Local environment and dynamics of PO4 tetrahedra in Na-Al-PO3 glasses and melts

Glasses and melts in the system (NaPO3)(1-x)(Al(PO3)3)x were studied with the aim of obtaining information about the structure on the next larger scale beyond the PO4 group. Magic angle spinning NMR was applied to the pure NaPO3 glass and Raman scattering to systems with x = 0.00, 0.03, 0.06, 0.15, and 0.60 in the temperature range T = 300-1100 K. Comparison of the 31P chemical shift between glass and crystalline forms revealed that polymerization of the metaphosphate into tricyclophosphatelike (PO3)3(3-) rings is the dominant structure, ca. 80%, formed by the twofold vertex-joined PO4 groups in the glass. In the Raman study we focused on the prominent polarized band at ca. 1170 cm(-1) which is due to the symmetric breathing mode of the tetrahedral PO4 group. This band was decomposed into a few Gaussian lines. These component lines could be identified using the NMR results: two narrow components are due to PO4 groups in the tricyclophosphatelike rings, which have either a Na or an Al counterion and a third broad component is due to chain-polymerized (PO3(-))n. The variations of the component lines (peak positions, widths, and intensities) with respect to x and T are presented. We derive the shifts of the symmetric breathing mode frequency which are caused by Na or Al counterions, by ring closure, by x > 0, etc. The relative intensities of the narrow and broad components in the 1170-cm(-1) band of the Raman spectra are discussed. The amount of ring-to-chain transformation on addition of Al3+, and as functions of T and x, is derived. Indications for ordering on a next larger scale, derivable from Raman, NMR, and thermodynamics, are compared.     

Gas-phase tautomeric equilibrium of 4-hydroxypyrimidine with its ketonic forms: a free jet millimeterwave spectroscopy study

4-Hydroxypyrimidine (4HP) has two conformational forms (the hydroxyl hydrogen cis or trans with respect to the adjacent nitrogen), which are in tautomeric equilibrium with two ketonic forms, 4-pyrimidinone (4PO) and 6-pyrimidinone (6PO). We have investigated the free jet absorption millimeterwave spectrum of this system, assigning the rotational spectra of 4HPcis and 4PO; the latter species is more stable by 2.0(9) kJ/mol. No lines corresponding to the trans isomer of 4-hydroxypyridine and to 6PO have been observed.     

Characterization of active phosphorus surface sites at synthetic carbonate-free fluorapatite using single-pulse 1H, 31P, and 31P CP MAS NMR

The chemically active phosphorus surface sites defined as PO(x), PO(x)H, and PO(x)H2, where x = 1, 2, or 3, and the bulk phosphorus groups of PO4(3-) at synthetic carbonate-free fluorapatite (Ca5(PO4)3F) have been studied by means of single-pulse 1H,31P, and 31P CP MAS NMR. The changes in composition and relative amounts of each surface species are evaluated as a function of pH. By combining spectra from single-pulse 1H and 31P MAS NMR and data from 31P CP MAS NMR experiments at varying contact times in the range 0.2-3.0 ms, it has been possible to distinguish between resonance lines in the NMR spectra originating from active surface sites and bulk phosphorus groups and also to assign the peaks in the NMR spectra to the specific phosphorus species. In the 31P CP MAS NMR experiments, the spinning frequency was set to 4.2 kHz; in the single-pulse 1H MAS NMR experiments, the spinning frequency was 10 kHz. The 31P CP MAS NMR spectrum of fluorapatite at pH 5.9 showed one dominating resonance line at 2.9 ppm assigned to originate from PO4(3-) groups and two weaker shoulder peaks at 5.4 and 0.8 ppm which were assigned to the unprotonated PO(x) (PO, PO2-, and PO3(2-)) and protonated PO(x)H (PO2H and PO3H-) surface sites. At pH 12.7, the intensity of the peak representing unprotonated PO(x) surface sites has increased 1.7% relative to the bulk peak, while the intensity of the peaks of the protonated species PO(x)H have decreased 1.4% relative to the bulk peak. At pH 3.5, a resonance peak at -4.5 ppm has appeared in the 31P CP MAS NMR spectrum assigned to the surface species PO(x)H2 (PO3H2). The results from the 1H MAS and 31P CP MAS NMR measurements indicated that H+, OH-, and physisorbed H2O at the surface were released during the drying process at 200 degrees C.     

