Building-up Remarkably Stable Magnesium Porphyrin Polymers Self-Assembled via Bidentate Axial Ligands: Synthesis, Structure, Surface Morphology, and Effect of Bridging Ligands
Building-up Remarkably Stable Magnesium Porphyrin Polymers Self-Assembled via Bidentate Axial Ligands: Synthesis, Structure, Surface Morphology, and Effect of Bridging Ligands
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DOI：
10.1021/ic300826p
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发表时间：
2012-09-17
影响因子：
4.6
通讯作者：
Rath, Sankar Prasad
中科院分区：
文献类型：
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作者：
Ikbal, Sk Asif;Brahma, Sanfaori;Rath, Sankar Prasad
合成了一系列由双齿轴向配体介导的四硝基八乙基镁卟啉超分子结构，并进行了结构表征。本研究中使用了六个链长不断增加的共轭轴向配体，其中连续离子之间的Mg中心点Mg非键距离也从0.73纳米增加到2.70纳米。据我们所知，这是第一个报告，稳定的金属卟啉聚合物与如此长的间隔已经在一锅合成如此容易。在六配位络合物的X射线结构中观察到线性一维（1D）聚合物链，其中卟啉单元彼此平行排列，具有所谓的"串"状结构，以保持偏移堆叠重叠。然而，在最佳Mg中心点Mg非键合距离之后，这些1D链不继续，而是它们形成具有"轮轴"状结构的五配位卟啉二聚体，然后通过π-π相互作用以垂直方式自聚集以更有效地填充由大桥接配体产生的空间，从而导致球形结构。研究了这些分子在溶液中的结构及其在高度有序热解石墨（HOPG）上的表面形貌。
A series of supramolecular architectures of magnesium tetranitrooctaethylporphyrins mediated by several bidentate axial ligands have been synthesized in excellent yields and structurally characterized. Six conjugated axial ligand with increasing chain lengths have been utilized in the present investigations in which the Mg center dot center dot center dot Mg nonbonding distance between successive ions also increases from 0.73 to 2.70 nm in the series. To the best of our knowledge, this is the first report where stable metallo-porphyrin polymers with such long spacers have been synthesized in one pot so easily. Linear one-dimensional (1D) polymeric chains were observed in the X-ray structure of the six-coordinated complexes in which porphyrin units are aligned parallel to each other to have so-called "shish kebab" like architectures to maintain offset-stacked overlap. However, after an optimum Mg center dot center dot center dot Mg nonbonding distance, these 1D chain do not continue, rather they form five-coordinated porphyrin dimers with "wheel-and-axle" like architectures which are then self-aggregated by pi-pi interactions in a perpendicular manner to fill space created by large bridging ligands more effectively which consequently results in spherical structures. The structures of the molecules in solution and their surface patterns on highly ordered pyrolytic graphite (HOPG) have also been investigated.