Pathways for C-H bond cleavage of propane σ-complexes on PdO(101)

We used dispersion-corrected density functional theory (DFT-D3) calculations to investigate the initial C-H bond cleavage of propane σ-complexes adsorbed on the PdO(101) surface. The calculations predict that propane molecules adsorbed in η(1) configurations can undergo facile C-H bond cleavage on PdO(101), where the energy barrier for C-H bond activation is lower than that for desorption for each molecular complex. The preferred pathway for propane dissociation on PdO(101) corresponds to cleavage of a primary C-H bond of a so-called staggered p-2η(1) complex which initially coordinates with the surface by forming two H-Pd dative bonds, one at each CH(3) group. Among all of the adsorbed propane complexes, the staggered p-2η(1) complex has the highest binding energy and must overcome the lowest energy barrier for C-H bond scission. Analysis of the atomic charges reveals that propane C-H bond cleavage occurs heterolytically on PdO(101), and suggests that primary C-H bond activation is favored because a more stabilizing charge distribution develops within the 1-propyl transition state structures. Lastly, we conducted kinetic simulations using microkinetic models derived from the DFT-D3 structures, and find that the models reproduce the apparent activation energy for propane dissociation on PdO(101) to within 14% of that determined experimentally. We show that the entropic contributions of the adsorbed transition structures greatly exceed those predicted by the harmonic oscillator model, and that quantitative agreement with the apparent dissociation pre-factor may be obtained by approximating two of the frustrated adsorbate motions as free motions while treating the remaining modes as harmonic vibrations.     

Calculation of average L shell fluorescence yields for the elements with 25≤Z≤101

Average L shell fluorescence yield , average L shell Auger yields and the total L shell X-ray fluorescence (LXRF) cross sections (σ _L ^x ) at 30 keV have been calculated theoretically for the elements with 25≤Z≤101. These calculated values have been compared with the other experimental and theoretical values.     

High selectivity for primary C-H bond cleavage of propane σ-complexes on the PdO(101) surface

We investigated regioselectivity in the initial C-H bond activation of propane σ-complexes on the PdO(101) surface using temperature programmed reaction spectroscopy (TPRS) experiments. We observe a significant kinetic isotope effect (KIE) in the initial C-H(D) bond cleavage of propane on PdO(101) such that the dissociation yield of C(3)H(8) is 2.7 times higher than that of C(3)D(8) at temperatures between 150 and 200 K. Measurements of the reactivity of (CH(3))(2)CD(2) and (CD(3))(2)CH(2) show that deuteration of the methyl groups is primarily responsible for the lower reactivity of C(3)D(8) relative to C(3)H(8), and thus that 1° C-H bond cleavage is the preferred pathway for propane activation on PdO(101). By analyzing the rate data within the context of a kinetic model for precursor-mediated dissociation, we estimate that 90% of the propane σ-complexes which dissociate on PdO(101) during TPRS do so by 1° C-H bond cleavage.     

WSHF-101新型红外水分仪

广东省测试分析研究所研制的WSHF-101型红外水分仪是广东省科委的重点攻关科研项目,于1990年6月下旬由省科委主持通过鉴定。WSHF-101型红外水分仪是一种非接触式的检测仪表,由传感器、二次仪表(带有CPU和微型打印     

Ir nanoclusters confined within hollow MIL-101(Fe) for selective hydrogenation of α,β-unsaturated aldehyde

Although the selective hydrogenation of α,β-unsaturated aldehyde to unsaturated alcohol(UOL) is an extremely important transformation, it is still a great challenge to achieve high selectivity to UOL due to thermodynamic favoring of the C=C hydrogenation over the C=O hydrogenation. Herein, we report that iridium nanoclusters(Ir NCs) confined within hollow MIL-101(Fe) expresses satisfied reaction activity(93.9%) and high selectivity(96.2%) for the hydrogenation of cinnamaldehyde(CAL) to cinnamyl ...     

