Exposed Equatorial Positions of Metal Centers via Sequential Ligand Elimination and Installation in MOFs

Abstract

Metal-organic frameworks (MOFs) provide highly designable platforms to construct complex coordination architectures for targeted applications. Herein, we demonstrate that trans-coordinated metal centers with exposed equatorial positions can be placed in a MOF matrix. A Zr-based MOF, namely, PCN-160, was initially synthesized as a scaffold structure. Postsynthetic linker labilization was subsequently implemented to partially remove the original dicarboxylate linkers and incorporate pyridinecarboxylates. A pair of neighboring pyridyl groups was arranged at proper proximity within the framework to form trans-binding sites that accommodate different metal cations including Mn, Fe, Co, Ni, Cu, and Pd. Furthermore, the trans-coordinated Ni sites in porous frameworks can be readily accessed by substrates along the equatorial plane, facilitating the catalysis as manifested by the superior activity in ethylene dimerization over that observed for a cis-chelated catalyst.

Metal–Organic Frameworks Based on Group 3 and 4 Metals

“…[254] Additionally, sequential linker elimination and installation were used for the construction of multicomponent Zr-MOFs by Zhou and co-workers. [255,256] For example, linker labilization was initially realized to partially eliminate original dicarboxylates in PCN-160 and pyridinecarboxylates were incorporated into the framework subsequently. Two neighboring pyridyl groups were arranged at precisely designed positions within the framework to form trans-binding sites that accommodate transition metal cations.…”

“…[165,171,176,180,215,238,248] In addition, ethylene dimerization or oligomerization were also catalyzed by nickel containing Zr-MOFs, PCN-160-47%Ni, HUST-2, HUST-3, HUST-4, and NiCl@DUT-133, with high conversion yields and selectivity. [168,187,255] Farha and co-workers also [241] Copyright 2019, American Chemical Society.…”

A cationic thorium–organic framework with triple single-crystal-to-single-crystal transformation peculiarities for ultrasensitive anion recognition

“…[11][12][13][14] However, SC-SC transformation remains to be a relatively uncommon peculiarity among the numerous numbers of existing MOFs, especially for the ones composed of tetravalent metal ions or clusters. [15][16][17][18][19] This is partially because the strong Lewis acidity of M 4+ cations and, correspondingly, robust metal-ligand coordination not only make bond cleavage and formation rather challenging, but also make the crystallinity hard to retain. 20 In addition, most reported SC-SC transformations of tetravalent metal-based MOFs involves framework breathing, transmetallation, linker installation, and guest exchange, while topological transition and interpenetration conversion seldomly occur.…”

Synthesis, Crystal Structure, and Properties of a New Coordination Polymer Built from N/O-Donor Mixed Ligands

“…In the past decades, the crystalline material of coordination polymers (CPs) has become an expanding research topic, not only due to their fascinating architectures and captivating topologies [1][2][3], but also for their potent applications in the fields of luminescence [4], gas adsorption/separation [5], chemical sensors [6], heterogeneous catalysis [7], and so on. Because the coordination polymers are composed of the metal ion and organic ligands, that is, the nature of metal ion and organic ligands are most important factors for constructing targeted CPs with desired properties [8][9][10].…”