排序方式: 共有73条查询结果,搜索用时 281 毫秒
61.
Carsten von Hänisch PD Dr. 《无机化学与普通化学杂志》2008,634(1):23-29
The range of molecular silicon phosphorus compounds has been extended by some new species containing oligosilane ((R2Si)n; n ≥ 2) or oligosiloxane ((R2SiO)mSiR2; m ≥ 1) fragments bound to phosphorus atoms. Primary and secondary compounds of these types allow for the synthesis of metal derivatives. Such metalated species usually form oligomers and exhibit a versatile structural chemistry with cyclic, polycyclic, and cage‐like patterns. The main results obtained in the field of oligosilane‐ and oligosiloxane‐bridged phosphines will be presented below and the structures of the metal derivatives will be discussed. Moreover, the synthesis of an inorganic ligand on the basis of siloxane‐bridged phosphines will be presented. This compound opens up a new chapter in host‐guest chemistry. 相似文献
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Dennis Rottschäfer Beate Neumann Dr. Hans-Georg Stammler Dr. Ryohei Kishi Prof. Dr. Masayoshi Nakano PD Dr. Rajendra S. Ghadwal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(13):3244-3247
Para-quinodimethane (pQDM) is a fundamental structural component in many π-conjugated organic molecules and materials. The incorporation of phosphorus atom into π-conjugated frameworks offers unique opportunities for controlling the properties of derived species. A phosphorus analogue of p-quinodimethane (pQDM), (IPrC)2P4 [ 5 , IPr=C{N(Ar)CH2}2; Ar=2,6-iPr2C6H3] featuring a planar P4 ring, was readily accessible by KC8-reduction of (IPrC)(PCl2)2 ( 2 ). Base-mediated C−H functionalization of IPrCH2 ( 1 ) with PCl3 afforded 2 . The formation of 5 was expected to occur through a dimerization of the transient 3H-diphosphirene (IPrC)P2 ( 4 ), which was theoretically suggested to have an intermediate diradical character. Compound 5 underwent photo-induced ring-contraction reaction to form the singlet diradicaloid (IPrCP)2 VI and white phosphorus (P4). The formation of and VI and P4 suggested the formal diphosphorus (P2) elimination from 5 . Indeed, photolysis of a mixture of 1,3-cyclohexadiene (CHD) and 5 led to the formation of P2-entrapped product (CHD)2P2 ( 6 ). The compound 5 represents the first organophosphorus species that functions as a P2 source. 相似文献
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Christian Gebhardt Dr. Martin Lehmann Dr. Maria M. Reif Prof. Dr. Martin Zacharias PD Dr. Gerd Gemmecker Prof. Dr. Thorben Cordes 《Chemphyschem》2021,22(15):1566-1583
The use of fluorescence techniques has an enormous impact on various research fields including imaging, biochemical assays, DNA-sequencing and medical technologies. This has been facilitated by the development of numerous commercial dyes with optimized photophysical and chemical properties. Often, however, information about the chemical structures of dyes and the attached linkers used for bioconjugation remain a well-kept secret. This can lead to problems for research applications where knowledge of the dye structure is necessary to predict or understand (unwanted) dye-target interactions, or to establish structural models of the dye-target complex. Using a combination of optical spectroscopy, mass spectrometry, NMR spectroscopy and molecular dynamics simulations, we here investigate the molecular structures and spectroscopic properties of dyes from the Alexa Fluor (Alexa Fluor 555 and 647) and AF series (AF555, AF647, AFD647). Based on available data and published structures of the AF and Cy dyes, we propose a structure for Alexa Fluor 555 and refine that of AF555. We also resolve conflicting reports on the linker composition of Alexa Fluor 647 maleimide. We also conducted a comprehensive comparison between Alexa Fluor and AF dyes by continuous-wave absorption and emission spectroscopy, quantum yield determination, fluorescence lifetime and anisotropy spectroscopy of free and protein-attached dyes. All these data support the idea that Alexa Fluor and AF dyes have a cyanine core and are a derivative of Cy3 and Cy5. In addition, we compared Alexa Fluor 555 and Alexa Fluor 647 to their structural homologs AF555 and AF(D)647 in single-molecule FRET applications. Both pairs showed excellent performance in solution-based smFRET experiments using alternating laser excitation. Minor differences in apparent dye-protein interactions were investigated by molecular dynamics simulations. Our findings clearly demonstrate that the AF-fluorophores are an attractive alternative to Alexa- and Cy-dyes in smFRET studies or other fluorescence applications. 相似文献
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Katrin Meier Raul Cardoso‐Gil Walter Schnelle Helge Rosner Ulrich Burkhardt Ulrich Schwarz PD Dr. 《无机化学与普通化学杂志》2010,636(8):1466-1473
