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51.
Guarino G Rastrelli F Scrimin P Mancin F 《Journal of the American Chemical Society》2012,134(17):7200-7203
Gd(3+) ions, once bound to the monolayer of organic molecules coating the surface of gold nanoparticles, produce a paramagnetic relaxation enhancement (PRE) that broadens and eventually cancels the signals of the nuclear spins located nearby (within 1.6 nm distance). In the case of nanoparticles coated with mixed monolayers, the signals arising from the different coating molecules experience different PRE, depending on their distance from the binding site. As a consequence, observation of the signal broadening patterns provides direct information on the monolayer organization. 相似文献
52.
Barbero M Cadamuro S Cauda F Dughera S Gervasio G Venturello P 《The Journal of organic chemistry》2012,77(9):4278-4287
An initial study has been accomplished into the synthetic feasibility of the preparation of diarylcarbenium salt via the direct coupling of aryl (or heteroaryl) aldehydes and arenes (or heteroaryl analogues) in the presence of a strong organic Br?nsted acid. A number of stabilized aryl or heteroaryl(3-indolyl)carbenium ions, never previously prepared in the solid state, have been isolated in excellent yields as highly stable o-benzenedisulfonimide salts and have been fully characterized. Their purity has been proven by spectroscopic methods and chemical reduction with NaBH(4). An X-ray crystal structure analysis has been performed on one of the products: an azafulvenium species was shown to be the exclusive structure in the solid state. 相似文献
53.
Manca F Giordano S Palla PL Zucca R Cleri F Colombo L 《The Journal of chemical physics》2012,136(15):154906
Stretching experiments on single molecules of arbitrary length opened the way for studying the statistical mechanics of small systems. In many cases in which the thermodynamic limit is not satisfied, different macroscopic boundary conditions, corresponding to different statistical mechanics ensembles, yield different force-displacement curves. We formulate analytical expressions and develop Monte Carlo simulations to quantitatively evaluate the difference between the Helmholtz and the Gibbs ensembles for a wide range of polymer models of biological relevance. We consider generalizations of the freely jointed chain and of the worm-like chain models with extensible bonds. In all cases we show that the convergence to the thermodynamic limit upon increasing contour length is described by a suitable power law and a specific scaling exponent, characteristic of each model. 相似文献
54.
Patrizia Scafato Francesca Caprioli Laura Pisani Daniele Padula Fabrizio Santoro Giuseppe Mazzeo Sergio Abbate France Lebon Giovanna Longhi 《Tetrahedron》2013
Three forms of chiroptical spectroscopies, electronic circular dichroism (ECD), vibrational circular dichroism (VCD), and optical rotatory dispersion (ORD) have been employed to study the configuration and conformational properties of the three molecules: (S)-3-phenylcyclopentanone, (S)-3-phenylcyclohexanone, and (S)-3-phenylcycloheptanone (including (S)-3-phenylcyclopentanone-2,2,5,5-d4 and (S)-3-phenylcyclohexanone-2,2,6,6-d4). ECD and VCD spectra in the mid-IR for the three molecular systems are marginally dependent on fine conformational details, as interpreted in terms of standard DFT computational methods, with common spectroscopic features to the three systems clearly identified. Accounting for vibronic coupling mechanisms reproduces the structuring of ECD n→π∗ band. The ORD curves are quite similar for the three types of molecules, but their interpretation highlights a crucial role played by conformations of the cycloalkanone ring in the case of (S)-3-phenylcycloheptanone. The same conclusions are reached by considering the VCD spectra in the CH-stretching region. 相似文献
55.
Reduction of nitrobenzene by excess organic electron donor, 12, affords diphenylhydrazine in a reaction where azobenzene oxide and azobenzene are likely intermediates. No cleavage of the N-N σ-bond is seen under photoactivation conditions, whereas traces are seen under thermal activation. Hydrazone derivatives were prepared to explore the cleavage of N-N σ-bonds; the results show that a low-lying LUMO assists the transition state for accepting an electron, and the stabilisation that the potential fragments from N-N bond cleavage afford to the fragments is important in determining whether cleavage is observed. 相似文献
56.
Jingjing Liu Dr. Daniel Reta Jake A. Cleghorn Yu Xuan Yeoh Dr. Fabrizio Ortu Dr. Conrad A. P. Goodwin Dr. Nicholas F. Chilton Dr. David P. Mills 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(32):7749-7758
As the dysprosocenium complex [Dy(Cpttt)2][B(C6F5)4] (Cpttt=C5H2tBu3-1,2,4, 1-Dy ) exhibits magnetic hysteresis at 60 K, similar lanthanide (Ln) complexes have been targeted to provide insights into this remarkable property. We recently reported homologous [Ln(Cpttt)2][B(C6F5)4] ( 1-Ln ) for all the heavier Ln from Gd–Lu; herein, we extend this motif to the early Ln. We find, for the largest LnIII cations, that contact ion pairs [Ln(Cpttt)2{(C6F5-κ1-F)B(C6F5)3}] ( 1-Ln ; La–Nd) are isolated from reactions of parent [Ln(Cpttt)2(Cl)] ( 2-Ln ) with [H(SiEt3)2][B(C6F5)4], where the anion binds weakly to the equatorial sites of [Ln(Cpttt)2]+ through a single fluorine atom in the solid state. For smaller SmIII, [Sm(Cpttt)2][B(C6F5)4] ( 1-Sm ) is isolated, which like heavier 1-Ln does not exhibit equatorial anion interactions, but the EuIII analogue 1-Eu could not be synthesised due to the facile reduction of EuIII precursors to EuII products. Thus with the exception of Eu and radioactive Pm this work constitutes a structurally similar family of Ln metallocenium complexes, over 50 years after the [M(Cp)2]+ series was isolated for the 3d metals. 相似文献
57.
