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101.
Exploring the Molecular Structure of Imidazolium–Silica‐Based Nanoparticle Networks by Combining Solid‐State NMR Spectroscopy and First‐Principles Calculations 下载免费PDF全文
Dr. Marie‐Alexandra Neouze Martin Kronstein Dr. Marco Litschauer Dr. Michael Puchberger Dr. Cristina Coelho Prof. Christian Bonhomme Prof. Christel Gervais Dr. Frederik Tielens 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15188-15196
A DFT‐based molecular model for imidazolium–silica‐based nanoparticle networks (INNs) is presented. The INNs were synthesized and characterized by using small‐angle X‐ray scattering (SAXS), NMR spectroscopy, and theoretical ab initio calculations. 11B and 31P HETCOR CP MAS experiments were recorded. Calculated 19F NMR spectroscopy results, combined with the calculated anion–imidazolium (IM) distances, predicted the IM chain density in the INN, which was also confirmed from thermogravimetric analysis/mass spectrometry results. The presence of water molecules trapped between the nanoparticles is also suggested. First considerations on possible π–π stacking between the IM rings are presented. The predicted electronic properties confirm the photoluminescence emissions in the correct spectral domain. 相似文献
102.
Titanium‐Catalyzed Hydroalumination of Conjugated Dienes: Access to Fulvene‐Derived Allylaluminium Reagents and Their Diastereoselective Reactions with Carbonyl Compounds 下载免费PDF全文
Dr. Jomy Joseph Dr. Florian Jaroschik Dr. Dominique Harakat Dr. K. V. Radhakrishnan Dr. Jean‐Luc Vasse Prof. Jan Szymoniak 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(18):5433-5438
The described titanium‐catalyzed hydroalumination of conjugated dienes opens up a new way to allylaluminium reagents. The reaction is carried out by using diisobutylaluminium hydride (DIBAL‐H) and a catalytic amount of [Cp2TiCl2] (Cp=cyclopentadienyl). When applied to mono‐ and disubstitued pentafulvenes, this reaction proceeds in a highly endocyclic manner. The formed allylaluminium compounds react regio‐ and stereoselectively with both aldehydes and ketones to afford homoallylic alcohols that are suitable synthons for functionalized cyclopentanones. An extension of this methodology to simple dienes was also investigated. In the proposed mechanism, the initially formed bimetallic species (Ti/Al) are involved in the two possible catalytic cycles with a direct hydroalumination or/and a hydrotitanation followed by a titanium to aluminium transmetallation. 相似文献
103.
Marcel Scheepstra Dr. Lidia Nieto Dr. Anna K. H. Hirsch Dr. Sascha Fuchs Dr. Seppe Leysen Chan Vinh Lam Leslie in het Panhuis Prof. Dr. Constant A. A. van Boeckel Dr. Hans Wienk Prof. Dr. Rolf Boelens Dr. Christian Ottmann Dr. Lech‐Gustav Milroy Prof. Dr. Luc Brunsveld 《Angewandte Chemie (International ed. in English)》2014,53(25):6443-6448
104.
Maxime Balestrat Abhijeet Lale Andr Vinícius Andrade Bezerra Vanessa Proust Eranezhuth Wasan Awin Ricardo Antonio Francisco Machado Pierre Carles Ravi Kumar Christel Gervais Samuel Bernard 《Molecules (Basel, Switzerland)》2020,25(22)
The pyrolysis (1000 °C) of a liquid poly(vinylmethyl-co-methyl)silazane modified by tetrakis(dimethylamido)titanium in flowing ammonia, nitrogen and argon followed by the annealing (1000–1800 °C) of as-pyrolyzed ceramic powders have been investigated in detail. We first provide a comprehensive mechanistic study of the polymer-to-ceramic conversion based on TG experiments coupled with in-situ mass spectrometry and ex-situ solid-state NMR and FTIR spectroscopies of both the chemically modified polymer and the pyrolysis intermediates. The pyrolysis leads to X-ray amorphous materials with chemical bonding and ceramic yields controlled by the nature of the atmosphere. Then, the structural evolution of the amorphous network of ammonia-, nitrogen- and argon-treated ceramics has been studied above 1000 °C under nitrogen and argon by X-ray diffraction and electron microscopy. HRTEM images coupled with XRD confirm the formation of nanocomposites after annealing at 1400 °C. Their unique nanostructural feature appears to be the result of both the molecular origin of the materials and the nature of the atmosphere used during pyrolysis. Samples are composed of an amorphous Si-based ceramic matrix in which TiNxCy nanocrystals (x + y = 1) are homogeneously formed “in situ” in the matrix during the process and evolve toward fully crystallized compounds as TiN/Si3N4, TiNxCy (x + y = 1)/SiC and TiC/SiC nanocomposites after annealing to 1800 °C as a function of the atmosphere. 相似文献
105.
