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121.
We present density functional theory calculations of the nuclear magnetic resonance spectroscopy of molecules encapsulated within single walled carbon nanotubes. Ring currents in the nanotube induce shifts in the chemical shift of the nuclei comprising the encapsulated molecule. These changes in the chemical shifts are shown to have characteristic dependence on the chirality of the surrounding nanotubes. 相似文献
122.
Kitchen JA Noble A Brandt CD Moubaraki B Murray KS Brooker S 《Inorganic chemistry》2008,47(20):9450-9458
The first dinuclear iron(II) complexes of any 4-substituted 3,5-di(2-pyridyl)-4H-1,2,4-triazole ligands, [Fe(II)2(adpt)2(H2O)1.5(CH3CN)2.5](BF4)4 and [Fe(II)2(pldpt)2(H2O)2(CH3CN)2](BF4)4, are presented [where adpt is 4-amino-3,5-di(2-pyridyl)-4H-1,2,4-triazole and pldpt is 4-pyrrolyl-3,5-di(2-pyridyl)-4H-1,2,4-triazole]. Both dinuclear complexes feature doubly triazole bridged iron(II) centers that are found to be [high spin-high spin] at all temperatures, 4-300 K, and to exhibit weak antiferromagnetic coupling. In the analogous monometallic complexes, [Fe(II)(Rdpt)2(X)2](n+), the spin state of the iron(II) center was controlled by appropriate selection of the axial ligands X. Specifically, both of the chloride complexes, [Fe(II)(adpt)2(Cl)2] x 2 MeOH and [Fe(II)(pldpt)2(Cl)2] x 2 MeOH x H2O, were found to be high spin whereas the pyridine adduct [Fe(II)(adpt)2(py)2](BF4)2 was low spin. Attempts to prepare [Fe(II)(pldpt)2(py)2](BF4)2 and the dinuclear analogues [Fe(II)2(Rdpt)2(py)4](BF4)4 failed, illustrating the significant challenges faced in attempts to develop control over the nature of the product obtained from reactions of iron(II) and these bis-bidentate ligands. 相似文献
123.
Robin?W.?TuckerEmail author David?A.?Burton Adam?Noble 《General Relativity and Gravitation》2005,37(9):1555-1574
A new geometric approximation scheme, designed to solve the covariant Maxwell equations inside a rotating hollow slender conducting
cavity (modelling a ring-laser) on a background spacetime, is constructed. It is shown that for well-defined conditions the
electromagnetic spectrum splits into TE- and TM-type modes. A twisted mode spectrum is found to depend on the integrated Frenet
torsion of the cavity and this in turn may affect the Sagnac beat frequency induced by a non-zero rotation of the cavity. 相似文献
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125.
J.V. Noble 《Nuclear Physics A》1979,329(3):354-364
The phenomenological relativistic theory of nuclear single-particle dynamics is reviewed and its salient characteristics discussed. The phenomenological (relativistic) potential strengths necessary to secure agreement with the usual low-energy properties of nuclei are determined. These phenomenological potentials are then related to the time-independent meson fields generated by nuclei, and it is shown by direct calculation that the potential strengths predicted on the basis of renormalized meson-nucleon couplings (as measured in, say, NN scattering) are consistent with those deduced empirically. Thus the phenomenological theory is shown to be consistent with a more microscopic approach, in agreement with the work of previous authors. The role of the ρ-meson is then examined, and it is shown that the time-independent ρ-field leads to isovector terms in both the central and spin-orbit terms of the equivalent Schrödinger potential. The signs and magnitudes of these terms agree with those determined from fits to the isobaric analogue (p, n) reactions, or to the systematics of single-particle energies. 相似文献
126.
Visible‐Light‐Mediated Decarboxylative Radical Additions to Vinyl Boronic Esters: Rapid Access to γ‐Amino Boronic Esters
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Dr. Adam Noble Riccardo S. Mega Dr. Daniel Pflästerer Dr. Eddie L. Myers Prof. Dr. Varinder K. Aggarwal 《Angewandte Chemie (International ed. in English)》2018,57(8):2155-2159
The synthesis of alkyl boronic esters by direct decarboxylative radical addition of carboxylic acids to vinyl boronic esters is described. The reaction proceeds under mild photoredox catalysis and involves an unprecedented single‐electron reduction of an α‐boryl radical intermediate to the corresponding anion. The reaction is amenable to a diverse range of substrates, including α‐amino, α‐oxy, and alkyl carboxylic acids, thus providing a novel method to rapidly access boron‐containing molecules of potential biological importance. 相似文献
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The orientation and dynamics of two 40-nm thick films of 4-n-pentyl-4'-cyanobiphenyl (5CB), a nematic liquid crystal, have been studied using step-scan Fourier transform infrared spectroscopy (FTIR). The films are confined in nanocavities bounded by an interdigitated electrode array (IDA) patterned on a zinc selenide (ZnSe) substrate. The effects of the ZnSe surface morphology (specifically, two variations of nanometer-scale corrugations obtained by mechanical polishing) on the initial ordering and reorientation dynamics of the electric-field-induced Freedericksz transition are presented here. The interaction of the 5CB with ZnSe surfaces bearing a spicular corrugation induces a homeotropic (surface normal) alignment of the film confined in the cavity. Alternately, when ZnSe is polished to generate fine grooves along the surface, a planar alignment is promoted in the liquid crystalline film. Time-resolved FTIR studies that enable the direct measurement of the rate constants for the electric-field-induced orientation and thermal relaxation reveal that the dynamic transitions of the two film structures are significantly different. These measurements quantitatively demonstrate the strong effects of surface morphology on the anchoring, order, and dynamics of liquid crystalline thin films. 相似文献