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51.
p-Phenylenediamine bearing terminal bipyridyl moieties was synthesized by palladium-catalyzed amination. The corresponding ruthenium(II) complex was formed and characterized, providing a redox-switchable photoinduced electron-transfer system. 相似文献
52.
利用~1H-NMR原位追踪在L-缬氨酸存在下合成花状纳米聚苯胺的形成过程中发现此结构的形成经历3个阶段:首先在苯胺与缬氨酸构成的类胶束结构内聚合成吩嗪类寡聚物;其次通过p-p重叠作用及胶束融合过程成为片状聚集体;最终通过与缬氨酸形成氢键组装成花瓣状纳米聚苯胺.通过改变反应条件,对比形成过程中核磁共振图谱及产物形貌的变化发现花状纳米聚苯胺的形成有如下特征:反应初期L-缬氨酸作为缓冲试剂可以避免苯胺的骤然质子化,有利于生成具有吩嗪结构的寡聚物;反应前苯胺单体与缬氨酸形成稳定的反应环境保证寡聚物始终在其内聚集生长,有效避免了外部环境的影响. 相似文献
53.
Yeliz Kara 《代数通讯》2017,45(8):3627-3635
In this article, we focus on modules with the property that every projection invariant submodule is essential in a fully invariant direct summand. In contrast to π-extending condition, it is shown that the former property is inherited by direct summands and Morita invariant. An application of our results yields that the endomorphism ring of a free module enjoys the property. Moreover, we characterize generalized triangular matrix rings with the aforementioned property and apply to somewhat special cases. 相似文献
54.
A biomimetic synthesis of the triterpene (±)-perovskone was achieved featuring a remarkable polycyclization process in which three rings, four bonds, and five stereocenters were created in a single operation in 82% yield. This convergent synthesis required 16 steps, starting from vanillin, and proceeded in 9% overall yield. A second route to prepare optically active quinone 2 took 15 steps in 36% overall yield and featured a palladium-catalyzed reductive allylic transposition to establish the C-5 chirality stereospecifically. Quinone (−)-2 was converted to (+)-perovskone (1) via a polycyclization cascade, which created four rings, five bonds, and six stereocenters in a single operation in 50% yield. 相似文献
55.
Single-component molecular conductors [M(tmdt)2] (tmdt = trimethylenetetrathiafulvalenedithiolate; M = Ni, Au, Pt, Cu), exhibit a variety of electromagnetic properties, which originate from the differences of the metal’s d-orbitals role in the band structure formation. The [Au(tmdt)2] crystal undergoes an antiferromagnetic transition at 110 K, while maintaining a metallic state at lower temperatures. The Au analog has a high magnetic transition temperature as compared to traditional magnetic molecular conductors due to the strong three-dimensional (3-D) structure and the contribution of the metal d-orbitals. The single-component molecular conductor, [Cu(tmdt)2], with π- and d-like frontier orbitals is isostructural with other metallic [M(tmdt)2] systems (M = Ni, Pt, Au). The Cu(tmdt)2 molecule is planar, which strikingly contrasts the tetrahedral coordination of Cu(dmdt)2 (dmdt = dimethyltetrathiafulvalenedithiolate) with similarly extended TTF type ligands. Interestingly, unlike other [M(tmdt)2] with metallic behavior, [Cu(tmdt)2] shows semiconducting behavior at room temperature (σ(RT) = ∼7 S cm−1). The RT conductivity increased linearly with increased pressure to 110 S cm−1 at 15 kbar despite the compressed pellet sample. The magnetic susceptibility indicates one-dimensional (1-D) Heisenberg behavior with J = 117 cm−1 and shows antiferromagnetic ordering at 13 K. The [Cu(tmdt)2] is a new multi-frontier π-d system, which introduces a d(σ)-type frontier orbital around the Fermi level of the π-like metal bands. 相似文献
56.
57.
En Ju Wang Guang Ying Chen 《中国化学快报》2011,22(7):847-850
The inclusion complex ofβ-cyclodextrin(β-CD) with 4-chlorobenzoic acid was synthesized and its crystal structure was determined by single crystal X-ray diffraction under cryogenic condition.The complex contains twoβ-CDs,two 4-chlorobenzoic acids and twenty-nine water molecules in the asymmetric unit,and can be formulated as 2(C42H70O35)·2(C7H5O2Cl)·29(H2O).In the crystal lattice,twoβ-CDs form a face-to-face dimer jointed together through hydrogen bonding between the secondary hydroxyl groups ofβ-CDs.Two 4-chlorobenzoic acid molecules which contact by C-Cl…πinteractions are included in theβ-CD dimer cavity.Theβ-CD dimers are arranged in brickwork-like pattern along the crystallographic a-axis.The effect of guest molecule length on the inclusion geometry was discussed by comparative study of someβ-CD complexes containing similar guests. 相似文献
58.
主要讨论局部有限维的Hopf π-代数的π-子代数与Hopf π-子代数,分别得到了Hopf π-代数的π-子代数和Hopf π-子代数的一些充分必要条件. 相似文献
59.
赵士银 《纯粹数学与应用数学》2011,27(1):45-50
设H为有限型Hopfπ-代数,研究Hopfπ-代数H上的Hopfπ-模与Hopf π-余代数H *上的Hopfπ-余模之间的对偶关系,得出了Hopfπ-子模与Hopfπ-子 余模之间的充分必要条件,推广了Hopf代数中的相关结论. 相似文献
60.
For a group G,we produce upper and lower bounds for the sum of the entries of the Brauer character table of G and the projective indecomposable character table of G.When G is a π-separable group,we show that the sum of the entries in the table of Isaacs' partial characters is a real number,and we obtain upper and lower bounds for this sum. 相似文献