Relationship between Channel and Sorption Properties in Coordination Polymers with Interdigitated Structures
Relationship between Channel and Sorption Properties in Coordination Polymers with Interdigitated Structures
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DOI：
10.1002/chem.201003734
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发表时间：
2011-04-01
影响因子：
4.3
通讯作者：
Kitagawa, Susumu
中科院分区：
文献类型：
--
作者：
Hijikata, Yuh;Horike, Satoshi;Kitagawa, Susumu
合成了具有线性联吡啶型配体的锌离子与间苯二甲酸酯的多孔性配位聚合物。[锌(Ip)(Bpb)](N)(CID-21；ip=间苯二甲酸酯，bpb=1，4-双(4-吡啶)苯)，[锌(Ip)(Bpt)](N)(CID-22；bpt=3，6-双(4-吡啶)-1，2，4，5-四嗪)和[锌(Ip)(Bpa)](N)(CID-23；bpa=1，4-双(4-吡啶)乙炔)都具有层状交错结构和相似的空穴体积(约27%)。在这些化合物中，一维瓶颈型通道沿着层堆积的垂直方向运行，其性质强烈地由联吡啶配体控制。粉末X-射线衍射研究表明，由于二维层堆积的不同，CID-21和CID-22具有相对刚性的多孔结构，而CID-23具有更大的柔性。被四嗪基团包围的CID-22的微孔吸附了极性分子，如甲醇和水。理论研究表明，CID-22对水的亲和力高于CID-21。CID-23的一维通道比其他两个化合物的通道宽，这使得芳香族分子能够被掺入。这是因为BPA连接物配体的形状产生了更宽的孔径(8.6埃)。只有CID-23分子筛能吸附苯分子，苯的吸附等温线呈开门型。这提供了客人住宿过程的证据，通过从无孔结构到多孔结构的大型结构转换。CID-23的柔韧性和受限的孔空间在298K时只允许苯进入通道，而不允许环己烷进入通道。这种多孔结构对这些相似的客人表现出明显的选择性。在2D配位层中引入细长的联吡啶配体，为设计具有不同柔韧性、微孔环境和分离能力的微孔化合物提供了一种策略。
Porous coordination polymers constructed from Zn2+ and isophthalate with linear bipyridyl-type ligands were synthesized. [Zn(ip)(bpb)](n) (CID-21; ip = isophthalate, bpb = 1,4-bis(4-pyridyl)benzene), [Zn(ip)(bpt)](n) (CID-22; bpt= 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine), and [Zn(ip)(bpa)](n) (CID-23; bpa= 1,4-bis(4-pyridyl)acetylene) all have interdigitated structures of layers and similar void volumes (approximate to 27%). In these compounds, 1D bottleneck-type channels run along the perpendicular direction of the layer stacking and their properties are strongly dominated by the dipyridyl linker ligands. Because of the difference in packing of 2D layers, CID-21 and CID-22 have relatively rigid porous structures, whereas CID-23 has greater flexibility, as indicated by the results of powder X-ray diffraction studies. The micropores of CID-22 surrounded by tetrazine moieties adsorb polar molecules, such as methanol and water. The higher affinity of CID-22 for water than CID-21 is supported by a theoretical study. The 1D channel of CID-23 is wider than that of the other two compounds, which enables the incorporation of aromatic molecules. This is because the shape of the bpa linker ligand generates a wider pore diameter (8.6 angstrom). Only CID-23 can adsorb a benzene molecule and the isotherm of benzene has a gate-openingtype profile. This offers proof of the guest accommodation process through large structural transformation from a nonporous to a porous structure. The flexibility and restricted pore space of CID-23, at 298 K, allows only benzene, but not cyclohexane, to enter the channels. The porous structure exhibits clear selectivity for these similar guests. The incorporation of an elongated dipyridyl linker ligand in the 2D coordination layers provides a strategy for the design of microporous compounds with different flexibilities, microporous environments, and separation abilities.