Radical-scavenging activity of the reaction products of isoeugenol with thiol, thiophenol, mercaptothiazoline or mercaptomethylimidazole using the induction period method

The reaction products in the presence of Lewis acid of isoeugenol (1) with ethanethiol, thiophenol, 2-mercaptothiazoline or 2-mercapto-1-methylimidazole (ISO-S1-ISO-S-4) were obtained. The radical-scavenging activity of these compounds was investigated using the induction period method for polymerization of methyl methacrylate (MMA) initiated by thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO) and monitored by differential scanning calorimetry (DSC). For BPO, the stoichiometric factor (number of free radicals trapped by one mole of antioxidant moiety, n) declined in the order isoeugenol (1.8) > ISO-S-1 (1.6) > ISO-S-2 (1.2) > ISOS- 3 (0.9) > ISO-S-4 (0.3), whereas for AIBN, their n values were about 1, except for ISOS- 3 (0.6). The ratio of the rate constant of inhibition to that of propagation (k(inh)/k(p)) for BPO declined in the order ISO-S-4 (56) > ISO-S-3 (15) > ISO-S-2 (11) >ISO-S-1 (9) > isoeugenol (8). Similarly, for AIBN the k(inh)/k(p) of the reaction products (33-57) was greater than that of isoeugenol (31). The reaction products of isoeugenol with a SH group showed greater inhibition rate constants (kinh) than the parent compound isoeugenol.     

Ba-catalyzed direct Mannich-type reactions of a beta,gamma-unsaturated ester providing beta-methyl aza-Morita-Baylis-Hillman-type products

Barium-catalyzed direct Mannich-type reactions of a beta,gamma-unsaturated ester are described. The Ba-catalyst not only promoted the Mannich-type reactions, but also isomerized Mannich adducts to afford beta-methyl aza-Morita-Baylis-Hillman-type products in 61-88% yield from various aryl, heteroaryl, and alkyl imines. Preliminary trials on enantioselective variants with a chiral biaryldiol ligand gave products in up to 80% ee.     

Surface plasmon resonance sensor for lysozyme based on molecularly imprinted thin films

Molecularly imprinted polymers (MIPs) selective for lysozyme were prepared on SPR sensor chips by radical co-polymerization with acrylic acid and N,N′-methylenebisacrylamide. Gold-coated SPR sensor chips were modified with N,N′-bis(acryloyl)cystamine, on which MIP thin films were covalently conjugated. The presence of NaCl during the polymerization and the re-binding tests affected the selectivity and the optimization of NaCl concentration in the pre-polymerization mixture and the re-binding buffer could enhance the selectivity in the target protein sensing. When the lysozyme-imprinted polymer thin films were prepared in the presence of 40 mM NaCl, the selectivity factor (target protein bound/reference protein bound) of MIP in the re-binding buffer containing 20 mM NaCl was 9.8, meanwhile, that of MIP in the re-binding buffer without NaCl was 1.2. A combination of SPR sensing technology with protein-imprinted thin films is a promising tool for the construction of selective protein sensors.     

Optical nanosensor design with uniform pore geometry and large particle morphology

Appropriate design of nanosensors for optically selective, sensitive sensing systems is needed for naked-eye detection of pollutants for environmental cleanup of toxic heavy-metal ions. Mesostructured materials with two- or three-dimensional (2D or 3D) geometries and large particle morphologies show promise as probe carriers, and can therefore be used to reproducibly fabricate uniformly packed nanosensors. This is the first report on the effects of significant key properties of the mesostructured carriers, such as morphology, geometry, and pore shape, on the functionality of optical nanosensor designs. Such mesostructured sensors with superior physical characteristics can be used as components in sensing systems with excellent stability and sensitivity, and with rapid detection response. The nanosensor design can enhance the selectivity even at low concentrations of the pollutant target ions (nanomolar level). Among the nanosensors developed here, the large pore-surface grains of highly ordered 3D monoliths (HOM) exhibited a high adsorption capability of the Pyrogallol Red probe and high accessibility to analyte ion transport, leading to possible naked-eye detection of Sb(III) ions at concentrations as low as 10(-9) mol dm(-3) and at a wide detection range of 0.5 ppb to 3 ppm. A key finding in our study was that our mesostructured nanosensor designs retained highly efficient sensitivity without a significant increase in kinetic hindrance, despite the slight decrease of the specific activity of the electron acceptor/donor strength of the probe functional group after several regeneration/reuse cycles. The results, in general, indicate that large-scale reversibility of optical nanosensors is feasible in such metal-ion sensing systems.     