NK-101分子筛的合成及表征

本文使用对二甲胺吡啶为模板剂,在水热条件下合成了一种新型热稳定的微孔磷铝分子筛NK-101, 并对其进行了XRD、扫描电镜(SEM)、正己烷吸附、红外吸收光谱(IR)、²⁷Al和³¹P的固体魔角旋转核磁共振(MAS-NMR)的表征.证明它具有微孔结构,其孔径大于0.43nm.晶粒为太米状多边形,尺寸在几个到十几个微米,命名为NK-101.     

大肠杆菌HB101感受态的热化学研究

利用LKB-2277生物活性检测系统,测定了在生理盐水中,采用氯化钙法建立大肠杆菌感受态过程中的代谢热输出。生理盐水中大肠杆菌及其感受态进行内源代谢的热化学方程满足:P=K~c+A,dc/dP~0=K'c^0,氯化钙处理后,K与P~0均增大,说明内源代谢活性增强,这与大肠杆菌感受态建立过程中一系列生理生化活性的调整是一致的,表明大肠杆菌感受态的建立很可能有其内在的调节机制,而不完全是人工诱导的。     

Novel Synthesis of Cu-Schiff Base Complex@Metal-Organic Framework MIL-101 via a Mild Method: A Comparative Study for Rapid Catalytic Effects

The use of metal complex immobilized/decorated porous materials as catalysts has found various applications. As such, finding a new and mild method for synthesis of metal complex immobilized over porous material is of great interest. Immobilized porous materials for styrene oxidation were reported in this work. Immobilized porous material of Cu-Schiff base complex @MIL-101 were described, in which immobilized Cu-Schiff base complex within super cage of a metal-organic framework (MOF)-based porous material, chromium (III) terephthalate MIL-101. They were systematically characterized by using elemental analysis, powder X-ray diffraction, fourier transform infrared spectroscopy, N₂ absorption-desorption, and so on, also used as catalyst for the selective oxidation of styrene to benzaldehyde. Comparatively, the immobilized heterogeneous catalyst of Cu-Schiff base complex@MIL-101 acted as an efficient heterostructure catalyst in the oxidation of styrene to benzaldehyde up to six cycles, and showed superior activity for styrene oxidation over MIL-101.     

关於101号元素——钔的制备

在1954年初,曾經發表过有关門捷列夫週期表上第99和100号兩个新元素的消息。这兩个元素的名称叫做鍰(En)和鐨(Fm)的元素是用快速的氮核和氧核轰击鈾靶并按下列反应合成的: _(92)U~(238)+_7N~(14)—→_99En _(92)U~(228)+_8O~(16)—→_100Fm 第一个反应是在加里福尼亚大学內,由錫波尔格领導的一批科学家們所完成的;而第二个反应是在斯德哥尔摩研究所由瑞典的科学家实現的。另一种制造一系列超鈾元素的方法处用鈾堆的慢中子强流照射在鐶的靶上。     

Cr-MIL-101-NH_2的手性后合成修饰

采用后合成修饰技术(postsynthetic modification,PSM)设计并合成手性金属-有机框架化合物(metal-organic frameworks,MOFs),将L型脯氨酸衍生物Boc-L-ProCl,后修饰到金属有机-框架化合物Cr-MIL-101-NH_2孔道中,制得手性金属有机-框架化合物Cr-MIL-101-PaB_2。经核磁(~1H NMR)结果证实,修饰产率高达64%,固体圆二色谱(CD)测试结果表明经后合成修饰后的CrMIL-101-PaB_2具有旋光性。红外光谱(IR)、氮气脱附-吸附、热重(TGA)、粉末X射线衍射(PXRD)手段对其进行表征。实验结果证实,为避免金属-有机框架化合物自组装的不确定性,采用后合成修饰技术,可按需合成手性金属有机-框架化合物。     

第101至109号元素的英文命名

第１０１至１０９号元素的英文命名ＩＵＰＡＣ无机化学命名委员会于１９９４年１２月发表第１０１至１０９号元素的命名如下。详见ＰｕｒｅＡｐｐｌ．Ｃｈｅｍ．，１９９４：６６（１２）：２４１９（童卫粟）第101至109号元素的英文命名@童卫粟...     

