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121.
L Andrews X Wang Y Gong T Schlöder S Riedel MJ Franger 《Angewandte Chemie (International ed. in English)》2012,51(33):8235-8238
Getting to the root of Hg: Experiments with amalgams as a source for laser-ablated Hg atoms as reaction partners with OF(2) gave strong HgF(2) IR absorptions and new bands in the Hg?F stretching region for OHgF and FOHgF molecules trapped in solid neon and argon. Assignment of these new bands to the first oxyfluoride of mercury, OHgF, and to the FOHgF insertion product is supported by quantum-chemical methods. 相似文献
122.
KN Daeffler HA Lester DA Dougherty 《Journal of the American Chemical Society》2012,134(36):14890-14896
The recently published crystal structure of the D3 dopamine receptor shows a tightly packed region of aromatic residues on helices 5 and 6 in the space bridging the binding site and what is thought to be the origin of intracellular helical motion. This highly conserved region also makes contacts with residues on helix 3, and here we use double mutant cycle analysis and unnatural amino acid mutagenesis to probe the functional role of several residues in this region of the closely related D2 dopamine receptor. Of the eight mutant pairs examined, all show significant functional coupling (Ω > 2), with the largest coupling coefficients observed between residues on different helices, C3.36/W6.48, T3.37/S5.46, and F5.47/F6.52. Additionally, three aromatic residues examined, F5.47, Y5.48, and F5.51, show consistent trends upon progressive fluorination of the aromatic side chain. These trends are indicative of a functionally important electrostatic interaction with the face of the aromatic residue examined, which is likely attributed to aromatic-aromatic interactions between residues in this microdomain. We also propose that the previously determined fluorination trend at W6.48 is likely due to a sulfur-π interaction with the side chain of C3.36. We conclude that these residues form a tightly packed structural microdomain that connects helices 3, 5, and 6, thus forming a barrier that prevents dopamine from binding further toward the intracellular surface. Upon activation, these residues likely do not change their relative conformation, but rather act to translate agonist binding at the extracellular surface into the large intracellular movements that characterize receptor activation. 相似文献
123.
提出了液相色谱串联质谱测定蜂蜜和鱼肉中烟曲霉素残留量的分析方法。蜂蜜样品和鱼肉样品分别用磷酸盐缓冲液和乙腈提取,经Oasis MAX固相萃取柱净化后,在Kinetex C18(2.6μm×2.1 mm×100 mm)反相色谱柱上以乙腈-0.1%甲酸酸水溶液(70+30)为流动相色谱分离,采用电喷雾正离子扫描、多反应监测模式(ESI+-MRM)进行质谱检测,外标法定量。方法的测定下限(10S/N)蜂蜜为2μg/kg,鱼肉为5μg/kg。在2~100μg/L的浓度范围内呈良好线性,线性相关系数>0.9997。方法在3个水平的添加回收率在75.4%~79.6%之间,相对标准偏差在6.4%~8.4%之间。方法适用于蜂产品和鱼肉中烟曲霉素残留的定量及确证检测。 相似文献
124.
125.
126.
The title molecules are prepared by reaction of OF2 molecules with laser ablated uranium and thorium atoms in solid argon and neon. 相似文献
127.
The title molecules are obtained from spontaneous reactions of coinage metals and NF3 in solid Ar and Ne matrices. 相似文献
128.
Fixed-node diffusion Monte Carlo (FNDMC) is used to simulate the x-ray absorption spectrum of a gas-phase pyrrole molecule at the nitrogen K-edge. Trial wave functions for core-excited states are constructed from ground-state Kohn-Sham determinants substituted with singly occupied natural orbitals from configuration interaction with single excitations calculations of the five lowest valence-excited triplet states. The FNDMC ionization potential (IP) is found to lie within 0.3 eV of the experimental value of 406.1 ± 0.1 eV. The transition energies to anti-bonding virtual orbitals match the experimental spectrum after alignment of IP values and agree with the existing assignments. 相似文献
129.
The outcomes following collisional quenching of electronically excited OH A (2)Σ(+) by O(2) and CO are examined in a combined experimental and theoretical study. The atomic products from reactive quenching are probed using two-photon laser-induced fluorescence to obtain H-atom Doppler profiles, O ((3)P(J)) atom fine structure distributions, and the relative yields of these products with H(2), O(2), and CO collision partners. The corresponding H-atom translational energy distributions are extracted for the H + O(3) and H + CO(2) product channels, in the latter case revealing that most of the available energy is funneled into internal excitation of CO(2). The experimental product branching ratios show that the O-atom producing pathways are the dominant outcomes of quenching: the OH A (2)Σ(+) + O(2) → O + HO(2) channel accounts for 48(3)% of products and the OH A (2)Σ(+) + CO → O + HCO channel yields 76(5)% of products. In addition, quenching of OH A (2)Σ(+) by O(2) generates H + O(3) products [12(3)%] and returns OH to its ground X (2)Π electronic state [40(1)%; L. P. Dempsey, T. D. Sechler, C. Murray, and M. I. Lester, J. Phys. Chem. A 113, 6851 (2009)]. Quenching of OH A (2)Σ(+) by CO also yields H + CO(2) reaction products [26(5)%]; however, OH X (2)Π (v(") = 0,1) products from nonreactive quenching are not observed. Theoretical studies characterize the properties of energy minimized conical intersections in four regions of strong nonadiabatic coupling accessible from the OH A (2)Σ(+) + CO asymptote. Three of these regions have the O-side of OH pointing toward CO, which lead to atomic H and vibrationally excited CO(2) products and∕or nonreactive quenching. In the fourth region, energy minimized points are located on a seam of conical intersection from the OH A (2)Σ(+) + CO asymptote to an energy minimized crossing with an extended OH bond length and the H-side of OH pointing toward CO in a bent configuration. This region, exoergic with respect to the reaction asymptote, is likely to be the origin of the dominant O + HCO product channel. 相似文献
130.
Infrared spectra of the matrix isolated OMS, OM(η(2)-SO), and OM(η(2)-SO)(η(2)-SO(2)) (M = Ti, Zr, Hf) molecules were observed following laser-ablated metal atom reactions with SO(2) during condensation in solid argon and neon. The assignments for the major vibrational modes were confirmed by appropriate S(18)O(2) and (34)SO(2) isotopic shifts, and density functional vibrational frequency calculations (B3LYP and BPW91). Bonding in the initial OM(η(2)-SO) reaction products and in the OM(η(2)-SO)(η(2)-SO(2)) adduct molecules with unusual chiral structures is discussed. 相似文献