title: Post-synthetic modification of metal-organic framework thin films using click chemistry: the importance of strained C-C triple bonds.
abstract: In this work, we demonstrate that strain-promoted azide-alkyne cycloaddition (SPAAC) yields virtually complete conversion in the context of the post-synthetic modification (PSM) of metal-organic frameworks (MOFs). We use surface-anchored MOF (SURMOF) thin films, [Zn2(N3-bdc)2(dabco)], grown on modified Au substrates using liquid-phase epitaxy (LPE) as a model system to first show that, with standard click chemistry, presently, the most popular method for rendering additional functionality to MOFs via PSM, quantitative conversion yields, cannot be reached. In addition, it is virtually impossible to avoid contaminations of the product by the cytotoxic Cu(I) ions used as a catalyst, a substantial problem for applications in life sciences. Both problems could be overcome by SPAAC, where a metal catalyst is not needed. After optimization of reaction conditions, conversion yields of nearly 100% could be achieved. The consequences of these results for various applications of PSM-modified SURMOFs in the fields of membranes, optical coatings, catalysis, selective gas separation, and chemical sensing are briefly discussed.
authors.affiliation: Institute of Functional Interfaces, ‡Soft Matter Synthesis Lab, Institute of Biological Interfaces, and ∥Institute of Toxicology and Genetics, Karlsruhe Institute of Technology , 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Zhengbang
authors.initials: Z
authors.lastname: Wang
authors.forename: Jinxuan
authors.initials: J
authors.lastname: Liu
authors.forename: Hasan K
authors.initials: HK
authors.lastname: Arslan
authors.forename: Sylvain
authors.initials: S
authors.lastname: Grosjean
authors.forename: Tobias
authors.initials: T
authors.lastname: Hagendorn
authors.forename: Hartmut
authors.initials: H
authors.lastname: Gliemann
authors.forename: Stefan
authors.initials: S
authors.lastname: Bräse
authors.forename: Christof
authors.initials: C
authors.lastname: Wöll
mesh_terms: D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry; D002384:Catalysis; D060326:Chemistry Techniques, Synthetic; D057930:Click Chemistry; D003300:Copper / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D017155:Wettability; D015032:Zinc / Q000737:chemistry*
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D005456:Fluorescent Dyes; D009942:Organometallic Compounds; D003300:Copper; D015032:Zinc