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J Vis Exp

Title:		Surface Functionalization of Metal-Organic Frameworks for Improved Moisture Resistance
Author(s):		Castells-Gil J; Novio F; Padial NM; Tatay S; Ruiz-Molina D; Marti-Gastaldo C;
Address:		"Instituto de Ciencia Molecular (ICMol), Universitat de Valencia. Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology. Instituto de Ciencia Molecular (ICMol), Universitat de Valencia; carlos.marti@uv.es"
Journal Title:		J Vis Exp
Year:		2018
Volume:		20180905
Issue:		139
Page Number:		-
DOI:		10.3791/58052
ISSN/ISBN:		1940-087X (Electronic) 1940-087X (Linking)
Abstract:		"Metal-organic frameworks (MOFs) are a class of porous inorganic materials with promising properties in gas storage and separation, catalysis and sensing. However, the main issue limiting their applicability is their poor stability in humid conditions. The common methods to overcome this problem involve the formation of strong metal-linker bonds by using highly charged metals, which is limited to a number of structures, the introduction of alkylic groups to the framework by post-synthetic modification (PSM) or chemical vapour deposition (CVD) to enhance overall hydrophobicity of the framework. These last two usually provoke a drastic reduction of the porosity of the material. These strategies do not permit to exploit the properties of the MOF already available and it is imperative to find new methods to enhance the stability of MOFs in water while keeping their properties intact. Herein, we report a novel method to enhance the water stability of MOF crystals featuring Cu2(O2C)4 paddle-wheel units, such as HKUST (where HKUST stands for Hong Kong University of Science & Technology), with the catechols functionalized with alkyl and fluoro-alkyl chains. By taking advantage of the unsaturated metal sites and the catalytic catecholase-like activity of Cu(II) ions, we are able to create robust hydrophobic coatings through the oxidation and subsequent polymerization of the catechol units on the surface of the crystals under anaerobic and water-free conditions without disrupting the underlying structure of the framework. This approach not only affords the material with improved water stability but also provides control over the function of the protective coating, which enables the development of functional coatings for the adsorption and separations of volatile organic compounds. We are confident that this approach could also be extended to other unstable MOFs featuring open metal sites"
Keywords:		Adsorption Catalysis Metal-Organic Frameworks/*chemistry Oxidation-Reduction Porosity Surface Properties Water/chemistry;
Notes:		"MedlineCastells-Gil, Javier Novio, Fernando Padial, Natalia M Tatay, Sergio Ruiz-Molina, Daniel Marti-Gastaldo, Carlos eng Research Support, Non-U.S. Gov't Video-Audio Media 2018/09/25 J Vis Exp. 2018 Sep 5; (139):58052. doi: 10.3791/58052"