title: Structural Effects in Visible-Light-Responsive Metal-Organic Frameworks Incorporating ortho-Fluoroazobenzenes.
abstract: The ability to control the interplay of materials with low-energy photons is important as visible light offers several appealing features compared to ultraviolet radiation (less damaging, more selective, predominant in the solar spectrum, possibility to increase the penetration depth). Two different metal-organic frameworks (MOFs) were synthesized from the same linker bearing all-visible ortho-fluoroazobenzene photoswitches as pendant groups. The MOFs exhibit different architectures that strongly influence the ability of the azobenzenes to isomerize inside the voids. The framework built with Al-based nodes has congested 1D channels that preclude efficient isomerization. As a result, local light-heat conversion can be used to alter the CO2 adsorption capacity of the material on exposure to green light. The second framework, built with Zr nodes, provides enough room for the photoswitches to isomerize, which leads to a unique bistable photochromic MOF that readily responds to blue and green light. The superiority of green over UV irradiation was additionally demonstrated by reflectance spectroscopy and analysis of digested samples. This material offers promising perspectives for liquid-phase applications such as light-controlled catalysis and adsorptive separation.
authors.affiliation: Catalysis Engineering, Chemical Engineering Department, Delft University of Technology, Julianalaan 136, 2628 BL Delft (The Netherlands). s.castellanosortega@tudelft.nl.
authors.forename: Sonia
authors.initials: S
authors.lastname: Castellanos
authors.affiliation: Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin (Germany).
authors.forename: Alexis
authors.initials: A
authors.lastname: Goulet-Hanssens
authors.affiliation: Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin (Germany).
authors.forename: Fangli
authors.initials: F
authors.lastname: Zhao
authors.affiliation: Catalysis Engineering, Chemical Engineering Department, Delft University of Technology, Julianalaan 136, 2628 BL Delft (The Netherlands).
authors.forename: Alla
authors.initials: A
authors.lastname: Dikhtiarenko
authors.affiliation: Catalysis Engineering, Chemical Engineering Department, Delft University of Technology, Julianalaan 136, 2628 BL Delft (The Netherlands).
authors.forename: Alexey
authors.initials: A
authors.lastname: Pustovarenko
authors.affiliation: Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin (Germany).
authors.forename: Stefan
authors.initials: S
authors.lastname: Hecht
authors.affiliation: Catalysis Engineering, Chemical Engineering Department, Delft University of Technology, Julianalaan 136, 2628 BL Delft (The Netherlands).
authors.forename: Jorge
authors.initials: J
authors.lastname: Gascon
authors.affiliation: Catalysis Engineering, Chemical Engineering Department, Delft University of Technology, Julianalaan 136, 2628 BL Delft (The Netherlands).
authors.forename: Freek
authors.initials: F
authors.lastname: Kapteijn
authors.affiliation: Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin (Germany). david.bleger@chemie.hu-berlin.de.
authors.forename: David
authors.initials: D
authors.lastname: Bléger
keywords: azo compounds; carboxylate ligands; metal-organic frameworks; photochromism; photoswitches