Main-chain metallopolymers at the static-dynamic boundary based on nickelocene
Main-chain metallopolymers at the static-dynamic boundary based on nickelocene
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DOI：
10.1038/nchem.2743
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发表时间：
2017-08-01
期刊：
影响因子：
21.8
通讯作者：
Manners, Ian
中科院分区：
文献类型：
--
作者：
Musgrave, Rebecca A.;Russell, Andrew D.;Manners, Ian
含金属聚合物中金属离子和配体之间的相互作用涉及两种极端的键合：持久的共价键合，其中聚合物本质上是静态的，或不稳定的配位键合，这导致动态超分子材料。基于二茂铁和二茂钴的主链聚异戊二烯属于前一类，因为存在强的金属-双键。在这里，我们描述了一个主链聚nickelocene-形成的开环聚合的适度应变[3]nickelocenophane单体-可以在静态和动态之间切换，因为相对较弱的镍-nickelocene配体的相互作用。这通过观察到在配位或极性溶剂中在低浓度下或在升高的温度下发生聚二茂镍的解聚来说明。这种动态聚合物-单体平衡的H-1 NMR光谱的研究允许相关的热力学参数的测定。然而，微观流变学数据表明，在类似条件下，聚二茂镍被认为是静态的较短的流变时间尺度。
Interactions between metal ions and ligands in metal-containing polymers involve two bonding extremes: persistent covalent bonding, in which the polymers are essentially static in nature, or labile coordination bonding, which leads to dynamic supramolecular materials. Main-chain polymetallocenes based on ferrocene and cobaltocene fall into the former category because of the presence of strong metal-cyclopentadienyl bonds. Herein, we describe a main-chain polynickelocene-formed by ring-opening polymerization of a moderately strained [3]nickelocenophane monomer-that can be switched between static and dynamic states because of the relatively weak nickel-cyclopentadienyl ligand interactions. This is illustrated by the observation that, at a low concentration or at an elevated temperature in a coordinating or polar solvent, depolymerization of the polynickelocene occurs. A study of this dynamic polymer-monomer equilibrium by H-1 NMR spectroscopy allowed the determination of the associated thermodynamic parameters. Microrheology data, however, indicated that under similar conditions the polynickelocene is considered to be static on the shorter rheological timescale.