Methods for the dynamic and structural analysis of photoswitches@MOF – DYSPHOM

The combination of photoswitches (PS) and Metal-Organic Frameworks (MOFs) results in materials with extraordinary properties. Understanding interactions occurring inside such host-guest systems represents a key step to pave the way towards advanced functional materials. Since the properties of the guest molecules are determined by their structure and host/guest interactions, adapted characterization techniques are mandatory to draw a full picture of material properties as a function of structural parameters. However, great challenges lie in the analysis of such crystalline, semi-crystalline, or even dynamic host materials with possibly dynamic or disordered guest molecules. It is thus obligatory to advance methods and combine complementary approaches.
Our aim is to establish a robust analytical workflow combining experimental and theoretical methods to fully characterize PS@MOF composites in order to derive the structure-property relationship. This knowledge will be exploited to adjust synthesis strategies for a systematic design of such functional materials.
Both the non- and the irradiated species will be studied via solid-state NMR (ssNMR) and total X-ray scattering coupled to PDF to trace light induced positional changes of the PS within the MOF. The complemetary experimental data will be confronted with self-consistent charge density functional tight binding molecular dynamics (SCC-DFTB MD) simulations to provide a structural model including molecular motion inside the material.
Exploiting a combination of ssNMR, PDF analysis and (SCC-DFTB MD) modelling will provide a complete picture of the PS@MOF including a structural model of the host and the guest, along with local molecular motion, and host-guest interactions in initial and photoisomerized states. This access to unprecedented multiscale structural information will significantly impact the concepts for systematic construction as well as structural and functional characterization of such PS@MOF systems.