Switchable Supramolecular Polymers from the Self-Assembly of a Small Monomer with Two Orthogonal Binding Interactions
Switchable Supramolecular Polymers from the Self-Assembly of a Small Monomer with Two Orthogonal Binding Interactions
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DOI：
10.1021/ja200941a
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发表时间：
2011-06-15
影响因子：
15
通讯作者：
Schmuck, Carsten
中科院分区：
文献类型：
--
作者：
Groeger, Gerd;Meyer-Zaika, Wolfgang;Schmuck, Carsten
通过红外激光动态光散射（DLS）、小角中子散射（SANS）、电子显微镜（TEM）、低温透射电镜（cro -TEM）和粘度测量，低分子量异位单体1在极性溶液中形成超分子聚合物。1的自组装是基于两个正交的结合相互作用，即铁(II)-三吡啶1:2金属配体配合物的形成和自互补的胍基羰基吡咯羧酸两性离子的二聚化。这两种结合相互作用在极性（DMSO）甚至水溶液中都具有足够的稳定性，以确保形成相当长度（高达100纳米）的线性聚合物。超分子聚合遵循环链机制，导致溶液在毫摩尔浓度及以上的粘度显著增加。然后，线性聚合物在溶液中进一步聚集成更大的球状聚集体，具有密集的核心和松散的外壳。这两种结合相互作用都可以通过添加竞争配体来去除金属离子并随后读取Fe（II）或通过添加酸或碱时两性离子的可逆质子化和去质子化来进一步打开和关闭。因此，1的自组装可以在四种不同的状态之间来回切换，单体，金属络合二聚体或离子对二聚体，最后是聚合物。
The low molecular weight heteroditopic monomer 1 forms supramolecular polymers in polar solution as shown, for example, by infrared laser-based dynamic light scattering (DLS), small-angle neutron scattering (SANS), electron microscopy (TEM, cryo-TEM), and viscosity measurements. Self-assembly of 1 is based on two orthogonal binding interactions, the formation of a Fe(II)-terpyridine 1:2 metal-ligand complex and the dimerization of a self-complementary guanidiniocarbonyl pyrrole carboxylate zwitterion. Both binding interactions have a sufficient stability in polar (DMSO) and even aqueous solutions to ensure formation of linear polymers of considerable length (up to 100 nm). The supramolecular polymerization follows a ring-chain mechanism causing a significant increase in the viscosity of the solutions at millimolar concentrations and above. The linear polymers then further aggregate in solution into larger globular aggregates with a densely packed core and a loose shell. Both binding interactions can be furthermore switched on and off either by adding a competing ligand to remove the metal ion and subsequent readdition of Fe(II) or by reversible protonation and deprotonation of the zwitterion upon addition of acid or base. The self-assembly of 1 can therefore be switched back and forth between four different states, the monomer, a metal-complexed dimer or an ion paired dimer, and finally the polymer.