C(膜)/Si(SiO2)(纳米微粒)/C(膜) 的光致发光性质研究

用直流辉光溅射法结合真空镀膜法制备出了一种"多层三明治结构"的光致发光材料-C(膜)/Si(SiO2)(纳米微粒)/C(膜)夹层膜,然后分别在400、650和750℃退火1 h.在波长为250 nm的紫外光激发下,刚制备出来未经退火处理的样品具有一个在398nm(3.12 eV)处的紫光宽带PL1峰.在650℃退火后,又出现了一个在360nm(3.44eV)附近的PL2峰.PL1和PL2峰形状和峰位与退火温度和激发波长无关,但强度却与退火温度和激发波长密切相关.结合形态结构分析可知,紫光PL1峰可用量子限制-发光中心(QC-LCs)模型进行解释:即光激发发生在8iO2微粒内部,而光发射源于SiO2与Si界面上的缺陷中心.紫外荧光PL2峰则源自SiC内部的电子-空穴复合发光.     

Small Gold(I) and Gold(I)–Silver(I) Clusters by C−Si Auration

Auration of o-trimethylsilyl arylphosphines leads to the formation of gold and gold–silver clusters with ortho-metalated phosphines displaying 3c–2e Au−C−M bonds (M=Au/Ag). Hexagold clusters [Au₆L₄](X)₂ are obtained by reaction of (L−TMS)AuCl with AgX, whereas reaction with AgX and Ag₂O leads to gold–silver clusters [Au₄Ag₂L₄](X)₂. Oxo-trigold(I) species [Au₃O]⁺ were identified as the intermediates in the formation of the silver-doped clusters. Other [Au₅], [Au₄Ag], and [Au₁₂Ag₄] clusters were also obtained. Clusters containing PAu−Au−AuP structural motif display good catalytic activity in the activation of alkynes under homogeneous conditions.     

C(膜)/Si(SiO2 )(纳米微粒)/C(膜)热处理的形态及结构分析

用直流辉光溅射+真空镀膜法制备了一种新型结构的硅基纳米发光材料- C(膜)/Si(SiO2)(纳米微粒)/C(膜)夹层膜,并对其进行了退火处理.用TEM、 SEM、 XRD和XPS对其进行了形态结构分析.TEM观察表明: Si(SiO2)纳米微粒基本呈球形,粒径在30 nm左右.SEM观察表明: 夹层膜样品总厚度约为50 μm,膜表面比较平整、致密.400℃退火后,样品表面变得凹凸不平,出现孔状结构; 650℃退火后,样品表面最平整、致密且颗粒均匀.XRD分析表明:制备出的夹层膜主要由SiO2和Si组成,在C原子的还原作用和氧气的氧化作用的共同作用下, SiO2和Si的含量随加热温度的升高而呈现交替变化: 400℃时, C的还原作用占主导地位, SiO2几乎全部被还原成了Si,此时Si含量最高; 400～650℃时,氧化作用占主导地位, Si又被氧化成SiO2, Si含量降低, SiO2含量逐渐上升,在650℃达到最高.XPS分析表明: 在加热过程中, C原子逐渐扩散进入Si(SiO2)微粒层,在650℃与Si反应生成了新的SiC.     

(Me3Si)2CH]2(i)PrSi(NHC)Si═Si(Me)Si(i)Pr[CH(SiMe3)2]2]+: a molecule with disilenyl cation character

Reaction of the disilyne-NHC complex 1 [RLSi═SiR: (R = Si(i)Pr[CH(SiMe(3))(2)](2), L = NHC)] with MeOTf gave the cation 2 [RLSi═SiRMe](+), which is the first example of a base-stabilized heavy group 14 element analogue with vinyl cation character. Cation 2 has been fully characterized by multinuclear NMR spectroscopy and X-ray diffraction analysis. The molecular structure indicates that there are significant contributions from the NHC-stabilized cationic resonance structure 2A, the disilene-like structure 2B, and even some contribution from the silylene-like structure 2C.     

