排序方式: 共有28条查询结果,搜索用时 15 毫秒
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Dr. Jean-Noël Rebilly Wenli Zhang Dr. Christian Herrero Dr. Hachem Dridi Dr. Katell Sénéchal-David Dr. Régis Guillot Prof. Frédéric Banse 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(3):659-668
Rieske dioxygenases are metalloenzymes capable of achieving cis-dihydroxylation of aromatics under mild conditions using O2 and a source of electrons. The intermediate responsible for this reactivity is proposed to be a cis-FeV(O)(OH) moiety. Molecular models allow the generation of a FeIII(OOH) species with H2O2, to yield a FeV(O)(OH) species with tetradentate ligands, or {FeIV(O); OH.} pairs with pentadentate ones. We have designed a new pentadentate ligand, mtL42, bearing a labile triazole, to generate an “in-between” situation. Two iron complexes, [(mtL42)FeCl](PF6) and [(mtL42)Fe(OTf)2]), were obtained and their reactivity towards aromatic substrates was studied in the presence of H2O2. Spectroscopic and kinetic studies reflect that triazole is bound at the FeII state, but decoordinates in the FeIII(OOH). The resulting [(mtL42)FeIII(OOH)(MeCN)]2+ then lies on a bifurcated decay pathway (end-on homolytic vs. side-on heterolytic) depending on the addition of aromatic substrate: in the absence of substrate, it is proposed to follow a side-on pathway leading to a putative (N4)FeV(O)(OH), while in the presence of aromatics it switches to an end-on homolytic pathway yielding a {(N5)FeIV(O); OH.} reactive species, through recoordination of triazole. This switch significantly impacts the reaction regioselectivity. 相似文献
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Perez Barrio J Rebilly JN Carter B Bradshaw D Bacsa J Ganin AY Park H Trewin A Vaidhyanathan R Cooper AI Warren JE Rosseinsky MJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(15):4521-4532
Substitution of the pillaring ligand in the homochiral open-framework [Ni(2)(L-asp)(2)(bipy)] by extended bipy-type ligands leads to a family of layer-structured, homochiral metal-organic frameworks. The 1D channel topology can be modified by the nature of the organic linker, with shape, cross-section and the chemical functionality tuneable. In addition, the volume of these channels can be increased by up to 36 % compared to the parent [Ni(2)(L-asp)(2)(bipy)]. The linker 1,4-dipyridylbenzene (3rbp) gives access to a new layered homochiral framework [Ni(2)(L-asp)(2)(3rbp)] with channels of a different shape. In specific cases, non-porous analogues with the linker also present as a guest can be activated to give porous materials after sublimation. Their CO(2) uptake shows an increase of up to 30 % with respect to the parent [Ni(2)(L-asp)(2)(bipy)] framework. 相似文献
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A Calix[6]arene scaffold was functionalized to provide a tridentate binding site at the small rim and three bidentate chelate sites at the large rim of the cone to generate a heteropolytopic ligand. Its complexation to one equivalent of Zn(II) at the small rim yields a funnel complex displaying both host-guest properties and preorganization of the three chelate groups at the large rim. These two aspects allowed the full control of the binding events to regioselectively form dinuclear Zn(II) and heteropolynuclear Zn(II)/Cu(I) complexes. The heteropolynuclear systems all rely on the host-guest relationship thanks to the induced-fit behavior of the calix cavity. With the short guest MeCN, the large rim is preorganized into a trigonal tris-triazole core and accommodates a single Cu(I) ion. A long guest breaks this spatial arrangement, and three Cu(I) ions can then be bound at the tris-bidentate triazole-dimethylamine site at the large rim. In a noncoordinating solvent however, the tetranuclear complex is submitted to scrambling and the addition of exogenous π-acceptor ligands is required to control the binding of Cu(I) in a well-defined environment. Hindrance selectivity was then induced by the accessibility at the small rim site. Indeed, while CO can stabilize Cu(I) at both coordination sites, PPh(3) cannot fit into the cavity and forces Cu(I) to relocate at the large rim. The resulting well-defined symmetrical tetranuclear complex thus arises from the quite remarkable selective supramolecular assembly of nine partners (1 Zn(II), 3 Cu(I), 1 calixarene, 1 guest alkylamine, 3 PPh(3)). 相似文献
