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81.
Cover Picture: Absolute Configuration from Different Multifragmentation Pathways in Light‐Induced Coulomb Explosion Imaging (ChemPhysChem 16/2016) 下载免费PDF全文
Dr. Martin Pitzer Gregor Kastirke Dr. Maksim Kunitski Dr. Till Jahnke Dr. Tobias Bauer Christoph Goihl Florian Trinter Carl Schober Kevin Henrichs Jasper Becht Stefan Zeller Helena Gassert Markus Waitz Andreas Kuhlins Hendrik Sann Felix Sturm Florian Wiegandt Dr. Robert Wallauer Dr. Lothar Ph. H. Schmidt Allan S. Johnson Manuel Mazenauer Benjamin Spenger Sabrina Marquardt Sebastian Marquardt Prof. Dr. Horst Schmidt‐Böcking Prof. Dr. Jürgen Stohner Prof. Dr. Reinhard Dörner Dr. Markus Schöffler Prof. Dr. Robert Berger 《Chemphyschem》2016,17(16):2448-2448
82.
Sebastian T. Marcus Lawrence R. Gahan Paul V. Bernhardt 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):655-658
The structures of diaqua(1,7‐dioxa‐4‐thia‐10‐azacyclododecane)nickel dinitrate, [Ni(C8H17NO2S)(H2O)2](NO3)2, (I), bis(nitrato‐O,O′)(1,4,7‐trioxa‐10‐azacyclododecane)mercury, [Hg(NO3)2(C8H17NO3)], (II), and aqua(nitrato‐O)(1‐oxa‐4,7,10‐triazacyclododecane)copper nitrate, [Cu(NO3)(C8H19N3O)(H2O)]NO3, (III), reveal each macrocycle binding in a tetradentate manner. The conformations of the ligands in (I) and (III) are the same and distinct from that identified for (II). These differences are in agreement with molecular‐mechanics predictions of ligand conformation as a function of metal‐ion size. 相似文献
83.
A series of synthetic [2Fe-2S] complexes with terminal thiophenolate ligands and tethered ether or thioether moieties has been prepared and investigated in order to provide models for the potential interaction of additional donor atoms with the Fe atoms in biological [2Fe-2S] clusters. X-ray crystal structures have been determined for six new complexes that feature appended Et (1(C)), OMe (1(O)), or SMe (1(S)) groups, or with a methylene group (2(C) ), an ether-O (2(O)), or an thioether-S (2(S)) linking two aryl groups. The latter two systems provide a constrained chelate arrangement that induces secondary bonding interactions with the ether-O and thioether-S, which is confirmed by density functional theory (DFT) calculations that also reveal significant spin density on those fifth donor atoms. Structural consequences of the secondary bonding interactions are analyzed in detail, and effects on the spectroscopic and electronic properties are probed by UV-vis, M?ssbauer, and (1)H NMR spectroscopy, as well by SQUID measurements and cyclic voltammetry. The potential relevance of the findings for biological [2Fe-2S] sites is considered. 相似文献
84.
Burck S Gudat D Nieger M Du Mont WW 《Journal of the American Chemical Society》2006,128(12):3946-3955
P-Hydrogen-substituted 1,3,2-diazaphospholenes 1 were prepared by an improved procedure from diazadienes and were characterized by spectroscopy and in one case by X-ray diffraction. A unique hydride-type reactivity of the P-H bonds was documented by extensive reactivity studies. Aldehydes and ketones were readily reduced to diazaphospholene derivatives of the corresponding alcohols, with alkyl-substituted ketones being converted at much lower rates than aldehydes or diaryl ketones. Reactions with the tetrachlorides of group 14 elements proceeded via hydride/chloride metathesis to give either partially chlorinated derivatives EH(n)Cl(4-n) (n = 0-3 for E = C, Si) or HCl and phosphenium salts 16c[ECl3] (for E = Ge, Sn) which were characterized by spectroscopic and X-ray diffraction studies. Tin dichloride was readily reduced to the element. Reactions of 1c with the P-chloro-diazaphospholene 3c and the salt 16c[OTf] allowed the first experimental detection of intermolecular exchange of a hydride, rather than a proton, between phosphine derivatives. Computational studies indicated that the hydride transfer between 1c and the cation 16c involves a transient H-bridged species with bonding properties similar to those of B2H7-. The preference for the formation of these bridged intermediates over P-P bonded phosphenium-phosphine adducts is attributed to the low electrophilicity of the diazaphospholenium cations and characterizes a novel reaction mode for phosphenium ions. 相似文献
85.
Daniel A. Vega John M. Sebastian Yueh‐Lin Loo Richard A. Register 《Journal of Polymer Science.Polymer Physics》2001,39(18):2183-2197
Triblock copolymers in midblock‐selective solvents can form physical gels. However, at low triblock contents (near the percolation threshold), the bridging of chains between micelles can lead to macrophase separation. Adding a styrene–isoprene diblock to a styrene–isoprene–styrene triblock copolymer in squalane can eliminate macrophase separation, yielding a wide range of stable, single‐phase gels with a disordered arrangement of micelles. The plateau modulus of these triblock gels scales with the 2.2 power of polymer content, indicating the importance of entanglements in dictating the modulus. Comparing gels made from the midblock‐saturated derivative of the same polymer [styrene‐(ethylene‐alt‐propylene)‐styrene] in squalane reveals that the modulus differences in the gels are a direct consequence of the difference in the entanglement molecular weight of the midblock homopolymer in bulk. Finally, the broad relaxation spectrum of these triblocks is well‐described by a recent theory for the dynamics of entangled star polymers, with the breadth of the relaxation spectrum dictated by the number of entanglements per midblock in the gel. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2183–2197, 2001 相似文献
86.