Metallocene based polyolefin: a potential candidate for the replacement of flexible poly (vinyl chloride) in the medical field

A comparative assessment of the performance properties of metallocene polyolefin (m‐PO) with those of plasticized poly (vinyl chloride) (pPVC) and ethylene vinyl acetate (EVA) copolymer having 18% vinyl acetate content (EVA‐18), the two common polymers used for flexible medical products, is carried out. The preliminary evaluation of the processability, mechanical properties, and thermal stability of the new material, m‐PO is described. The processability parameters like mixing torque and melt viscosity of m‐PO are found to be comparable with those of pPVC and EVA‐18. Mechanical properties such as tensile strength, elongation at break, and tear strength (TS) of m‐PO are much higher than that of pPVC and EVA‐18. Thermo gravimetric analysis (TGA) indicates that the thermal degradation of m‐PO takes place only at temperatures above 340°C and can be processed at 170°C without much damage. Oxygen and carbon dioxide permeabilities of m‐PO at three different temperatures (10, 25, and 40°C) are evaluated and compared with those of pPVC and EVA‐18. It could be seen that the permeabilities of both the gases for m‐PO at three temperatures were lower than those of pPVC and EVA. Biological evaluation of m‐PO is carried out by assessing its cytotoxicity, hemolytic property, and blood clotting initiation. The cytotoxicity studies indicate that m‐PO is non‐toxic to the monolayer of L929 mammalian fibroblast cell lines on direct contact or the exposure of its extract. Non‐hemolytic property of m‐PO by direct contact as well as test on extract is revealed both in static and in dynamic conditions. Blood clotting time experiments indicate that the initiation of blood clotting due to m‐PO is faster than that of pPVC and EVA‐18. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis, Structure Characterization and Biological Activity of a Novel Polyoxovanadate Cluster: [NH3(CH2)2NH2(CH2)2NH3]4·[VⅤ6VⅣ12O42(PO4)](PO4)·2H2O

A new polyoxovanadate cluster,[NH3(CH2)2NH2(CH2)2NH3]4[VⅤ6VⅣ12O42(PO4)](PO4)·2H2O, has been synthesized and characterized by means of elemental analysis, IR spectrometry, EPR spectrometry, TG analysis and single crystal X-ray diffraction. This compound crystallizes in a monoclinic space group C2/c with a=2.3912(5) nm, b=1.3002(3) nm, c=2.0172(4) nm, β=105.75(3)°, V=6.036(2) nm3, Z=2, R1=0.0572, wR2=0.1476. It has a superKeggin structure with a Keggin unit capped by six [VO5] moieties on the pits on every side of the Keggin unit. The anti-tumor activity of the compound was estimated in three human tumor cell lines in vitro.     

Thermal,mechanical and water barrier properties of graphene oxide/polyvinyl alcohol/polyol composite films

The novel polymer composite of polyvinyl alcohol (PVA), polyol(PO) and graphene oxide (GO) was used to prepare the PVA/PO and GO/PVA/PO with different weight percents of GO (0.5 and 1% denoted as (0.5 wt%)GO/PVA/PO and (1 wt%)GO/PVA/PO, respectively) through solution casting blend technique. The structure–properties of all used films were confirmed by scanning electron microscope (SEM), Transmission Electron Microscope (TEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and mechanical properties. The SEM results exhibited the uniform and homogeneous dispersion of GO in the PVA/PO blend matrix. The TEM and XRD analysis confirmed the structure and exfoliation of GO nanosheets, respectively. Thermal stability suggested that (0.5 wt%)GO/PVA/PO and (1 wt%) GO/PVA/PO films are more stable than PVA/PO. The tensile strength of (0.5 wt%)GO/PVA/PO and (1 wt%)GO/PVA/PO films reached 270.5% and 1349.6%, respectively, which are higher than that of the PVA/PO film. The decrease in the water absorption (WA) of GO/PVA/PO was found from 110.5 to 38.4%. The physico-mechanical properties of used films suggested that the prepared GO/PVA/PO blend composite films can be applied in food packaging areas.     