David E. Salazar Marcano Mhamad Aly Moussawi Alexander V. Anyushin Sarah Lentink Luc Van Meervelt Ivana Ivanovi-Burmazovi Tatjana N. Parac-Vogt 《Chemical science》2022,13(10):2891
Hybrid structures incorporating different organic and inorganic constituents are emerging as a very promising class of materials since they synergistically combine the complementary and diverse properties of the individual components. Hybrid materials based on polyoxometalate clusters (POMs) are particularly interesting due to their versatile catalytic, redox, electronic, and magnetic properties, yet the controlled incorporation of different clusters into a hybrid structure is challenging and has been scarcely reported. Herein we propose a novel and general strategy for combining multiple types of metal-oxo clusters in a single hybrid molecule. Two novel hybrid POM structures (HPOMs) bis-functionalised with dipentaerythritol (R–POM1–R; R = (OCH2)3CCH2OCH2C(CH2OH)) were synthesised as building-blocks for the formation of heterometallic hybrid triads (POM2–R–POM1–R–POM2). Such a modular approach resulted in the formation of four novel heterometallic hybrids combing the Lindqvist {V6}, Anderson–Evans {XMo6} (X = Cr or Al) and trisubstituted Wells–Dawson {P2V3W15} POM structures. Their formation was confirmed by multinuclear Nuclear Magnetic Resonance (NMR), infrared (IR) and UV-Vis spectroscopy, as well as Mass Spectrometry, Diffusion Ordered Spectroscopy (DOSY) and elemental analysis. The thermal stability of the hybrids was also examined by Thermogravimetric Analysis (TGA), which showed that the HPOM triads exhibit higher thermal stability than comparable hybrid structures containing only one type of POM. The one-pot synthesis of these novel compounds was achieved in high yields in aqueous and organic media under simple reflux conditions, without the need of any additives, and could be translated to create other hybrid materials based on a variety of metal-oxo cluster building-blocks.A versatile modular approach has been developed for incorporating different metal-oxo nanoclusters with characteristic structures into a single hybrid molecule by covalently linking them with polyol ligands. 相似文献
106.
107.
Pim J. de Vink Auke A. Koops Giulia D'Arrigo Gabriele Cruciani Francesca Spyrakis Luc Brunsveld 《Chemical science》2022,13(9):2744
Nuclear Receptors (NRs) are highly relevant drug targets, for which small molecule modulation goes beyond a simple ligand/receptor interaction. NR–ligands modulate Protein–Protein Interactions (PPIs) with coregulator proteins. Here we bring forward a cooperativity mechanism for small molecule modulation of NR PPIs, using the Peroxisome Proliferator Activated Receptor γ (PPARγ), which describes NR–ligands as allosteric molecular glues. The cooperativity framework uses a thermodynamic model based on three-body binding events, to dissect and quantify reciprocal effects of NR–coregulator binding (KID) and NR–ligand binding (KIID), jointly recapitulated in the cooperativity factor (α) for each specific ternary ligand·NR·coregulator complex formation. These fundamental thermodynamic parameters allow for a conceptually new way of thinking about structure–activity-relationships for NR–ligands and can steer NR modulator discovery and optimization via a completely novel approach.A cooperativity framework describes the formation of nuclear receptor ternary complexes and deconvolutes ligand and cofactor binding into intrinsic affinities and a cooperativity factor, providing a conceptually new understanding of NR modulation. 相似文献
108.
Letters in Mathematical Physics - We characterize quantum perfect state transfer on real-weighted graphs of the Johnson scheme $${\mathcal {J}}(n,k)$$ , which represent spin networks with... 相似文献
109.
Dispersion compensation up to the third order is experimentally demonstrated by using a dual-fibre stretcher combined with the coma of an imaging lens, in a fibre-based scan-free time domain optical coherence tomography system, leading to an axial resolution of less than 3 μm. 相似文献
110.
Cucurbituril‐mediated immobilization of fluorescent proteins on supramolecular biomaterials 下载免费PDF全文
Olga J. G. M. Goor Ralph P. G. Bosmans Luc Brunsveld Patricia Y. W. Dankers 《Journal of polymer science. Part A, Polymer chemistry》2017,55(21):3607-3616
The reversible introduction of functionality at material surfaces is of interest for the development of functional biomaterials. In particular, the use of supramolecular immobilization strategies facilitates mild reaction and processing conditions, as compared to other covalent analogues. Here, the engineering of multicomponent supramolecular materials, beyond the use of a single supramolecular entity is proposed. Cucurbit[8]uril (Q8) mediated host–guest chemistry is combined with hydrogen bonding supramolecular 2‐ureido‐4‐pyrimidinone (UPy)‐based materials. The modular incorporation of a UPy‐additive that presents one guest to incorporate into the Q8 host allows for selective supramolecular functionalization at the water–polymer material interface. Supramolecular ternary complex formation at the material surface was studied by X‐ray photoelectron spectroscopy, which as a result of large overlap in atomic composition of the different components showed minor changes is surface composition upon complex formation. Surface MALDI‐ToF MS measurements revealed useful insights in the formation of complexes. Protein immobilization was monitored using both fluorescence spectroscopy and quartz crystal microbalance with dissipation monitoring, which successfully demonstrated ternary complex formation. Although proteins could selectively be immobilized onto the surfaces, control of the system's stability remains a challenge as a result of the dynamicity of the host–guest assembly. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3607–3616 相似文献