Fe-MIL-101催化Paal-Knorr反应合成吡咯衍生物

以Fe-MIL-101为非均相催化剂,通过多种伯胺与2,5-二甲氧基四氢呋喃进行Paal-Knorr反应,高效合成相应的吡咯衍生物.在Fe-MIL-101结构中,裸露的Fe(Ⅲ)配位点作为催化活性中心参与吡咯衍生物的催化合成反应.同时Fe-MIL-101的高比表面积和大的孔尺寸确保了底物分子与催化活性中心的充分接触以及产物的自由脱离,从而促进了催化反应的快速进行.Fe-MIL-101在催化反应过程中具有很好的稳定性,多次循环使用后仍能表现出良好的催化性能.此外,该催化剂在伯胺(包括脂肪胺、芳香胺)与2,5-己二酮的Paal-Knorr缩合反应中也具有优异的催化性能.     

合成氨装置101D堵塞物中晶体定性分析

基于Boentgen、Laue与Ewald、W.H.Bragg及W.L.Bragg、Friedrich和Knipping等前辈X射线及其晶体学的研究与发现,X射线晶体结构分析已成为研究原子或离子在晶体点阵中结合、鉴定晶体化合物空间结构的可靠方法.Debye-Scherrer粉晶X射线衍射法(XRPD)在合成氨装置101D工况技术分析中,比较有意义的实际应用是解决由不同单质或化合物组成的复杂混合堵塞物中晶体的鉴定问题.采用XRPD定性分析了合成氨装置101D堵塞物样品中的主要晶体成分.实验结果表明:本法对合成氨装置101D工况技术分析具有重要的意义.     

CoSAPO-101分子筛大单晶的合成与表征

<正>1982年Wilson等首次以有机胺作为模板剂,通过水热法合成了由Al-O和P-O共享氧桥交替组合而成的磷酸铝分子筛(AlPO4)[1],由于其骨架呈中性,表面酸性和催化能力较弱,使其应用受到影响。通过在磷酸铝分子筛骨架上引入金属或非金属杂原子,同晶置换部分骨架中的磷和铝,使骨架电荷     

Salen-Cu(Ⅱ)@MIL-101(Cr) as an efficient heterogeneous catalyst for cycloaddition of CO_2 to epoxides under mild conditions

A double active center system, namely Salen-Cu(Ⅱ)@MIL-101(Cr), was successfully synthesized via the"ship in a bottle" approach, which acted as a bifunctional material for both capture and conversion of CO_2 in a single process. For the first time, Salen-Cu(Ⅱ)@MIL-101(Cr) catalyst was developed for the synthesis of propylene carbonate from CO_2 and propylene oxide under room temperature and ambient pressure with a yield of 87.8% over 60 h. Furthermore, the reaction mechanism was also discussed.     

农抗101-己及庚的分离及结构

农抗101是从制霉菌素产生菌金色链霉菌A-94菌株发酵液中得到的抗真菌油状物.经逆流分溶和分部结晶等方法从农抗101中分到了八个成分,农抗101-己及庚为其中两个成分.经元素分析、紫外光谱、红外光谱、核磁共振及质谱等分析,证明农抗101-己的结构为β-氨甲酰甲基-γ-(2-羟基-3,5-二甲基苯甲酰)-丁内酯;农抗101-庚的结构为β-[(2-羟基-3,5-二甲基苯甲酰)羟甲基]-戊二酰亚胺.     

以醋酸盐为矿化剂合成金属有机骨架MIL-101

以醋酸钠为矿化剂, 通过水热合成法直接获得了较纯净的Material Institut Lavoisier-101(MIL-101). 样品经粉末X射线衍射、比表面积及孔径分布和热重分析表征, 并与以氢氟酸为矿化剂合成的MIL-101进行了比较. 结果表明, 以醋酸钠为矿化剂合成的MIL-101的性能优于以氢氟酸作为矿化剂合成的MIL-101, 并且样品经后续纯化处理后能进一步提高比表面积和孔容; 用非定域密度泛函法(NLDFT)分析计算得到了MIL-101的孔结构信息. 合成的MIL-101骨架能稳定至300 ℃以上, 其热稳定性略低于以氢氟酸作为矿化剂合成的MIL-101.