Shetty V Spellman DS Neubert TA 《Journal of the American Society for Mass Spectrometry》2007,18(8):1544-1551
Cysteine sulfenic acid (Cys-SOH) is an elusive intermediate in reactive oxygen species-induced oxidation reactions of many proteins such as peroxiredoxins and tyrosine phosphatases. Cys-SOH is proposed to play a vital role in catalytic and signaling functions. The formation of cysteine sulfinic acid (Cys-SO(2)H) and cysteine sulfonic acid (Cys-SO(3)H) has been implicated in the activation of matrix metalloproteinase-7 (MMP-7) and oxidation of thiol to cysteine sulfinic acid has been associated with the autolytic cleavage of MMP-7. We have examined the formation of cysteine sulfenic acid in a synthetic peptide PRCGVPDVA, which is a cysteine switch domain of MMP-7 and other matrix metalloproteases. We have prepared the cysteine sulfenic acid containing peptide, PRC(SOH)GVPDVA, by reaction with hydroxyl radicals generated by the Fenton reaction (Fe(+2)/H(2)O(2)). We characterized this modified peptide by tandem mass spectrometry and accurate mass measurement experiments. In addition, we used 7-chloro-4-nitrobenzo-2-oxa-1,3-diazol (NBD-Cl) reagent to form an adduct with PRC(SOH)GVPDVA to provide additional evidence for the viability of PRC(SOH)GVPDVA in solution. We also characterized an intramolecular cysteine sulfinamide cross-link product PRC[S(O)N]GVPDVA based on tandem mass spectrometry and accurate mass measurement experiments. These results contribute to the understanding of a proteolytic cleavage mechanism that is traditionally associated with MMP activation. 相似文献
87.
Metallo-β-lactamases (mβls) cause bacterial resistance toward a broad spectrum of β-lactam antibiotics by catalyzing the hydrolytic cleavage of the four-membered β-lactam ring, thus inactivating the drug. Minutiae of the mechanism of these enzymes are still not well understood, and reports about binding studies of the substrates to the enzymes as well as to synthetic model systems are rare. Here we report a new pyrazolate-based bioinspired dizinc complex (1) reminiscent of the active site of binuclear mβls. Since 1 does not mediate hydrolytic degradation of β-lactams, the binding of a series of common β-lactam antibiotics (benzylpenicillin, cephalotin, 6-aminopenicillanic acid, ampicillin) as well as the inhibitor sulbactam and the simplest β-lactam, 2-azetidinone, to the dizinc core of 1 could now be studied in detail by NMR and IR spectroscopy as well as mass spectrometry. X-ray crystallographic information was obtained for 1 and its complexes with 2-azetidinone (2) and sulbactam (3); the latter represents the first structurally characterized dizinc complex with a bound β-lactam drug. While 2-azetidinone was found deprotonated and bridging in the clamp of the two zinc ions in 2, in 3 and all other cases the substrates preferentially bind via their carboxylate group within the bimetallic pocket. The relevance of this binding mode for mβls and consequences for the design of functional model systems are discussed. 相似文献
88.
Zhang M Imm S Bähn S Neubert L Neumann H Beller M 《Angewandte Chemie (International ed. in English)》2012,51(16):3905-3909
Amid(e) them all: primary carboxamides and ureas react with aromatic and aliphatic amines in the presence of a copper catalyst to give a wide range of functionalized amides. 相似文献
89.
Thermophysical properties and material modelling of acrylic bone cements used in vertebroplasty 总被引:1,自引:0,他引:1
Sebastian Kolmeder Alexander Lion Ralf Landgraf Jörn Ihlemann 《Journal of Thermal Analysis and Calorimetry》2011,105(2):705-718
The stabilization of osteoporotic vertebrae with acrylic bone cement, called vertebroplasty, is a common procedure in modern
surgery. However, the thermomechanical-chemically coupled material behaviour of curing bone cements makes the application
even for experienced surgeons difficult and can lead to potential complications like heat necrosis, leaking bone cement, embolisms
and postoperative load shifting. In order to reduce these potential complications, to minimize the risks and to better understand
the occurring effects, the thermophysical properties of a commercial acrylic bone cement were investigated in detail using
differential scanning calorimetry, volumetric dilatometry and temperature controlled rheometry. More specifically, the reaction
kinetics, the specific heat, the thermal conductivity, the thermal expansion, the chemical shrinkage as well as the mechanical
behaviour was studied during the reaction process of the bone cement. Furthermore, the explored material behaviour is described
by a customized material model that takes into account all observed effects. With the aid of this model the inhomogeneous
chemical, thermal and mechanical states that appear during the application and curing of acrylic bone cements, can be studied
by finite element treatment. 相似文献
90.
Xie W Herrmann C Kömpe K Haase M Schlücker S 《Journal of the American Chemical Society》2011,133(48):19302-19305
The synthesis of bifunctional Au/Pt/Au nanoraspberries for use in quantitative in situ monitoring of platinum-catalyzed reactions by surface-enhanced Raman scattering (SERS) is presented. Highly convolved SERS spectra of reaction mixtures can be decomposed into the contributions of distinct molecular species by multivariate data analysis. 相似文献