Z-机制磷酸银/钨酸铋复合物的构建及其可见光催化降解有机污染物(英文)

环境危害不仅对人类健康构成巨大威胁,而且也阻碍了经济社会的快速发展.光催化剂通过利用太阳能来降解污染物为环境问题提供一条理想的途径.光催化剂的制备应该考虑以下几点:(1)对可见光响应;(2)高量子效率和稳定性;(3)安全、廉价、无毒的原材料.早期的一些催化剂如二氧化钛、氧化锌、硫化锌、锗酸锌和磷酸铋等在紫外线照射下表现出优秀的光催化活性.但是紫外光是稀有的,而且对人体健康有害.近年来,对宽带隙半导体的改性如掺杂、贵金属沉积、构建异质结或固溶体催化剂取得了有效进展.遗憾的是,受限于材料的固有属性,有限的改进仍然不能满足实际应用的需求.因此,探索高效稳定的可见光驱动的光催化剂依然是十分有意义的.磷酸银在可见光下表现出超强的光催化降解有机污染物和产氧的能力,但是磷酸银容易受到光腐蚀,光催化活性和稳定性很难维持.另外,磷酸银导带上的电子电势较正,这将导致其很难在光催化过程中被利用.而磷酸银导带上电子的积累会抑制其内部电子空穴对的分离,从而对磷酸银的光催化活性和稳定性造成不利影响.本文选择钨酸铋纳米片与磷酸银复合去抑制电子空穴对的复合和进一步提高磷酸银的活性和稳定性.样品的粉末X射线衍射、能谱和X光电子能谱的分析证实了磷酸银/钨酸铋复合物已经被成功合成.稳态荧光光谱证实了磷酸银/钨酸铋复合物的构建可以作为一种有效抑制电子和空穴对复合的手段.通过对样品进行光催化降解次甲基蓝的实验,我们发现磷酸银/钨酸铋复合材料展现出比磷酸银和钨酸铋更强的光催化活性.其中,磷酸银/钨酸铋光催化降解次甲基蓝的速率为0.61385 min~(-1),这是磷酸银(0.47179 min~(-1))和钨酸铋(0.10270 min~(-1))活性的1.3和6.0倍.同时,磷酸银/钨酸铋表现出耐久的稳定性,在连续五次光降解过程中几乎没有明显的活性损失.进一步通过对磷酸银/钨酸铋复合材料进行光催化活性成分的捕获实验,我们发现空穴、超氧负离子自由基和羟基自由基都发挥了一定的作用.最后,我们讨论了光催化机制,Z-机制光催化机制被认为是合理的.     

二氧化硅负载型磷酸及磷酸二氢钠初始反应：试验和理论研究

利用XRD、TG、DRIFTS、^31 PMASNMR和密度泛函理论研究了浸渍法制各的硅胶负载型磷酸和磷酸二氢钠催化剂,阐明了催化剂制备过程中生成的初始缩合产物和其反应机理．光谱试验结果显示,存二氧化硅负载的磷酸上,除了聚磷酸外,还有硅磷酸盐的存在;在二氧化硅负载的磷酸二氢钠上,仅发现聚磷酸钠存在．密度泛函模拟结果也证明,磷酸与二氧化硅表面硅羟基之间的反应在缩合反应的初始阶段比其自身的二聚反应更为有利．但是在硅胶负载的磷酸二氢钠上,磷酸二氢钠的二聚和三聚是缩合反应初始阶段的主要反应．     

