Dresden 2017 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 27: Photoswitchable Materials

CPP 27.7: Talk

Tuesday, March 21, 2017, 15:30–15:45, ZEU 114

Thin Films of Photoswitchable Metal-Organic Frameworks — •Lars Heinke — Karlsruhe Institute of Technology (KIT)

Metal-organic frameworks (MOFs) are nanoporous, crystalline materials, assembled from metal notes and organic linker molecules. In addition to many potential applications of the (conventional) powder MOF material, well-defined thin films seem perfectly suited for challenging uses and as unique model systems, where certain molecular and MOF properties can be precisely measured by applying surface sensitive techniques. These thin films are prepared in a layer-by-layer fashion on a solid substrate by using liquid-phase epitaxy, referred to as the SURMOF-approach. Incorporating photochromic molecules like azobenzene in the crystalline structure enables the switching of physical and chemical MOF properties by light. The trans-to-cis switching or vice versa of the azobenzene groups by UV or visible light, respectively, can be used for various uses, such as realizing the remote-controlled release of guest molecules from a nanoporous container. Furthermore, these films can be used as membranes for the separation of molecular mixtures. There, the photoswitchable MOF films enable a dynamic control of the selectivity by remote signals, thus enabling a continuous adjustment of the permeate flux. For H2:CO2, the separation factor can be tuned between 3 and 8 by switching the photochromic moieties. Moreover, by loading the MOF pores with conducting organic molecules, the conduction of the guest molecules can be controlled in the fully remote by trans-cis photoswitching of the host structure.