一维链状锰配合物的合成、结构及磁性研究

合成了邻硝基苯磺酰化丙氨酸配体2-NBS-AlaH (1)(2-NBS-AlaH=邻硝基苯磺酰化丙氨酸)及其锰的配合物[Mn(4，4′-bipy)(H₂O)₄]₂[(4，4′-bipy)₂(H₂O)₃(2-NBS-Ala)₄] (2)。通过X-射线单晶衍射测定了其结构：配体通过氢键形成了一维链状结构；配合物2中，4，4′-bipy把锰离子连成了一维链状结构。磁性研究表明，配合物由于分子间的自旋耦合呈现出弱的铁磁性。     

Experimental and theoretical investigation on the relative stability of the PdS2- and pyrite-type structures of PdSe2

Under ambient condition PdSe2 has the PdS2-type structure. The crystal structure of PdSe2 under pressure (up to 30 GPa) was investigated at room temperature by X-ray diffraction in an energy-dispersive configuration using a diamond anvil cell with a mixture of water/ethanol/methanol as a pressure transmitting medium. A reversible structural transition from the PdS2-type to the pyrite-type structure occurs around 10 GPa, and the applied pressure reduces the spacing between adjacent 2/proportional to [PdSe2] layers of the PdS2-type structure to form the three-dimensional lattice of the pyrite-type structure. First principles and extended Hückel electronic band structure calculations were carried out to confirm the observed pressure-induced structural changes. We also examined why the isoelectronic analogues NiSe2 and PtSe2 adopt structures different from the PdS2-type structure on the basis of qualitative electronic structure considerations.     

Ba4Si3Br2: a double salt of barium bromide and barium silicide containing a novel cyclotrisilicide unit

A new compound of the composition Ba4Si3Br2 was obtained by reacting BaSi with a melt of BaBr2. Ba4Si3Br2 may be described as a double salt between a Zintl phase and a halide. The structure was determined by single-crystal X-ray diffraction (P21c, a= 1504.1(2), b = 884.5(1), c = 880.2(1) pm, beta = 101.93(2) degrees, R = 0.041 Rw = 0.079). The crystal structure contains isolated barium cations and bromide anions as well as novel singly bonded cyclotrisilicid units. The electronic structure has been studied by linear Muffin tin orbital (LMTO) band structure calculations, which reveal semiconducting behavior with a band gap of about 0.1 eV, and by an analysis of the electron localization function.     

溶剂热合成片状介孔CeO2及光致发光性能

本文以乙二醇为溶剂,Ce(NO3)3·6H2O为铈源,尿素为沉淀剂,采用了溶剂热法一步合成了二维片状结构的介孔CeO2,同时讨论了不同反应时间对晶型的影响。通过SEM、TEM、XRD、EDS和N2吸附-脱附等检测手段进行了表征,结果表明所合成CeO2是由大量较规整的片状结构单元组成,在片状结构上分布着均匀有序的介孔,产物具有立方萤石型结构,并考察了相应的光致发光性能。     

一氧化氮选择还原锡锆固溶体催化剂的结构特性

采用双股并流共沉淀方法制备了SnO2含量从10％至90％的锡锆体系DeNOx催化剂,用XRD、微区电子衍射、FT-Raman及FT-IR等技术深入研究了锡锆体系氧化物的结构及其随组成的变化规律.结果表明，由于Sn4＋与Zr4＋离子半径接近,SnO2与ZrO2易于形成固溶体,并随组成变化表现出不同的结构特征.纯ZrO2为单斜相,当少量Sn4＋（SnO2 ≤ 20％）进入ZrO2晶格时形成四方相富锆固溶体,Sn4＋起到稳定ZrO2四方相的作用;随着SnO2含量的增大,结构从无定形或微晶态的富锆固溶体(含SnO2 30～50％)经富锆固溶体与金红石结构的富锡固溶体在55％ SnO2含量的共存状态变化到具有金红石结构的富锡固溶体（SnO2 ≥ 60％）.FT-Raman和FT-IR光谱测试证明,Zr进入SnO2晶格使得Sn－O键的结合减弱,Sn离子上的有效正电荷减小,降低了SnO2对丙烯的燃烧能力,从而提高了对NO的还原活性.     

