Four‐ and Five‐Coordinate Gallium Complexes Stabilized by Bidentate 2‐(Dimethylaminomethyl)Pyrrole Ligand: Molecular Structures of Ga[NC4H3(CH2NMe2)‐2]3 and GaMe2[NC4H3(CH2NMe2)‐2]

Treatment of GaCl₃ with one equiv of Li[NC₄H₃(CH₂NMe₂)‐2] (n = 1, 2, 3) in diethyl ether at ?78 °C yields GaCl_3‐n[NC₄H₃(CH₂NMe₂)‐2]_n (n = 1, 1 ; n = 2, 2 ; n = 3, 3 ). Compound 1 reacts with two equiv of RLi to afford GaR₂[NC₄H₃(CH₂NMe₂)‐2] ( 4a, R=Me; 4b, R=Bu ) via transmetallation. Reacting 2 with one equiv of RLi in diethyl ether, 3 and 4 are formed via ligand redistribution. Variable temperature ¹H NMR spectroscopic experiments reveal that the five‐coordinate gallium compound 3 is fluxional and results in a coalescence temperature at 5 °C, at which ΔG^≠ is calculated at ca. 10.4 Kcal/mole. All the new compounds have been characterized by ¹H and ¹³C NMR spectroscopy and the structures of compounds 3 and 4a have also been determined by X‐ray crystallography.     

Three New Triterpenoids from Lycopodium japonicum Thunb

Three new triterpenoids, (3β,8β,14α,21α)‐26,27‐dinoronocerane‐3,8,14,21‐tetrol ( 1 ), (3β,8β,14α,21β)‐26,27‐dinoronocerane‐3,8,14,21‐tetrol ( 2 ), and lycopodiin A ( 3 ), together with four known compounds, lycoclavanol ( 4 ), lycoclaninol ( 5 ), α‐onocerin ( 6 ), and 3‐epilycoclavanol ( 7 ), were isolated from Lycopodium japonicum Thunb (Lycopodiaceae). Their structures were established by means of spectroscopic analyses. Compounds 3 and 7 showed moderate antitumor activity. Compounds 4 and 6 exhibited acetylcholinesterase inhibition activity.     

New Dammarane Monodesmosides from the Acidic Deglycosylation of Notoginseng‐Leaf Saponins

Three new dammarane monodesmosides, named notoginsenosides Ft₁ ( 1 ), Ft₂ ( 2 ), and Ft₃ ( 3 ), together with three known ginsenosides, were obtained from a mild acidic hydrolysis of the saponins from notoginseng (Panax notoginseng (Burk .) F. H. Chen ) leaves. Their structures were elucidated to be (3β,12β,20R)‐12,20‐dihydroxydammar‐24‐en‐3‐yl O‐β‐D ‐xylopyranosyl‐(1 → 2)‐O‐β‐D ‐glucopyranosyl‐(1 → 2)‐β‐D ‐glucopyranoside ( 1 ), (3β,12β)‐12,20,25‐trihydroxydammaran‐3‐yl O‐β‐D ‐xylopyranosyl‐(1 → 2)‐O‐β‐D ‐glucopyranosyl‐(1 → 2)‐β‐D ‐glucopyranoside ( 2 ), and (3β,12β,24ξ)‐12,20,24‐trihydroxydammar‐25‐en‐3‐yl O‐β‐D ‐xylopyranosyl‐(1 → 2)‐O‐β‐D ‐glucopyranosyl‐(1 → 2)‐β‐D ‐glucopyranoside ( 3 ), by means of spectroscopic evidences. The known ginsenosides Rh₂ and Rg₃ 4 – 6 were obtained as the major products from this acidic deglycosylation.     

Phenolic compounds from the aerial parts of Clematis viticella L. and their in vitro anti-inflammatory activities*

Phytochemical investigations on the EtOH extract of Clematis viticella led to the isolation of six flavonoid glycosides, isoorientin (1), isoorientin 3′-O-methyl ether (2), quercetin 7-O-α-L-rhamnopyranoside (3), quercetin 3,7-di-O-α-L-rhamnopyranoside (4), manghaslin (5) and chrysoeriol 7-O-β-D-glucopyranoside (6), one phenylethanol derivative, hydroxytyrosol (7), along with three phenolic acids, caffeic acid (8), (E)-p-coumaric acid (9) and p-hydroxybenzoic acid (10). The structures of the isolates were elucidated on the basis of NMR and HR-MS data. All compounds were isolated from C. viticella for the first time. Compounds 7 and 8 showed significant anti-inflammatory activity at 100 μM by reducing the release of NO in LPS-stimulated macrophages comparable to positive control indomethacin. Compounds 3 and 7 exhibited anti-inflammatory activity through lowering the levels of TNF-α while 1, 3 and 5 decreased the levels of neopterin better than the positive controls.     

Promotion of Ionic Liquid to Dimethyl Carbonate Synthesis from Methanol and Carbcn Dioxide

Promotion of ionic liquid, 1-ethyl-3-methylimidazolium bromide (emimBr), to the synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide in the presence of potassium carbonate and less amount of methyl iodide under mild conditions was investigated. The results showed that the high selectivity and raised yield of DMC was achieved due to the addition of emimBr in the reaction system. And effect of several reaction conditions such as temperature, pressure and amount of emimBr was discussed.     

