B-X and C-X Band Systems of CuCl Revisited: Laser-induced Fluorescence Study in 465−490 nm

We have reinvestigated the B-X and C-X band systems of CuCl by recording the laser-induced fluorescence excitation spectra in 20400?21800 cm^?1. The rotational analyses in Hund’s case (a) revealed unambiguously a singlet-to-singlet transition nature. The radiative lifetimes were measured to be 4.670 and 4.667 μs, respectively, which are much longer than that expected for a pure singlet of CuCl. This implies that the fluorescence mechanism in the B or C band systems lies in the mixing of the singlets (¹Пand ¹∑⁺) and triplets (³П_0,1,2) and that the two excited states observed in our experiment might be the singlets that have been strongly “contaminated” by their triplet neighbors.     

In situ polymerization of methyl methacrylate/multi-walled carbon nanotube composites using cationic stearyl methacrylate copolymers as dispersants

Novel water-soluble amphiphilic copolymers (poly[(stearyl methacrylate)-stat-([2-(methacryloyloxy)ethyl] trimethyl ammonium iodide)]) for dispersing multi-walled carbon nanotubes (MWCNTs) were used to carry out in situ methyl methacrylate (MMA) polymerization. The morphology of the poly(methyl methacrylate)/MWCNT composites and the dispersion of the MWCNTs were analyzed by transmission electron microscopy. The dispersion of multi-walled carbon nanotubes in the composites was excellent for cationic SMA (stearyl methacrylate) copolymers, even at high MWCNT loading (6.0 wt.%). The mechanical properties and electrical and thermal conductivities of the composites were also analyzed. Mechanical properties were improved by MWCNTs; the strain at break values remained stable up to 6.0 wt.% MWCNT loading. Both electrical and thermal conductivities were improved by the addition of MWCNTs.     

Novel Zn-Fe LDH/MWCNTs and Graphene/MWCNTs Nanocomposites Based Potentiometric Sensors for Benzydamine Determination in Biological Fluids and Real Water Samples

Two sensitive and selective potentiometric sensors based on zinc-iron layered double hydroxides/multiwalled carbon nanotubes (Zn−Fe LDH/MWCNTs) (sensor I) and graphene/multiwalled carbon nanotubes (Gr/MWCNTs) (sensor II) nanocomposites were developed for benzydamine hydrochloride (Benz) determination. The investigated sensors displayed excellent Nernstian slopes 58.5±0.7 and 59.5±0.5 mV decade⁻¹, detection limits 8.3×10⁻⁷ and 1.9×10⁻⁷ mol L⁻¹, long lifetimes, adequate selectivity, high chemical, and thermal stability within pH range of 2.4–8.5 for sensors І and ІІ, respectively. The surface morphology of sensors was analyzed using a Transmission Electron Microscope (TEM). The analytical method was efficiently implemented for Benz determination in biological fluids and surface water samples.     

Photoelectron Imaging Spectroscopy of ZrO- Diatomic Anion

The diatomic ZrO^- anion has been prepared by laser ablation and studied by photoelectron imaging spectroscopy combined with quantum chemistry calculations. The observed photoelectron spectra can be well assigned on the basis of reported optical spectroscopy and high-level ab initio calculations. The ground state of ZrO^- is a ²△ state with spin-orbit splitting of 578±12 cm^-. The electron affinity of ZrO is 1.249±0.005 eV. For the first time, the c³Σ^- state of ZrO has been experimentally observed at 13316±24 cm^- with respect to the X¹∑⁺ ground state. A comparison between ZrO and the isoelectronic molecule NbN has been made.     

In situ Growth of a Cobalt‐based Metal‐organic Framework on Multi‐walled Carbon Nanotubes for Simultaneously Detection of Hydroquinone and Catechol.

