Uniform, Binary Functionalization of a Metal–Organic Framework Material

Abstract

General routes to confined spaces of welldefined chemical composition and complex three-dimensional structure have long been sought by materials chemists. Here, we introduce metal−organic framework (MOF) materials as an ideal scaffold upon which such organized complexity can be built. Employing an orthogonal coordination strategy, we constructed a large-pore MOF material with two different modifiable linkers in well-defined positions relative to each other. The independent and quantitative covalent grafting of two distinct chemical groups onto these differently reactive linkers yielded a uniformly bifunctionalized MOF material. Not only does this methodology offer an efficient route via which the properties of well-defined microporous materials can be fine-tuned, but it also creates a solid-state platform for synthetically accessing constructs that better emulate the well-ordered intricacy of biological structures.

Hydrogen-Bonding Linkers Yield a Large-Pore, Non-Catenated, Metal-Organic Framework with pcu Topology

“…Of the three pillared paddle-wheel MOF topologies that can be formed, only the kag topology, formed from the kgm net, has consistently been non-catenated. While low temperature nucleation has been suggested as a method for generating these wide-channel MOFs [13], this topology is relatively rare, with a handful of reports in the last several years [10][11][12][13]16,17]. The more common sql net, formed by di-and tetratopic dicarboxylate ligands, is pillared to form the pcu and fsc nets, respectively [15].…”

“…A major focus of our group is the uniform multifunctionalization of MOFs. To this end, we have been synthesizing pillared paddle-wheel MOFs where the two different linkers bear reactive groups that can be addressed independently post MOF assembly [10,11]. In this work, we specifically target non-catenated frameworks that can accommodate additional functionality.…”

Postsynthetic Modification of Metal–Organic Frameworks by Vapor-Phase Grafting

“…Fei et al realized both metal substitution and linker exchange of MOFs by stepwise “tandem” postsynthetic modification . Grafting involved the reaction between the active sites of MOFs and introduced molecules with functional groups. − Nguyen and Cohen incorporated a hydrophobic alkyl chain in IRMOF-3 to improve its moisture stability . In terms of synthesis methods, most postsynthetic modification processes are implemented by solvent-based techniques.…”

Uniform and simultaneous orthogonal functionalization of a metal–organic framework material

“…[12,13] Our recent contribution to this work is a strategy for the uniform bifunctionalization of MOF materials. [14] We constructed a large-channel, pillared MOF, KSU-1, composed of two linkers that have distinct coordination chemistry and that bear independently reactive functionalities. The different coordination chemistry of the linkers guarantees that the independently reactive groups are in well-defined locations throughout the structure, [9,15] resulting in uniform binary functionalization (Figure 1A).…”

“…Previously we reacted DPG with a cyclic anhydride resulting in products with ester linkages. [14] The advantage of the current reaction is that the carbamate linkage has higher chemical stability, [30] which simplifies characterization of the products. Following a modified procedure, [31] we immersed KSU-2triazole in a solution of isopropyl isocyanate in acetonitrile, with continuous agitation at 80 °C for 48 h to produce KSU-2bi-Path1.…”