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大四写论文金虫 (正式写手)
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Our attempts at targeted design of networks started with the choice of suitable building units and a coupling reaction with an effective catalyst. Figure 1 summarizes general aspects of our design: D4R cages with haloaryl terminal groups are versatile, highly connectable units for formation of inorganic–organic hybrid polymers by means of well-developed cross-coupling reactions, for example, Heck reaction,Suzuki coupling, and Sonogashira coupling. Compound BrPh-D4R was chosen because it can be synthesized on a practical scale with high regio- and stereoselectivity by state-of-the-art cross-metathesis. As D4R cages resemble the secondary building units of several crystalline zeolite frameworks, linker molecules were selected by considering the default three-periodic nets that have practically been used to design crystalline framework materials including COFs. As mentioned above, however, it is nearly impossible to achieve polymer networks with long-range order, since most of them are formed under kinetic control. As a result, the three-periodic nets serve as merely qualitative guides to ideal structures. Three zeolite topologies (ACO,AFY, and LTA) can be built from D4R cages as the sole secondary building units. In their frameworks, the D4R cages are connected through two-coordinate linear linkers;the only difference is the orientation of the D4R cages. Considering the periodic arrangement of the discrete cages in such frameworks, the maximum symmetry of the ACO topology can be constructed from 1808 linear linkers without the need to rotate the D4R cages, and thus ACO appears to be the default topology. Accordingly, one can expect connection of the D4R cages with rigid, linear molecules (e.g.,1 and 2) to lead networks with local ACO-like structure 。 |
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jiangguofeng
金虫 (著名写手)
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大四写论文(RXMCDM代发): 金币+20, 多谢应助！ 2015-09-02 23:15:59
大四写论文(RXMCDM代发): 金币+20, 多谢应助！ 2015-09-02 23:15:59
| 我们的网络目标设计的尝试是从选择合适的结构单元和用一种有效的催化剂进行的偶联反应开始的。图１归纳了我们设计的一般睛况: 带有卤芳端基的D4R笼是多用途的、高度可连接的单元，可用于通过诸如赫克反应、铃木偶联反应和薗头偶合反应等精心研制的交叉偶联反应形成无机-有机杂化高分子材料。 之所以选择化合物BrPh - D4R是因为它可以在一个具有高度区选和立体选择性的实际规模上通过最新的复分解反应进行合成。 由于D4R笼类似几种晶体沸石骨架的二级构造单元,连结分子是通过设想实际上已经用于设计包括COF在内的晶体骨架材料的预置三-周期网来选择的。 然而,如上所述,获得具有长程序聚合物网络几乎是不可能的,因为它们中的大多数是在动态控制下形成的。 结果,三-周期网仅仅起到定性导向到理想结构的作用。三沸石拓扑结构（ACO,AFY,和LTA）可以从作为这种溶胶二级构造单元的D4R笼来建造。 在它们的骨架中, D4R笼通过两个-坐标直线的接头连接;唯一的区别在于D4R笼的方向。鉴于在此类骨架中这种分散笼的周期性排列, ACO拓扑结构的最大对称性可以根据1808直线接头而构思，而不需要旋转D4R笼,因此ACO看起来是这种预置[默认]拓扑结构。据此,人们可以预期D4R笼与刚性的线型分子(例如1，2)的连接以导致形成具有局部ACO状结构。 |
2楼2015-04-05 16:01:06
