Thanneeru Srinivas, Duay Searle S, Jin Lei, Fu Youjun, Angeles-Boza Alfredo M, He Jie
Department of Chemistry, and ‡Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, United States.
Department of Chemistry, and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, United States.
ACS Macro Lett. 2017 Jul 18;6(7):652-656. doi: 10.1021/acsmacrolett.7b00300. Epub 2017 Jun 12.
Metal-containing single chain polymeric nanoparticles (SCPNs) can be used as synthetic mimics of metalloenzymes. Currently, the role of the folded polymer backbones on the activity and selectivity of metal sites is not clear. Herein, we report our findings on how polymeric frameworks modulate the coordination of Cu sites and the catalytic activity/selectivity of Cu-containing SCPNs mimicking monophenol hydroxylation reactions. Imidazole-functionalized copolymers of poly(methyl methacrylate--3-imidazolyl-2-hydroxy propyl methacrylate) were used for intramolecular Cu-imidazole binding that triggered the self-folding of polymers. Polymer chains imposed steric hindrance which yielded unsaturated Cu sites with an average coordination number of 3.3. Cu-containing SCPNs showed a high selectivity for the hydroxylation reaction of phenol to catechol, >80%, with a turnover frequency of >870 h at 60 °C. The selectivity was largely influenced by the flexibility of the folded polymer backbone where a more flexible polymer backbone allows the cooperative catalysis of two Cu sites. The second coordination sphere provided by the folded polymer that has been less studied is therefore critical in the design of active mimics of metalloenzymes.
含金属的单链聚合物纳米颗粒（SCPNs）可作为金属酶的合成模拟物。目前，折叠的聚合物主链对金属位点的活性和选择性的作用尚不清楚。在此，我们报告了关于聚合物框架如何调节铜位点的配位以及含铜SCPNs模拟单酚羟基化反应的催化活性/选择性的研究结果。聚（甲基丙烯酸甲酯 - 3 - 咪唑基 - 2 - 羟基丙基甲基丙烯酸酯）的咪唑官能化共聚物用于分子内铜 - 咪唑结合，引发聚合物的自折叠。聚合物链产生空间位阻，产生平均配位数为3.3的不饱和铜位点。含铜SCPNs对苯酚羟基化为邻苯二酚的反应表现出高选择性，>80%，在60°C下的周转频率>870 h⁻¹。选择性在很大程度上受折叠聚合物主链柔韧性的影响，其中更灵活的聚合物主链允许两个铜位点协同催化。因此，较少研究的由折叠聚合物提供的第二配位层在金属酶活性模拟物的设计中至关重要。
