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51.
Photoabsorption and photofragmentation of isolated cationic silver cluster-tryptophan hybrid systems
Mitrić R Petersen J Kulesza A Bonacić-Koutecký V Tabarin T Compagnon I Antoine R Broyer M Dugourd P 《The Journal of chemical physics》2007,127(13):134301
We present a theoretical study of the size and structure selective absorption properties of cationic silver cluster-tryptophan Trp-Ag(n)(+) (n = 2-5,9) hybrid systems supported by photofragmentation experiments. Our time-dependent density functional theory calculations provide insight into the nature of excitations in interacting nanoparticle-biomolecule subunits and allow to determine characteristic spectral features as fingerprints of two different classes of structures: charge solvated and zwitterionic. Moreover, different types of charge transfer transitions have been identified. Charge transfer from pi system of tryptophan to silver cluster occurs for charge solvated structures while charge transfer from silver to the NH(3) (+) group takes place for zwitterionic structures. This has been confirmed by experimentally measured photofragmentation channels and molecular dynamics simulations. Our findings provide fundamental insight into the structure- and size-dependent mechanism responsible for the enhanced absorption and emission in nanoparticle-biomolecular hybrid systems. 相似文献
52.
Jing Su Thibault Cheisson Alex McSkimming Conrad A. P. Goodwin Ida
M. DiMucci Thomas Albrecht-Schnzart Brian L. Scott Enrique R. Batista Andrew J. Gaunt Stosh A. Kozimor Ping Yang Eric J. Schelter 《Chemical science》2021,12(40):13343
There is significant interest in ligands that can stabilize actinide ions in oxidation states that can be exploited to chemically differentiate 5f and 4f elements. Applications range from developing large-scale actinide separation strategies for nuclear industry processing to carrying out analytical studies that support environmental monitoring and remediation efforts. Here, we report syntheses and characterization of Np(iv), Pu(iv) and Am(iii) complexes with N-tert-butyl-N-(pyridin-2-yl)hydroxylaminato, [2-(tBuNO)py]−(interchangeable hereafter with [(tBuNO)py]−), a ligand which was previously found to impart remarkable stability to cerium in the +4 oxidation state. An[(tBuNO)py]4 (An = Pu, 1; Np, 2) have been synthesized, characterized by X-ray diffraction, X-ray absorption, 1H NMR and UV-vis-NIR spectroscopies, and cyclic voltammetry, along with computational modeling and analysis. In the case of Pu, oxidation of Pu(iii) to Pu(iv) was observed upon complexation with the [(tBuNO)py]− ligand. The Pu complex 1 and Np complex 2 were also isolated directly from Pu(iv) and Np(iv) precursors. Electrochemical measurements indicate that a Pu(iii) species can be accessed upon one-electron reduction of 1 with a large negative reduction potential (E1/2 = −2.26 V vs. Fc+/0). Applying oxidation potentials to 1 and 2 resulted in ligand-centered electron transfer reactions, which is different from the previously reported redox chemistry of UIV[(tBuNO)py]4 that revealed a stable U(v) product. Treatment of an anhydrous Am(iii) precursor with the [(tBuNO)py]− ligand did not result in oxidation to Am(iv). Instead, the dimeric complex [AmIII(μ2-(tBuNO)py)((tBuNO)py)2]2 (3) was isolated. Complex 3 is a rare example of a structurally characterized non-aqueous Am-containing molecular complex prepared using inert atmosphere techniques. Predicted redox potentials from density functional theory calculations show a trivalent accessibility trend of U(iii) < Np(iii) < Pu(iii) and that the higher oxidation states of actinides (i.e., +5 for Np and Pu and +4 for Am) are not stabilized by [2-(tBuNO)py]−, in good agreement with experimental observations.The coordination modes and electronic properties of a strongly coordinating hydroxylaminato ligand with Np, Pu and Am were investigated.Complexes were characterized by a range of experimental and computational techniques. 相似文献
53.
54.
55.
Thibault P 《Rapid communications in mass spectrometry : RCM》2006,20(10):1487-1491
56.
Marianne Kjellberg Alexia Ohleier Pierre Thury Emmanuel Nicolas Lucile Anthore-Dalion Thibault Cantat 《Chemical science》2021,12(30):10266
The accumulation of nitrogen oxides in the environment calls for new pathways to interconvert the various oxidation states of nitrogen, and especially their reduction. However, the large spectrum of reduction potentials covered by nitrogen oxides makes it difficult to find general systems capable of efficiently reducing various N-oxides. Here, photocatalysis unlocks high energy species able both to circumvent the inherent low reactivity of the greenhouse gas and oxidant N2O (E0(N2O/N2) = +1.77 V vs. SHE), and to reduce pyridine N-oxides (E1/2(pyridine N-oxide/pyridine) = −1.04 V vs. SHE). The rhenium complex [Re(4,4′-tBu-bpy)(CO)3Cl] proved to be efficient in performing both reactions under ambient conditions, enabling the deoxygenation of N2O as well as synthetically relevant and functionalized pyridine N-oxides.A rhenium-based photocatalyst enables the deoxygenation of several compounds containing N–O bonds, such as N2O and pyridine N-oxides. 相似文献
57.
