Synthesis and characterization of carbon-bridged bis(phenolate) lanthanum alkoxides and their catalytic behavior for the polymerization of L-lactide

Four lanthanum alkoxides stabilized by a carbon-bridged bis(phenolate) ligand were synthesized and their catalytic behavior for the ring-opening polymerization of L-lactide was explored. Reactions of [(MBMP)LaCp(THF) 2 ] (MBMP 2 = 2,2′-methylene-bis(6-tert-butyl-4-methyl phenoxo)) with HOCH 2 Ph, HOCH 2 CF 3 , HOCH(CH 3 ) 2 , and HOCH 2 CH 2 N(CH 3 ) 2 , respectively, in a 1:1 molar ratio in THF gave the dimeric lanthanum alkoxo complexes [(MBMP)Ln(μ-OR)(THF) 2 ] 2 (OR = OCH 2 Ph(1), OCH 2 CF 3 (2), OCH(CH 3 ) 2 (3), OCH 2 CH 2 N(CH 3 ) 2 (4)]. These complexes were well characterized, and the definitive molecular structure of complex 1 was determined. It was found that complexes 1 to 4 are efficient initiators for the ring-opening polymerization of L-lactide. The structure of the alkoxo groups has a significant effect on the catalytic behavior, and complex 2 can initiate L-lactide polymerization in a controlled manner.     

Improved dehydriding property of polyvinylpyrrolidone coated Mg-Ni hydrogen storage nano-composite prepared by hydriding combustion synthesis and wet mechanical milling

In this work, polyvinylpyrrolidone(PVP) coated Mg_(95)Ni_5 nano-composites were prepared by hydriding combustion synthesis(HCS) plus wet mechanical milling(WM) with tetrahydrofuran(THF) and donated as WM-x wt% PVP(x = 1, 3, 5 and 7) respectively. The phase compositions, microstructures and dehydriding property, as well as the co-effect of PVP and THF were investigated in detail. XRD results showed that the average crystal size of MgH_2 in the milled Mg_(95)Ni_5 decreased from 23 nm without PVP to 18 nm with 1 wt% PVP. The peak temperature of dehydrogenation of MgH_2 in the milled Mg_(95)Ni_5 decreased from 293.0 ℃ without THF to 250.4 ℃ with THF. The apparent activation energy for decomposition of MgH_2 in WM-7 wt% PVP was estimated to be 66.94 kJ/mol, which is 37.70 kJ/mol lower than that of milled Mg_(95)Ni_5 without THF and PVP. PVP and THF can facilitate the refinement of particle size during mechanical milling process. Attributed to small particle sizes and synergistic effect of PVP and THF, the composites exhibit markedly improved dehydriding properties.     

High Oil-absorptive Composites Prepared from Non-woven Fiber and Sponges with 4-tert- butylstyrene-EPDM-divinylbenzene Graft Polymer

4-tert-butylstyrene-EPDM-divinylbenzene graft terpolym-er (PBED) was prepared by graft cross-polymerization in toluene using BPO as an initiator. The gel-PBED and sol-PBED were isolated from extraction of tetrahydrofuran (THF), and then they were identified by IR spectr-oscopy. The maximum oil-absorptivity of gel-PBED produced from the optimum reaction conditions was 8420% but its swelling rate was very low. The highest oil-absorptivity of photocrosslinked sol-PBED film was 5 800%. Although its oil absorbency was not as high as gel-PBED' s, swelling rate was higher than that of gel-PBED and was suitable for commercial purpose. After swelling in oil, neither gel-PBED nor photocrosslinked sol-PBED film having high oil-absorptivity had sufficient mechanical strength to be taken out of oil wholly. As is known, composite technique is one of the useful methods for reinforcing them. Fibers, sponges and non-woven cloths were used as reinforcers or supporters in this work. Oil-absorptivities and swelling kinetics     

New Palladium-Imidazole and Imidazoline Complexes:Structures and Reactivity in Coupling Reaction

