Sub-micron Polymer–Zeolitic Imidazolate Framework Layered Hybrids via Controlled Chemical Transformation of Naked ZnO Nanocrystal Films

Abstract

Here we show that sub-micron coatings of zeolitic imidazolate frameworks (ZIFs) and even ZIF−ZIF bilayers can be grown directly on polymers of intrinsic microporosity from zinc oxide (ZnO) nanocrystal precursor films, yielding a new class of all-microporous layered hybrids. The ZnO-to-ZIF chemical transformation proceeded in less than 30 min under microwave conditions using a solution of the imidazole ligand in N,N-dimethylformamide (DMF), water, or mixtures thereof. By varying the ratio of DMF to water, it was possible to control the morphology of the ZIFon-polymer from isolated crystallites to continuous films. Grazing incidence X-ray diffraction was used to confirm the presence of crystalline ZIF in the thin films, and X-ray absorption spectroscopy was used to quantify film purity, revealing films with little to no residual ZnO. The role solvent plays in the transformation mechanism is discussed in light of these findings, which suggest the ZnO nanocrystals may be necessary to localize heterogeneous nucleation of the ZIF to the polymer surface.

A tale of two membranes: from poly (ionic liquid) to metal–organic framework hybrid nanoporous membranesviapseudomorphic replacement

“…In the crystallization of the MOFs, large crystals form when nucleation is slow, relative to crystal growth. 44,45 In our study, the nucleation principally occurs as long as free carboxylate groups are exposed to the metal containing solution, and crystal growth stops when all accessible carboxylate groups, after being gradually released from the crosslinks, are depleted. In the PIL membrane, the carboxylate groups in the upper part are highly crosslinked with PIL, i.e., less free carboxylate groups are available for immediate coordination with Cu(II), which in turn makes nucleation with Cu(II) kinetically slower in comparison to that at the membrane bottom.…”

Nanoparticle@Metal‐Organic Frameworks as a Template for Hierarchical Porous Carbon Sponges

“…ZIF‐8 has been synthesized at room temperature using ZnO nanoparticles as a metal source . ZIF‐8 single‐crystals are usually obtained from ZnO nanoparticle dispersions, while ZIF‐8 in a polycrystalline form is obtained in the conversion of ZnO coatings due to larger amount of ZnO available . ZnO nanoparticles are slowly dissolved in a 2‐methylimidazole solution in methanol releasing Zn II , which is subsequently coordinated to the 2‐methylimidazole encapsulating the ZnO nanoparticles in ZIF‐8 crystals.…”

“…[18] ZIF-8 single-crystals are usually obtained from ZnO nanoparticle dispersions, [18] while ZIF-8 in ap olycrystalline form is obtainedi nt he conversion of ZnO coatingsd ue to larger amount of ZnO available. [19,21] ZnO nanoparticles are slowly dissolved in a2 -methylimidazole solution in methanolr eleasing Zn II ,w hich is subsequently coordinated to the 2-methylimidazole encapsulatingt he ZnO nanoparticles in ZIF-8 crystals.I nt his work, the conversion of ad ispersion of ZnO nanoparticles was carriedo ut in al arge excess of 2-methylimidazole (10:1), obtaining ah igh ZnO to ZIF-8 conversion yield. As ar esult, the correspondingp owder X-ray diffraction pattern showed intense ZIF-8 characteristic peaks at 2q = 7.308,1 0.358,1 2.708,a nd 18.008 ( Figure 1a).…”

“…[16] ZIF-8 is typicallyc rystallized from solution precursors. [2,17] However,Z IF-8 has been obtained from solid ZnO precursors in form of nanoparticles, [18][19][20] or thin layers. [21] This approach facilitatedt he growth of ZIF-8 coatings in core-shell structures, [22,23] or polymer monoliths.…”

Metal Oxide Assisted Preparation of Core–Shell Beads with Dense Metal–Organic Framework Coatings for the Enhanced Extraction of Organic Pollutants

“…Recently,a napproachbased on the sequential deposition of am etal oxide precursor followed by the partial or total conversion of the precursor into the desired MOF emerged as ap otential way to position MOFs. [30][31][32][33][34][35][36][37][38] Metal oxides are first anchored to the substrate directly from chemical vapor deposition or solution-based growth methods. The conversion of the precursor metal oxide is performed in solution in the presence of the desired organic linker.A lternatively, the organic linker can be supplied in the vapor phase to achieve the complete chemical vapor deposition of MOFs.…”