Mixed block copolymer aggregates with tunable temperature behavior

A block copolymer of propylene oxide (PO) and ethoxyethyl glycidyl ether (EEGE), (PO)(2)(EEGE)(6)(PO)(2), that has been found to possess lower critical solution temperature properties in water in the temperature range below 20 degrees C was mixed at 1:0.1, 1:1, and 1:10 weight ratios with commercially available Pluronic (L64 or P85) block copolymers. The cooperative association of the copolymers in aqueous solution was studied by dynamic light scattering over a wide temperature range (5-60 degrees C). At lower temperatures, the systems containing either L64 or P85 behave similarly irrespective of the composition: three species corresponding to (PO)(2)(EEGE)(6)(PO)(2) unimers, Pluronic-dominated mixed micelles, and large (50-60 nm in radius) composite (PO)(2)(EEGE)(6)(PO)(2)/Pluronic aggregates were identified. At a certain temperature, which is composition-dependent, the systems phase-separate [(PO)(2)(EEGE)(6)(PO)(2)/L64 1:0.1], enter an interval of instability [(PO)(2)(EEGE)(6)(PO)(2)/L64 1:1 and 1:10], or rearrange by dissociation of the large composite particles [(PO)(2)(EEGE)(6)(PO)(2)/P85]. The presence of a Pluronic micellar peak in the relaxation time distribution at lower temperatures, the dimensions of the composite particles, and the different behavior of the systems at elevated temperatures are discussed. A possible application of the thermosensitive mixtures in delivery/release of active substances is suggested.     

Binding of propylene oxide to porphyrin- and salen-M(III) cations, where M = Al, Ga, Cr, and Co

The binding of propylene oxide (PO) to a series of metal cations LM(III)(+), where for L = tetraphenylporphyrin (TPP) M = Al, Ga, Cr, and Co, and for L = (R,R)-N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexenediamine (salen) M = Al and Cr, was studied in the gas phase by electrospray tandem mass spectroscopy, and the relative stabilities of LM(PO)(2)(+) and LM(PO)(+) cations were determined. The chromium(III) and aluminum(III) cations most tenaciously bind PO, and for M = Al, coordination to the TPP ligated metal center was favored relative to salen. For (TPP)M(PO)(2)(+), the dissociation of PO followed the order M = Al > Cr, but for (TPP)M(PO)(+) the dissociation was M = Cr > Al. The single-crystal structural determinations on (R,R-salen)AlOCHMe(S)CH(2)Cl.0.5PO and (R,R-salen)AlO(2)CMe.1.5py grown in neat PO and pyridine, respectively, reveal five-coordinate aluminum(III) centers with the alkoxide/acetate ligands in the axial position of a square-based pyramid. These results are discussed in terms of the reactivity of these metal complexes in ring-opening polymerizations and copolymerizations with PO and CO(2), respectively.     

高倍率性能正极材料LiFe_(0.9)Mg_(0.1)PO_4的结构

应用高温固相反应合成锂离子电池正极材料LiFePO4和LiFe0.9Mg0.1PO4.不同浓度的K2S2O8水溶液氧化LiFe0.9Mg0.1PO4制备部分脱锂两相混合物Li0.4Fe0.9Mg0.1PO4及完全脱锂单相化合物Li0.1Fe0.9Mg0.1PO4.X射线衍射物相分析(XRD),选区电子衍射(SAED)和高分辨原子图像(HRTEM)测试表明,脱锂相Li0.1Fe0.9Mg0.1PO4是单相化合物,没有发生相分离.点阵参数计算表明,LiFe0.9Mg0.1PO4体系嵌锂相和脱锂相的晶格错配度与LiFePO4体系相比有所降低,这正是锂离子电池正极材料LiFe0.9Mg0.1PO4具有高倍率循环充放电比容量的结构基础.     

乙烷PBI/H_3PO_4质子传导膜燃料电池性能

研究了以乙烷作为燃料、掺杂了H3PO4的聚苯并咪唑(PBI)材料作为质子传导膜、Pt/C作为电极催化剂构成的燃料电池电化学性能。采用溶液铸造法制备了PBI/H3PO4质子传导膜,考察了在PBI膜中H3PO4的掺杂量与时间的关系及乙烷气体在增湿和不增湿条件下PBI/H3PO4燃料电池的电化学性能;探讨了电池的反应机理及不同操作温度对电池性能的影响。结果表明,PBI膜H3PO4适宜的掺杂时间为8h,电解质中掺杂600mol%H3PO4;乙烷气体增湿后,电池性能变好;操作温度提高,电化学反应速率加快,电池的输出电流与功率密度增加。结构为C2H6,(Pt/C阳极)/PBI/H3PO4膜/(Pt/C阴极),O2的单电池,在200℃和0.1Mpa、乙烷气体的湿度从0增加到0.02kgH2O/kg乙烷时,电池的最大输出电流密度从1.5mA·cm-2增加到34mA·cm-2,最大功率密度从0.33mW·cm-2增加到5.5mW·cm-2。     

