Network diversity through decoration of trigonal-prismatic nodes: two-step crystal engineering of cationic metal-organic materials.-猫眼课题宝

DOI：

10.1002/anie.201104688

发表时间：

2011-11

期刊：

Angewandte Chemie

影响因子：

通讯作者：

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作者：

Alexander Schoedel;L. Wojtas;Steven P. Kelley;R. Rogers;M. Eddaoudi;M. Zaworotko

在过去的十年中，由金属基节点（金属离子或金属簇）和桥接有机配体（连接体）构建的多孔金属有机材料（Metal-Organic Material，简称MOs）网络吸引了越来越多的科学兴趣。它们的模块化性质赋予了结构和组成的多样性，可调功能性以及单一材料中的多种特性。特别是，MOM可以表现出超大的表面积，这意味着它们代表了一类独特的有前途的材料，以解决与气体储存和分离，环境修复，催化，传感和药物输送相关的技术挑战。晶体工程在MOM的早期发展中发挥了重要作用，例如可以通过连接多边形或多面体节点（如四面体（dia），八面体（pcu），正方形（nbo）和三棱柱（acs））生成的高对称性网络。上述网络可以被描述为平台，因为它们在规模和属性方面都是可微调的，因为有许多节点和链接器可以维持这些结构。吡啶基连接体如4，4 '-联吡啶最初以这种能力被开发，但大多数超大表面积MOM基于羧酸酯连接体，如苯-1，3-二羧酸（1，3-BDC）、苯-1，4-二羧酸（1，4-BDC）和苯-1，3，5-三羧酸（BTC）。这样的接头补充合成上可接近的和高度对称的金属羧酸盐节点，例如[Cu 2（CO2）4]、[Zn 4（m4-O）（CO2）6]和[{M3（m3-O）（CO2）}6]（M=Cr，Fe）。[Cu 2（CO2）4]的开发，“方形叶轮”，已被证明是特别富有成效的，因为配体设计或混合配体的使用促进了大量的高度多孔的多面体网。[{M3（m3-O）（CO2）}6]，即“三棱柱”，也提供了高度多孔的材料，如MIL-100和MIL-101所示。然而，即使这种节点非常坚固，其结构往往只形成微晶材料，需要苛刻的合成条件。我们在此描述了一种晶体工程策略，该策略利用基于用吡啶基部分装饰的水稳定三角棱柱的预成型分子构建块（MBB）。一个两步模块化的方法，开辟了一个广泛的新类的MOMs，从而促进。形成杂环骨架的两步法是已知的，并且基于随后连接到不同金属离子的金属络合物的合成。据我们所知，在这种情况下尚未研究过能够提供具有超大通道的高对称性网络的高连接性金属配合物。我们的两步过程包括分离由吡啶基部分装饰的三棱柱，然后通过其六个外齿吡啶基部分将这种高度可溶的三棱柱初级分子构建块（tpPMBB-1）与不同的金属配位（方案1）。我们创造了术语PMMB来类比沸石化学中的主要结构单元（PBU）。在这种情况下，PMBs与各种二级分子构建块（SMBB）的不同连接导致结构多样性。这种方法使我们能够利用金属-羧酸盐和金属-吡啶基键，并确保由此产生的网络将带正电荷。本文描述了此类网络的前三个示例tp-PMBB-1 snx-1、-snw-1和-stp-1（命名法描述了主要构建块和最终网络的拓扑）。结构单元tp-PMBB-1 [Cr 3（m3-O）（isonic）6] +（isonic=吡啶-4-羧酸酯）代表离散且稳健的“六吡啶基”6-连接节点，其非常适合于随后合成过多的具有纳米级特征的网络。其与两种金属的配位化学在本文中详述：线性但可弯曲的连接体（Ag）和刚性方形平面金属节点（Cd）。我们的研究结果证明了Ag存在于非线性几何中的能力，并促进了两种新的三角棱柱节点网络拓扑结构，snx（六连通网络类型x）（6，6）和snw（六连通网络类型w）（6，6），而不是默认的acs网络。由另一个tp-PMBB形成的具有acs拓扑结构的阳离子网也可以形成，并将在别处报道。对于刚性CdN 4节点，我们预期stp（正方形三棱柱）（6，4）拓扑结构由三角棱柱和矩形顶点图形组成，并且该网络的第一个纳米多孔变体确实是孤立的。[*]答：Schoedel，Dr. L Wojtas，Prof. Dr. M.南佛罗里达大学化学系，4202 East Fowler Ave.，SCA 400，坦帕，FL 33620（USA）电子邮件：xtal@usf.edu主页：http://chemistry.usf.edu/faculty/zaworotko/