Vijay S. Parmar Dr. Fabrizio Ortu Dr. Xiaozhou Ma Dr. Nicholas F. Chilton Dr. Rodolphe Clérac Dr. David P. Mills Prof. Dr. Richard E. P. Winpenny 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(35):7774-7778
A new family of five-coordinate lanthanide single-molecule magnets (Ln SMMs) [Dy(Mes*O)2(THF)2X] (Mes*=2,4,6-tri-tert-butylphenyl; X=Cl, 1 ; Br, 2 ; I, 3 ) is reported with energy barriers to magnetic reversal >1200 K. The five-coordinate DyIII ions have distorted square pyramidal geometries, with halide anions on the apex, and two Mes*O ligands mutually trans- to each other, and the two THF molecules forming the second trans- pair. These geometrical features lead to a large magnetic anisotropy in these complexes along the trans-Mes*O direction. QTM and Raman relaxation times are enhanced by varying the apex halide from Cl to Br to I, or by dilution in a diamagnetic yttrium analogue. 相似文献
58.
Elisa Roda Fabrizio De Luca Carlo Alessandro Locatelli Daniela Ratto Carmine Di Iorio Elena Savino Maria Grazia Bottone Paola Rossi 《Molecules (Basel, Switzerland)》2020,25(22)
Bioactive metabolites isolated from medicinal mushrooms (MM) used as supportive treatment in conventional oncology have recently gained interest. Acting as anticancer agents, they interfere with tumor cells and microenvironment (TME), disturbing cancer development/progression. Nonetheless, their action mechanisms still need to be elucidated. Recently, using a 4T1 triple-negative mouse BC model, we demonstrated that supplementation with Micotherapy U-Care, a MM blend, produced a striking reduction of lung metastases density/number, paralleled by decreased inflammation and oxidative stress both in TME and metastases, together with QoL amelioration. We hypothesized that these effects could be due to either a direct anticancer effect and/or to a secondary/indirect impact of Micotherapy U-Care on systemic inflammation/immunomodulation. To address this question, we presently focused on apoptosis/proliferation, investigating specific molecules, i.e., PARP1, p53, BAX, Bcl2, and PCNA, whose critical role in BC is well recognized. We revealed that Micotherapy U-Care is effective to influence balance between cell death and proliferation, which appeared strictly interconnected and inversely related (p53/Bax vs. Bcl2/PARP1/PCNA expression trends). MM blend displayed a direct effect, with different efficacy extent on cancer cells and TME, forcing tumor cells to apoptosis. Yet again, this study supports the potential of MM extracts, as adjuvant supplement in the TNBC management. 相似文献
59.
Badaloni E Barbarino M Cabri W D'Acquarica I Forte M Gasparrini F Giorgi F Pierini M Simone P Ursini O Villani C 《Journal of chromatography. A》2011,1218(25):3862-3875
New monolithic HPLC columns were prepared by γ-radiation-triggered polymerization of hexyl methacrylate and ethylene glycol dimethacrylate monomers in the presence of porogenic solvents. Polymerization was carried out directly within capillary (250-200 μm I.D.) and nano (100-75 μm I.D.) fused-silica tubes yielding highly efficient columns for cap(nano)-LC applications. The columns were applied in the complete separation of core (H2A, H2B, H3, and H4) and linker (H1) histones under gradient elution with UV and/or electrospray ionization (ESI) ion trap mass spectrometry (MS) detections. Large selectivity towards H1, H2A-1, H2A-2, H2B, H3-1, H3-2 and H4 histones and complete separation were obtained within 8 min time windows, using fast gradients and very high linear flow velocities, up to 11 mm/s for high throughput applications. The method developed was the basis of a simple and efficient protocol for the evaluation of post-translational modifications (PTMs) of histones from NCI-H460 human non-small-cell lung cancer (NSCLC) and HCT-116 human colorectal carcinoma cells. The study was extended to monitoring the level of histone acetylation after inhibition of Histone DeACetylase (HDAC) enzymes with suberoylanilide hydroxamic acid (SAHA), the first HDAC inhibitor approved by the FDA for cancer therapy. Attractive features of our cap(nano)-LC/MS approach are the short analysis time, the minute amount of sample required to complete the whole procedure and the stability of the polymethacrylate-based columns. A lab-made software package ClustMass was ad hoc developed and used to elaborate deconvoluted mass spectral data (aligning, averaging, clustering) and calculate the potency of HDAC inhibitors, expressed through a Relative half maximal Inhibitory Concentration parameter, namely R_IC(50) and an averaged acetylation degree. 相似文献
60.
Fabrizio Melani Lucia Cecchi Giovanna Palazzino Guido Filacchioni 《Journal of heterocyclic chemistry》1986,23(1):173-176
Following our reports on synthetic tricyclic analogues of antitumor anthramycin the synthesis of some isomers pyrazolo[4,5-d]- and pyrazolo[4,5-c][1]benzazepine derivatives is reported. 相似文献