Nuclearity control of a trisaloph zinc cluster complex dependent on minute structural differences in the bridging anions

The Zn(6) cluster complex 2 of the trisaloph ligand was synthesized using EtCO(2)(-) anions as bridging ligands. Complex 2 has a dimeric structure in the crystalline state, while two monomeric isomers were in equilibrium in solution. The anion-exchange reaction successfully resulted in nuclearity control from Zn(7) to Zn(6).     

A method for generating single crystals that rely on internal fluid dynamics of microdroplets

The single crystallization method by focusing on the characteristic internal fluid dynamics of the microdroplets was explored. Also the theoretical background was discussed, and the droplet size for obtaining only a single crystal within a microdroplet was estimated.     

Immuno-pillar chip: a new platform for rapid and easy-to-use immunoassay

We present a new rapid and easy-to-use immunoassay chip which we have named the immuno-pillar chip. It has hydrogel pillars, fabricated inside a microchannel, with many antibody molecules immobilized onto 1 μm diameter polystyrene beads. To evaluate the chip performance, we applied it to the sandwich assay of C-reactive protein (CRP), α-fetoprotein (AFP) and prostate-specific antigen (PSA), a cardiac and inflammation marker, tumors and prostate cancer markers, respectively. For detection of disease markers, we confirmed the chip provides rapid analysis (total assay time of about 4 min) with high sensitivity, it is easy-to-use (no special skills are needed), and it uses small volumes of the sample and reagent (0.25 μL each). Moreover, multiplex assay for three biomarkers was also possible. Additionally, the immuno-pillar chip has a big advantage of having hardly any influence on the assay results even if the introduction quantities of the sample or reagents are different.     

Simultaneous determination of ten antihistamine drugs in human plasma using pipette tip solid-phase extraction and gas chromatography/mass spectrometry

Ten antihistamine drugs, diphenhydramine, orphenadrine, chlorpheniramine, diphenylpyraline, triprolidine, promethazine, homochlorcyclizine, cyproheptadine, cloperastine and clemastine, have been found to be extractable from human plasma samples using MonoTip C18 tips, inside which C18- bonded monolithic silica gel was fixed. Human plasma (0.1 mL) containing the ten antihistamines was mixed with 0.4 mL of distilled water and 25 microL of a 1 M potassium phosphate buffer (pH 8.0). After centrifugation of the mixture, the supernatant fraction was extracted to the C18 phase of the tip by 25 repeated aspirating/dispensing cycles using a manual micropipettor. The analytes retained on the C18 phase were then eluted with methanol by five repeated aspirating/dispensing cycles. The eluate was injected into a gas chromatography (GC) injector without evaporation and reconstitution steps, and was detected by a mass spectrometer with selected ion monitoring in the positive-ion electron impact mode. The separation of the ten drugs from each other and from impurities was generally satisfactory using a DB-1MS column (30 m x 0.32 mm i.d., film thickness 0.25 microm). The recoveries of the ten antihistamines spiked into plasma were 73.8-105%. The regression equations for the ten antihistamines showed excellent linearity with detection limits of 0.02-5.0 ng/0.1 mL. The within-day and day-to-day coefficients of variation for plasma were not greater than 9.9%. The data obtained from determination of diphenhydramine and chlorpheniramine in human plasma after oral administration of the drugs are also presented.     

Maskless microfabrication of thermosensitive gels using a microscope and application to a controlled release microchip

Here we show a simple and convenient method to prepare micropatterned gels by the use of a microscope, without large-scale or special-order experimental setup. UV light focused by an objective lens was locally irradiated to a pre-gel solution in a microchannel. This method would be useful for preparing microgels at target positions in microchips. A controlled drug-release microchip has actually been fabricated by utilizing this local photo-irradiation method, and pulsatile drug release in response to temperature changes was demonstrated.     

