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大四寫論文

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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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大四寫論文(RXMCDM代發(fā)): 金幣+20, 多謝應(yīng)助！ 2015-09-02 23:15:59

我們的網(wǎng)絡(luò)目標(biāo)設(shè)計(jì)的嘗試是從選擇合適的結(jié)構(gòu)單元和用一種有效的催化劑進(jìn)行的偶聯(lián)反應(yīng)開始的。圖１歸納了我們?cè)O(shè)計(jì)的一般睛況: 帶有鹵芳端基的D4R籠是多用途的、高度可連接的單元，可用于通過諸如赫克反應(yīng)、鈴木偶聯(lián)反應(yīng)和薗頭偶合反應(yīng)等精心研制的交叉偶聯(lián)反應(yīng)形成無(wú)機(jī)-有機(jī)雜化高分子材料。之所以選擇化合物BrPh - D4R是因?yàn)樗梢栽谝粋€(gè)具有高度區(qū)選和立體選擇性的實(shí)際規(guī)模上通過最新的復(fù)分解反應(yīng)進(jìn)行合成。由于D4R籠類似幾種晶體沸石骨架的二級(jí)構(gòu)造單元,連結(jié)分子是通過設(shè)想實(shí)際上已經(jīng)用于設(shè)計(jì)包括COF在內(nèi)的晶體骨架材料的預(yù)置三-周期網(wǎng)來選擇的。然而,如上所述,獲得具有長(zhǎng)程序聚合物網(wǎng)絡(luò)幾乎是不可能的,因?yàn)樗鼈冎械拇蠖鄶?shù)是在動(dòng)態(tài)控制下形成的。結(jié)果,三-周期網(wǎng)僅僅起到定性導(dǎo)向到理想結(jié)構(gòu)的作用。三沸石拓?fù)浣Y(jié)構(gòu)（ACO,AFY,和LTA）可以從作為這種溶膠二級(jí)構(gòu)造單元的D4R籠來建造。在它們的骨架中, D4R籠通過兩個(gè)-坐標(biāo)直線的接頭連接;唯一的區(qū)別在于D4R籠的方向。鑒于在此類骨架中這種分散籠的周期性排列, ACO拓?fù)浣Y(jié)構(gòu)的最大對(duì)稱性可以根據(jù)1808直線接頭而構(gòu)思，而不需要旋轉(zhuǎn)D4R籠,因此ACO看起來是這種預(yù)置[默認(rèn)]拓?fù)浣Y(jié)構(gòu)。據(jù)此,人們可以預(yù)期D4R籠與剛性的線型分子(例如1，2)的連接以導(dǎo)致形成具有局部ACO狀結(jié)構(gòu)。

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2樓2015-04-05 16:01:06