These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
Cooperative Light-Induced Breathing of Soft Porous Crystals via Azobenzene Buckling
preprintsubmitted on 25.11.2020, 12:12 and posted on 26.11.2020, 05:19 by Simon Krause, Jack D. Evans, Volodymyr Bon, Stefano Crespi, Wojciech Danowski, Wesley R Browne, Sebastian Ehrling, Francesco Walenszus, Dirk Wallacher, Nico Grimm, Daniel D. Többens, Manfred S. Weiss, Stefan Kaskel, Ben L. Feringa
Although light is a prominent stimulus for smart materials, the application of photoswitches as light-responsive triggers for phase transitions of porous materials remains poorly explored. Here we incorporate an azobenzene photoswitch in the backbone of a metal-organic framework producing light-induced structural contraction of the porous network in parallel to gas adsorption. Light-stimulation enables non-invasive spatiotemporal control over the mechanical properties of the framework, which ultimately leads to pore contraction and subsequent guest release via negative gas adsorption. The complex mechanism of light-gated breathing is established by a series of in situ diffraction and spectroscopic experiments, supported by quantum mechanical and molecular dynamic simulations. Unexpectedly, this study identifies a novel light-induced deformation mechanism of constrained azobenzene photoswitches relevant to the future design of light-responsive materials.