Structure and reactivity of alkoxycarbonyl (ester)-terminated monolayers on silicon: sum frequency generation spectroscopy

Carboxylic acid-terminated monolayers on crystalline silicon surfaces can be readily modified with biological macromolecules for the fabrication of semiconductor-based biosensing devices. They were prepared by acid-catalyzed hydrolysis of alkoxycarbonyl (ester)-terminated monolayers and studied by vibrational sum frequency generation (SFG) spectroscopy. The C-H vibration region of the SFG spectra consists of strong methyl bands with significant contributions from methylene stretching modes, indicating that these monolayers are generally ordered but with considerable gauche defects in the alkyl chains in comparison with n-alkyl monolayers. After hydrolysis, the methylene stretching modes prevail, with "residues" of the methyl bands, indicating incomplete hydrolysis and disruption of the monolayer structure. This work demonstrates that SFG is capable of providing quantitative information on structure-reactivity correlations in organic monolayers.     

Rh-catalyzed intermolecular and enantioselective [4 + 2] cycloaddition of 1,3-dienes with dimethyl acetylenedicarboxylate

A Rh-BINAP complex catalyzed an intermolecular and enantioselective [4 + 2] cycloaddition of 1-monosubstituted, 1,1- or 1,2-disubstituted buta-1,3-dienes with dimethyl acetylenedicarboxylate to give chiral cyclohexa-1,4-dienes.     

Inflammation-induced synergetic enhancement of nanoparticle treatments with DOXIL<Superscript>®</Superscript> and <Superscript>90</Superscript>Y-Lactosome for orthotopic mammary tumor

Polymeric micelles (Lactosome) in the size of 20–30 nm were labeled with radionuclides of ¹¹¹In (¹¹¹In-DOTA-Lactosome) for SPECT imaging and ⁹⁰Y (⁹⁰Y-DOTA-Lactosome) for β-ray irradiation for mammary tumor in mice. The tumor site at the femoral right leg grafted with 4T1 cells was clearly imaged at 24 h after the intravenous injection. Biodistribution revealed that the half-life time of ¹¹¹In-DOTA-Lactosome was 11 h, which enabled the nanoparticle selectively accumulated in tumor site due to the enhanced permeability and retention (EPR) effect. The anti-tumor therapeutic effect of ⁹⁰Y-DOTA-Lactosome was observed depending on the dose frequency and amount. Under the condition of the percutaneous ethanol injection treatment, the therapeutic effect of ⁹⁰Y-DOTA-Lactosome was enhanced due to the super EPR effect. Owing to the super EPR effect, co-administration of ⁹⁰Y-DOTA-Lactosome and DOXIL^® inhibited the tumor growth during 15 days with their administrations.     

Multinuclear Cu-catalysts based on SPINOL-PHOS in asymmetric conjugate addition of organozinc reagents

Multinuclear Cu/Zn complex-catalyzed efficient asymmetric conjugate addition of organozinc reagents to acyclic and cyclic enones has been developed in the presence of a wide variety of regioisomeric chiral diols bearing phosphorus moieties as ligands. The regioisomeric SPINOL-PHOS ligands based on a SPINOL architecture showed an unexpected inversion of stereoselectivity.     

Superconductivity in the graphite-potassium intercalation compound C8K

Superconducting properties of pseudo-single crystals of C₈K were investigated by low frequency a.c. magnetic susceptibility and electrical resistivity measurements. The measured values of T_c were between 128 and 198 mK for 13 samples. Measurements of the superconducting transition in a magnetic field revealed a remarkable anisotropy, such that if θ is defined as the angle between the applied magnetic field and the layer plane, type II superconductivity was observed for 0° ≦ ∣ θ ∣ ? 25° and type I superconductivity for 25° ? ∣ θ ∣≦ 90°. The angular dependences of H_c2 and H_c3 were fairly well-explained by the effective mass model.     

First total synthesis and absolute stereochemical assignment of vittarilide-A,an antioxidant extractive component isolated from Vittaria anguste-elongata Hayata

The first stereocontrolled synthesis of vittarilide-A and its C5-epimer was completed from d-glucuronolactone. Comparison with the spectroscopic properties reported for authentic material has given a clear indication as to the absolute stereochemistry of the natural vittarilide-A.     

Silafunctional Compounds in Organic Synthesis. XXXVII. Metalated (Allyl) Aminosilanes: Regioselective Coupling with Alkyl Halides to (E)-1-Alkenylsilanes with a Functional Group on Silicon

(E)-1-Alkenylsilanes with an amino or an alkoxy group on silicon can be conveniently synthesized by regioselective coupling of a potassium reagent derived from an allyl(amino)silane with alkyl halides.     

Single‐Crystalline Optical Microcavities from Luminescent Dendrimers

Microcrystallites are promising minute mirrorless laser sources. A variety of luminescent organic compounds have been exploited along this line, but dendrimers have been inapplicable owing to their fragility and extremely poor crystallinity. Now, a dendrimer family that overcomes these difficulties is presented. First‐, second‐, and third‐generation carbazole (Cz) dendrimers with a carbon‐bridged oligo(phenylenevinylene) (COPV2) core (GnCOPV2, n=1–3) assemble to form microcrystals. The COPV2 cores align uni/bidirectionally in the crystals while the Cz units in G2‐ and G3COPV2 align omnidirectionally. The dendrons work as light‐harvesting antennas that absorb non‐polarized light and transfer it to the COPV2 core, from which a polarized luminescence radiates. Furthermore, these crystals act as laser resonators, where the lasing thresholds are strongly coupled with the crystal morphology and the orientation of COPV2, which is in contrast with the conventional amorphous dendrimers.     

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Spin-inversion dynamics in O₂ binding to a model heme complex, which consisted of Fe(II)-porphyrin and imidazole, were studied using nonadiabatic wave packet dynamics calculations. We considered three active nuclear degrees of freedom in the dynamics, including the motions along the Fe–O distance, Fe–O–O angle, and Fe out-of-plane distance. Spin-free potential energy surfaces for the singlet, triplet, quintet, and septet states were developed using density functional theory calculations, and spin–orbit coupling elements were obtained from CASSCF-level electronic structure calculations. The spin-inversion mainly occurred between the singlet state and one of the triplet states due to large spin–orbit couplings and the contributions of other states were extremely small. The present quantum dynamics calculations suggested that the narrow crossing region model plays a dominant role in the O₂ binding dynamics. In addition, the one-dimensional Landau–Zener model underestimated the nonadiabatic transition probability.     

Large Deformation of a DNA‐Origami Nanoarm Induced by the Cumulative Actuation of Tension‐Adjustable Modules

Making use of the programmability and structural flexibility of the DNA molecule, a DNA‐origami nanoarm capable of undergoing large deformation is constructed. This DNA‐origami nanoarm comprised serially repeated tension‐adjustable modules, the cumulative actuation of which resulted in a large deformation of the arm structure, which transformed from a linear shape into an arched shape. Combining atomic force microscopy and theoretical analyses based on the mechanics of materials, we demonstrate that the degree of deformation can be systematically controlled by merely replacing a set of strands that is required for the actuation of the module. Moreover, by employing a G‐quadruplex‐forming sequence for the actuation, we could achieve reversible ion‐induced contraction and relaxation of the nanoarm. The adjustability and scalability of this design could enable the production of DNA nanodevices that exhibit large deformation in response to external stimuli.