Co-ion Effects in the Self-Assembly of Macroions: From Co-ions to Co-macroions and to the Unique Feature of Self-Recognition
Co-ion Effects in the Self-Assembly of Macroions: From Co-ions to Co-macroions and to the Unique Feature of Self-Recognition
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DOI：
10.1021/acs.langmuir.0c01797
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发表时间：
2020-09-08
期刊：
影响因子：
3.9
通讯作者：
Liu, Tianbo
中科院分区：
文献类型：
--
作者：
Chen, Jiahui;Qian, Kun;Liu, Tianbo
大分子离子作为纳米尺度的可溶离子，表现出不同于简单离子和大胶体悬浮液的独特溶液行为。在大离子溶液中，反离子被认为是重要的和被充分探索的。然而，共离子(带有与大分子离子相同类型电荷的离子)的作用常常被忽视。在这里，我们通过实验和模拟研究，展示了共离子作为共离子大小的函数在它们与大离子(以{Mo72Fe30}和{SrPd12}为模型)相互作用中的作用，以及相关的在稀溶液中自组装成黑莓结构的作用。几种独特的共离子效应被清楚地识别出来：小离子(卤化物、氧酸离子)、亚纳米尺度的大离子(空位的Keggin离子和十二硼酸根离子)，以及大小与大离子相当的离子。小共离子对全亲水的{Mo72Fe30}的自组装没有明显的影响，但由于疏水作用和分子间氢键的作用，小共离子对疏水的{SrPd12}的自组装有影响。亚纳米离子，又名。超混沌离子，仍然太小，不能单独组装成黑莓，但它们可以与大离子共组装，显示出与大离子体系的强烈相互作用。当共离子的大小与大离子的大小相当时，它们独立组装，而不是与大离子组装，导致了先前报道的大离子独特的自识别现象。
Macroions, as soluble ions with a size on the nanometer scale, show unique solution behavior different from those of simple ions and large colloidal suspensions. In macroionic solutions, the counterions are known to be important and well-explored. However, the role of co-ions (ions carrying the same type of charge as the macroions) is often ignored. Here, through experimental and simulation studies, we demonstrate the role of co-ions as a function of co-ion size on their interaction with the macroions (using {Mo72Fe30} and {SrPd12} as models) and the related self-assembly into blackberry-type structures in dilute solutions. Several regimes of unique co-ion effects are clearly identified: small ions (halides, oxoacid ions), subnanometer-scaled bulky ions (lacunary Keggin and dodecaborate ions), and those with sizes comparable to the macroions. Small co-ions have no observable effect on the self-assembly of fully hydrophilic {Mo72Fe30}, while due to hydrophobic interaction and intermolecular hydrogen bonds, the small co-ions show influences on the self-assembly of hydrophobic {SrPd12}. Subnanometer ions, a.k.a. superchaotropic ions, are still too small to assemble into a blackberry by themselves, but they can coassemble with the macroions, showing a strong interaction with the macroionic system. When the co-ion size is comparable to that of the macroions, they assemble independently instead of assembling with the macroions, leading to the previously reported unique self-recognition phenomenon for macroions.