Comparative Study of Silk Fibroin-Based Hydrogels and Their Potential as Material for 3-Dimensional (3D) Printing

Three-dimensional (3D) printing is regarded as a critical technology in material engineering for biomedical applications. From a previous report, silk fibroin (SF) has been used as a biomaterial for tissue engineering due to its biocompatibility, biodegradability, non-toxicity and robust mechanical properties which provide a potential as material for 3D-printing. In this study, SF-based hydrogels with different formulations and SF concentrations (1–3%wt) were prepared by natural gelation (SF/self-gelled), sodium tetradecyl sulfate-induced (SF/STS) and dimyristoyl glycerophosphorylglycerol-induced (SF/DMPG). From the results, 2%wt SF-based (2SF) hydrogels showed suitable properties for extrusion, such as storage modulus, shear-thinning behavior and degree of structure recovery. The 4-layer box structure of all 2SF-based hydrogel formulations could be printed without structural collapse. In addition, the mechanical stability of printed structures after three-step post-treatment was investigated. The printed structure of 2SF/STS and 2SF/DMPG hydrogels exhibited high stability with high degree of structure recovery as 70.4% and 53.7%, respectively, compared to 2SF/self-gelled construct as 38.9%. The 2SF/STS and 2SF/DMPG hydrogels showed a great potential to use as material for 3D-printing due to its rheological properties, printability and structure stability.     

基于聚丙烯酸交联组装单层SiO_2纳米粒粗糙表面及其细胞捕获

以玻片为载体(Subs),聚丙烯酸(PAA)为交联剂和柔性体,SiO_2纳米粒为刚性体,人B淋巴细胞瘤Ramos细胞为目标细胞,TD05适体为细胞捕获配体(Apt),在载体上交联组装了结构为Subs-PAA1-SiO_2-PAA2-Apt的细胞捕获支架。该支架既有小尺度的刚性结构,即SiO_2纳米粒,又有柔性结构,即聚丙烯酸PAA1和PAA2。前者增加了载体的粗糙度,而后者不仅能够固载多重捕获配体,也能够有效降低宏观载体对细胞捕获的空间位阻。结果表明,支架具有良好的纳米粒结构,未发现纳米粒的融合甚至消失;支架的特异性捕获是非特异性吸附的16倍,被捕获细胞表现出较高的纯度;同时,支架具有较高的捕获效率,捕获细胞数是通常的单层刚性纳米粒支架的8.3倍。由此表明,该文构建的结构新颖的纳米粒柔性支架实现了目标细胞的高效率、高纯度捕获,将为肿瘤细胞的分析检测提供可靠的样本。     

Water structure and its influence on the flotation of carbonate and bicarbonate salts

Interfacial water structure is a most important parameter that influences the collector adsorption by salt minerals such as borax, potash and trona. According to previous studies, salts can be classified as water structure makers and water structure breakers. Water structure making and breaking properties of salt minerals in their saturated brine solutions are essential to explain their flotation behavior. In this work, water structure making-breaking studies in solutions of carbonate and bicarbonate salts (Na(2)CO(3), K(2)CO(3), NaHCO(3) and NH(4)HCO(3)) in 4 wt% D(2)O in H(2)O mixtures have been performed by FTIR analysis of the OD stretching band. This method reveals a microscopic picture of the water structure making/breaking character of the salts in terms of the hydrogen bonding between the water molecules in solution. The results from the vibrational spectroscopic studies demonstrate that carbonate salts (Na(2)CO(3) and K(2)CO(3)) act as strong structure makers, whereas bicarbonate salts (NaHCO(3) and NH(4)HCO(3)) act as weak structure makers. In addition, the changes in the OD band parameters of carbonate and bicarbonate salt solutions are in agreement with the viscosity characteristics of their solutions.     

