Liquid Phase Heteroepitaxial Growth of Moisture‐Tolerant MOF‐5 Isotype Thin Films and Assessment of the Sorption Properties by Quartz Crystal Microbalance

Abstract

The moisture‐tolerant metal‐organic frameworks (MOFs) of formula [Zn4O(L)3]n (L = di‐substituted carboxypyrazolate derivatives) are fabricated as thin films on self‐assembled monolayer (SAM) functionalized gold substrates by employing the step‐by‐step liquid phase epitaxial (LPE) deposition method in a continuous operation mode. The in situ monitoring of the deposition by quartz crystal microbalance (QCM) and grazing incidence X‐ray diffraction reveal different growth regimes and crystallinities of the obtained thin films in dependence of the chosen alkyl side chain functionality at the carboxypyrazolate linkers, L. To overcome the relatively poor crystallinity and low porosity of a particular homostructured metal‐organic framework type B film, the step‐by‐step heteroepitaxial growth of this MOF B on top of the crystallite surfaces of a well‐grown and lattice‐matched MOF type A is applied. This approach enables the fabrication of oriented, core‐shell‐like MOF B@A surface mounted heterocrystals as an intergrown homogeneous coating for the selective adsorption of volatile organic compounds. The accessible pore volumes of the individual components and the heterostructured films are characterized by performing adsorption measurements of different organic probe molecules using an environmentally controlled QCM instrument. The results show good adsorption capacity, excellent size exclusion selectivity for alcohols, and a high degree of moisture‐tolerance of the heteroepitaxial MOF films.

Liquid-Phase Epitaxial Growth of Highly Oriented and Multivariate Surface-Attached Metal–Organic Frameworks

“…In contrast to the tilted nanorods observed in SURMOF-D, D-on-A exhibits dense films composed of vertically aligned nanorods (Figure S44). The seeding layer effect with respect to the crystal orientation of SURMOFs is in line with previous reports. , To the best of our knowledge, the improved orientational growth of SURMOFs induced by a mixture of linkers is observed for the first time. Because these SURMOFs possess the same cell parameters, no position differences in either (001) or (100) diffraction can be observed in SXRD, meaning that the differences in the crystallographic “phase” caused by appending groups are undetectable by SXRD.…”

High-Performance, Room Temperature Hydrogen Sensing With a Cu-BTC/Polyaniline Nanocomposite Film on a Quartz Crystal Microbalance

“…This may be due to the formation of nanocomposite that may lower the degree of Cu-BTC crystallinity. As shown in Figure 5, the very small peak corresponds to PANI appear in the region between 2θ = 25-30 o which matches with previous reports [25], [26]. The morphology of the prepared films is investigated by SEM.…”

Surface-Mounted Metal–Organic Frameworks: Past, Present, and Future Perspectives

“…A combination of the hybrid natures and functionalities arising from individual SURMOFs offers properties that are early indicators of adsorptive separations of industrial and/or environmental relevance. For example, Wannapaiboon et 38 Other similar works further confirm the advantages of hetero-SURMOFs in adsorptive separation. 72,96,97 Normally, the adsorption capacity of the hetero-SURMOFs was found to be in between those of the respective MOFs.…”