Relation Between Coordination and Lewis‐Acid Property of MOF‐Derived Mononuclear Zn(II) Catalyst Toward Epoxide Hydroxylation

Abstract

Lewis-acid properties of the coordinatively unsaturated metal ions are highly relevant to the coordination environment; however, it remains a challenge to establish the coordination structure-activity relationship, especially in heterogeneous catalysis. Here, a typical metal-organic framework, ZIF-8, is selected as the precursor to prepare Lewis-acid based ZnÀ N/ PÀ C mononuclear catalysts, with well-designed external structures but difference in the local coordination. The obtained mononuclear Zn(II) catalysts can not only inherit the advantages of MOF in coordination, but also simulate the homogeneous environment during the catalysis owing to the monodispersed metal sites in ZIF-8. Eventually, relation between coordination and Lewis-acid property toward epoxide hydroxylation has been illustrated. Results show the substituted coordination atom of P and the decrease of coordination number strongly enhance the Lewis-acidity of Zn 2 + , causing the TOF values changes from 8.7 to 80.1 h À 1 based on Zn content. The work affords an understanding and inspiration of coordination environment matters toward Lewis-acid catalysis in organic transformations.

Modulating acid site spatial location of Zn/ZSM‐5 catalyst to boost the stable aromatization of hexane

“…To clarify the acidic site spatial location directly, the Zn/ZSM‐5 and Zn/ZSM‐5‐ x Si catalysts were treated by triphenylphosphine oxide to poison the outer surface acidity 28,29 . Table S3 shows that the total acid content of the Zn/ZSM‐5 catalyst decreases significantly from 1.10 to 0.35 mmol/g, while the total acid content of the Zn/ZSM‐5‐Si, Zn/ZSM‐5‐4Si, and Zn/ZSM‐5‐6Si catalysts changes little before and after poisoning.…”

“…and Zn/ZSM-5-xSi catalysts were treated by triphenylphosphine oxide to poison the outer surface acidity. 28,29 Table S3 shows that the total acid content of the Zn/ZSM-5 catalyst decreases significantly from 1.10 to 0.35 mmol/g, while the total acid content of the Zn/ZSM-5-Si, Zn/ZSM-5-4Si, and Zn/ZSM-5-6Si catalysts changes little before and after poisoning. Notably, the total acid amount of the Zn/ZSM-5 catalyst after poisoning is 0.35 mmol/g, which is close to the acid amount of the Zn/ZSM-5-Si catalyst without poisoning (0.37 mmol/g).…”

Atomically Dispersed Iron Sites on the Hollow Nitrogen-Doped Carbon Framework with a Highly Efficient Performance on Carbon Dioxide Cycloaddition

“…Metal catalysts supported on porous carbon media have attracted increasing attention of researchers and have been widely used in many types of chemical catalytic reactions in recent years because of their large and uniform pores, which facilitate substrate enrichment, mass transfer, and product release. − Metal–organic frameworks (MOFs) have high porosity, a controllable pore structure, and a large specific surface area, and they are the most ideal porous carbon media material. − However, the lower stability of most of the MOFs and metal aggregated during the pyrolysis process limits their application in the construction of heterogeneous catalysts. − …”