Tetrakis(2-fluorophenylamino)silan und sein erstes Kondensationsprodukt N-(2-fluorophenyl)-Si,Si, Si,Si′, Si′, Si′-hexakis(2-fluorophenylamino)-disilazan. Synthesen und Kristallstrukturen

Zusammenfassung Tetrakis(2-fluorophenylamino)silan (1) wurde als Precursor zur Darstellung poröser, nitridischer Festkörper synthetisiert und mit Hilfe der Einkristallröntgenstrukturanalyse charakterisiert (C2/c;a=16.771(7) Å,b=16.827(5) Å,c=16.753(6) Å, ß=111.00(2)°,z=8). Beim Erhitzen mit Ammoniumcarbamat als Katalysator wurde N-(2-fluorophenyl)-Si, Si, Si, Si, Si, Si, -hexakis(2-fluorophenylamino)disilazan (2) als erstes Kondensationsprodukt isoliert ( ;a=9.331(1) Å,b=13.698(5) Å,c=16.164(4) Å, =90.34(2)°, ß=103.03(2), =103.04(3)°, Z=2).

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Tetrakis(2-fluorophenylamino)silane and its first product of condensation N-(2-fluorophenyl-Si, Si, Si, Si, Si, Si-hexakis(2-fluorophenylamino)disilazane. Syntheses and crystal structures

Summary The synthesis and crystal structure determination of silanetetramine N,N,N,N2-fluorophenyl(C2/c;a=16.771(7) Å,b=16.827(5) Å,c=16.753(6) Å, ß=111.00(2)°, z=8) are reported. In a search for suitable condensation pathways to silicon/nitrogen based porous solids, N-(2-fluorophenyl)-Si,Si,Si,Si,Si,Si-hexakis(2-fluorophenylamino)disilazane (2) has been obtained from the ammonium carbamate catalyzed condensation of the silanetetramine in teflon lined autoclaves. The X-ray crystal structure determination ( ;a=9.331(1) Å,b=13.698(5) Å,c=16.164(4) Å, =90.34(2)°, ß=103.03(2)°, =103.04(3)°, Z=2) shows the disilazane to be a dimer formed by linear condensation from the monomeric silazane.

     

异噻唑-3-三烷基(苯基)硅醚的~(29)Si和~(13)C NMR谱

自然界中含硅的有机化合物非常丰富,因此,在结构解析中,利用NMR技术作为分析手段是很有用的。~(29)Si的磁矩(μ=-0.691核磁子)比~(13)C的(μ-1.216核磁子)小,但天然丰度为4.70％,在相同的磁场下,实际的灵敏度应为~(13)C的二倍。然而~(29)Si的自旋-晶格弛豫时间T_1,从数秒到100秒,普通在20秒左右,故脉冲FT累加不能提高灵敏度,加之     

~(13)C核磁共振(六)

分子式为C_6H_8O的哪一个化合物与图E-11符合? 取谱条件: 溶剂:CDCl_3(δ77.2三重峰) 浓度:50V/V％温度:28℃测定频率:22.63MHz 去偶:上——~1H偏共振去偶(500次) 下——~1H宽带去偶(100次) [解答]C_6H_8O含有三个双键当量。在~(13)C谱中找到一个羰基(δ198.65)以及一个C=C键(δ150.6及129.85)。还余下一个双键与三个次甲基(δ38.2,25.75及22.95)。总结起     

~(13)C核磁共振(五)

习题1 分子式为C_4H_(10)S的哪一个化合物符合图E-1的~(13)C谱?对此谱作出归属。取谱条件: 溶剂:CDCl_3(δ77.25处有三重峰,图中未画出) 浓度:50V/V％温度:28℃测定频率:22.63MHz 去偶:上——~1H偏共振去偶(200次) 下——~1H宽带去偶(100次)     

~(13)C核磁共振(七)

习题16 1,3,5-三硝基苯与丙酮在氢氧化钾的乙醇溶液存在下反应生成一种蓝紫色的Meisenheimer钾盐,见谱E-16。分析此谱并给出从谱所得最重要的论点以支持此盐的结构。取谱条件: 溶剂,(eD,),50(3,.7七重峰,Je-一20.5Hz) 浓度:饱和溶液温度:28℃测定频率:22.63 MHz 去偶.上.偶合谱(25000次),附有放大四倍的部分谱下:几H宽带去偶( 5000次)〔解答〕谱的归属     

