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61.
Dr. Christopher J. Shaffer Dr. Detlef Schröder Dr. Christian Alcaraz Dr. Ján Žabka Dr. Emilie‐Laure Zins 《Chemphyschem》2012,13(11):2688-2698
Even in the highly diluted gas phase, rather than electron transfer the benzene dication C6H62+ undergoes association with dinitrogen to form a transient C6H6N22+ dication which is best described as a ring‐protonated phenyl diazonium ion. Isotopic labeling studies, photoionization experiments using synchrotron radiation, and quantum chemical computations fully support the formation of protonated diazonium, which is in turn a prototype species of superacidic chemistry in solution. Additionally, reactions of C6H62+ with background water involve the transient formation of diprotonated phenol and, among other things, afford a long‐lived C6H6OH22+ dication, which is attributed to the hydration product of Hogeveen’s elusive pyramidal structure of C6H62+, as the global minimum of doubly ionized benzene. Nitrogen is essential for the formation of the C6H6OH22+ dication in that it mediates the formation of the water adduct, while the bimolecular encounter of the C6H62+ dication with water only leads to (dissociative) electron transfer. 相似文献
62.
The complex surface structure of gold-thiolate nanoparticles is known to affect the calculated density functional theory (DFT) excitation spectra. However, as the nanoparticle size increases, it becomes impractical to calculate the excitation spectrum using DFT. In this study, a new method is developed to determine the energy levels of the thiolate-protected gold nanoparticles [Au(25)(SR)(18)](-), Au(102)(SR)(44) and Au(144)(SR)(60). A 3 nm thiolate-protected nanoparticle is also modeled. The particle-in-a-sphere model is used to represent the core while the ligands are treated as point charge perturbations. The electronic structures obtained with this model are qualitatively similar to DFT results. The symmetry of the arrangement of the perturbations around the core plays a major role in determining the splitting of the orbitals. The radius chosen to represent the core also affects the orbital splitting. Increasing the number of perturbations around the core shifts the orbitals to higher energies but does not significantly change the band gaps and orbital splitting as long as the symmetrical arrangement of the perturbations is conserved. This model can be applied to any gold nanoparticle with a spherical core, regardless of its size or the nature of the ligands, at very low computational cost. 相似文献
63.
Laux S Lureau F Radier C Chalus O Caradec F Casagrande O Pourtal E Simon-Boisson C Soyer F Lebarny P 《Optics letters》2012,37(11):1913-1915
Transverse parasitic lasing is well known for limiting the signal gain and the pulse energy that can be extracted from Ti:sapphire petawatt amplifiers. We have developed a technique for suppressing these parasitic lasing modes based on perfect refractive index-matching liquid doped with a broad-bandwidth absorber to suppress the transverse lasing while ensuring proper heat removal from the Ti:sapphire crystal. The 800 nm laser output with a bandwidth of 41 nm (FWHM) and peak energy of 22.7 J at a repetition rate of 1 Hz is demonstrated. 相似文献
64.
A Echalier E Cot A Camasses E Hodimont F Hoh P Jay F Sheinerman L Krasinska D Fisher 《Chemistry & biology》2012,19(8):1028-1040
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65.
Emilie David-Guillou 《Journal of Functional Analysis》2006,238(2):734-750
We consider a family of real NA groups with rank two, and we prove that these groups have sub-Laplacians with differentiable Lp functional calculus for all p?1. 相似文献
66.
Laurent El Kaim Laetitia Gaultier Laurence Grimaud Emilie Vieu 《Tetrahedron letters》2004,45(43):8047-8048
Isocyanides react readily with trichloroacetic acid anhydride forming stable hydrates of trichloropyruvamides. These compounds are valuable intermediates for obtaining oxamides by reaction with TMSCl/NEt3 followed by addition of an amine. 相似文献
67.
We report structure-activity trends among helix-forming beta-amino acid oligomers that are intended to mimic alpha-helical host-defense peptides. Parallel synthesis of two small, focused beta-peptide libraries allowed us to identify relatively short (11-residue) beta-peptides that display antimicrobial activity. These beta-peptides exhibit selectivity for bacteria relative to human red blood cells. A large hydrophobic helical surface is necessary for antimicrobial activity. Longer analogues (16 residues) of the most active library members were prepared and evaluated. Some of these longer beta-peptides showed very good antimicrobial activity, but none was more active than a previously reported beta-peptide [Porter, E. A.; Wang, X.; Lee, H.-S.; Weisblum, B.; Gellman, S. H. Nature 2000, 404, 565]. The extensive literature on alpha-helical host-defense peptides and related alpha-peptides indicates that such molecules are seldom active at concentrations below 1 microg/mL, and our results suggest that amphiphilic helical beta-peptides are subject to a comparable limit. 相似文献
68.
[chemical reaction: see text]. An expedient synthesis of (-)-pochonin A is reported (seven steps). This natural product is closely related to radicicol and was shown to be a 90 nM inhibitor of HSP90. 相似文献
69.
Jonathan M. Curtis Peter J. Derrick Andr Schnell Emilie Constantin Richard T. Gallagher John R. Chapman 《Journal of mass spectrometry : JMS》1992,27(11):1176-1180
Electrospray ionization on Ln(tfc)3 complexes (Ln = Eu, Yb; tfc = D -3-trifluoroacetylcamphorate) was performed with samples dissolved in methanol–water containing acetic acid. The spectra were obtained with a four-sector mass spectrometer. The mass spectra exhibit ions containing tfc ligand in addition to ions with acetato ligand. Electro-spray and tandem mass spectra are presented. 相似文献
70.
Fenske Emilie K. Roach Benjamin D. Glasgow David C. Ilgner Ralph H. Giaquinto Joseph M. 《Journal of Radioanalytical and Nuclear Chemistry》2019,320(1):153-163
Journal of Radioanalytical and Nuclear Chemistry - An automated online separation–direct analysis method, RAPID (rapid analysis of post-irradiation debris), has been developed for the... 相似文献