1 Results We have recently reported the Mizoroki-Heck reaction catalyzed by PdCl2 and imidazole ligands[1]. During the course of our study of palladium imidazole complex,we disclosed the synthesis of trans-Pd(Ln)2Cl2 by the reaction of PdCl2 with Ln (where L1=2-phenylimidazole,L2=2-phenylimidazole) in a 1∶2 molar ratio.The single crystals of trans-Pd(L1)2Cl2·2DMF (1a) and trans-Pd(L2)2Cl2 (2a) were obtained by following slow evaporation of DMF as a solvent. The single crystal of trans-Pd(L2)2Cl2 (2b) was obtained by slow diffusion of toluene into the DMF solution of complexes,Pd(L1)2Cl2 (1b) was obtained in powder by this way. The compositions of isolated complexes have been determined by elemental analyses. The molecular structures of complex 1a,2a and 2b have been characterized by single crystal X-ray analysis (Fig.1). To compare their catalytic efficiency,the coupling reactions between 4-bromotoluene and tere-butylacrylate using isolated complexes were carried out. In the present of 0.1 mol% palladium complex 1a and 1b,the coupling product were obtained with a yield of 96% after 24 hours and 97% after 12 hours,respectively. The behaviors of obtained complexes in solution based on 1H NMR analysis will be also discussed in the symposium.     

Synthesis and characterization of N-aryloxo-functiona- lized β-ketoiminate rare-earth complexes and their catalytic activity for the polymerization of ε-caprolactone

The synthesis and characterization of dimeric rare-earth amides stabilized by a dianionic N-aryloxo functionalized ,8-ketoiminate ligand are described. Reactions of 4-（2-hydroxy-5-methyl-phenyl） imino-2-pentanone （LH2） with Ln[N（SiMe3）2]3（μ-Cl）Li（THF）3 in a 1：1 molar ratio in THF gave the dimeric rare-earth amido complexes [LLn{N（SiMe3）2}（THF）]2 [Ln = Nd （1）, Sm （2）, Yb （3）, Y （4）]. These complexes were well characterized, and the definitive molecular structures of complexes 3 and 4 were determined. It was found that complexes 1-4 can initiate the ring-opening polymerization of ε-caprolactone, and the ionic radii of the central metals have significant effect on the catalytic activity.     

Preparation and Structural Analysis of Lanthanide Complexes with α-Hydroxyl-phenyl-acetic Acid and 1, 10-Phenanthroline as Ligands

A series of ternary lanthanide complexes Ln （C6H5CHOHCOO）3（phen） （H2O） （Ln= La, Ce, Pr, Nd, Sm, Eu） were synthesized with α-hydroxyl-phenyl-acetic acid and 1, 10-phenanthroline （phen） as ligands. The sturcture and property of complexes were characterized by elemental analysis, IR, 1^H-NMR, UV and TGA, and the coordinate mede of both ligands was discussed. It was shown that the co-ordinate mode of 1, 10-phenanthroline was chelated, while α-hydraxyl-phenyl-acetate ion was monedentate or bridging. The mechanism of thermal determinde by thermogravimetry was indicated that the degree of co-ordinate ability of ligand was： α-hydroxyl-phenyl-acetate ion 〉 1, 10- phenanthroline（phen）.     

Degradation of the antibiotic sulfamonomethoxine sodium in aqueous solution by photo-Fenton oxidation

In this study, photo-Fenton oxidation was applied to degradation of sulfamonomethoxine sodium (SMMS) in aqueous solution. The operation parameters of pH, temperature, and concentrations of H2O2, Fe2+ and SMMS were investigated. The optimum conditions for the photo-Fenton process were determined as follows: [SMMS]=4.53 mg/L, pH 4.0, [H2O2]=0.49 mmol/L, [Fe2+]= 19.51 μmol/L and T=25°C. Under these conditions 98.5% of the SMMS degraded. The kinetics were also studied, and degradation of SMMS by the photo-Fenton process could be described by first-order kinetics. The apparent activation energy was calculated as 23.95 kJ/mol. Mineralization of the process was investigated by measuring the chemical oxygen demand (COD), and the COD decreased by 99% after 120 min. This process could be used as a pretreatment method for wastewater containing sulfamonomethoxine sodium.     