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Jean-Noël Rebilly 《Supramolecular chemistry》2014,26(7-8):454-479
Metallo-enzymes are natural catalysts carrying out highly selective and demanding reactions under mild conditions, using readily available metal ions (iron, copper, zinc, etc.). Understanding the factors explaining these performances is thus of fundamental and applicative interest. Classical model complexes displaying significant limitations in reactivity led to the development of supramolecular systems associating a reactive complex to a molecular cavity receptor, in order to not only mimic the first coordination sphere of the metal, but also the supramolecular enzymatic environment (access channel and binding pocket) responsible for their remarkable kinetics and selectivities. Calixarenes and resorcinarenes are particularly suited to this goal due to their wide range of sizes and flexibility. This review illustrates several specific aspects of enzymatic systems that were successfully mimicked with such supramolecular model systems. This toolbox of supramolecular effects could be used for future developments of bioinorganic supramolecular catalysts. 相似文献
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Polubarinova-Kochina's analytical differential equation methodis used to determine the pseudo-steady-state solution to problemsinvolving the freezing (solidification) of wedges of liquidwhich are initially at their fusion temperature. In particular,we consider four distinct problems for wedges which are: freezingwith the same constant boundary temperature, freezing with thesame constant boundary heat fluxes, freezing with distinct constantboundary temperatures and freezing with distinct constant fluxesat the boundaries. For the last two problems, a Heun's differentialequation with an unknown singularity is derived, which in bothcases admits a particularly elegant simple solution for thespecial case when the wedge angle is . The moving boundariesobtained are shown pictorially. 相似文献
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Rebilly JN Catala L Rivière E Guillot R Wernsdorfer W Mallah T 《Inorganic chemistry》2005,44(23):8194-8196
The reaction of Cr(Bztacn)(CN)3 (Bztacn is 1,4,7-trisbenzyl-1,4,7-triazacyclononane) with Ni(iPrtacn)Cl2 (iPrtacn is 1,4,7-trisisopropyl-1,4,7-triazacyclononane) affords a CrNi3 tetranuclear complex. Variable temperature and magnetization versus field measurements show a S = 9/2 ground state and an appreciable magnetic anisotropy with a negative D(9/2) value equal to -0.54 cm(-1). Magnetization studies on one single crystal using a micro-SQUID show a fast tunneling process at zero field at very low temperature. 相似文献
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Lea Gimeno Dr. Errol Blart Dr. Jean-Noël Rebilly Marina Coupeau Magali Allain Thierry Roisnel Alexis Quarré de Verneuil Dr. Christophe Gourlaouen Prof. Chantal Daniel Dr. Yann Pellegrin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(51):11887-11899
A strategy is presented to improve the excited state reactivity of homoleptic copper–bis(diimine) complexes CuL2+ by increasing the steric bulk around CuI whereas preserving their stability. Substituting the phenanthroline at the 2-position by a phenyl group allows the implementation of stabilizing intramolecular π stacking within the copper complex, whereas tethering a branched alkyl chain at the 9-position provides enough steric bulk to rise the excited state energy E00. Two novel complexes are studied and compared to symmetrical models. The impact of breaking the symmetry of phenanthroline ligands on the photophysical properties of the complexes is analyzed and rationalized thanks to a combined theoretical and experimental study. The importance of fine-tuning the steric bulk of the N–N chelate in order to stabilize the coordination sphere is demonstrated. Importantly, the excited state reactivity of the newly developed complexes is improved as demonstrated in the frame of a reductive quenching step, evidencing the relevance of our strategy. 相似文献