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首页> 外文期刊>Chemistry: A European journal >meso-substituted aromatic 34 pi core-modified octaphyrins: Syntheses, characterization and anion binding properties
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meso-substituted aromatic 34 pi core-modified octaphyrins: Syntheses, characterization and anion binding properties

机译：介观取代的芳香族34 pi核修饰八氟卟啉：合成，表征和阴离子结合性质

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Modified octaphyrins with 34pi electrons have been synthesized and characterized following a simple synthetic methodology. An acid-catalyzed alpha,alpha coupling of tetrapyrranes containing furan, thiophene and selenophene rings resulted in the formation of the respective octaphyrins in relatively good yield. Solution studies by H-1 NMR and 2D NMR methods and single crystal X-ray structural characterization reveal an almost flat structure with two heterocyclic rings inverted. Specifically, in 14 two selenophene rings (one on each biselenophene unit) are inverted while in 15 two furan rings (one on each bifuran unit) are inverted when the meso substituent are mesityl groups. On changing the mesityl substituent to m-xylyl group as in 19, the location of ring inversion shifts to pyrrole rings (one on each bipyrrole unit) indicating the dependence of structure on the meso substituents. UV/Vis studies, both in freebase and protonated forms reveal typical porphyrinic character and the aromatic nature of the octaphyrins. The Deltadelta values evaluated by H-1 NMR spectroscopy also support their aromatic nature. The protonated forms of octaphyrins bind TFA anion in a 1:2 ratio. The TFA anions are located one above and below the plane of the octaphyrin macrocycle and they are held by weak electrostatic N-H-O interactions similar to that observed for protonated rubyrins. However, in the present case, there is an additional non-electrostatic C-H-O interaction involving beta-CH of the inverted heterocyclic ring and the carbonyl oxygen of the TFA. Furthermore, inter molecular interactions between the C-H of the meso-mesityl group and the fluorine of CF3 group of bound TFA leads to the formation of one-dimensional supramolecular arrays with interplanar distance of 13 Angstrom between two octaphyrins. [References: 51]
机译：已通过简单的合成方法合成并表征了具有34pi电子的改性八硫卟啉。含有呋喃，噻吩和硒烯环的四吡喃经酸催化的α，α偶联导致形成了相对较高产率的相应八卟啉。通过H-1 NMR和2D NMR方法进行的溶液研究以及单晶X射线结构表征显示，具有两个倒置的杂环的几乎平坦的结构。具体地，当内消旋取代基为均三甲苯基时，在14个中亚硒基环（每个双硒烯单元上一个）反转，而在15个中二呋喃环（每个双呋喃单元一个）上反转。当如在19中那样将异丁基取代基转变为间二甲苯基时，环反转的位置移动到吡咯环（每个双吡咯单元上一个），表明结构对内取代基的依赖性。游离碱和质子化形式的UV / Vis研究均显示了典型的卟啉特性和八卟啉的芳香性质。通过H-1 NMR光谱评估的δ值也支持其芳香性。八卟啉的质子化形式以1：2的比例结合TFA阴离子。 TFA阴离子位于八氢卟啉大环平面的上方和下方，它们通过弱静电N-H-O相互作用保持，类似于质子化的红宝石素所观察到的。然而，在当前情况下，存在另外的非静电的C-H-O相互作用，其涉及倒置的杂环的β-CH和TFA的羰基氧。此外，中-间苯二甲酰基的C-H与结合的TFA的CF 3基团的氟之间的分子间相互作用导致形成两个八碳八氢化合物之间的晶面间距为13埃的一维超分子阵列。 [参考：51]

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