~(13)C核磁共振(四)

9 ~(13)C自旋-晶格弛豫时间(T_1)的测量及应用 9.1 测定T_1的方法 9.1.1 倒向—恢复法此法是用(180°-τ-90°)_n脉冲系列作用于样品。磁化矢量M_0在180°脉冲作用下倒向(图20b),在自旋-晶格弛豫过程中,磁化矢量从-M_0经0到 M_0弛豫,在这一过程中,即过了时间τ后,90°脉冲将部份弛豫的磁化矢量M_τ旋转到X(?)Y平面中,并在接收线圈中感应出FID信号。如果τ很短,M_τ还是负的(M_τ<0),90°脉冲(?)_1,作用后M_τ沿X向负Y轴旋转(图20c),     

~(13)C核磁共振(三)

8.1 通过一个键的C与H偶合除了化学位移之外,C—H的偶合常数也能提供重要的信息,测量J值时必须取不去偶或用交替脉冲双共振方法。这两种方法都需时较长,并且要求样品量较多。~1J_(CH)也可从~1H谱的~(13)C卫星线测得。 ~1J_(CH)在120-130Hz之间~2J(CH)、~3J(CH)~4J(CH)都小于     

~(13)C核磁共振(一)

自从物理学家发现核磁共振(NMR)有化学位移,从而使NMR进入了有机化学实验室,到现在已有三十年了。早期,最常见的是高分辨~1H谱。70年代以后,由于引入了PFT技术,NMR灵敏度低的困难已经解决了,因此,测定低丰度核的工作受到广泛重视,其中最重要的是~(13)C。自从有了PFT的商品仪器,~(13)C NMR工作蓬勃开展,文献急剧增加,可以认为:~(13)C与~1H NMR相辅相成,是目前有机化学家手中最强有力的武器。我国建立NMR技术已有十多年的历史,~(13)C方面也有了不少工作。到目前为止,介绍~(13)C谱基础知识的资料还十分少,为此,我们编译了德同化学家von E.Breitmaier及G.Bauer所著的《~(13)C NMR Spektroskopie》一书,并选译部分练习题,以供有机化学工作者参考。本文将以连载方式在本刊载出。限于编译者的水平,错误难免,请批评指正。     

~(13)C核磁共振(二)

4.识别图谱的化学方法 4.1 氘代用化学方法将样品中的某些位置上的氢以重氢(~2D)代替之后,与这个氢键接的~(13)C共振峰就发生相应变化,利用这种变化可以识别谱峰。~2D的I=1,因此,CD,CD_2,CD_3的碳顺次表现为三重峰(1:1:1),五重峰(1:3:5:3:1)及七重峰(1:3:5:7:5:3:1),又由于~2D有四极弛豫作用,使~(13)C讯号加宽,这两重原     

Ylenes in the M(II)→Si(IV) (M=Si, Ge, Sn) coordination mode

The reaction of the methimazolyl (mt, i.e., 2-mercapto-1-methylimidazolide) substituted silane Si(mt)(4) with SnCl(2) and GeCl(2) in dioxane affords the paddlewheel-shaped complexes [ClSi(μ-mt)(4)MCl] (M=Sn (1) and Ge (2), respectively). These compounds represent the first crystallographically characterized hexacoordinate silicon complexes comprising a Sn or Ge atom in the Si coordination sphere. An attempt to synthesize the related silicon compound 3 [ClSi(μ-mt)(4)SiCl] instead afforded the trisilane [ClSi(μ-mt)(4)Si-SiCl(3)] (3a), which provides the first crystallographic evidence for the feasibility of oligosilanes with adjacent hexacoordinate Si atoms. One of the hexacoordinate Si atoms of 3a features the unprecedented (Si(2)S(4))Si skeleton. Natural bonding orbital (NBO) analyses of compounds 1, 2, 3a (and the target compound 3) revealed characteristics of M(II)→Si(IV) (for 2 and 3) or M(I)→Si(IV) (for 3a) dative bonding in the systems with M=Si and Ge, whereas compound 1 exhibits a covalent Sn(III)-Si(III) bond.     