In the present study, we report a facile method for preparing a porous MWCNTs/ZIF‐67 nanocomposite with the help of a morphology‐maintained ZIF‐67 in situ growth on multi‐walled carbon nanotubes. Interesting, the MWCNTs/ZIF‐67 nanocomposite demonstrated excellent electrochemical activity for hydroquinone (HQ) and catechol (CC) attribute to the effective interconnections ZIF‐67 crystals and MWCNTs. The analytical curves for HQ and CC obtained by differential pulse voltammetry (DPV) were linear in the range from 0.5 to 100 μM. Benefitting from the excellent conductivity of MWCNTs as well as the high surface area and porosity of ZIF‐67, the advanced nanocomposite displayed good reproducibility, high selectivity and excellent stability, and was successfully employed to assay the content of dihydroxybenzene isomers in the lake water samples.     

Crossed Molecular Beam Study of the F+D2(v=1, j=0) Reaction

The reaction dynamics of the fluorine atom with vibrationally excited D₂(v=1, v=0) was investigated using the crossed beam method. The scheme of stimulated Raman pumping was employed for preparation of vibrationally excited D₂ molecules. Contribution from the reaction of spin-orbit excited F^?(²P_1/2) with vibrationally excited D₂ was not found. Reaction of spin-orbit ground F(²P_3/2) with vibrationally excited D2 was measured and DF products populated in v‘=2, 3, 4, 5 were observed. Compared with the vibrationally ground reaction, DF products from the vibrationally excited reaction of F(²P_3/2)+D₂(v=1, j=0) are rotationally “hotter”. Differential cross sections at four collision energies, ranging from 0.32 kcal/mol to 2.62 kcal/mol, were obtained. Backward scattering dominates for DF products in all vibrational levels at the lowest collision energy of 0.32 kcal/mol. As the collision energy increases, angular distribution of DF products gradually shifts from backward to sideway. The collision-energy dependence of differential cross section of DF(v’=5) at forward direction was also measured. Forward-scattered signal of DF(v'=5) appears at thecollision energy of 1.0 kcal/mol, and becomes dominated at 2.62 kcal/mol.     

Tcn and Tcn@C70 Endohedral Metalofullerenes: ab initio Spin-density-functional Calculations

Ab initio spin-density-functional calculations have been performed to study the equilibrium structural, electronic, and magnetic properties of Tcn and Tc_n@C₇₀ endohedral metalofullerenes. Our results indicate that C₇₀ can encapsulate Tcn clusters with up to n=9 atoms. Except n=2, the formation of Tc_n@C₇₀ endohedral metalofullerenes is predicted to be exothermic when n≤5, while the encapsulation process becomes increasingly endothermic beyond n=5. When encapsulating into the C₇₀ cage, the geometries as well as electronic structures of the Tc cluster undergo comparative changes. Especially, compared to the isolated Tcn clusters, the total magnetic moments of Tc_n@C₇₀ reduce significantly. The analyses of the orbital population, Hirshfeld population and density of states show that electrons transfer from the Tc cluster to the carbon cage through the Tc-C efficient hybridization, which is responsible for such reduction of the whole magnetism.     

铂纳米颗粒的可见光化学制备及其对p-硝基苯酚催化还原反应

在可见光照射下,以乙二醇（EG）作为还原剂和稳定剂,在多壁碳纳米管（MWCNTs）上一步合成了铂纳米颗粒,成功制备Pt/MWCNTs复合材料,并通过p-硝基苯酚（p-NP）的催化还原反应研究了Pt/MWCNTs的催化性能。用傅里叶变换红外光谱（FT-IR）、X射线衍射（XRD）、透射电子显微镜（TEM）和X射线光电子能谱（XPS）对所制备材料的形貌和晶体结构进行了表征。实验结果显示,可见光照射促进了EG水溶液中[PtCl₄]^2-前驱体的水解。通过金属界面的电子效应,铂前驱体被还原成了均匀分散的平均直径2.1 nm的超小颗粒Pt（Pt ultra-small particles,Pt UPs）。所制备的Pt/MWCNTs能有效地催化p-NP还原为p-氨基苯酚（p-AP）,表现出较高的催化性能,其表观速率常数为0.25 min^-1。Pt/MWCNTs多次使用后没有显著的活性损失,显示出了良好的稳定性。上述实验结果证明,除了传统的紫外光照射等手段以外,可见光照射也同样是制备铂金属催化剂非常有效的方法。而且,催化剂的形貌控制也完全可以通过简单而非复杂的实验条件加以实现。     