Electrochemical reversibility of magnesium deposition-dissolution on aluminum substrates in Grignard reagent/THF solutions

The electrochemical behavior of magnesium deposition-dissolution on scratched aluminum foils in Grignard reagent/tetrahydrofuran (THF) solutions (1 mol L-1 EtMgBr/THF), which is regarded as a potential electrolyte of rechargeable magnesium batteries, was studied by using various methods such as cyclic voltammetry (CV), scanning electron microscopy (SEM), X-ray diffraction (XRD) and charge-discharge (deposition-dissolution) tests. The results present that the obtained magnesium deposits do not exhibit the morphology of dendrite and the Mg-Al alloy is not found on the surface of aluminum foils. The magnesium deposited on the aluminum substrates have excellent electrochemical cyclic performance in 1 mol L-1 EtMgBr/THF solution. The aluminum can be used as a candidate material of the negative current collector for rechargeable magnesium batteries.     

Colorimetric detection of glucose and an assay for acetylcholinesterase with amine-terminated polydiacetylene vesicles

The colorimetric response of amine-terminated polydiacetylene (PDA) vesicles was initially demonstrated by varying the pH of the solution. Convenient colorimetric methods to detect glucose and acetylcholinesterase (AChE) activity were successfully established using amine-terminated PDA vesicles by taking advantage of the following features: (1) the amine-terminated PDA vesicles undergo a colorimetric transition as the pH of the solution changes; (2) glucose can be oxidized to gluconic acid in the presence of glucose oxidase; and (3) AChE catalyzes the hydrolysis of acetylcholine to acetic acid. The visual detection of glucose levels and AChE activity showed good selectivity and acceptable sensitivity. The detection limit of glucose was ~2.5 μmol/L and the level of AChE activity was assayed as low as 10.0 mU/mL. Moreover, the amine-terminated PDA vesicles can be used for screening the activity of inhibitors against AChE.     

Specific structural features of LnZrOx (Ln: La, Sm) mixed oxides prepared by different methods

LnZrOx(Ln: La, Sm) mixed oxides of Ln: Zr = 1 were prepared by different methods(complex polymerized method, sorption of cations on starch from aqueous salt solution and conventional co-precipitation with additional redispersion of precipitate by ultra sound) and calcined at 700–1300 °C. Their specific structural features and changes were studied and discussed. Various characterization methods were used such as X-ray diffraction,Electron microscopy, Fourier-transform infrared and Raman spectroscopy, UV–Vis spectroscopy, X-Ray absorption fine structure and X-ray photoelectron spectroscopy.The formation of pyrochlore structure occurred at 1100–1300 °C from fluorite-like pseudocubic phase ZrO_2 regardless the method of preparation. This phase had a block-like structure consisting of ZrO_2 nanocrystals stabilized by Ln cations and residual anions such as hydroxyls and carbonates. The desorption of such anions with heating already started at 900 °C and lead to local changes of Zr cations coordination to octahedral and to the formation of pyrochlore nanodomains inclusions within fluorite-like phase. The increased cation mobility and further elimination of anions caused by further heating was accompanied by the formation of bulk pyrochlore phase at 1100–1300 °C. Even after calcination at 1300 °C the local microheterogeneity as well as defects were identified at domains boundaries or sintered microstructure. These specific features of the formed pyrochlores depend on the method of preparation.     

Enolate chelating N-heterocyclic carbene complexes of Fe(II): Synthesis, structure and their catalytic activity for ring-opening polymerization of ε-caprolactone

The reaction of anhydrous FeBr2 with two equivalents of anionic N-heterocyclic carbene (NaL1 and NaL2), which are generated in situ by the reaction of the corresponding salt [4-R-C6H4COCH2{CH- (NCHCHNiPr)}Br] (R = OCH3, H2L1Br, 1; R = F, H2L2Br, 2) with two equivalents of NaN(SiMe3)2, affords bis-ligand Fe(II) complexes of L12Fe (3) and L22Fe (4) in high yield, respectively. Attempt to synthesize mono-ligand Fe(II) bromide by the 1:1 molar ratio of NaL to FeBr2 is unsuccessful, and the same com- plexes of 3 and 4 were obtained. Both 3 and 4 have been depicted by elemental analysis and X-ray structure determination. Preliminary studies show that both 3 and 4 can be used as single-component catalyst for the ring-opening polymerization of ε-caprolactone, and the catalytic activity of 3 is higher than that of 4.     