Stabilization of new forms of the intermetallic phases beta-RENiGe2 (RE = Dy, Ho, Er, Tm, Yb, Lu) in liquid indium

Flux conditions using liquid indium bypass the thermodynamically stable structure and yield new forms of the phases RENiGe2 (RE = Dy, Er, Yb, Lu). The compounds crystallize in the orthorhombic Immm space group and possess the YIrGe2 structure type. Lattice parameters for ErNiGe2, DyNiGe2, YbNiGe2, and LuNiGe2 are a = 4.114(1) A, b = 8.430(2) A, c = 15.741(5) A; a = 4.1784(9) A, b = 8.865(2) A, c = 15.745(3) A; a = 4.0935(6) A, b = 8.4277(13) A, c = 15.751(2) A, and a = 4.092(1) A, b = 8.418(3) A, c = 15.742(5) A, respectively. These phases represent a new structural arrangement (beta) of the compound type RENiGe2 as another set of compounds with identical stoichiometry are known to adopt the orthorhombic Cmcm CeNiSi2 type structure (alpha). In this paper we report the crystal and electronic band structure of four new members of the YIrGe2 structure type, as well as an investigation of the relative thermodynamic stabilities of the two forms.     

Spec2D: a structure elucidation system based on 1H NMR and H-H COSY spectra in organic chemistry

A system for structure elucidation based on proton NMR spectra has been developed. The system, named Spec2D (system for spectra from 2D-NMR), incorporates 1H NMR and H-H correlation spectroscopy (COSY) spectral information obtained from 2D-NMR experiments. 2D-NMR is important for the structure elucidation because it provides information about the relationships among differently situated protons in the structures of unknown compounds. The system uses the concepts of molecular graphs. The improved representation of substructures as well as several novel algorithms for structure generation have been devised to solve the combinatorial problem and to reduce the processing time. Spec2D consists of a knowledge base, an analysis module, and a candidate structure generator module. Spec2D proposes candidate structures from only 1H NMR and H-H COSY spectral information of an unknown compound without any 13C NMR spectral or structural information, such as molecular formulas. Spec2D has the capability to propose the "new" structure of an unknown compound, if the corresponding substructures are included in the knowledge base.     

One-dimensional Infinite Chain Organotin Compounds: Synthesis and Structural Characterization of Triphenyltin Thiazole-2-carboxylate and Triphenyltin 3-Pyridinylcarboxylate

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Coordination polymers of La(III) as bunched infinite nanotubes and their conversion into an open-framework structure

Pyridine-2,6-dicarboxylic acid (pdcH2) reacts with LaCl3 x 7H2O under hydrothermal conditions followed by evaporation at room temperature to give a metal-organic framework structure of the empirical formula, [La(pdc)(H2O)4] x Cl (1), in the form of infinitely long bunched nanotubes. The chloride ions and water molecules occupy the tubular as well as the inter-tubular spaces. When La(NO3)3 x 7H2O is used in place of LaCl3 x 6H2O, a similar structure is formed with the empirical formula, [La(pdc)(H2O)4] x NO3 (2), where water molecules and the nitrate anions occupy the voids as in the case of 1. When an aqueous solution of AgNO3 is added to an aqueous solution of 1, the Cl- ions are replaced completely by NO3- ions to form 2; thus, the tubular structure is conserved. However, when AgBF4 is used in place of AgNO3, the tubular structure breaks down, and a new 3-D MOF structure, [La(pdc)(pdcH)(H2O)2] x 4H2O (3), is formed where the cavities are occupied by hexameric and dimeric water clusters. Structure 3 is also formed as the sole product when La(OAc)3 x xH2O is treated with pyridine-2,6-dicarboxylic acid following the method adopted for 1 and 2. Formation of the tubular structure depends on the molar ratio of the ligand and the metal. When higher than 1 equiv of the metal is taken, a linear coordination polymer, [La2(pdc)3(H2O)6] x 2H2O (4), is formed. This study provides the first nanotubular structure of a pure lanthanide metal.     

