Dresden 2014 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 23: Interfaces and Thin Films III

CPP 23.2: Talk

Tuesday, April 1, 2014, 15:15–15:30, ZEU 114

Optically triggered release from a molecular container: Photoswitching in thin films of metal-organic frameworks — •Lars Heinke¹, Murat Cakici², Stefan Bräse², and Christof Wöll¹ — ¹Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Karlsruhe — ²Institute of Organic Chemistry (IOC), Karlsruhe Institute of Technology (KIT), Karlsruhe

The remote control of surface properties is one of the key challenges in interfacial science. Here, we are going to show the great potential of thin porous films of metal-organic frameworks (MOFs) containing linkers with photoswitchable azobenzene side groups. The state of the azobenzene side groups can be switched by UV light from trans to cis and vice versa by visible light. This photoswitching influences the mass transfer of the guest molecules in the pores, i.e. the pores are ideally opened and closed by light. By means of liquid-phase epitaxy, SURMOFs (surface mounted metal-organic framework) with vertical compositional gradients can be synthesized. This enables the preparation of thin porous films with a passive bottom layer, which serves as a storage container, and a photoswitchable top layer serving as a valve, which opens and closes the container. After loading the porous coating with guest molecules, its release is initiated by illumination with visible light and monitored by a quartz crystal microbalance (QCM).