Acidification and assembly of porphyrin at an interface: counterion matching, selectivity, and supramolecular chirality.
Acidification and assembly of porphyrin at an interface: counterion matching, selectivity, and supramolecular chirality.
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DOI：
10.1021/am900399w
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发表时间：
2009-09
影响因子：
9.5
通讯作者：
Yiqun Zhang;Penglei Chen;Yanping Ma;Shenggui He;Minghua Liu
中科院分区：
文献类型：
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作者：
Yiqun Zhang;Penglei Chen;Yanping Ma;Shenggui He;Minghua Liu
研究了一种游离碱非手性卟啉5，10，15，20-四（3，5-二甲氧基苯基）-21H，23H-卟啉在不同酸性亚相中的界面双质子化和组装。它已被证明，该化合物可以在原位双质子化的酸性亚相，并可以形成组件。将这种界面有序的超分子组装体转移到固体基底上，组装体表现出超分子手性。有趣的是，双质子化物种组装的超分子手性表现出反离子依赖行为。对于从含水HCl亚相制造的组件，可以观察到强烈的棉花效应（CE），虽然卟啉本身是非手性的。当使用HBr水溶液作为亚相时，组装体显示出弱CE，而对于从HNO 3或HI亚相配制的组装体没有检测到CE。有趣的是，当HBr和NaCl，或硝酸和NaCl的混合物，采用作为亚相，所形成的组件显示手性功能类似于那些制造的盐酸亚相，这表明Cl（-）可以优先可视化的超分子手性，虽然系统本身是由非手性物种。实验事实和理论计算的基础上，已经提出了一个解释与不同大小的抗衡离子和不同的结合亲和力的抗衡阴离子的双质子化的卟啉物种。我们的研究结果提供了新的见解组装的双质子化卟啉以及界面发生的对称性破缺。
The interfacial diprotonation and assemblies of a free-base achiral porphyrin, 5,10,15,20-tetrakis(3,5-dimethoxyphenyl)-21H,23H-porphine, on various acidic subphases were investigated. It has been shown that the compound could be diprotonated in situ on an acidic subphase and can form assemblies. The interfacially organized supramolecular assemblies were transferred onto a solid substrate, and the assemblies showed supramolecular chirality. Interestingly, the supramolecular chirality of the assemblies of the diprotonated species showed a counterion-dependent behavior. For the assemblies fabricated from the aqueous HCl subphases, a strong Cotton effect (CE) could be observed, although the porphyrin itself is achiral. When an aqueous HBr solution was used as the subphase, the assemblies showed a weak CE, whereas no CE could be detected for the assemblies formulated from the HNO3 or HI subphase. Interestingly, when a mixture of HBr and NaCl, or HNO3 and NaCl, was employed as the subphase, the formed assemblies displayed chiral features similar to those fabricated on the HCl subphase, suggesting that the Cl(-) could be preferentially visualized in terms of supramolecular chirality, although the system itself is composed of achiral species. On the basis of the experimental facts and a theoretical calculation, an explanation with regard to the different sizes of the counterions and the distinct binding affinities of the counteranions to the diprotonated porphyrin species has been proposed. Our findings provide new insights into the assembly of the diprotonated porphyrins as well as the interfacially occurring symmetry breaking.