A series of isotypic rare‐earth metal pentagermanides including the new compound TbGe5 were prepared by high‐pressure synthesis. They crystallize in the orthorhombic space group Immm [No. 71; a = 395.70(9) pm; b = 611.1(2) pm, and c = 983.6(3) pm for TbGe5]. The crystal structure is isotypic to LaGe5 and consists of puckered germanium slabs, which sandwich a second germanium species and the rare‐earth metal atoms. At ambient pressure, the thermal decomposition of the phases REGe5 (RE = La, Nd, Sm, Gd, and Tb) proceeds via discrete intermediate steps into Ge(cF8) and thermodynamically stable germanium‐poorer phases. The investigated compounds REGe5 are paramagnetic metallic conductors, which order antiferromagnetically at low temperatures. Specific heat measurements reveal that the superconducting state of LaGe5 below Tc = 7.1(1) K is characterized by a critical field of μ0Hc2 = 0.2 T and weak electron‐phonon coupling. Density‐functional based band‐structure calculations yield a very similar electronic structure for all the isotypic REGe5 compounds. Besides a slight increase in the width of the valence band for smaller RE atoms, only minor differences are found for the two different germanium environments. 相似文献
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Diaryl‐substituted triazenides Ar(Ar′)N3HgX [Ar/Ar′ = Dmp/Mph, X = Cl ( 2a ), Br ( 3a ), I ( 4a ); Ar/Ar′ = Dmp/Tph, X = Cl ( 2b ), I ( 4b ) with Mph = 2‐MesC6H4, Mes = 2,4,6‐Me3C6H2, Tph = 2′,4′,6′‐triisopropylbiphenyl‐2‐yl and Dmp = 2,6‐Mes2C6H3] were synthesized by salt‐metathesis reactions in ethyl ether from the readily available starting materials Ar(Ar′)N3Li and HgX2. These compounds may be used for redox‐transmetallation reactions with rare‐earth or alkaline earth metals. Thus, reaction of 4b or 2b with magnesium or ytterbium in tetrahydrofuran afforded the triazenides Dmp(Tph)N3MX(thf) ( 5b : M = Mg, X = I; 6b : M = Yb, X = Cl) in good yield. All new compounds were characterized by melting point, 1H and 13C NMR spectroscopy and for selected species by IR spectroscopy or mass spectrometry. In addition, the solid‐state structures of triazenides 2a , 2b , 3a , 4b , 5b and 6b were investigated by single‐crystal X‐ray diffraction. 相似文献
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Christian Schenk Florian Henke Marco Neumaier Matthias Olzmann Hansgeorg Schnöckel Prof. Dr. Andreas Schnepf PD Dr. 《无机化学与普通化学杂志》2010,636(7):1173-1182
The cluster anion {Ge9[Si(SiMe3)3]3}– ( 1 ) is transferred intact into the gas phase via the electro spray method. Subsequently the fragmentation of 1 after resonant excitation as well as the oxidation reaction with O2 and Cl2 are investigated in an FT‐ICR mass spectrometer (Fourier Transform Ion Cyclotron Resonance). Unlike former results with off‐resonant excitation the fragmentation leads mainly to the end‐product Ge9–. Moreover, applying an on‐resonant excitation the dissociation experiment can be quantified; 2.0 ± 0.15 eV (193 ± 15kJ · mol–1) for the elimination of the first two ligands and 2.7 ± 0.15 eV (261 ± 15 kJ · mol–1) for all ligands, respectively. Particular attention is turned on the first step, where sterically encumbered Si2(SiMe3)6 molecules are formed in a concerted reaction. This result, which is also important for elemental reactions on metal surfaces in catalyses, is based on experimentally determined threshold energies, DFT calculations and calculations on the lifetime of the involved species., In contrast to the high reactivity of crystalline 1 ·Li(THF)4, gaseous 1 is inert against oxygen. The analogy to recently published spin forbidden reactions of Al13– with O2 hints to a general importance of spin conversion during gas phase reactions of larger cluster molecules. The oxidation of 1 with Cl2 proceeds through different reaction channels. DFT calculations give a first insight on the complex primary oxidation steps. These calculations also reveal that the delocalized bonding situation in the Ge9 core is distorted upon oxidation. This result together with the dissociation experiments shed more light on differences and similarities between metalloid clusters and Zintl ions. 相似文献
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Novel alkali trimolybdates of the triclinic (M, M′)2Mo3O10 (M = Rb; M′ = K, Cs) type were obtained through a systematic hydrothermal approach based on the reaction of MoO3 with alkali halide solutions at 180 °C. The crystal structures were determined from X‐ray single crystal data. The alkali trimolybdates extend the family of known alkali trimolybdates in an unexpected fashion, because they contain a distorted variation of [Mo3O10]2? chains as a key structural motif that has only been found in a single compound before, namely ethylenediammonium trimolybdate, (C2H10N2)[Mo3O10]. The applied hydrothermal strategy is discussed in the general context of systematic pathways to polyoxomolybdates. Furthermore, the templating role of the alkali cations and their interaction with the polyoxomolybdate surroundings is compared to (C2H10N2)[Mo3O10] in terms of electrostatic calculations. 相似文献