Strategies for Improving the Functionality of Zeolitic Imidazolate Frameworks: Tailoring Nanoarchitectures for Functional Applications

Abstract

Zeolitic imidazolate frameworks (ZIFs), a subclass of metal-organic frameworks (MOFs) built with tetrahedral metal ions and imidazolates, offer permanent porosity and high thermal and chemical stabilities. While ZIFs possess some attractive physical and chemical properties, it remains important to enhance their functionality for practical application. Here, an overview of the extensive strategies which have been developed to improve the functionality of ZIFs is provided, including linker modifications, functional hybridization of ZIFs via the encapsulation of guest species (such as metal and metal oxide nanoparticles and biomolecules) into ZIFs, and hybridization with polymeric matrices to form mixed matrix membranes for industrial gas and liquid separations. Furthermore, the developed strategies for achieving size and shape control of ZIF nanocrystals are considered, which are important for optimizing the textural characteristics as well as the functional performance of ZIFs and their derived materials/hybrids. Moreover, the recent trends of using ZIFs as templates for the derivation of nanoporous hybrid materials, including carbon/metal, carbon/oxide, carbon/sulfide, and carbon/phosphide hybrids, are discussed. Finally, some perspectives on the potential future research directions and applications for ZIFs and ZIF-derived materials are offered.

MOF‐Derived Cobalt Phosphide/Carbon Nanocubes for Selective Hydrogenation of Nitroarenes to Anilines

“…300 °C) in high‐boiling organic solvents, the method developed here is simple and convenient. Further, this method yields a homogeneous Co 2 P phase, all while avoiding the formation of toxic PH 3 , which occurs when using NaH 2 PO 2 as the phosphorus source …”

“…Further,t his method yields ah omogeneous Co 2 Pp hase, all while avoiding the formation of toxic PH 3 ,w hicho ccurs when using NaH 2 PO 2 as the phosphorus source. [13] The morphology of the materials acquired in each step was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). From the TEM and SEM images (Figures 1a and S1 in the Supporting Information), it was found that the prepared ZIF-67c ubes had smooths urfaces and an average size of about 400 nm.…”

“…For instance, often hydrodehalogenation reactions occur when halogens ubstituted nitroarenes were employed as substrates in the presence of Pd-catalysts; [19] when using Co 2 P/CN x nanocubes as the catalyst, all chlorine, bromine and iodine substituted substrates, no matter the position of the substituent group (located in the ortho-, meta-o r para-p osition), underwent hydrogenation with excellent selectivity and no dehalogenation by-products were detected (entries 7-10). Moreover,n itroarenes with strongly coordinating functional groups such as cyano, quinoline N, or amino groups,are known to poison Pd-catalysts through coordination with the Pd active sites;h owever,t hese same substrates readily formed the corresponding amino derivatives with high activity and selectivity using Co 2 P/CN x (entries [11][12][13] as the catalyst. [20] In addition to facile separation from products, heterogeneous catalysts must offer stability and recyclability to achieve a true cost advantage over their homogeneous counterparts.…”

Recent Advances in Micro‐/Nanostructured Metal–Organic Frameworks towards Photonic and Electronic Applications

“…Meanwhile, the high‐quality resonant channels of MOFs will provide an opportunity to construct low‐threshold miniaturized lasers . Strategies for positioning functional units within MOFs have involved ship‐in‐bottle (assembly of guests inside MOFs), bottle‐around‐ship (assembly of MOFs around guests), sandwich assembly (embedding NPs between MOF layers), and in situ encapsulation (simultaneous synthesis of MOF and guest nanoentities) (Scheme ) . For example, by a facile one‐pot method, He et al.…”

“…[52] Strategies for positioning functional units within MOFs have involved ship-in-bottle (assembly of guests inside MOFs), bottle-around-ship (assembly of MOFs aroundg uests), sandwich assembly (embedding NPs between MOF layers), and in situ encapsulation( simultaneous synthesis of MOF andg uest nanoentities)( Scheme 3). [51,53,54] For example, by af acile one-pot method, He et al reported that individual Au nanoparticles can be encapsulated within a single MOF-5 particle. [55] Moreover,w ith as imilar approach, ZIF-8 crystalsc ontaining luminescent quantum dots and lanthanide-doped NaYF 4 nanoparticles have also been prepared successfully.…”