陕西师范大学曹睿团队通过Co卟啉催化剂的空间效应实现双电子和四电子氧化还原的调控。 相关研究成果发表在2021年3月19日出版的国际学术期刊《德国应用化学》。

实现选择性的2e或4e氧还原反应（ORR）非常关键但具有挑战性。

该文中，研究人员只调整空间效应实现控制Co卟啉的ORR选择性。研究人员设计了带有中间苯基的Co卟啉1，每个中间苯基都带有大量的邻氨基。由于空间位阻的存在，1有四种电子结构相似但空间效应不同的阿托品。异构体αβαβ和αααα分别催化ORR，n=2.10和3.75（n是每O2转移的电子数），但ααββ和ααβ的选择性较差，n=2.89‐3.10。

异构体αβαβ通过阻止双分子O 2活化路径来催化2e ORR，而αα通过改善其口袋处O 2结合来提高4e ORR选择性，这一特征通过O K边近边X射线吸收精细结构等光谱方法得到证实。

该工作代表了一个只调整空间效应而不改变分子和电子结构，以改善2e和4e的ORR的无与伦比的例子。

附：英文原文

Title: Controlling Oxygen Reduction Selectivity through Steric Effects: Electrocatalytic Two‐Electron and Four‐Electron Oxygen Reduction with Cobalt Porphyrin Atropisomers

Author: Bin Lv, Xialiang Li, Kai Guo, Jun Ma, Yanzhi Wang, Haitao Lei, Fang Wang, Xiaotong Jin, Qingxin Zhang, Wei Zhang, Ran Long, Yujie Xiong, Ulf-Peter Apfel, Rui Cao

Issue&Volume: 2021-03-19

Abstract: Achieving a  s elective 2e     or 4e     oxygen reduction reaction (ORR) is critical but challenging. Herein, we report controlling ORR selectivity of Co porphyrins by tuning only steric effects. We designed Co porphyrin   1   with   meso  ‐phenyls each bearing a bulky   ortho  ‐amido group. Due to the resulted steric hinderance,   1   has four atropisomers with similar electronic structures but dissimilar steric effects. Isomers   αβαβ   and   αααα   catalyze ORR with   n   = 2.10 and 3.75 (  n  is the electron number transferred per O  2  ), respectively, but   ααββ   and   αααβ   show poor selectivity with   n   = 2.89‐3.10. Isomer   αβαβ   catalyzes 2e     ORR by preventing a bimolecular O  2   activation path, while   αααα   improves 4e     ORR selectivity by improving O  2   binding at its pocket, a feature confirmed by spectroscopy methods, including  O K‐edge  near‐edge  X‐ray absorption fine structure . This work represents an unparalleled example to improve 2e     and 4e     ORR by tuning only steric effects without changing molecular and electronic structures.

DOI: 10.1002/anie.202102523

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202102523