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41.
D3h‐Symmetric Porphyrin‐Based Rigid Macrocyclic Ligands for Multicofacial Multinuclear Complexes in a One‐Nanometer‐Sized Cavity 下载免费PDF全文
Yohei Ohkoda Akane Asaishi Tomoya Namiki Tomoaki Hashimoto Midori Yamada Koichiro Shirai Yuta Katagami Dr. Tomoaki Sugaya Prof. Makoto Tadokoro Prof. Akiharu Satake 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(33):11745-11756
The one‐step synthesis of D3h‐symmetric cyclic porphyrin trimers 1 composed of three 2,2′‐[4,4′‐bis(methoxycarbonyl)]bipyridyl moieties and three porphyrinatozinc moieties was achieved from a nickel‐mediated reductive coupling of meso‐5,15‐bis(6‐chloro‐4‐methoxycarbonylpyrid‐2‐yl)porphyrinatozinc. Although cyclic trimers 1 were obtained as a mixture that included other cyclic and acyclic porphyrin oligomers, an extremely specific separation was observed only for cyclic trimers 1 when using columns of silica gel modified with pyrenylethyl, cyanopropyl, and other groups. Structural analysis of cyclic trimers 1 was carried out by means of NMR spectroscopy and X‐ray crystallography. Treatment of an η3‐allylpalladium complex with a cyclic trimer gave a tris(palladium) complex containing three η3‐allylpalladium groups inside the space, which indicated that the bipyridyl moieties inside the ring could work as bidentate metalloligands. 相似文献
42.
以典型的双稳态系统——屈曲梁结构为例,基于等效模型,结合解析、数值和实验手段,研究了双稳态结构中的1/2次谐波共振特性、演化过程、参数调节规律及其对隔振特性的影响.研究发现,当非线性刚度系数或激励幅值增加到一定程度时,系统会在一定带宽下产生显著的1/2次谐波共振;随着激励幅值增加,阻尼系统的1/2次谐波遵循“产生-增强-衰退-消失”的过程,该过程对峰值频率和峰值传递率有重要影响;适当提高非线性强度能有效改善双稳态结构隔振特性.针对双稳态屈曲梁结构开展的实验验证了1/2次谐波特性和隔振特性变化规律. 相似文献
43.
Flow physics of transvalvular flows in the aorta with bioprosthetic valves are investigated using computational modelling. For the efficient simulations of flow-structure-interaction in transvalvular flows, a simplified, reduced degree of freedom valve model is employed with a sharp interface immersed boundary based incompressible flow solver. Simulations are performed for normal as well as abnormal valves with reduced leaflet motion that models the effect of early leaflet thrombosis. The structure of the aortic jet and the hemodynamic stresses on the aortic wall are analysed to understand the hemodynamic impacts and possible long-term clinical implications of sub-clinical, reduced leaflet motion. The simulation results have shown that the reduced leaflet motion tilts the direction of aortic jet and generates stronger flow separation and re-attachment on the aortic wall downstream from the reduced motion leaflets. The modified flow pattern increases the wall pressure fluctuation and average wall shear stress on the downstream aortic wall, and results in the asymmetric oscillatory shear index distributions, which may have long-term clinical implications such as aortic wall damage and remodelling. 相似文献
44.
45.
Synthesis,Electronic Properties and WOLED Devices of Planar Phosphorus‐Containing Polycyclic Aromatic Hydrocarbons 下载免费PDF全文
Dr. François Riobé Rózsa Szűcs Dr. Pierre‐Antoine Bouit Dr. Denis Tondelier Bernard Geffroy Fátima Aparicio Julia Buendía Prof. Luis Sánchez Prof. Régis Réau Prof. László Nyulászi Prof. Muriel Hissler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(17):6547-6556
We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P‐containing PAHs exhibit properties expected for an emitter in white organic light‐emitting diodes (WOLEDs). 相似文献
46.