Inorganic-organic hybrids constructed of bis（undecatungstogerma- nate）lanthanates polyoxoanions and oxalate-bridged dinuclear copper complexes and their magnetic properties

A series of inorganic-organic hybrids K₂Na _m H_9−m [{Ln(GeW₁₁O₃₉)₂}{Cu₂(bpy)₂(μ-ox)}]·nH₂O (bpy = 2,2-bipyridine and ox = oxalate; Ln = La, Nd, Sm, Eu, Gd; n = 19, 17, 22, 20, 19; m = 4, 4, 4, 9, 2) were isolated after reacting in a potassium acetate buffer. X-ray structural analyses show that compounds 1–5 are isomorphic and consist of [Ln(GeW₁₁O₃₉)₂]¹³⁻ polyoxoanion building blocks and oxalate-bridged dinuclear copper metalorganic complex with a 1D chain structure. The 1D chain further connects into the 3D framework by π-π interactions with neighboring bpy groups. The magnetic susceptibility data indicate that antiferromagnetic coupling between the neighboring Cu²⁺ ions in the structure and the rare earth ions affects magnetic property of the structure.     

Preparation of (R)- and (S)-2-Allyl-1, 3, 2-dinaphtho (α, β) [d.f] dioxaborepin and their reactions with aldehydes

(R)- and(S)-2-Allyl-1,3,2-dinaphtho (α,β) [d.f] dioxaborepin ((R)-2 and(S)-2) have been first prepared by the reaction of(R)-(+)- or(S)-(−)-1, 1′-bi-2-naphthol and triallylborane in THF at room temperature, respectively.(S)-2 and(R)-2 are sensitive to moisture and oxygen in air and disproportionate easily to triallylborane and 1,1′-bi-2 naphthyl bis (1,1′-bi-2-naphtholborate) at ambient temperature. However, THF is a stabilizer for them. The reactions of(R)-2 or(S)-2 and some aliphetic or aromatic aldehydes in CH₂Cl₂ at −78°C for several hours afforded β-alkylenyl alcohols in up to 84.8%ee. Among them, optically active 1-(3, 5-dichlorophenyl)-3-butenol and 1-(2-methoxyphenyl)-3-butenol were first prepared Foundation item: Supported by the National Natural Science Foundation of China (29972033) Biography: Liu Dejun (1973), male, Ph. D, research direction: asymmetric synthesis     

Preparation and characterization of three-dimensionally ordered macroporous polystyrene <Emphasis Type="Italic">via</Emphasis> atom-transfer radical polymerization

Three-dimensionally ordered macroporous polystyrene （3DOM PS） with pore size of 350 nm was fab- ricated using Cp2Co/Ethyl 2-bromoisobutyrate （EBiB） catalytic system by ATRP. The resulting polymers were detected by FT-IR, 1H-NMR, SEM, and GPC. The microstructure of 3DOM PS was confirmed by FT-IR and 1H-NMR. SEM micrographs show that both silica spheres within the templates and pores in the 3DOM polystyrene are arranged in highly ordered fashion, and the shrinkage of the pores in the 3DOM PS is 24%. GPC curves show that the 3DOM PS possesses slightly lower Mn and narrow MWD compared with bulk one. This result indicats that living polymerization is different from non-living polymerizationin in the confined space.     

A convenient preparation of enantiopure 1,1′-bi-2-naphtholsvia an inclusion complexation in the solid state

Inclusion reaction of racemic 1,1′-bi-2-naphthol and (S)-proline was examined under the solid state and the solid-liquid conditions. The results indicated that a solid mixture of racemic 1,1′-bi-2-naphthol and (S)-proline in a 1∶1 molar ratio was kept at 50–80 °C for 3–4 h, followed by treatment with benzene to give an insoluble solid and a benzene solution, from which (S)-(−)- and (R)-(+)-1,1′-bi-2-naphthols of a modest level of optical purity were obtained. After “kinetic” crystallization, both essentially enantiopure isomers were provided in 15%–35% overall yields, respectively. Foundation item: Supported by the National Natural Science Foundation of China (29972033) and the Key Science Research Foundation of Hubei Province (891P1305) Biography: Shan Zi-xing (1945-), male, Professor, research direction: asymmetric synthesis.     