短柄雪胆中的三萜葫芦素及其皂苷

从短柄雪胆的块根中分离得到了14个三萜葫芦素类化合物. 经波谱分析及化学方法鉴定了它们的结构, 其中有新化合物5个, 分别命名为短柄雪胆苷A～E (1～5), 以及肉花雪胆苷元A (6), 藤三七雪胆苷R8 (7), 肉花雪胆苷I (8), 肉花雪胆苷II (9), 肉花雪胆苷III (10), 雪胆甲素(11), 雪胆乙素(12), 雪胆甲素苷(13), 藤三七雪胆苷R1 (14)等9个已知化合物. 6是首次从自然界中得到的化合物.     

Crystal Structure and Magnetic Property of 2-(Imidazo[1,2-a]pyri-din-2-yl)-2-oxoacetic Acid and Its Perchlorate

We herein report two crystals based on 2-(imidazo[1,2-a]pyridin-2-yl)-2-oxoacetic acid radical and its perchlorate, and investigate the relationship between magnetic properties and crystal stacking structures or supramolecular interactions. 2-(Imidazo[1,2-a]pyridin-2-yl)-2-oxoacetic acid radical in two crystals mainly exist as diamagnetic dimer formed via short atomic contacts or supramolecular interactions (hydrogen bonds, anion-π or lonepair-π interactions), leading to low magnetic susceptibilities. 2-(Imidazo[1,2-a]pyridin-2-yl)-2-oxoacetic acid radical crystal exhibits quasi-one-dimensional columnar stacking chain and weak antiferromagnetism. However, its perchlorate crystal possesses one-dimensional doublestranded chain structure assembled through double hydrogen bonds and anion-π interactions, and reveals weak ferromagnetism.     

Effects of functionalized multiwalled carbon nanotubes on the morphologies and mechanical properties of PP/EVA blend

The maleic anhydride‐grafted multiwalled carbon nanotubes (MWCNTs‐g‐MA) have been introduced into polypropylene/ethylene‐co‐vinyl acetate (PP/EVA) blend. To clearly describe the effects of MWCNTs‐g‐MA on the morphology and mechanical properties of PP/EVA blends, the selective distribution of MWCNTs‐g‐MA in the blends is realized through different sample preparation methods, namely, MWCNTs‐g‐MA disperse in EVA phase and MWCNTs‐g‐MA disperse in PP matrix. The results show that the distribution of MWCNTs‐g‐MA has an important effect on the final morphology of EVA and the crystallization structure of PP matrix. Compared with PP/EVA binary blend, distribution of MWCNTs‐g‐MA in PP matrix induces the aggregation of EVA phase at high EVA content and the decrease of spherulite diameters of PP matrix simultaneously. However, when MWCNTs‐g‐MA are dispersed in the EVA phase, they induce more homogeneous distribution of EVA, and the crystallization behavior of PP is slightly affected by MWCNTs‐g‐MA. The corresponding mechanical properties including impact strength and tensile strength are tested and analyzed in the work. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1481–1491, 2009     

