TMEDA-Na2O-SiO2-Al2O3-H2O系统沸石的水热结晶

在四甲基乙基二胺(TMEDA)-Na2O-SiO2-Al2O3-HO2系统中,水热反应产物的沸石相,随配料硅铝比提高,依次为Md(丝光沸石),TMEDA-Md,ZSM-35,ZSM-5,ZSM-39及一种我们称为CF-3的新沸石.从沸石的组成,性质,晶体结构与"模极分子"的构型等方面,讨论了TMEDA对诱导上述沸石的生成所起的电荷平衡与孔道充填的共同作用向笼的充填作用的转变.     

THF-FER沸石的系列研究—Ⅱ．模板剂分子THF的位置

用^13C HPDEC MAS NMR与热分析方法表征了在四氢呋喃（THF）-Na2O-SiO2- Al2O3-H2O体系中水热合成的高硅Na-THF-FER沸石、酸交换后的H-THF-FER沸石以及 吸附于Na-FER和H-FER沸石中的THF。结果证明，模板剂分子THF位于Na-THF-FER沸 石骨架的FER笼内，平衡骨架阳离子Na^+主要存在于十元环孔道；而吸附子FER沸石 中的THF仅处于十元环孔道中，合成样品中THF的化学位移与液态THF相比，向低场 移动，谱线明显变宽，表明THF分子与FER笼之间存在很强的相互作用。     

模板分子TMEDA成CF—3及ZSM—39沸石笼中的位置及其与骨…

用ＸＲＤ、ＦＴＩＲ、ＴＧ－ＤＴＡ、＾１３Ｃ魔角固体核磁共振表征用四甲基乙基二胺（ＴＭＥＤＡ）为结构异向剂合成的高硅沸石ＣＦ－３及ＺＳＭ－３９．ＴＭＥＤＡ不同基团的＾１３Ｃ化学位移，共振峰相对强度在交叉极化（ＣＰ）及高功率去偶（ＨＰＤＥＣ）核磁共振谱中的变化，揭示出模板分子在尺寸不同的沸石笼中的位置、运动状态及其与骨架的相互作用。在ＺＳＭ－３９沸石中的ＴＭＥＤＡ分子，它的－Ｃ２Ｈ４－基团＾１３Ｃ共振     

~(13)C核磁共振中的APT技术

在脉冲傅里叶变换~(13)C核磁共振研究中,~(13)C偏共振谱,因为它谱线的多重性直接与碳原子的类型有关,从残余偶合常数的大小又可以定性地了解碳原子与分子中电负性基因之间的相对位置,所以与宽带质子去偶~(13)C谱一起成了确定谱线归属和研究分子结构最常用的~(13)C图谱。然而,正是因为在偏共振谱中~(13)C信号以多重峰形式出现,信噪比随之下降,使得实     

高硅沸石合成中四氢呋喃模板作用的初步研究

在四氢呋喃(THF)-Na~2O-SiO~2-Al~2O~3-H~2O体系中,水热条件下合成出的沸石相,随配料硅铝比提高,依次为MOR(丝光沸石),ZSM-35,ZSM-5和ZSM-39,1^3^CCP/MASNMR谱,TG/DTG/DTA和EDX成分分析方法对沸石中的THF进行表征,1^3^C谱化学位移的显著变化,以及THF高的脱除温度,证明作为模板剂的THF分子进入所合成的沸石结构,并与骨架发生强的相互作用。     

钛、锆、铪有机化合物的研究——双(环戊二烯基)及双(甲基环戊二烯基)二芳基衍生物的合成和性质

本文由Cp_2MCl_2和CP′_2MCl_2(CP=η~5-C_5H_5,CP′=η~5-CH_3C_5H_4,M=Ti,Zr,Hf)与芳基锂反应合成了一系列新的钛、锆、铪的双(环戊二烯基),双(甲基环戊二烯基)二芳基衍生物,研究了这些金属芳基衍生物的水解反应,锆和铪衍生物易发生水解,钛衍生物不易水解,它们与氯化氢、乙酰氯、溴和氢卤酸反应形成相应金属的双(环戊二烯基)二卤化物,文中还讨论了(η~5-CH_3C_5H_4)_2MAr_2和(η~5-CH_3C_5H_4)_2MX_2系列衍生物的核磁共振和红外光谱。     