Preparation of nitrogen-substituted TiO2 thin film photocatalysts by the radio frequency magnetron sputtering deposition method and their photocatalytic reactivity under visible light irradiation

Nitrogen-substituted TiO2 (N-TiO2) thin film photocatalysts have been prepared by a radio frequency magnetron sputtering (RF-MS) deposition method using a N2/Ar mixture sputtering gas. The effect of the concentration of substituted nitrogen on the characteristics of the N-TiO2 thin films was investigated by UV-vis absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses. The absorption band of the N-TiO2 thin film was found to shift smoothly to visible light regions up to 550 nm, its extent depending on the concentration of nitrogen substituted within the TiO2 lattice in a range of 2.0-16.5%. The N-TiO2 thin film photocatalyst with a nitrogen concentration of 6.0% exhibited the highest reactivity for the photocatalytic oxidation of 2-propanol diluted in water even under visible (lambda > or = 450 nm) or solar light irradiation. Moreover, N-TiO2 thin film photocatalysts prepared on conducting glass electrodes showed anodic photocurrents attributed to the photooxidation of water under visible light, its extent depending on wavelengths up to 550 nm. The absorbed photon to current conversion efficiencies reached 25.2% and 22.4% under UV (lambda = 360 nm) and visible light (lambda = 420 nm), respectively. UV-vis and photoelectrochemical investigations also confirmed that these thin films remain thermodynamically and mechanically stable even under heat treatment at 673 K. In addition, XPS and XRD studies revealed that a significantly high substitution of the lattice O atoms of the TiO2 with the N atoms plays a crucial role in the band gap narrowing of the TiO2 thin films, enabling them to absorb and operate under visible light irradiation as a highly reactive, effective photocatalyst.     

Optical properties of oligo(2,3-dioxyfunctionalized)naphthalenes

The properties of two series of oligo(2,3-dioxyfunctionalized)naphthalenes which are connected at the 1,4-positions, that is, methoxy derivatives 1-4 and derivatives that possess two pyrene groups on the central scaffolding oxygen functions 5-8, are described. In 1-4, the fluorescence quantum yields increased by about 20-80% as the number of naphthalene units increased. The intramolecular energy transfer quantum yields of 5-8 were around 20% regardless of the number of naphthalene units.     

Palladium-catalyzed selective 2,3-diarylation of alpha,alpha-disubstituted 3-thiophenemethanols via cleavage of C-H and C-C bonds

Alpha,alpha-disubstituted 3-thiophenemethanols undergo selective diarylation accompanied by cleavage of the C-H and C-C bonds of the 2- and 3-positions, respectively, upon treatment with aryl bromides in the presence of a palladium catalyst to give the corresponding 2,3-diarylthiophenes in good yields.     

Convenient synthesis of chiral lignin model compounds via optical resolution: four stereoisomers of guaiacylglycerol-β-guaiacyl ether and both enantiomers of 3-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-propan-1-one (erone)

Guaiacylglycerol-β-guaiacyl ether (GGE) is one of the most important phenolic compound for studying the chemistry and biochemistry of lignin. GGE contains two asymmetric carbons at the alpha and beta positions of its side chain; therefore, theoretically it can exist as four different stereoisomers. It has been proposed that a Gram-negative bacterium, Sphingobium sp. SYK-6 (formerly referred as Sphingomonas paucimobilis SYK-6), degrades GGE enantiospecifically via cleavage of the ether bond. The cleavage was thought to proceed in two steps, each catalyzed by a different enantiospecific enzyme. In the first step, the alcohol residue at the alpha position of the side chain in GGE was thought to be oxidized enantiospecifically by four distinct Cα-dehydrogenases (LigD, LigN, LigL and LigO), to produce two enantiomers of 3-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-propan-1-one (erone). To study this enantiospecific degradation step by the four dehydrogenases, we synthesized all four stereoisomers of GGE and both enantiomers of erone and separated them into enantiopure samples. The stereoisomers and our synthetic methods to prepare them are useful both for microbial and chemical investigations of lignin degradation.     

Enantioselective conjugate addition of alkylboranes catalyzed by a copper-N-heterocyclic carbene complex

The first catalytic enantioselective conjugate addition of alkylboron compounds has been achieved. Reactions between alkylboranes and imidazol-2-yl α,β-unsaturated ketones proceeded with high enantioselectivity under the influence of a Cu(I) catalyst system, prepared in situ from CuCl, a new chiral imidazolium salt as a precursor for the N-heterocyclic carbene ligand, and PhOK. Alkylboranes are widely obtained via alkene hydroboration. A variety of functional groups are tolerated in alkylboranes and α,β-unsaturated ketones.