During the past decade porous metal–organic material (MOM) networks constructed from metal-based nodes (metal ions or metal clusters) and bridging organic ligand (linkers) have attracted ever increasing scientific interest. Their modular nature imparts structural and compositional diversity, tunable functionality, and multiple properties within a single material. In particular, that MOMs can exhibit extralarge surface area means that they represent a uniquely promising class of materials to solve technological challenges related to gas storage and separation, environmental remediation, catalysis, sensing, and drug delivery. Crystal engineering played a major role in the early development of MOMs as exemplified by the high symmetry nets that can be generated by linking polygonal or polyhedral nodes such as tetrahedra (dia), octahedra (pcu), squares (nbo), and trigonal prisms (acs). The aforementioned nets might be described as platforms because they are fine-tunable in terms of both scale and properties as there are many nodes and linkers that can sustain these structures. Pyridyl linkers such as 4,4’-bipyridine were initially exploited in such a capacity but the majority of extra-large surface area MOMs are based upon carboxylate linkers such as benzene-1,3-dicarboxylic acid (1,3-BDC), benzene-1,4-dicarboxylic acid (1,4-BDC), and benzene-1,3,5-tricarboxylic acid (BTC). Such linkers complement synthetically accessible and highly symmetrical metal carboxylate nodes such as [Cu2(CO2)4], [Zn4(m4-O)(CO2)6] and [{M3(m3-O)(CO2)}6] (M=Cr, Fe). The exploitation of [Cu2(CO2)4], the “square paddlewheel”, has proven to be particularly fruitful since ligand design or the use of mixed ligands facilitates a plethora of highly porous polyhedral nets. [{M3(m3-O)(CO2)}6] , the “trigonal prism”, has also afforded highly porous materials, as exemplified by MIL-100 and MIL-101. However, even though this node is remarkably robust, its structures tend to form only microcrystalline materials and require harsh synthetic conditions. We describe herein a crystal engineering strategy that exploits preformed molecular building blocks (MBBs) based upon water-stable trigonal prisms that are decorated with pyridyl moieties. A two-step modular approach that opens up a broad new class of bimetallic MOMs is thereby facilitated. Two-step processes to form heterobimetallic frameworks are known and are based on the synthesis of a metal complex that is subsequently connected to a different metal ion. To the best of our knowledge, high-connectivity metal complexes that afford high symmetry nets with extra-large channels have not yet been studied in this context. Our twostep process involves isolation of a trigonal prism decorated by pyridyl moieties and then coordinating this highly soluble trigonal-prismatic Primary Molecular Building Block (tpPMBB-1) to different metals through its six exodentate pyridyl moieties (Scheme 1). We coin the term PMMB to draw analogies to the primary building unit (PBU) in zeolite chemistry. In this context the different connections of PMBBs to various Secondary Molecular Building Blocks (SMBBs) lead to the structural diversity. This approach enables us to exploit both metal–carboxylate and metal–pyridyl bonds and ensures that the nets thereby generated will be positively charged. The first three examples of such nets, tp-PMBB-1snx-1, -snw-1, and -stp-1 (nomenclature describes both the primary building block and the topology of the resulting net) are described herein. The building block tp-PMBB-1 [Cr3(m3-O)(isonic)6] + (isonic= pyridine-4-carboxylate) represents a discrete and robust “hexapyridyl” 6-connected node that is well-suited for the subsequent synthesis of a plethora of networks with nanoscale features. Its coordination chemistry with two metals is detailed herein: a linear but bendable linker (Ag) and a rigid square-planar metal node (Cd). Our results demonstrate the ability of Ag to exist in nonlinear geometry and facilitate two new network topologies for trigonalprismatic nodes, snx (six-connected net type x) (6,6) and snw (six-connected net type w) (6,6), rather than the default acs net. A cationic net with acs topology formed by another tp-PMBB can also be formed and will be reported elsewhere. For the rigid CdN4 node we anticipated stp (square trigonal prism) (6,4) topology consisting of a trigonal-prismatic and a rectangular-vertex figure, and the first nanoporous variant of this net was indeed isolated. [*] A. Schoedel, Dr. L. Wojtas, Prof. Dr. M. J. Zaworotko Department of Chemistry, University of South Florida 4202 East Fowler Ave., SCA400, Tampa, FL 33620 (USA) E-mail: xtal@usf.edu Homepage: http://chemistry.usf.edu/faculty/zaworotko/

Network diversity through decoration of trigonal-prismatic nodes: two-step crystal engineering of cationic metal-organic materials.

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