A new asymmetric Salamo‐based ligand H2L was synthesized using 3‐tert‐butyl‐salicylaldehyde and 6‐methoxy‐2‐[O‐(1‐ethyloxyamide)]‐oxime‐1‐phenol. By adjusting the ratio of the ligand H2L and Cu (II), Co (II), and Ni (II) ions, mononuclear, dinuclear, and trinuclear transition metal (II) complexes, [Cu(L)], [{Co(L)}2], and [{Ni(L)(CH3COO)(CH3CH2OH)}2Ni] with the ligand H2L possessing completely different coordination modes were obtained, respectively. The optical spectra of ligand H2L and its Cu (II), Co (II) and Ni (II) complexes were investigated. The Cu (II) complex is a mononuclear structure, and the Cu (II) atom is tetracoordinated to form a planar quadrilateral structure. The Co (II) complex is dinuclear, and the two Co (II) atoms are pentacoordinated and have coordination geometries of distorted triangular bipyramid. The Ni (II) complex is a trinuclear structure, and the terminal and central Ni (II) atoms are all hexacoordinated, forming distorted octahedral geometries. Furthermore, optical properties including UV–Vis, IR, and fluorescence of the Cu (II), Co (II), and Ni (II) complexes were investigated. Finally, the antibacterial activities of the Cu (II), Co (II), and Ni (II) complexes were explored. According to the experimental results, the inhibitory effect was found to be enhanced with increasing concentrations of the Cu (II), Co (II), and Ni (II) complexes. 相似文献
47.
《Current Applied Physics》2020,20(8):925-930
The well-known quaternary Cu2ZnSnS4 (CZTS) chalcogenide thin films are playing an important role in modern technology. The CZTS nanocrystal were successfully prepared by solution method using water, ethylene glycol and ethylenediamine as different solvent. The pure phase material was used for thin film coating by thermal evaporation method. The prepared CZTS thin films were characterized by XRD, Raman spectroscopy, FESEM, XPS and FT-IR spectroscopy. The XRD and Raman spectroscopy analysis revealed the formation of polycrystalline CZTS thin film with tetragonal crystal structure after annealing at 450 °C. The oxidation state of the annealed film was studied by XPS. A direct band gap about 1.36 eV was estimated for the film from FT-IR studies, which is nearly close to the optimum value of band gap energy of CZTS materials for best solar cell efficiency. The CZTS annealed thin films are more suitable for using as a p-type absorber layer in a low-cost solar cell. 相似文献
48.
In this paper, we investigate the evolution of joint invariants under invariant geometric flows using the theory of equivariant moving frames and the induced invariant discrete variational complex. For certain arc length preserving planar curve flows invariant under the special Euclidean group , the special linear group , and the semidirect group , we find that the induced evolution of the discrete curvature satisfies the differential‐difference mKdV, KdV, and Burgers' equations, respectively. These three equations are completely integrable, and we show that a recursion operator can be constructed by precomposing the characteristic operator of the curvature by a certain invariant difference operator. Finally, we derive the constraint for the integrability of the discrete curvature evolution to lift to the evolution of the discrete curve itself. 相似文献
49.
A new dinuclear iron(Ⅲ) complex has been synthesized and structurally characterized by X-ray crystallography: [FeⅢ2(L)(C6H5COO)(SO4)(CH3OH)2]·CH3CN·CH3OH(1, H3 L = N,N'-bis(salicylidene)-1,3-diamino-2-propanol). Complex 1 belongs to orthorhombic space group Pna21 with a = 11.4400(8), b = 22.9705(2), c = 12.5712(9) , V = 3303.5(4) 3, Z = 4, F(000) = 1576, Dc = 1.531 g·cm–3, Mr = 761.36, μ = 1.007 mm–1, S = 1.014, the final R = 0.0505 and wR = 0.1018. The crystal packing is stabilized by intermolecular O–H···O hydrogen bonds, forming an extended one-dimensional chain structure. The temperature dependence of magnetic susceptibility measurement shows that antiferromagnetic interaction is propagated between the metal centers. Fit as dinuclear arrangement gave parameters of J = 19.7 cm-1, g = 1.89 and R2 = 0.9999. 相似文献
50.
《中国物理 B》2021,30(5):56201-056201
A new three-dimensional(3 D) cellular model based on hinging open-cell Kelvin structure is proposed for its negative compressibility property. It is shown that this model has adjustable compressibility and does exhibit negative compressibility for some certain conformations. And further study shows that the images of compressibility are symmetrical about the certain lines, which indicates that the mechanical properties of the model in the three axial directions are interchangeable and the model itself has a certain geometric symmetry. A comparison of the Kelvin model with its anisotropic form with the dodecahedron model shows that the Kelvin model has stronger negative compressibility property in all three directions.Therefore, a new and potential method to improve negative compressibility property can be derived by selecting the system type with lower symmetry and increasing the number of geometric parameters. 相似文献