茂金属催化剂催化1-癸烯齐聚研究（英文）

考察了1-癸烯和不同结构的茂金属催化剂((η~5-C_5H_5)_2ZrC l_2,A;[μ,μ-(Me_2Si)_2(η~5-C_5H_3)_2][(η~5-C_5H_5)ZrC l_52)]2,B;[(C_6H_5)C(Me)_2(η~5-C_5H_4)]_2ZrC l_2,C;t BuN C(Me)_2(η-C_5H_4)ZrC l_2,D;(η-C_5H_4)C(C_5H_(10))(η~5-C_513H_8)ZrC l_2,E;(η~5-C_5H_4)C(Me)_2(η-C_(13)H_8)ZrC l_2,F;(η_5-C_5H_4)C(C_6H_5)_2(η~5-C_(13)H_8)ZrC l_2,G)/MAO的齐聚反应,并探讨了茂金属F的用量,聚合温度和Al/Zr比对聚合反应和齐聚物性能的影响.实验结果表明,由于其不同的位阻效应和电子效应,不同结构的茂金属对1-癸烯的催化活性和齐聚物组分分布影响显著.其中,Cp_2ZrCl_2,双核硅桥联的茂金属B和大位阻的茂金属C主要合成低粘度的齐聚物(100℃Kv:2~3 cS t,二聚体含量约为60%);限制构型的茂金属D因为有更加开放的配位结构呈现出高的催化活性,齐聚物的粘度也略高(100℃Kv:3~4 cS t);Cs-对称型茂金属E,F,G都有较高的催化活性,合成的齐聚物粘度也较高(100℃Kv20cS t),主要归因于茂金属的特殊结构和聚合机理.GC-MS结果表明茂金属催化1-癸烯合成的齐聚物异构化较少,主要由二聚体到五聚体的混合物组成.茂金属F催化1-癸烯较优的齐聚条件是催化剂用量10μmol,聚合温度80℃,Al/Zr比300∶1.     

呋喃多烯酸酯类三岔共轭体系结构和性能之间的定量关系——(Ⅰ)紫外光谱

本文合成及制备了下述六个系列的化合物并测定了它们的紫外光谱、质谱。结果表明: α-C_4H_3O-(CH=CH)nCHO (FA-n) n=2,3,4,5。 α-C_4H_3O-(CH=CH)nCN FN-n) n=1,2,3~*,4~*,5~*。 α-C_4H_3O-(CH=CH)nCO_2Et (FE-n) n=1,2,3~*,5~*。 α-C_4H_3O-(CH=CH)nCH=C(CN)CO_2H (FNA-n)n=0,1,3~*,4~*。 α-C_4H_3O-(CH=CH)nCH=C(CN)CO_2Et (FNE-n)n=0,1,3~*,4~*, α-C_4H_3O-(CH=CH)nCH=C(CO_2Et)_2·(FM-n) n=0,1,3~*,4~*,5~*。 (*:表示文献中未知的化合物) 在环己烷、乙醇,甲醇和四氯化碳溶剂中各组电子吸收峰的波数与同系因子相联系时,都各有一条而且只有一条良好的直线。同系线性规律的专一性表明了,在呋喃多烯三岔系列中,呋喃环的端基当量仍然是2。并不因为在烯链的另一端具有两个强吸电子的共轭分岔基团的存在而增大呋喃环的端基当量。在FM-n系列中,利用经验公式算得的Sj′以及利用相似三角形式算得的sj的平均值都在0.4左右。这就定量地表明了,在末端二个羧酸酯基中,只可能有一个是端基,而另一个是代基。λ′计-λ实的最大值小于80的事实表明,FM-n系列的紫外吸收频率与结构之间的定量关系可以用扩大同系方程来近似地表示。但在FNE-n系列中,由于氰基的存在,用扩大同系方程计算得到的λ值与实验值偏差较大,?     

ZSM—35,ZSM—5及丝光沸石中模板分子TMEDA质子化的研究

用＾１３Ｃ魔角固体核磁共振及化学分析研究处在高硅沸石ＺＳＭ－３５、ＺＳＭ－５及丝光沸石孔道中模板分子四甲基乙撑二胺（ＴＭＥＤＡ）的质子化。＾１３Ｃ核磁共振谱中δ＝３４～３７ｐｐｍ的共振峰可归属于单端质子化的模板分子。它们有序地分布在上述沸石的主孔道中。质子告近－ＣＨ３基团，远离－Ｃ２Ｈ４－基团。     

三取代环丙烷的^1^3C核磁共振谱研究

前文曾报道三取代环丙烷的质子核磁共振谱及其解析结果,讨论了取代基对化学位移和偶合常数的影响.环丙烷的~(13)C核磁共振谱研究报道极少。Monti等人研究了甲基、溴代和乙炔基环丙烷的~(13)C核磁共振谱,发现在多取代的环丙烷中,取代基相互之间的影响是很显著的.Clague等人亦报道了一系列环丙烷的~(13)C核磁共振谱,但未有详细的分析.本文报道10种尚未见载于文献的三取代环丙烷的~(13)C核磁共振谱,数据见表1. 在1,2,3-三取代环丙烷中,由于取代基的相互作用,影响环上碳的化学位移的因素是比较复杂的.从我们测定化合物的数据来看,取代基为CH_3的环上碳的平均化学位移为29.24     

