Hydrogen Molecules Trapped in Interstitial Host Channels of α‐Hydroquinone

Easy come, easy go: Hydroquinone forms a channel structure of cages with hydrogen‐bonded hexagons. These may provide an ideal route for the fast inclusion and facile release of hydrogen molecules (see figure), which can lead to reversible hydrogen storage under mild conditions.

     

Adsorption of unsaturated hydrocarbon moieties on H:Si(111) by Grignard reaction

Grafting of unsaturated hydrocarbon moieties (-CH(2)-CH=CH(2), -CH=CH(2), -CH(2)-CH=CH-CH(3), and -CCH) by a C-Si covalent bond was attempted by the Grignard reaction on hydrogen-terminated Si(111) in tetrahydrofuran solutions. The product adsorbates were monitored by vibrational methods of high-resolution electron energy loss spectroscopy and multiple internal infrared reflection absorption spectroscopy, as well as Auger electron spectroscopy. The temperature and the period of reaction were adjusted so as to preserve the unsaturated carbon-carbon bonds. The -CH(2)-CH=CH(2) group was introduced by a mild reaction condition, with the reservation of the C=C double bond confirmed. The unsaturated bonds in -CH(2)-CH=CH-CH(3) and -CCH were also reserved. Only in the case of -CH=CH(2) was the reservation of the C=C double bond not realized. Unsaturated hydrocarbon moieties are applicable for further organic modification to introduce functional groups, and are prospective materials in nanofabrication and biological application on silicon wafer surfaces.     

Geometric isotope effect of various intermolecular and intramolecular C-H...O hydrogen bonds, using the multicomponent molecular orbital method

The geometric isotope effect (GIE) of sp- (acetylene-water), sp(2)- (ethylene-water), and sp(3)- (methane-water) hybridized intermolecular C-H...O and C-D...O hydrogen bonds has been analyzed at the HF/6-31++G level by using the multicomponent molecular orbital method, which directly takes account of the quantum effect of proton/deuteron. In the acetylene-water case, the elongation of C-H length due to the formation of the hydrogen bond is found to be greater than that of C-D. In contrast to sp-type, the contraction of C-H length in methane-water is smaller than that of C-D. After the formation of hydrogen bonds, the C-H length itself in all complexes is longer than C-D and the H...O distance is shorter than D...O, similar to the GIE of conventional hydrogen bonds. Furthermore, the exponent (alpha) value is decreased with the formation of the hydrogen bond, which indicates the stabilization of intermolecular C-H...O hydrogen bonds as well as conventional hydrogen bonds. In addition, the geometric difference induced by the H/D isotope effect of the intramolecular C-H...O hydrogen bond shows the same tendency as that of intermolecular C-H...O. Our study clearly demonstrates that C-H...O hydrogen bonds can be categorized as typical hydrogen bonds from the viewpoint of GIE, irrespective of the hybridizing state of carbon and inter- or intramolecular hydrogen bond.     

Photoassisted adsorption of allylamine and 1-butene on H:Si(111) studied by surface vibrational spectroscopies

Ultraviolet photoassisted adsorption of terminally double-bonded molecules, allylamine (CH2=CH-CH2-NH2) and 1-butene (CH2=CH-CH2-CH3), on hydrogen-terminated silicon (111) surface was attempted to obtain adsorbates covalently terminating the surface Si atoms. The adsorption process was monitored by high-resolution electron energy loss spectroscopy, multiple internal infrared reflection-absorption spectroscopy, and Auger electron spectroscopy. Allylamine adsorbates emerged upon delivery of allylamine gas under ultraviolet irradiation. The N-H bonds in allylamine were evidenced to survive over the photoadsorption process by vibrational analysis and by the reaction with ketene. CH3- groups were detected at low coverage, indicating anchoring of the organic moieties by the secondary (sec-) type carbon atoms, which were taken over by the primary (n-) type with increasing coverage. C-D bonds were detected after deposition on deuterium-terminated Si(111) upon incorporation of Si-terminating H into the hydrocarbon part of adsorbates. In the case of 1-butene, not only the C=C end but also the CH3- end of a molecule might attach on Si, resulting in emergence of adsorbates composed of CH2 groups. The newly obtained adsorbates are prospective as a material applied for nanolithography, fine electrochemistry, and nano-biotechnology.     

