Tuning the Reactivity of Cofacial Porphyrin Prisms for Oxygen Reduction Using Modular Building Blocks
Tuning the Reactivity of Cofacial Porphyrin Prisms for Oxygen Reduction Using Modular Building Blocks
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DOI：
10.1021/jacs.0c11895
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发表时间：
2021-01-20
影响因子：
15
通讯作者：
Cook, Timothy R.
中科院分区：
文献类型：
--
作者：
Crawley, Matthew R.;Zhang, Daoyang;Cook, Timothy R.
我们使用MTPyP（M = Co（II）或Zn（II），TPyP = 4-tetrapidylpyrrophin）和官能化的基于铼的“分子夹”使用配位驱动的自组装八个共面卟啉棱镜。我们的方法允许这些架构的快速合成，在隔离产率高达98%的组装步骤。结构和反应性研究提供了对氧还原反应（ORR）的构建块的作用的更深入的理解。通过使用循环伏安法和流体动力学伏安法在水性介质中的非均相催化剂油墨上探测催化功效。报道的棱镜对动力学受阻的4 e（-）/4 H * 还原O-2生成H2O的选择性（>98%）优于动力学更容易的2 e（-）/12 H * 还原生成H2 O2。此外，我们已经证明了显着的共面增强所观察到的催化速率常数k（s）（类似于5个数量级）的单核类似物。我们的结论是，立体散装的剪辑起着重要的作用，在这些棱镜的结构动力学，这反过来又调制ORR反应的选择性和动力学。
We assembled eight cofacial porphyrin prisms using MTPyP (M = Co(II) or Zn(II), TPyP = 4-tetrapyridylporphyrin) and functionalized ruthenium-based "molecular clips" using coordination-driven self-assembly. Our approach allows for the rapid synthesis of these architectures in isolated yields as high as 98% for the assembly step. Structural and reactivity studies provided a deeper understanding of the role of the building blocks on the oxygen reduction reaction (ORR). Catalytic efficacy was probed by using cyclic and hydrodynamic voltammetry on heterogeneous catalyst inks in aqueous media. The reported prisms showed outstanding selectivity (>98%) for the kinetically hindered 4e(-)/4H* reduction of O-2 to H2O over the kinetically more accessible 2e(-)/12H* reduction to H2O2. Furthermore, we have demonstrated significant cofacial enhancement in the observed catalytic rate constant k(s) (similar to 5 orders of magnitude) over the mononuclear analogue. We conclude that the steric bulk of the clip plays an important role in the structural dynamics of these prisms, which in turn modulates the ORR reactivity with respect to selectivity and kinetics.