Crawford AG Liu Z Mkhalid IA Thibault MH Schwarz N Alcaraz G Steffen A Collings JC Batsanov AS Howard JA Marder TB 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(16):5022-5035
An efficient synthetic route to 2- and 2,7-substituted pyrenes is described. The regiospecific direct C-H borylation of pyrene with an iridium-based catalyst, prepared in situ by the reaction of [{Ir(μ-OMe)cod}(2)] (cod = 1,5-cyclooctadiene) with 4,4'-di-tert-butyl-2,2'-bipyridine, gives 2,7-bis(Bpin)pyrene (1) and 2-(Bpin)pyrene (2, pin = OCMe(2)CMe(2)O). From 1, by simple derivatization strategies, we synthesized 2,7-bis(R)-pyrenes with R = BF(3)K (3), Br (4), OH (5), B(OH)(2) (6), and OTf (7). Using these nominally nucleophilic and electrophilic derivatives as coupling partners in Suzuki-Miyaura, Sonogashira, and Buchwald-Hartwig cross-coupling reactions, we obtained 2,7-bis(R)-pyrenes with R = (4-CO(2)C(8)H(17))C(6)H(4) (8), Ph (9), C≡CPh (10), C≡C[{4-B(Mes)(2)}C(6)H(4)] (11), C≡CTMS (12), C≡C[(4-NMe(2))C(6)H(4)] (14), C≡CH (15), N(Ph)[(4-OMe)C(6)H(4)] (16), and R = OTf, R' = C≡CTMS (13). Lithiation of 4, followed by reaction with CO(2), yielded pyrene-2,7-dicarboxylic acid (17), whilst borylation of 2-tBu-pyrene gave 2-tBu-7-Bpin-pyrene (18) selectively. By similar routes (including Negishi cross-coupling reactions), monosubstituted 2-R-pyrenes with R = BF(3)K (19), Br (20), OH (21), B(OH)(2) (22), [4-B(Mes)(2)]C(6)H(4) (23), B(Mes)(2) (24), OTf (25), C≡CPh (26), C≡CTMS (27), (4-CO(2)Me)C(6)H(4) (28), C≡CH (29), C(3)H(6)CO(2)Me (30), OC(3)H(6)CO(2)Me (31), C(3)H(6)CO(2)H (32), OC(3)H(6)CO(2)H (33), and O(CH(2))(12)Br (34) were obtained from 2. These derivatives are of synthetic and photophysical interest because they contain donor, acceptor, and conjugated substituents. The crystal structures of compounds 4, 5, 7, 12, 18, 19, 21, 23, 26, and 28-31 have also been obtained from single-crystal X-ray diffraction data, revealing a diversity of packing modes, which are described in the Supporting Information. A detailed discussion of the structures of 1 and 2, their polymorphs, solvates, and co-crystals is reported separately. 相似文献
58.
Fromentin C Sanders P Nau F Anton M Fromentin G Tomé D Thibault JN Gaudichon C 《Rapid communications in mass spectrometry : RCM》2012,26(1):43-48
The aim of this study was to produce intrinsically and uniformly doubly (15)N-(13)C-labeled proteins. These proteins can be used as intrinsic tracers of dietary amino acids, both α-amino groups and carbon skeletons, during postprandial metabolic utilization. Two (Rhodes) laying hens were fed for 16 days with a standard poultry diet supplemented with 0, 0.2% or 0.4% of a mixture of 20 doubly (15)N-(13)C-labeled AAs. A third hen was given a non-enriched diet, as the control. The eggs laid were collected over 24 days, from 3 days before to 4 days after supplementation. The (15)N and (13)C enrichments in proteins from white and yolk were measured by EA-IRMS and GC-C-IRMS for enrichment in individual amino acids. After 10 days of supplementation, the (15)N enrichment reached an isotopic plateau at 1500 to 3000 ‰, depending on the supplementation level, in both white and yolk while the (13)C enrichment was 220 to 650 ‰ in white and was 100 to 250 ‰ in yolk. The (15)N enrichment was similar among the amino acids, except for the aromatic ones in which the enrichment was lower. The δ(13)C values were variable among amino acids in both white and yolk, ranging from 77 ‰ for tyrosine to 555 ‰ for proline with the 0.2 % supplementation level. In conclusion, the incorporation of 0.2 % labeled amino acids in the hen diet allowed us to achieve sufficient enrichment for metabolic studies. However, due to the non-homogeneity of the (13)C labeling, adequate (13)C enrichment of individual amino acids must be considered depending on the investigated metabolic pathway. 相似文献
59.
Franck Thibault Laura Gomez Sergey V. Ivanov Oleg G. Buzykin Christian Boulet 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(15):1887-1897
We perform dynamical calculations on two robust N2–N2 potential energy surfaces in order to intercompare pressure broadening coefficients derived from close coupling and coupled states quantum dynamical methods, the semi-classical model of Robert and Bonamy and a full classical method. The coupled states and full classical results compare well with the experimental results or with close coupling values when available. This study confirms that the classical method is a good alternative at room and high temperatures to quantum dynamical methods. The results obtained using the semi-classical method however deviate from the other sets of data at all temperatures considered here (77–2400 K). 相似文献
60.
San-jun ZHANG Lotfi BERGUIGA Nicolas HUGO Thibault ROLAND Francoise ARGOUL Juan ELEZGARAY Wen-xueLI He-ping ZENG 《Frontiers of Physics》2009,4(4):469
This article reviews our recent advances in surface plasmon resonance (SPR) based biochips. It includes four issues, which are the preparation and characterization of high quality gold film, the preparation and characterization of self-assembled monolayer (SAM), dynamics of DNA adsorption on SAMs, and SPRbased microscopies. Numerous topics related to SPR, such as, the modeling of SPR by transmission matrix, effective medium theory, applications of SPR in biology, and SPR-based novel microscopies, are discussed. A novel electrochemical technique, which is extremely useful for the preparation and characterization of high quality SAMs, is also discussed. 相似文献