2D NMR方法研究抗癌药物冬凌草乙素的结构与谱线归属

用异核化学位移相关谱、远程异核化学位移相关谱和同核化学位移相关谱等现代核磁共振技术对抗癌中草药冬凌草中分离出的抗癌、抗菌有效成分冬凌草乙素分子的~(13)C和~1H化学位移进行了完全归属,为冬凌草乙素分子溶液中的三维空间结构研究提供了可靠的结构参数。     

强酸性环境中氧氟沙星的质子化模型研究

利用核磁共振波谱技术研究了不同浓度硫酸溶液中氧氟沙星(OFL)的1H,19F和13C核磁共振谱,对不同硫酸浓度引起的δH,δF,δC和JFC耦合常数的变化进行比较分析,由此推测其结构状态.综合1H,19F和13C核磁共振谱特点及其变化,提出OFL分子在强酸性环境中N1'被进一步质子化的结构模型.在浓硫酸溶液中,N1'被进一步质子化,并与F9形成氢键(N1'—H+┈F9),该结构使分子的共轭程度大幅降低,导致其荧光发射波长、荧光激发波长及紫外吸收波长均发生蓝移.硫酸溶液中氧氟酸和甲基氧氟沙星的荧光光谱行为进一步证明了OFL分子在浓硫酸溶液中质子化模型的合理性.     

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.     

Assessing the reactivity of sodium zincate [(TMEDA)Na(TMP)Zn(t)Bu2] towards benzoylferrocene: deprotonative metalation vs. alkylation reactions

Exploring the reactivity of the mixed-metal reagent [(TMEDA)Na(TMP)Zn(t)Bu(2)] (1) towards substituted metallocene benzoylferrocene 2, this study has found that two competing reactivity pathways are available for the sodium TMP-zincate, namely (i) remote 1,6-nucleophilic addition of a tert-butyl group to the phenyl ring of 2, and (ii) simultaneous alpha-deprotonation of the substituted cyclopentadienyl ring of the metallocene and alkylation (1,2-addition) across the C=O bond of the carbonyl group. A key organometallic intermediate [(TMEDA)Na(μ-TMP)Zn{OC((t)Bu)(Ph)(η(5)-C(5)H(3))Fe(η(5)-C(5)H(5))}] (3), resulting from the latter reaction has been trapped and characterised by X-ray crystallography and multinuclear ((1)H and (13)C) NMR spectroscopy. Its molecular structure revealed a unique two-fold activation of the tert-butyl groups bonded to zinc in the bimetallic base 1, showing for the first time that each alkyl group can exhibit markedly different reactivities (deprotonation vs. 1,2-addition) towards the same substrate molecule. Iodine interception of the organometallic intermediates of the reaction between 1 and 2 allowed the isolation and characterization ((1)H, (13)C NMR and X-ray crystallography) of the ferrocenyl derivatives [PhC(OH)((t)Bu)(η(5)-C(5)H(3)I)Fe(η(5)-C(5)H(5))] (4) and [4-(t)Bu-C(6)H(4)C([double bond, length as m-dash]O)(η(5)-C(5)H(4))Fe(η(5)-C(5)H(5))] (5) in a 29% and 24% isolated yield respectively. The low yield observed for the formation of 5 (resulting from the 1,6-addition reaction followed by spontaneous aerobic oxidation during aqueous workup) could be increased to 41% when the reaction mixture was hydrolysed in the presence of the radical oxidant TEMPO.     

NMR studies of viomycin

The ¹H and ¹³C NMR spectra of antibiotic Viomycin sulphate and its constituent aminoacids in H₂O and D₂O were examined in a wide range of pH values. The spectra were analysed by proton spin-spin decoupling experiments and measurements of the relative intensities of the resonance and chemical shift values. Exchange experiments were also carried out and an almost complete assignment of the resonances of the spectra was possible. The data obtained are discussed in terms of possible structures for Viomycin and the presence of intramolecular hydrogen bonds. Some information about the conformation of the molecule is also given. A tentative assignment of the ¹³C spectrum of Viomycin is given and the experimental ¹³C chemical shift values compare well with the theoretical ones evaluated by Grant's rule.     