Geochemical association of137Cs and239,240Pu in the oligotrophic and mesotrophic lake sediments

Geochemical association of¹³⁷Cs and^239,240Pu in the surface sediments from two oligotrophic and mesotrophic lakes in Japan was studied by sequential chemical extractions. The fractions separated were exchangeable and bound to carbonate, bound to oxides, bound to organic mattersulfides, and residual. The¹³⁷Cs and^239,240Pu were mainly associated with the organic matter-sulfides and residual fractions but exhibited the different vertical profiles at both lakes. The differences in association patterns between the lakes may be controlled by transport of these nuclides by organic settling particles to the bottom sediments and decomposition of the organics in the sediments.     

Sokodosides, steroid glycosides with an isopropyl side chain, from the marine sponge Erylus placenta

Two novel steroid glycosides, sokodosides A and B (1 and 2, respectively), were isolated from the marine sponge Erylus placenta as growth-inhibitory principles against several strains of yeast and a cancer cell line. Sokodosides possess the novel carbon skeleton as characterized by the presence of a combination of isopropyl side chain and the 4,4-dimethyl steroid nucleus. Sokodoside B has another unique characteristic in the presence of delta(8,14,16) unsaturation. The structures of sokodosides were determined by analysis of spectral data and chemical degradation. The absolute stereochemistry of sokodoside A (1) was determined by the application of the modified Mosher analysis to the aglycon obtained by acid hydrolysis, whereas the absolute stereochemistry of the monosaccharide units in 1 and 2 was determined by chiral GC analyses of the acid hydrolysates.     

Bismuth-catalyzed intermolecular hydroamination of 1,3-dienes with carbamates, sulfonamides, and carboxamides

A Bi(OTf)(3)/Cu(CH(3)CN)(4)PF(6) system efficiently promoted intermolecular 1:1 hydroamination of 1,3-dienes with various carbamates, sulfonamides, and carboxamides to afford allylic amines in good yield (up to 96%). Reaction proceeded with 0.5-10 mol % catalyst loading at 25-100 degrees C (generally at 50 degrees C) in 1,4-dioxane within 24 h. The Bi(OTf)(3)/Cu(CH(3)CN)(4)PF(6) system constitutes a new entry into series of intermolecular hydroamination catalysis. Mechanistic studies and the postulated reaction mechanism are also discussed.     

Novel intercluster compound between a heptakis{triphenylphosphinegold(i)}dioxonium cation and an α-Keggin polyoxometalate anion

A novel intercluster compound, [{{Au(PPh(3))}(4)(μ(4)-O)}{{Au(PPh(3))}(3)(μ(3)-O)}][α-PW(12)O(40)]·EtOH (1) constructed between a heptakis{triphenylphosphinegold(i)}dioxonium cation and an α-Keggin polyoxometalate (POM) is synthesized and unequivocally characterized by elemental analysis, TG/DTA, FTIR, X-ray crystallography, solid-state CPMAS (31)P NMR and solution ((1)H, (31)P{(1)H}) NMR. The heptagold(i) cluster was formed during the course of carboxylate elimination of a monomeric phosphinegold(i) carboxylate precursor, i.e., [Au((RS)-pyrrld)(PPh(3))] ((RS)-Hpyrrld = (RS)-2-pyrrolidone-5-carboxylic acid), in the presence of the sodium salt of an α-Keggin POM, Na(3)[α-PW(12)O(40)]·9H(2)O. Compound 1 was formed by ionic interaction between the heptagold(i) cluster cation and the α-Keggin POM anion. The heptagold(i) cluster unit was formed by four inter-cationic aurophilic interactions between the tetragold(i) cluster unit and trigold(i) cluster unit. The tetragold(i) cluster unit and trigold(i) cluster unit contained μ(4)-O and μ(3)-O atoms, respectively.