Enhanced thermal properties and flame retardancy from a thermosetting blend of a phosphorus‐containing bismaleimide and epoxy resins

Epoxy resins modified by an organosoluble phosphorus‐containing bismaleimide (3,3′‐bis(maleimidophenyl) ­phenylphosphine oxide; BMPPPO) were prepared by simultaneously curing epoxy/diaminodiphenylmethane (DDM), and BMPPPO. The resulted epoxy resins were found to exhibit glass transition temperatures as high as 212 °C, thermal stability at temperatures over 350 °C, and excellent flame retardancy with Limited oxygen index (LOI) values around 40. Incorporation of BMPPPO into epoxy resins via the thermosetting blend was demonstrated to be an effective way to enhance the thermal properties and flame retardancy simultaneously. Copyright © 2003 John Wiley & Sons, Ltd.     

Tricarbonyl Complexes of Rhenium(I) with Acetylpyridine Benzoylhydrazone and Related Ligands

Novel rhenium(I) tricarbonyl complexes have been prepared by reactions of (Et₄N)₂[Re(CO)₃Br₃] with acetylpyridine benzoylhydrazone, Hapbhyd, di(2‐pyridyl)ketone benzoylhydrazone, Hpy₂bhyd, bis(2‐pyridine)ketone, py₂CO, and pyridinealdehyde terephtalaldehydebishydrazone, pytehyd. The ligands remain protonated when no supporting base is added and the following complexes have been isolated: [Re(CO)₃Br(Hapbhyd)], [Re(CO)₃Br(Hpy₂bhyd‐py, hyd)], [Re(CO)₃Br(Hpy₂bhyd‐py¹, py²)], [Re(CO)₃Br(py₂CO‐N, N)] and [Re(CO)₃Br(pytehyd)]. Addition of triethyl amine results in deprotonation of Hapbhyd and the formation of [Re(CO)₃(OH₂)(apbhyd)], whereas Hpy₂bhyd is hydrolysed and a rhenium complex with the monoanionic bis(2‐pyridyl)hydroxymethanolato ligand, {py₂C(OH)O}^‐, is formed. The same compound, [Re(CO)₃{py₂C(OH)O}], is obtained when triethyl amine and water are added to a mixture of (Et₄N)₂[Re(CO)₃Br₃] and py₂CO. The air‐stable products have been studied by spectroscopic methods and X‐ray crystallography.     

Immobilization of single-stranded deoxyribonucleic acid on gold electrode with self-assembled aminoethanethiol monolayer for DNA electrochemical sensor applications

A synthesized 24-mer single-stranded deoxyribonucleic acid (ssDNA) was covalently immobilized onto a self-assembled aminoethanethiol monolayer modified gold electrode, using water-soluble 1-ethyl-3(3-dimethylaminopropyl)-carbodiimide (EDC). The covalently immobilized ssDNAs were hybridized with complementary ssDNA (cDNA) or yAL(3) gene in solution, forming double-stranded DNAs (dsDNA). Meanwhile, daunomycin as an electrochemical active intercalator in the hybridization buffer solution was intercalated into the dsDNA to form a dsDNA/daunomycin system on the gold electrode surface, which was used for DNA electrochemical sensor. The cathodic waves of daunomycin bound to the double-stranded DNA (dsDNA) by linear sweep voltammetry were utilized to detect the cDNA. The cathodic peak current (i(pc)) of duanomycin was linearly related to the concentrations of cDNA between 0.1 mug ml(-1) and 0.1 ng ml(-1). The detection limit was about 30 pg ml(-1).     

Silicon Carbide Supported Palladium‐Iridium Bimetallic Catalysts for Efficient Selective Hydrogenation of Cinnamaldehyde

Selective hydrogenation of α,β‐unsaturated carbonyls into saturated carbonyls is important to obtain remunerative products. However, it is still a challenge to achieve high activity and selectivity under mild conditions. Herein, Pd, Ir and bimetallic Pd‐Ir nanoparticles were uniformly deposited with high dispersity on the surface of SiC by a facile impregnation method, respectively. The as‐prepared Pd/SiC catalysts efficiently hydrogenate cinnamaldehyde to hydrocinnamaldehyde at room temperature and atmospheric pressure, and the activity of Pd/SiC is observed further enhanced by adding Ir component (conversion of 100%). In addition, the dependence of Pd‐Ir catalyst activity on Pd/Ir molar ratio confirms a synergistic effect between Ir and Pd, which originates from the electron transfer between Pd and Ir.     

Blends of starch with ethylene vinyl alcohol copolymers: effect of water,glycerol, and amino acids as plasticizers

Blends of thermoplastic starch with poly(ethylene‐co‐vinyl alcohol) copolymer (EVOH) were melt extruded with water/glycerol as plasticizer and a series of amino acid additives. The biggest factor in end‐use mechanical properties proved to be the relative humidity (RH) during storage. Plasticized starch‐EVOH blends stored at 0 and 50% RH changed significantly over time, with, for example, the tensile strength (TS) of the glycerol‐plasticized blend increasing from 4.7 to 26.3 MPa over 8 weeks when maintained at 0% RH. In contrast, the TS of this same sample stored at 75% RH remained unchanged for 8 weeks. Amino acids provided relatively minor, but significant changes in mechanical properties with time. Based on TS, elongation‐to‐break, and modulus, it may be concluded that β‐alanine, sarcosine, and L ‐proline were more effective than glycerol at maintaining strong flexible blends. Increases in crystallinity and changes in morphology with time, as described by modulated DSC were correlated to these changes in mechanical properties. Published in 2007 by John Wiley & Sons, Ltd.