镁合金化学转化膜的制备及其性能研究

在磷酸钠-磷酸二氢铵-高锰酸钾体系中对镁合金进行化学转化处理.研究了磷酸钠、磷酸二氢铵、高锰酸钾、温度、时间和添加剂对转化膜性能的影响.通过对转化膜结构、成分及性能的测试评价,得到了性能较好的化学转化溶液配方:Na3PO4为5g·L-1,NH4H2PO4为15 g· L-1,KMnO4为1g· L-1,添加剂(NH4)6 Mo7O24为0.5g·L-1.由SEM可观察到转化膜的表面成“干枯河床”状.XRD和EDS检测表明,膜层的主要成分是Mg,Al12 Mg17和无定形相,膜层表面主要有Mn,Mg,K,O和Al等元素组成.腐蚀实验和电化学测试表明,添加剂能够降低转化膜的腐蚀率,转化膜较基体的腐蚀电位正移了0.73 V,提高了镁合金的耐蚀性.     

MoSe2/Ag3PO4复合材料的制备及其可见光降解罗丹明B的光催化性能

通过原位沉积法合成了一种光催化活性强、稳定性高的MoSe2/Ag3PO4复合材料。MoSe2/Ag3PO4形成的异质结构能有效分离光生电子-空穴对,从而提高光催化活性。光生电子从Ag3PO4表面向MoSe2的转移降低了Ag+向金属Ag的可能性。当MoSe2和Ag3PO4的质量分数为1∶5(最优组合)时,MoSe2/Ag3PO4在可见光照射下30 min内降解RhB效率达98%,并且经过4次重复试验,其可见光照射下RhB降解效率仍可达到89%。通过液相色谱/质谱(LC/MS)技术测定光催化过程中产物的变化,提出了MoSe2/Ag3PO4光催化降解RhB的途径。     

NH4PO3-SiO2复合电解质的溶胶凝胶法制备和导电性能

用溶胶凝胶法制备了复合固体电解质xNH₄PO₃-SiO₂(x=1，2，4)，并研究了该电解质在125～250 ℃范围内的导电性能。复合电解质的相结构分析表明，NH₄PO₃和SiO₂在溶胶凝胶法制备过程中没有发生化学反应;复合电解质的电导率随着NH₄PO₃含量增大而提高，并与NH₄PO     

Synthesis and characterization of new calcium phenylphosphonates and 4-carboxyphenylphosphonates

Three new calcium phenylphosphonates, CaC(6)H(5)PO(3).2H(2)O, Ca(3)(C(6)H(5)PO(3)H)(2)(C(6)H(5)PO(3))(2).4H(2)O, and CaC(6)H(5)PO(3).H(2)O, and two calcium 4-carboxyphenylphosphonates, Ca(HOOCC(6)H(4)PO(3)H)(2) and Ca(3)(OOCC(6)H(4)PO(3))(2).6H(2)O, were prepared. It was found that CaC(6)H(5)PO(3).2H(2)O transformed into previously known Ca(C(6)H(5)PO(3)H)(2) via Ca(3)(C(6)H(5)PO(3)H)(2)(C(6)H(5)PO(3))(2).4H(2)O in the presence of phenylphosphonic acid, and vice versa, Ca(C(6)H(5)PO(3)H)(2) turned into CaC(6)H(5)PO(3).2H(2)O in a weak basic medium. A similar relationship was found between Ca(HOOCC(6)H(4)PO(3)H)(2) and Ca(3)(OOCC(6)H(4)PO(3))(2).6H(2)O; i.e., Ca(3)(OOCC(6)H(4)PO(3))(2).6H(2)O transformed into Ca(HOOCC(6)H(4)PO(3)H)(2) in the presence of 4-carboxyphenylphosphonic acid. On the contrary, Ca(3)(OOCC(6)H(4)PO(3))(2).6H(2)O is formed from Ca(HOOCC(6)H(4)PO(3)H)(2) in the presence of ammonium as a weak base. The structure of Ca(HOOCC(6)H(4)PO(3)H)(2) was solved from X-ray powder diffraction data by an ab initio method using a FOX program. The compound is monoclinic, space group C2/c (No. 15), a = 49.218(3) A, b = 7.7609(4) A, c = 5.4452(3) A, beta = 128.119(3) degrees , and Z = 4. Its structure is one-dimensional with [Ca(2)(HOOCC(6)H(4)PO(3)H)(4)](infinity) ribbons forming basic building blocks. The ribbons are held together by hydrogen bonds between carboxylic groups.     

