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A comprehensive overview of characterization tools for the analysis of well-known metal–organic frameworks and physico-chemical phenomena associated to their applications.

The physical properties and morphologies of polymers are pivotal for their manufacturing and processing at the industrial scale. Here, we present the formation of either fibers or micrometer-sized polyethylene beads by using the MIL-100(Cr) and MIL-101(Cr) zeotypes. The MOF structures have been used for ethylene polymerization with diethylaluminum chloride (DEA) as a cocatalyst, resulting in very different activities and morphologies. In situ DR UV−vis−NIR and CO-probe FT-IR spectroscopy revealed the formation of different types of Cr species for each catalyst material, suggesting that the linker (for the same metal and topological structure) plays a crucial role in the formation of Cr olefin polymerization sites. Activity in ethylene polymerization in toluene at 10 bar and 298 K was related to the observed spectra, corroborating the presence of different types of active sites, by their different activities for high-density polyethylene (HDPE) formation. SEM micrographs revealed that although MIL-100 and MIL-101 exhibit identical zeolitic MTN topology, only the latter is able to collapse upon addition of DEA and subsequent ethylene insertion and to fracture forming polymer beads, thus showing noticeable activity in HDPE formation. We ascribed this effect to the higher pore volume and, thus, fragility of MIL-101, which allowed for polymer formation within its larger cages. MOFs were compared to the nonporous chromium(III) benzoate [Cr 3 O(O 2 CPh) 6 (H 2 O) 2 ]-(NO 3 )•nH 2 O complex (1), in order to study the effect of the embodiment in the porous framework. The properties of the polymer obtained under identical reaction conditions were comparable to that of MIL-101(Cr) but very different morphologies were observed, indicating that the MIL-101(Cr) structure is necessary to impart a certain architecture at the microscale. This work clearly shows that MOFs can be used as catalytically active morphology regulators for ethylene polymerization. Moreover, even for an identical topology and metal in a MOF structure, the linker and the pore structure play crucial roles and have to be carefully considered in the design microporous coordination polymers for catalytic purposes.

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Because of their high tunability and surface area, metal-organic frameworks (MOFs) show great promise as supports for metal nanoparticles. Depending on the synthesis route, MOFs may contain defects. Here, we show that highly crystalline MIL-100(Fe) and disordered Basolite® F300, with identical iron 1,3,5-benzenetricarboxylate composition, exhibit very divergent properties when used as a support for Pd nanoparticle deposition. While MIL-100(Fe) shows a regular MTN-zeotype crystal structure with two types of cages, Basolite® F300 lacks long-range order beyond 8 Å and has a single-pore system. The medium-range configurational linker-node disorder in Basolite® F300 results in a reduced number of Lewis acid sites, yielding more hydrophobic surface properties compared to hydrophilic MIL-100(Fe). The hydrophilic/hydrophobic nature of MIL-100(Fe) and Basolite® F300 impacts the amount of Pd and particle size distribution of Pd nanoparticles deposited during colloidal synthesis and dry impregnation methods, respectively. It is suggested that polar (apolar) solvents/precursors attractively interact with hydrophilic (hydrophobic) MOF surfaces, allowing tools at hand to increase the level of control over, for example, the nanoparticle size distribution.

Metal-organic frameworks (MOFs) are ap romising class of materials form any applications, due to their high chemical tunability and superb porosity.B yg rowing MOFs as (thin-)films, additional properties and potentiala pplications become available. Here, copper( II) 1,3,5-benzenetricarboxylate (Cu-BTC) metal-organic framework (MOF) thin-films are reported, which were synthesized by spin-coating, resulting in "nanowebs", that is, fiber-like structures. These surface-mounted MOFs (SURMOFs) were studied by using photoinduced force microscopy (PiFM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The optimal concentration of precursors (10 mm)w as determined that resulted in chemically homogeneous, pure nanowebs. Furthermore, the morphology and (un)coordinated Cu sites in the web were tuned by varyingt he rotation speed of the spin-coating process. X-ray diffraction (XRD) analysis showed that ro-tation speeds ! 2000 rpm (with precursors in aw ater/ethanol solution) generatet he catena-triaqua-m-(1,3,5-benzenetricarboxylate)-copper(II), or Cu(BTC)(H 2 O) 3 coordinationp olymer.X -ray photoelectrons pectroscopy (XPS) highlighted the strongd ecrease in number of (defective) Cu + sites, as the nanowebs mainly consist of coordinated Cu 2 + Lewis acid sites (LAS) and organic linker-linker,f or example, hydrogenbonding, interactions. Finally, the Lewis-acidic character of the Cu sites is illustrated by testing the films as catalysts in the isomerization of a-pineneo xide. The highern umber of LAS (! 3000 rpm), result in higher campholenic aldehyde selectivity reachingu pt o87.7 %. Furthermore, the strength of ac ombined micro-and spectroscopica pproach in understandingt he nature of MOF thin-films in as patially resolved manner is highlighted.[a] L.

Guest@MOF materials have potential in next-generation materials for electroconductive devices. Micro-spectroscopy studies of TCNQ@HKUST-1 electroconductive composites revealed the effects of spatial distribution and water vapor on this material.

Surface-mounted metal-organic frameworks (SUR-MOFs) show promising behavior for am anifold of applications.AsMOF thin films are often unsuitable for conventional characterization techniques,understanding their advantageous properties over their bulk counterparts presents ag reat analytical challenge.Inthis work, we demonstrate that MOFs can be grown on calcium fluoride (CaF 2)w indows after proper functionalization. As CaF 2 is optically (in the IR and UV/Vis range of the spectrum) transparent, this makes it possible to study SURMOFs using conventional spectroscopic tools typically used during catalysis or gas sorption. Hence,wehave measured HKUST-1 during the adsorption of CO and NO.We show that no copper oxide impurities are observed and also confirm that SURMOFs grown by al ayer-by-layer (LbL) approach possess Cu + species in paddlewheel confirmation, but 1.9 times less than in bulk HKUST-1. The developed methodology paves the way for studying the interaction of any adsorbed gases with thin films,n ot limited to MOFs,l ow temperatures,o rt hese specific probe molecules,p ushing the boundaries of our current understanding of functional porous materials.