Dynamic assembly of coordination boxes from (en)Pd(II) unit and a rectangular panel-like ligand: NMR, CSI-MS, and X-ray studies
Dynamic assembly of coordination boxes from (en)Pd(II) unit and a rectangular panel-like ligand: NMR, CSI-MS, and X-ray studies
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DOI：
10.1021/ja003043o
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发表时间：
2001-02-07
影响因子：
15
通讯作者：
Yamaguchi, K
中科院分区：
文献类型：
--
作者：
Yamanoi, Y;Sakamoto, Y;Yamaguchi, K
Pd（II）或Pt（II）的正方形平面配位几何形状与基于吡啶的配体的简单组合提供了用于纳米尺寸的框架如大环、笼、索烃、管和胶囊的自组装的有效方法。1为了将吡啶基配位的Pd（II）配合物的结构扩展到更刚性和更大的配位框架，可以用双配位的3，5-双-（3-吡啶基）苯基单元取代单配位的4-吡啶基。根据这一想法，将最简单的基于吡啶的桥连配体4，4 '-联吡啶修饰成四齿配体1）。该配体具有板状构象，与（en）Pd（NO3）2（2）络合后，组装成大的离散盒结构，如312+和416+，类似于2和4，4′-联吡啶的三核和四核环状配合物的组装。2，3在这里，我们报告说，这些预期的盒结构是有效地形成一个动态的方式。也就是说，盒子处于平衡状态并且可以平滑地相互转换。冷喷雾电离质谱（CSIMS）是近年来发展起来的一种研究组装过程中动力学和热力学产物的有效方法（方案1）2的处理（1.25× 10-2 mmol）与配体1（0.62× 10-2 mmol），50 ℃，在D2 O-CD 3 OD中孵育4天（1：1，0.5mL）产生一种主要产物，在以88%产率分离为PF 6盐后，通过CSI-MS将其指定为四聚体框416+（在m/z处的突出峰）1688.8 [4，13 PF 6] 3+和1230.8 [4，12 PF 6] 4+）。在1H NMR中，观察到与416+的D4 h结构一致的一组六个质子。除了框416+之外，在1H NMR中还检测到未表征的次要产物。在平衡状态下，所有的产物构成了一个动态库的框结构从一个单一的配体。5从库中，我们发现两个盒子结构，
The simple combination of square planar coordination geometry of Pd (II) or Pt (II) with pyridine-based ligands offers an efficient method for the self-assembly of nanometer-sized frameworks such as macrocycles, cages, catenanes, tubes, and capsules. 1 To expand the structures of pyridyl-coordinated Pd (II) complexes into more rigid and bigger coordination frameworks, one can replace a mono-coordinating 4-pyridyl group by a doubly ligating 3, 5-bis-(3-pyridyl) phenyl unit. According to this idea, 4, 4′-bipyridine, which is the simplest pyridine-based bridging ligand, is modified into tetradentate ligand 1). This ligand is expected to take a panellike conformation and, on complexation with (en) Pd (NO3) 2 (2), assemble into large discrete box structures such as 312+ and 416+ in analogy to the assembly of trinuclear and tetranuclear cyclic complexes from 2 and 4, 4′-bipyridine. 2, 3 Here we report that these expected box structures are efficiently formed in a dynamic fashion. Namely, the boxes are in equilibrium and smoothly interconvertable. Coldspray ionization mass spectroscopy (CSIMS), which was developed recently by some of us, 4 is found to be very effective to study both kinetic and thermodynamic products in the assembly process (Scheme 1).Treatment of 2 (1.25× 10-2 mmol) with ligand 1 (0.62× 10-2 mmol) at 50 C for 4 d in D2O-CD3OD (1: 1, 0.5 mL) gave rise to one major product, which was assigned as tetrameric box 416+ by CSI-MS after being isolated as PF6 salt in 88% yield (prominent peaks at m/z) 1688.8 [4 ‚13PF6] 3+ and 1230.8 [4 ‚12PF6] 4+). In 1H NMR, a set of six protons was observed in consistent with the D4h structure of 416+. In addition to box 416+, uncharacterized minor products were also detected in 1H NMR. Being in equilibrium, all of the products constituted a dynamic library of box structures from a single ligand. 5 From the library, we found that two box structures, both