Improved 2-nitrobenzenesulfenyl method: optimization of the protocol and improved enrichment for labeled peptides

We have developed the NBS (2-nitrobenzenesulfenyl) method, a quantitative proteome analysis method utilizing stable isotope labeling followed by mass spectrometry. The potential of this method was reported previously, and the procedure has now been further optimized. Here, we describe a procedure utilizing urea or guanidine hydrochloride as a protein denaturant, in conjunction with an improved chromatographic enrichment method for the NBS-labeled peptides using a phenyl resin column. By using this new protocol, both sample loss throughout the protocol and the elution of unwanted unlabeled peptides can be minimized, improving the efficiency of the analysis significantly.     

HREELS, STM, and STS study of CH(3)-terminated Si(111)-(1x1) surface

An ideally (1x1)-CH(3)(methyl)-terminated Si(111) surface was composed by Grignard reaction of photochlorinated Si(111) and the surface structure was for the first time confirmed by Auger electron spectroscopy, low energy electron diffraction, high-resolution electron energy loss spectroscopy (HREELS), scanning tunneling microscopy (STM), and scanning tunneling spectroscopy (STS). HREELS revealed the vibration modes associated to the CH(3)-group as well as the C-Si bond. STM discerned an adlattice with (1x1) periodicity on Si(111) composed of protrusions with internal features, covering all surface terraces. The surface structure was confirmed to be stable at temperatures below 600 K. STS showed that an occupied-state band exists at gap voltage of -1.57 eV, generated by the surface CH(3) adlattice. This CH(3):Si(111)-(1x1) adlayer with high stability and unique electronic property is prospective for applications such as nanoscale lithography and advanced electrochemistry.     

On-chip screening method for cell migration genes based on a transfection microarray

Cell migration plays a major role in a variety of biological processes and a detailed understanding of associated mechanisms should lead to advances in the medical sciences, for example, in drug discovery for cancer therapy. However, the traditional methods used for analysis of cell migration cannot easily be scaled up for high-throughput screening. In this study, we have attempted to develop a novel simple method for high-throughput phenotypic screening for the identification of genes that are required for cell migration. As the appropriate cell line for the method, we found NBT-L2b cells that would be suitable for screening of migration-related genes in our method without influence by other cellular processes. Moreover, the idea for printing both the labeled fibronectin, for identification of the starting region of a cell, and the green fluorescent protein (GFP) expression vector, for identification of cells that had been transfected with siRNA and of the end point of migration, brings a rapid and efficient high-throughput screening procedure. Our new method will lead to an enhanced understanding of cell migration.     

Near‐Infrared Emission from Tin–Lead (Sn–Pb) Alloyed Perovskite Quantum Dots by Sodium Doping

Phase‐stable CsSn_xPb_1?xI₃ perovskite quantum dots (QDs) hold great promise for optoelectronic applications owing to their strong response in the near‐infrared region. Unfortunately, optimal utilization of their potential is limited by the severe photoluminescence (PL) quenching, leading to extremely low quantum yields (QYs) of approximately 0.3 %. The ultra‐low sodium (Na) doping presented herein is found to be effective in improving PL QYs of these alloyed QDs without alerting their favourable electronic structure. X‐ray photoelectron spectroscopy (XPS) studies suggest the formation of a stronger chemical interaction between I^? and Sn²⁺ ions upon Na doping, which potentially helps to stabilize Sn²⁺ and suppresses the formation of I vacancy defects. The optimized PL QY of the Na‐doped QDs reaches up to around 28 %, almost two orders of magnitude enhancement compared with the pristine one.     

Supramolecular Light‐Harvesting Antennas of Metal‐Coordinated Bis(8‐Hydroxyquinoline)‐Substituted Porphyrin Networks

Artificial antenna complexes of metal‐coordinated bis(8‐hydroxyquinoline)‐substituted porphyrin networks that mimic antenna chromophores in plants were organized on titanium dioxide electrodes in photoelectrochemical cells. The generated photocurrents can be optimized according to the two ways of porphyrin self‐assembly due to the “antenna effect”: changing the number of assembled porphyrin monolayers and the number of generations of the metal‐coordinated porphyrin networks.