Ultra-Fast Rotors and Light Emitting Ligands in MOFs

Rotors, motors and switches in the solid state find a favorable playground in porous materials, such as Metal Organic Frameworks (MOFs) and Porous Aromatic Frameworks (PAFs), thanks to their large free volume, which allows for fast dynamics. We fabricated MOFs and PAFs with reorientable linkers and benchmark mobility also at very low temperature, to reduce the energy demand for motion-activation and light stimulus-response.[1] A fast molecular rotor in a Zn-MOF endowed with continuous, unidirectional hyperfast rotation with energy barrier of 6.2 cal/mol and high frequency persistent for several turns is achieved (Figure 1). Ligh responsive porous switchable frameworks took advantage of quantitative photoisomerization in the solid state and porosity of the framework to modulate the gas adsorption in response to light.[2] MOF nanocrystals comprising high-Z linking nodes interacting with the ionizing radiation, arranged in an orderly fashion at a nanometric distance from ligand emitters showed ultrafast sensitization of the ligand fluorescence, thus supporting the development of new engineered scintillators.[3] References [1] A. Comotti, P. Sozzani et al. Nat. Chem. 12 (2020) 845; [2] A. Comotti, B. Feringa, et al. Nature Chem. 12 (2020) 595; [3] A. Comotti, A. Vedda, A. Monguzzi, et al. Nature Photonics (2021), https://doi.org/10.1038/s41566-021-00769-z. Financial support from the Italian Ministry of University and Research (MIUR) through the grant ‘Dipartimenti di Eccellenza-2017 Materials For Energy’ is acknowledged. This research was funded by the PRIN-2015CTEBBA-003.