Protonation of carbon single-walled nanotubes studied using 13C and 1H-13C cross polarization nuclear magnetic resonance and Raman spectroscopies

The reversible protonation of carbon single-walled nanotubes (SWNTs) in sulfuric acid and Nafion was investigated using solid-state nuclear magnetic resonance (NMR) and Raman spectroscopies. Magic-angle spinning (MAS) was used to obtain high-resolution 13C and 1H-13C cross polarization (CP) NMR spectra. The 13C NMR chemical shifts are reported for bulk SWNTs, H2SO4-treated SWNTs, SWNT-Nafion polymer composites, SWNT-AQ55 polymer composites, and SWNTs in contact with water. Protonation occurs without irreversible oxidation of the nanotube substrate via a charge-transfer process. This is the first report of a chemically induced change in a SWNT 13C resonance brought about by a reversible interaction with an acidic proton, providing additional evidence that carbon nanotubes behave as weak bases. Cross polarization was found to be a powerful technique for providing an additional contrast mechanism for studying nanotubes in contact with other chemical species. The CP studies confirmed polarization transfer from nearby protons to nanotube carbon atoms. The CP technique was also applied to investigate water adsorbed on carbon nanotube surfaces. Finally, the degree of bundling of the SWNTs in Nafion films was probed with the 1H-13C CP-MAS technique.     

1-Methylphenanthro[3,4-b]thiophene: Determination of the tertiary structure in solution and in the crystalline state by NMR spectroscopy and X-ray diffraction

1-Methylphenanthro[3,4-b]thiophene was prepared by the photocyclization of 1-(4′-methyl-2′-thienyl)-2-(2″-naphthyl)ethene. The ¹H and ¹³C-nmr spectra were assigned using two-dimensional ¹H/¹³C heteronuclear chemical shift correlation and relayed coherence transfer (RELAY) experiments. From nuclear Overhauser difference spectra, the H11-C1 methyl-H intramolecular distance was determined to be 2.10 Å. The molecule crystallized from chloroform in the monoclinic system, space group P2₁/c. A total of 3536 unique reflections were measured and the structure was solved by direct methods and refined to a final R = 0.049. The molecule is helical with both chiral forms observed in the crystal. The H11-C1 methyl-H distance in the crystal was 2.12(3)Å in excellent agreement with the distance measured in solution by NOE techniques.     

UV-visible and 1H or 13C NMR spectroscopic studies on the specific interaction between lithium ions and the anion from tropolone or 4-isopropyltropolone (hinokitiol) and on the formation of protonated tropolones in acetonitrile or other solvents

The specific interaction between lithium ions and the tropolonate ion (C(7)H(5)O(2)-: L-) was examined by means of UV-visible and 1H or 13C NMR spectroscopy in acetonitrile and other solvents. On the basis of the electronic spectra, we can propose the formation of not only coordination-type species (Li+(L-)2) and the ion pair (Li+L-) but also a "triple cation" ((Li+)2L-) in acetonitrile and acetone; however, no "triple cation" was found in N,N-dimethylformamide (DMF) and in dimethylsulfoxide (DMSO), solvents of higher donicities and only ion pair formation between Li+ and L- in methanol of much higher donicity and acceptivity. The 1H NMR chemical shifts of the tropolonate ion with increasing Li+ concentration verified the formation of (Li+)2L- species in CD3CN and acetone-d6, but not in DMF-d6 or CD(3)OD. With increasing concentration of LiClO(4) in CD(3)CN, the 1H NMR signals of 4-isopropyltropolone (HL') in coexistence with an equivalent amount of Et(3)N shifted first toward higher and then toward lower magnetic-fields, which were explained by the formation of (Li+)(Et(3)NH+)L'- and by successive replacement of Et(3)NH+ with a second Li+ to give (Li+)2L'-. In CD(3)CN, the 1,2-C signal in the 13C NMR spectrum of tetrabutylammnium tropolonate (n-Bu(4)NC(7)H(5)O) appeared at an unexpectedly lower magnetic-field (184.4 ppm vs TMS) than that of tropolone (172.7 ppm), while other signals of the tropolonate showed normal shifts toward higher magnetic-fields upon deprotonation from tropolone. Nevertheless, with addition of LiClO(4) at higher concentrations, the higher and lower shifts of magnetic-fields for 1,2-C and other signals, respectively, supported the formation of the (Li+)2L- species, which can cause redissolution of LiL precipitates. All of the data with UV-visible and 1H and 13C NMR spectroscopy demonstrated that the protonated tropolone (or the dihydroxytropylium ion), H(2)L+, was produced by addition of trifluoromethanesulfonic or methanesulfonic acid to tropolone in acetonitrile. The order of the 5-C and 3,7-C signals in 13C NMR spectra of the tropolonate ions was altered by addition of less than an equivalent amount of H+ to the tropolonate ion in CD(3)CN. Theoretical calculations satisfied the experimental 13C NMR chemical shift values of L-, HL, and H(2)L+ in acetonitrile and were in accordance with the proposed reaction schemes.