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Liquid Phase Heteroepitaxial Growth of Moisture‐Tolerant MOF‐5 Isotype Thin Films and Assessment of the Sorption Properties by Quartz Crystal Microbalance
Author(s) -
Wannapaiboon Suttipong,
Tu Min,
Fischer Roland A.
Publication year - 2014
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201302854
Subject(s) - quartz crystal microbalance , materials science , crystallite , crystallinity , chemical engineering , adsorption , thin film , monolayer , sorption , selective adsorption , metal organic framework , nanotechnology , composite material , organic chemistry , chemistry , engineering , metallurgy
The moisture‐tolerant metal‐organic frameworks (MOFs) of formula [Zn 4 O(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.