N,N'-二(二乙氧基硫代磷酰基)-1,4-苯二胺的合成、晶体结构及热性能研究

通过二乙氧基硫代磷酰氯与对苯二胺反应生成了标题化合物N,N'-二(二乙氧基硫代磷酰基)-1,4-苯二胺，并应用元素分析, FTIR及¹H NMR对标题化合物进行了表征. 利用X射线单晶衍射测定了其晶体结构, 同时应用TG分析法对其热性能进行了分析. 标题化合物的相对分子质量M_r＝412.42, 为正交晶系, Pbca空间群, 晶胞参数为a＝0.86936(16) nm, b＝1.2787(2) nm, c＝1.8897(3) nm, β＝90°, V＝2.1006(7) nm³, Z＝8, D_c＝1.304 g/cm³, μ(Mo Kα)＝0.425 mm^－1, F(000)＝872, S＝1.052. 最终偏离因子R＝0.0628, wR＝0.1860, 可观测衍射点1852个[I＞2σ(I)]. 该晶体通过对苯二胺连接并以中心对称分布, 并形成层状结构, 且存在弱的分子内氢键N—H…S. TG分析表明该化合物有很好的热稳定性及成炭性, 通过其阻燃聚丙烯腈表明, 该物质是一种高效能的膨胀型阻燃剂.     

手性硼酸酯介入的不对称合成3† (R)-或(S)-1,1'-联-2-萘酚硼酸-(S)-脯氨酸酐促进的前手性亚胺的不对称硼烷还原

手性螺硼酸酯(R)-或(S)-1,1'-联-2-萘酚硼酸-(S)-脯氨酸酐[(R,S)-1或(S,S)-1]对前手性亚胺硼烷还原的不对称催化活性被观察到. 在(R,S)-1或 (S,S)-1存在下, 由前手性二烷基酮或烷基苯酮与苯胺缩合生成的前手性亚胺在THF中被硼烷还原, 高产率地给出手性仲胺, 其对映体纯度高达74% ee. 其中, 三种手性仲胺[N-(2-戊基)苯胺, N-(3-甲基-2-丁基)苯胺和N-(4-甲基-2-戊基)苯胺]系首次合成.     

槲树叶中的5种酚性成分

从槲树叶Quercus dentata Thunb中分离纯化得到五种酚性成分. 通过理化性质分析和光谱解析等手段确定其化学结构分别为: 2-新橙皮糖基-2,6-二羟基苯甲酸苯甲酯(1), 龙胆酸5-O-(6-O-没食子酰基)--D-吡喃葡萄糖苷(2), 3,5,7-三羟基色原酮-3-O--D-吡喃葡萄糖苷(3), 没食子酸(4), 儿茶素(5), 其中化合物1和3为新化合物.     

碳纳米管含量对炭炭复合材料组织及力学性能的影响

炭纤维上原位合成了均匀生长且具有伸张形貌的碳纳米管,借助化学气相渗透制备了碳纳米管增强的炭炭复合材料,研究了不同含量的碳纳米管对炭炭复合材料组织和力学性能的影响。结果表明：炭纤维上生长碳纳米管改变了热解炭的沉积行为,诱导了各向同性热解炭的生成,且随着碳纳米管含量的增加,各向同性热解炭的厚度增加,但是复合材料的d002值却明显降低。微量的碳纳米管即可显著提高复合材料的力学强度,随着其含量的增加,复合材料的力学强度和模量迅速提高,但材料的断裂行为却急剧恶化,断裂模式由最初的假塑性断裂转变为脆性断裂。     

Carbon Nanotubes with Phthalocyanine-Decorated Surface Produced by NH3-Assisted Microwave Reaction and Their Catalytic Performance in Li/SOCl2 Battery

Multiwalled carbon nanotube (MWCNT)‐templated cobalt phthalocyanine (CoPc) assemblies are prepared by microwave reaction with the aid of NH₄Cl. The assemblies of CoPc/MWCNTs are added to the electrolyte of Li/SOCl₂ battery to show their potential application in the field of catalysis. The assemblies display a uniform coaxial nanotube structure. In the control test, the CoPc/MWCNTs synthesized without NH₄Cl exhibit the aggregation of the nanotubes of CoPc/MWCNTs. It indicates that the use of NH₄Cl as gas source is efficient in enhancing diffusion of the MWCNTs and controlling the growth of CoPc. The catalytic reduction of SOCl₂ can be carried out by CoPc molecules outside the assemblies and the MWCNTs inside the assemblies. The assemblies of CoPc/ MWCNTs exhibit excellent electrochemical catalytic activity to Li/SOCl₂ battery. The discharge energy of Li/SOCl₂ battery catalyzed by CoPc/MWCNTs is 144% higher than that of the battery without catalyst, and is 94% higher than the energy of Li/SOCl₂ battery catalyzed by bulk CoPc.     