磷酸根离子在阴离子交换树脂上的保留行为及其机理探讨

首次发现磷酸根离子在阴离子交换柱上以两个色谱峰流出。在研究磷酸根离子的保留行为的基础上,提出了Ｈ２ＰＯ－４在固定相中进一步离解的保留机理,即Ｈ２ＰＯ－４在与阴离子交换树脂交换基进行离子交换的过程中,由于树脂交换基和淋洗离子的电荷相互作用促使一部分Ｈ２ＰＯ－４进行第２级离解。由于Ｈ２ＰＯ－４和ＨＰＯ２－４在阴离子交换树脂上的保留值不同,导致磷酸根离子出现“双峰”。     

Synthesis and use of α-methoxyphenylmethylium hexachloroantimonate as a novel initiator for the polymerization of propylene oxide

α-Methoxyphenylmethylium hexachloroantimonate was prepared from α-methoxybenzyl chloride and antimony pentachloride at 0°C and isolated for the first time, and its visible and ¹H-NMR spectra were measured. This salt was used as a novel initiator for the polymerization of propylene oxide (PO) in the temperature range ?20 to 30°C with dichloromethane as solvent. PO polymerized spontaneously but a limit yield was observed. The microstructure of PO polymer is amorphous by ¹³C-NMR. The PO polymerization is thought to proceed in the conventional cationic mechanism on the basis of the polymerization behavior and the analyses of both the polymer structure and end groups attached to the PO polymer.     

Surface characterization and platelet compatibility evaluation of the binary mixed self-assembled monolayers

This report describes a technique that used mixed self-assembled monolayer (SAM) as a model surface to evaluate the effect of steric hindrance on the SAM packing quality and its platelet compatibility. Two series of binary mixed SAMs were formed by mixing the bulky terminated alkanethiol (HS(CH2)10PO3H2) with a smaller terminated one (HS(CH2)9CH3 and HS(CH2)11OH) respectively. Surface characterization results showed the hydrophilicity on these two series of mixed SAMs changed with the solution mole fraction of PO3H2 terminated thiol, chi(PO3H2,soln), and reached to a nearly constant value as chi(PO3H2,soln) was 0.6 for PO3H2+CH3 SAM and 0.4 for PO3H2+OH SAM. This finding should be due to the gradual saturation of surface PO3H2 functionality on these mixed SAMs. The XPS analysis indicated the addition of the CH3 and OH terminated thiol could reduce the steric hindrance effect of PO3H2 functionality on monolayer formation and, henceforth, improve the SAM packing quality. In vitro platelet adhesion assay revealed the platelet compatibility on the PO3H2+OH SAMs was better than that on the PO3H2+CH3 and the pure PO3H2 ones. Moreover, the PO3H2+OH SAM with a low chi(PO3H2,soln) value exhibited the least platelet activating property of these two mixed SAM systems. These findings suggested that material's surface wettability and surface charge density should act collectively in affecting its platelet compatibility.     

γ-苄基膦酸-磷酸锆的合成、表征及插层性能研究

于220℃水热晶化下制备了高结晶度的γ-ZrP,合成了3种γ-苄基膦酸-磷酸锆层状化合物Zr(PO₄).(H₂PO₄)_0.15(C₆H₅CH₂PO₃H)_0.85·0.4H₂O(1,d=1.86nm),Zr(PO₄)(H₂PO₄)_0.30(C₆H₅CH₂PO₃H)_0.70·0.6H₂O(2,d=1.78nm)和Zr(PO₄)(H₂PO₄)_0.50(C₆H₅CH₂PO₃H)_0.50·0.7H₂O(3,d=1.66nm).用X射线粉末衍射和³¹P固态核磁共振等手段表征其结构,并研究了其与α-苯乙胺的插层性能.