Si4X(X=C,N,O,Si,P,S)原子簇结构的理论研究

在密度泛函B3LYP/6-311G*水平上, 对具有C3v对称的Si4X (X = C, N, O, P, S)原子簇进行了几何构型优化计算, 并讨论它们的热力学稳定性、动力学活性、Mulliken布居、SiX键长、占据价轨道的对称性以及HOMO能级位置等周期递变规律。     

格尔德霉素C(11)～C(21)片段的合成

以D-三乙酰葡萄糖烯为最初原料,经三步反应合成了已知内酯化合物5.以羰基α位亚甲基化、底物诱导的不对称催化氢化反应为关键步骤,构建了关键的C(14)位手性中心.最终,经10步反应、以24%的总产率合成了苯醌安莎霉素类天然产物格尔德霉素(Geldanamycin)的C(11)~C(21)片段.     

(Me3Si)2NBCl2和(Me3Si)2NB(Cl)NHSiMe3的合成及其成环反应

自从氮化硼陶瓷纤维用聚合物先驱体法[1]合成以后,硼氮六元环化合物越来越为人们所重视[2],文中在制备氮化硼纤维先驱体的过程中,合成了其中间产物,通过热缩合成环反应,合成了含有硼氮六员环的化合物,并采用色-质联用技术对其进行了表征。1　实验部分参照文献[3],改用液氮和丙酮为冷冻剂,控制温度在-50到-40℃,搅拌下向三氯化硼的正戊烷溶液中缓慢滴加三乙胺的正戊烷溶液,滴完后Ｎ2气氛下-50℃加丙酮冷凝回流2ｈ,慢慢由-50℃升至室温,抽滤即得到白色产物Ｅｔ3ＮＢＣｌ3(Ａ)。将Ａ溶于适量苯中[4,5],加入等物质的量的三乙胺,加热回流搅拌…     

Tris(pentafluoroethyl)silanol Derivatives and the Lewis Amphoteric Tris(pentafluoroethyl)silanolate Anion, [Si(C2F5)3O]−

While alkyl-substituted siloxanes are widely known, virtually nothing is known about perfluoroalkyl siloxanes and their congener species, the silanols and silanolates. We recently reported on the tris(pentafluoroethyl)silanide ion, [Si(C₂F₅)₃]⁻, which features Lewis amphoteric character deriving from the pentafluoroethyl substituents and their strong electron-withdrawing properties. Transferring this knowledge, we investigated the Lewis amphoteric behavior of the tris(pentafluoroethyl)silanolate, [Si(C₂F₅)₃O]⁻. In order to examine such Lewis amphoteric behavior, we first developed a strategy for the synthesis of the corresponding silanol Si(C₂F₅)₃OH, which readily condenses at room temperature to the hexakis(pentafluoroethyl)disiloxane, (C₂F₅)₃SiOSi(C₂F₅)₃. Deprotonation of Si(C₂F₅)₃OH employing a sterically demanding phosphazene base allows the characterization of the first example of a dimeric triorganosilanolate: the dianionic hexakis(pentafluoroethyl)disilanolate, [{Si(C₂F₅)₃O}₂]²⁻, implies Lewis amphoteric character of the monomeric [Si(C₂F₅)₃O]⁻ anion.     

Mn-mediated reductive C(sp3)–Si coupling of activated secondary alkyl bromides with chlorosilanes

The construction of secondary alkylsilanes is a challenging subject in the synthetic community. The cross-coupling provides a practical solution to address this problem, but it typically relies on organometallic species. Herein, we report an Mn-mediated reductive C(sp³)–Si coupling to synthesize these compounds from alkyl and silyl electrophiles. This approach avoids the requirement for activation of Si–Cl by transition metals and thus allows for the coupling of various common chlorosilanes. The reaction proceeds under mild conditions and shows good functional group compatibility. The method offers access to α-silylated organophosphorus and sulfones with a scope that is complementary to those obtained from the established methods.     

Total synthesis of erythronolide B. 2. Skeleton assembly in (C5C9) + (C3C4) + (C1C2) + (C11C13) sequence.

Erythronolide B has been synthesized starting from levoglucosan.