β-二酮钛非茂催化剂催化降冰片烯聚合

用 (dibenzoylmethanato) 2 Ti(OPh) 2 [(dbm) 2 Ti(OPh) 2 ]/甲基铝氧烷 (MAO)为代表的新型 β 二酮钛非茂催化剂实现了降冰片烯的聚合 ,得到加成聚合和开环易位聚合的混合物 ,研究了实现高聚合活性所需的特殊条件及所得的聚合物结构 ,主要应用傅立叶转变红外技术 (FTIR)对聚合物结构进行了表征和分析     

The conversion process of hydrocarbon hydrates into CO2 hydrates and vice versa: thermodynamic considerations

Microscopy, confocal Raman spectroscopy and powder X-ray diffraction (PXRD) were used for in situ investigations of the CO(2)-hydrocarbon exchange process in gas hydrates and its driving forces. The study comprises the exposure of simple structure I CH(4) hydrate and mixed structure II CH(4)-C(2)H(6) and CH(4)-C(3)H(8) hydrates to gaseous CO(2) as well as the reverse reaction, i.e., the conversion of CO(2)-rich structure I hydrate into structure II mixed hydrate. In the case of CH(4)-C(3)H(8) hydrates, a conversion in the presence of gaseous CO(2) from a supposedly more stable structure II hydrate to a less stable structure I CO(2)-rich hydrate was observed. PXRD data show that the reverse process requires longer initiation times, and structural changes seem to be less complete. Generally, the exchange process can be described as a decomposition and reformation process, in terms of a rearrangement of molecules, and is primarily induced by the chemical potential gradient between hydrate phase and the provided gas phase. The results show furthermore the dependency of the conversion rate on the surface area of the hydrate phase, the thermodynamic stability of the original and resulting hydrate phase, as well as the mobility of guest molecules and formation kinetics of the resulting hydrate phase.     

Snapshots of dioxygen activation by copper: the structure of a 1:1 Cu/O(2) adduct and its use in syntheses of asymmetric Bis(mu-oxo) complexes

The X-ray structure of a 1:1 Cu/O(2) adduct revealed side-on (eta(2)) O(2) coordination. Density functional calculations corroborated the structure, indicated a significant contribution of a Cu(III)-(O(2)(2-)) resonance form, and provided insights into the key bonding interactions. Reaction of a 1:1 adduct supported by a slightly different beta-diketiminate ligand with Cu(I) reagents resulted in the formation of novel asymmetric bis(mu-oxo) complexes that were identified by EPR, UV-vis, and Raman spectroscopy, as well as by an X-ray structure in one instance.     

Structure and diffusion in amorphous aluminum silicate: a molecular dynamics computer simulation

The amorphous aluminum silicate (Al2O3)2(SiO2) [AS2] is investigated by means of large scale molecular dynamics computer simulations. We consider fully equilibrated melts in the temperature range 6100 K> or =T> or =2300 K as well as glass configurations that were obtained from cooling runs from T=2300 to 300 K with a cooling rate of about 10(12) K/s. Already at temperatures as high as 4000 K, most of the Al and Si atoms are fourfold coordinated by oxygen atoms. Thus, the structure of AS2 is that of a disordered tetrahedral network. The packing of AlO4 tetrahedra is very different from that of SiO4 tetrahedra in that Al is involved with a relatively high probability in small-membered rings and in triclusters in which an O atom is surrounded by four cations. We find as typical configurations two-membered rings with two Al atoms in which the shared O atoms form a tricluster. On larger length scales, the system shows a microphase separation in which the Al-rich network structure percolates through the SiO2 network. The latter structure gives rise to a prepeak in the static structure factor at a wave number q=0.5 A(-1). A comparison of experimental x-ray data with the results from the simulation shows good agreement for the structure function. The diffusion dynamics in AS2 is found to be much faster than in SiO2. We show that the self-diffusion constants for O and Al are very similar and that they are by a factor of 2-3 larger than the one for Si.     

