Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720-1460, USA.
Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720-1460, USA.
Angew Chem Int Ed Engl. 2022 Sep 12;61(37):e202207666. doi: 10.1002/anie.202207666. Epub 2022 Aug 8.
Microenvironments tailored by multifunctional secondary coordination sphere groups can enhance catalytic performance at primary metal active sites in natural systems. Here, we capture this biological concept in synthetic systems by developing a family of iron porphyrins decorated with imidazolium (im) pendants for the electrochemical CO reduction reaction (CO RR), which promotes multiple synergistic effects to enhance CO RR and enables the disentangling of second-sphere contributions that stem from each type of interaction. Fe-ortho-im(H), which poises imidazolium units featuring both positive charge and hydrogen-bond capabilities proximal to the active iron center, increases CO binding affinity by 25-fold and CO RR activity by 2000-fold relative to the parent Fe tetraphenylporphyrin (Fe-TPP). Comparison with monofunctional analogs reveals that through-space charge effects have a greater impact on catalytic CO RR performance compared to hydrogen bonding in this context.
多功能二次配位球基团定制的微环境可以增强自然系统中主金属活性位点的催化性能。在这里，我们通过开发一系列带有咪唑（im）侧链的铁卟啉来在合成系统中捕捉到这一生物概念，用于电化学 CO 还原反应（CO RR），这促进了多种协同效应，增强了 CO RR，并能够解开源自每种相互作用的第二球贡献。Fe-ortho-im(H)，使咪唑单元具有正电荷和氢键能力，使其靠近活性铁中心，与母体 Fe 四苯基卟啉（Fe-TPP）相比，增加了 25 倍的 CO 结合亲和力和 2000 倍的 CO RR 活性。与单功能类似物的比较表明，在这种情况下，与氢键相比，空间电荷效应对催化 CO RR 性能的影响更大。
