand and lithium salt structures. To obtain robust and long-lived solvates, a ligand exhibiting a chelate effect is essential and n = 3 and 4 (i.e. triglyme and tetraglyme) are suitable for the formation of lithium solvates. The Lewis basicity of the lithium salt anion also significantly affects the formation of SILs. Specifically, a weak Lewis basicity promotes the formation of a SIL, since the ligand-Li+ interaction overwhelms the Li+-anion interaction. SILs can be diluted with rather low polarity solvents to increase the ionic conductivity, where the solvate structure is maintained even after the dilution. SILs exhibit unique features as electrolytes, including the enhancement of oxidation stability of the component glymes, unique Li+ transport through ligand exchange when interfacial electrochemical reactions are occurring, the inhibition of aluminum corrosion when Al foil is used as a cathode current collector, poorly-solubilizing towards ionic electroactive materials, and electrochemical graphite intercalation reactions. These features greatly enhance the possibility for application of SILs as next generation lithium battery electrolytes. Furthermore, new polymer electrolytes containing SILs have been proposed, simultaneously enabling film-processability, high ionic conductivity, thermal stability, and a wide potential window. Preservation of the solvate structure in the polymeric phases is pivotal to such achievements.