An evidence for the strong association of <Emphasis Type="Italic">N</Emphasis>-methyl-2-pyrrolidinone with some organic species in three Chinese bituminous coals

Three Chinese bituminous coals collected from Shenfu, Heidaigou and Feicheng coal fields were respectively extracted with carbon-disulfide/N-methyl-2-pyrrolidinone （CS2/NMP） mixed solvent （volume ratio 1：1） at room temperature followed by distillation of CS2 under ambient pressure and subsequent removal of most of NMP by distillation at 110℃ under reduced pressure to afford mixed solvent-extractable fractions （MSEFs） with small amount of NMP. Acetone-extractable fraction 1 （AEF1） was obtained by extracting each MSEF under ultrasonic irradiation at room temperature and subsequently using a Soxhlet extractor. Direct extraction of each bituminous coal affords acetone-soluble fraction 2 （AEF2）. GC/MS analysis shows that m/z of base or secondary peak in mass spectra of a series of components from each AEF1 is 98, whereas such components were not detected in AEF2. Since m/z of base peak in mass spectrum of NMP itself is 99, the base or secondary peak at m/z 98 should result from loss of α-H from NMP, i.e., NMP is strongly associated with some organic species （OSs） and thereby the components detected with base or secodary peak at m/z 98 in their mass spectra should be associated NMP-OS.     

Enhanced hydrosen production by insertional inactivation of adhE gene in Klebsiella oxytoca HP1

Ethanol is the main byproduct of anaerobic H2-producing fermentation in Klebsiella oxytoca HP1. Two moles of NAD（P）H are consumed to yield one mole of ethanol that may decrease bacterial hydrogen production. In this article the adhE gene that codes for acetaldehyde dehydrogenase was disrupted for the first time. A homologous recombination vector pTA-Str was constructed in which the adhE gene was disrupted by inserting an aminoglycoside-3＇-adenyltransferase （aadA） gene. As expected, the vector includes the insertion 5＇-adhE-aadA-adhE-3＇. The amplified DNA fragment 5＇-adhE-aadA-adhE-3＇ from pTA-Str was transformed into K. oxytoca HP1 and one recombinant was obtained. PCR analysis of the resulting genomic DNA indicated the appropriate deletion and insertion. Compared with the H2-production of wild type K. oxytoca HP1, the hydrogen yield of the mutant increased by 16.07% and ethanol concentration decreased by 77.47%, suggesting that inactivation of the adhE gene in K. oxytoca HP1 is a potential method for enhancing bacterial H2-production.     

<Emphasis Type="Italic">Ab initio</Emphasis> study of the effects of Ag/Mn doping on the electronic structure of LiFePO<Subscript>4</Subscript>

Based on density functional theory （DFT） of the first-principle for the cathode materials of lithium ion battery, the electronic structures of Li（Fe1-x）PO4 （Me = Ag/Mn, x = 0-0.40） are calculated by plane wave pseudo-potential method using Cambridge serial total energy package （CASTEP） program. The calculated results show that the Fermi level of mixed atoms Fe1-xAgx moves into its conduction bands （CBs） due to the Ag doping. The Li（Fe1-xAgx）PO4 system displays the periodic direct semiconductor characteristic with the increase of Ag-doped concentration. However, for Fe1-xMnx mixed atoms, the Fermi level is pined at the bottom of conduction bands （CBs）, which is ascribed to the interaction between Mn（3d） electrons and Fe（4s） electrons. The intensity of the partial density of states （PDOS） near the bottom of CBs becomes stronger with the increase of Mn-doped concentration. The Fermi energy of the Li（Fe1-xMnx）PO4 reaches maximum at x = 0.25, which is consistent with the experimental value of x = 0.20. The whole conduction property of Mn-doped LiFePO4 is superior to that of Ag-doped LiFePO4 cathode material, but the structural stability is reverse.