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Prof. Allan J. Canty Prof. Alireza Ariafard Prof. Gerard van Koten 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(67):15629-15635
Density Functional Theory studies of square-planar PtII pincer structures, (4-Z-NCN)PtCl ([4-Z-NCN]−=[4-Z-2,6-(Me2NCH2)2C6H2-N,C,N]−, Z=H, NO2, CF3, CO2H, CHO, Cl, Br, I, F, SMe, SiMe3, tBu, OH, NH2, NMe2), enable characterisation of mesomerism for the pincer-Pt interaction. Relationships between Hammett σp substituent parameters of Z and DFT data obtained from NBO6 and AOMix computation are used to probe the interaction of the 5dyz orbital of platinum with π-orbitals of the arene ring. Analogous computation for 2,6-(Me2CH2)2C6H3Z (Z=H, CF3, CHO, Cl, Br, I, F, SMe, SiMe3, tBu, OH, NH2) and (4-H-NCN)PtZ allows an estimation of the relative substituent effects of “(CH2NMe2)2PtZ” on π-delocalisation in the pincer system. 相似文献
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Agustin Forchetti Casarino Adrián Moreno Marina Galià Diana A. Estenoz Gerard Lligadas Marisa E. Spontón 《Journal of polymer science. Part A, Polymer chemistry》2021,59(23):3029-3039
An efficient strategy to synthesize novel biobased multifunctional benzoxazine compounds was developed using the 1,1,3,3-tetramethyl guanidine (TMG)-triggered esterification of natural phloretic acid with organic halides as a key synthetic step. First, phloretic acid was combined with either aniline or furfurylamine to prepare the corresponding carboxylic acid-functional monobenzoxazine monomer. Next, the use of TMG enabled an efficient esterification of these compounds with di-, tri-, and tetra-functional benzyl bromide compounds at room temperature to afford a series of new multi-benzoxazine monomers tethered to an aromatic core. The effect of the functionality of the monomers on the curing process was analyzed, indicating that the reactivity during the thermally induced ring-opening increases with the number of furan and oxazine rings in the monomers. The resulting thermosets revealed good correlation between the number of oxazine rings in the structure of the monomer and the properties of the crosslinked materials. Furfurylamine-based polybenzoxazines showed improved thermal behavior compared to the aniline-based systems, due to the role of furan rings. All materials showed high Tg, good thermal stability, and promising flame retardancy properties. 相似文献
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Bastiaan Kooij Paul Varava Farzaneh Fadaei-Tirani Rosario Scopelliti Dimitrios A. Pantazis Gerard P. Van Trieste III David C. Powers Kay Severin 《Angewandte Chemie (International ed. in English)》2023,62(4):e202214899
Homometallic copper complexes with alkenylidene ligands are discussed as intermediates in catalysis but the isolation of such complexes has remained elusive. Herein, we report the structural characterization of copper complexes with bridging and terminal alkenylidene ligands. The compounds were obtained by irradiation of CuI complexes with N-heterocyclic diazoolefin ligands. The complex with a terminal alkenylidene ligand required isolation in a crystalline matrix, and its structural characterization was enabled by in crystallo photolysis at low temperature. 相似文献
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Roos C. W. van Lier Dr. A. Dowine de Bruijn Prof. Dr. Gerard Roelfes 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(4):1430-1437
Dehydroalanine (Dha) residues are attractive noncanonical amino acids that occur naturally in ribosomally synthesised and post-translationally modified peptides (RiPPs). Dha residues are attractive targets for selective late-stage modification of these complex biomolecules. In this work, we show the selective photocatalytic modification of dehydroalanine residues in the antimicrobial peptide nisin and in the proteins small ubiquitin-like modifier (SUMO) and superfolder green fluorescent protein (sfGFP). For this purpose, a new water-soluble iridium(III) photoredox catalyst was used. The design and synthesis of this new photocatalyst, [Ir(dF(CF3)ppy)2(dNMe3bpy)]Cl3, is presented. In contrast to commonly used iridium photocatalysts, this complex is highly water soluble and allows peptides and proteins to be modified in water and aqueous solvents under physiologically relevant conditions, with short reaction times and with low reagent and catalyst loadings. This work suggests that photoredox catalysis using this newly designed catalyst is a promising strategy to modify dehydroalanine-containing natural products and thus could have great potential for novel bioconjugation strategies. 相似文献
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G.?IoossEmail author P. I.?Plotnikov J. F.?Toland 《Archive for Rational Mechanics and Analysis》2005,177(3):367-478
The existence of two-dimensional standing waves on the surface of an infinitely deep perfect fluid under gravity is established. When formulated as a second-order equation for a real-valued function w on the 2-torus and a positive parameter μ, the problem is fully nonlinear (the highest order x-derivative appears in the nonlinear term but not in the linearization at 0) and completely resonant (there are infinitely many linearly independent eigenmodes of the linearization at 0 for all rational values of the parameter μ). Moreover, for any prescribed order of accuracy there exists an explicit approximate solution of the nonlinear problem in the form of a trigonometric polynomial. Using a Nash-Moser method to seek solutions of the nonlinear problem as perturbations of the approximate solutions, the existence question can be reduced to one of estimating the inverses of linearized operators at non-zero points. After changing coordinates these operators become first order and non-local in space and second order in time. After further changes of variables the main parts become diagonal with constant coefficients and the remainder is regularizing, or quasi-one-dimensional in the sense of [22]. The operator can then be inverted for two reasons. First, the explicit formula for the approximate solution means that, restricted to the infinite-dimensional kernel of the linearization at zero, the inverse exists and can be estimated. Second, the small-divisor problems that arise on the complement of this kernel can be overcome by considering only particular parameter values selected according to their Diophantine properties. A parameter-dependent version of the Nash-Moser implicit function theorem now yields the existence of a set of unimodal standing waves on flows of infinite depth, corresponding to a set of values of the parameter μ>1 which is dense at 1. Unimodal means that the term of smallest order in the amplitude is cos x cos t, which is one of many eigenfunctions of the completely resonant linearized problem. 相似文献
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A simple one-dimensional model is used to simulate numerically the propagation oflinear and nonlinear waves in a deformable ceramic.The nummrical scheme used providesthe response in stress or strain and electric field within the sample and the voltage at aresistive external circuit connecting the two faces of the sample.Space-time diagrams of thepropagation are obtained for various mechanical loads.The voltage response obtainedagress well with experimental results in the linear regime.In the nonlinear one,thesteepening of the electromechanical wave yielding a shock wave is exhibited. 相似文献
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Yu. A. Pisarenko O. O. Usol’tseva C. A. Cardona O. T. Gerard 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(9):1433-1441
Linear independent forms of the azeotropy rule applicable to diagrams of distillation (reaction distillation) and their fragments are established and presented as simple polyhedra of arbitrary dimensions. 相似文献