Donors and acceptors based on triangular dehydrobenzo[12]annulenes: formation of a triple-layered rosette structure by a charge-transfer complex

We present here the results of studies of the synthesis and properties of donors and acceptors based on triangular dehydrobenzo[12]annulene ([12]DBA) system as a pi core. These studies were aimed at controlling the supramolecular crystal structure. Toward this end, the tricyano[12]DBA 2 and dodecafluoro[12]DBA ( 3) were synthesized as acceptors (A) and the tris(dialkylamino)[12]DBAs 4a-d as donors (D), and their electronic properties were determined by electronic absorption spectroscopy and electrochemical measurements. The main focus, though, was the formation of supramolecular structures in crystals. These compounds form distinct packing patterns as a result of the different intermolecular interactions. Tricyano[12]DBA 2 forms a two-dimensional (2D) sheet structure via hydrogen-bonding interactions, whereas a tilted-stack structure was found for 3 because of the lack of significant intermolecular interactions. Tris(dibutylamino)[12]DBA 4b exhibits a ladder-type 2D structure, probably because of van der Waals interactions between the butyl groups. The most significant finding is that charge-transfer interactions between donor 4a and acceptor 3 combined with their triangular molecular shapes and lateral CH...F hydrogen bonding result in the formation of a 2D rosette structure consisting of two different trimeric (DAD- and ADA-type) sandwich structures with 1:2 and 2:1 A/D ratios, respectively.     

Characterization of complicated new polymorphs of chlorothalonil by X-ray diffraction and computer crystal structure prediction

A simultaneous experimental and computational search for polymorphs of chlorothalonil (2,4,5,6-tetrachloro-1,3-benzenedicarbonitrile) has been conducted, leading to the first characterization of forms 2 and 3. The crystal structure prediction study, using a specifically developed anisotropic atom-atom potential for chlorothalonil, gave as the global minimum in the lattice energy a structure that was readily refined against powder diffraction data to the known form 1 (P2(1)/a). The structure of form 2 was solved and refined from powder diffraction data, giving a disordered structure in the Rm (166) space group (Z = 3). It could also be refined against a P1 ordered model, starting from a low-energy hypothetical sheet structure found in the computational search. This shows that the disorder could be associated with the stacking of ordered sheets. The disordered structure for form 2 was later confirmed by single-crystal X-ray diffraction. The structure of form 3, determined from single-crystal diffraction, contains three independent molecules in the asymmetric unit in P2(1) (4) (Z = 6). Powder diffraction showed that this single-herringbone structure was similar to two low-energy structures found in the search. Further analysis confirmed that form 3 has a similar lattice energy and contains elements from both these predicted structures, which can be considered as good approximations to the form 3 structure.     

Systematic investigation on durability of glass–ceramics containing CePO4: orthogonal analysis

Journal of Radioanalytical and Nuclear Chemistry - CeO2 was applied as a structure analog to radionuclides that tents to have similar structure such as Np, Pu, and Ce. Element Ce in CeO2 was...     

掺杂铁酸盐的制备、结构及其催化分解CO2成C的性能

采用混合离子共沉淀法制备掺杂铁酸盐,采用XRD,TGA和H2-TPR等手段对其结构进行了表征,并考察了其直接催化分解CO2成C的性能.研究结果表明,用混合离子共沉淀法能够制备出纳米级晶粒、且为单一尖晶石结构的Cr3+掺杂的NiFe2O4.所掺杂的Cr3+进入NiFe2O4的晶格B位,极大地促进了NiFe2O4在还原氧化过程中结构的稳定性,分解CO2反应后,NiFe2O4的结构易恢复,从而明显地提高了其分解CO2成C反应的循环寿命(35次以上)和积炭量(25.3%).