Ultrafast Dynamics of Water Molecules Excited to Electronic F States: A Time-Resolved Photoelectron Spectroscopy Study

The ultrafast dynamics of water molecules excited to the two F states is studied by combining two-photon excitation and time-resolved photoelectron imaging techniques. The lifetimes of the F₁A₁ and F₁B₁ states of H₂O (D₂O) were derived to be 1.0±0.3 (1.9±0.4) and 10±3 (30±10) ps, respectively. We propose that the F₁A₁ state mainly decays through the D state, due to the nonadiabatic coupling between them, while the F₁B₁ state decays through the F₁A₁ state via Coriolis interaction.     

[1-芳基甲羰基-2-(1,2,4-三唑-1-基)]乙基-N,N-二烷基二硫代氨基甲酸酯衍生物的合成、结构表征及生物活性研究

以芳香基三唑类杀菌剂三唑酮为先导物设计并合成了5个含N,N-二烷基二硫代氨基甲酸酯的芳香三唑类化合物, 通过元素分析、红外光谱、核磁共振氢谱和质谱对其结构进行了表征. 用X射线单晶衍射测定了[α-(4-甲氧基苯甲酰基)-2-(1,2,4-三唑-1-基)]乙基-N,N-二甲基二硫代氨基甲酸酯的晶体结构, 晶体属于三斜晶系, 空间群, 晶胞参数为: a＝0.73482(15) nm, b＝1.1051(2) nm, c＝1.1209(2) nm, α＝90.32(3)°, β＝101.97(3)°, γ＝105.13(3)°, V＝0.8578(3) nm³, Z＝2, D_c＝1.357 g/cm³, F(000)＝368, µ＝0.324 mm^－1. 生物测试结果显示这5种有机化合物都具有杀菌性和植物生长调节活性     

Effects of noncovalently functionalized multiwalled carbon nanotube with hyperbranched polyesters on mechanical properties of epoxy composites

In order to improve the dispersibility and interface properties of multi-walled carbon nanotubes (MWCNTs) in epoxy resin (EP), aromatic hyperbranched polyesters with terminal carboxyl (HBP) and aromatic hyperbranched polyesters with terminal amino groups (HBPN) were used for noncovalent functionalization of MWCNTs. Epoxy composites reinforced by different types of MWCNT were prepared. The effects of noncovalent functionalization of MWCNTs on the dispersibility, wettability, interface properties and mechanical properties of epoxy composites were investigated. The results show that the dispersibility and wettability of MWCNTs are significantly improved after noncovalent functionalization. A large number of terminal primary amines (NH₂) on noncovalently functionalized MWCNT with HBPN (HBPN-MWCNT) form covalent bonds with EP matrix, and thus the interfacial adhesion is enhanced significantly, resulting in high load transfer efficiency and substantial increase in mechanical properties. The interface with covalent bonding formed between the flexible hyperbranched polyester layer on the surface of HBPN-MWCNT and the EP matrix promotes plastic deformation of the surrounding EP matrix. The toughening mechanisms of HBPN-MWCNT are MWCNT pull-out and a large amount of plastic deformation of the surrounding EP matrix.     

Lewisx五糖的有效合成: 发展DC-靶向疫苗的有效分子

将选择性保护的乳糖二醇与Lewis^x三糖在N-碘代丁二酰亚胺(NIS)/TfOH催化下高立体、高区域选择性糖苷化得Lewis^x五糖, 后者脱保护后获得目标五糖, 总收率67.7%. 化合物结构经NMR, MS和元素分析确证.