Ultra-fast Switchable Dipolar Rotors in Metal Organic Frameworks at 4 K

The proponents' recent discovery of molecular rotors (Nature Chem. 2020, 12, 845) which can retain their fast dynamics down to very low temperature, such as 2 K, with nearly negligible activation energy (as low as 6 cal/mol), led to a rich multiplicity of distinct rotary phenomena, mirrored in NMR relaxation complex profiles. Now we have reached a neat advancement by inserting ultra-fast dipolar rotors in metal-organic framework (MOFs) of the family of frustrated trigonal rotors (FTRs), generating fast responsive and switchable ferroelectric materials for memories and electrically driven optical devices. Therefore, it would be challenging to detect order-disorder transitions of such new dynamical materials at extremely low temperatures by synchrotron-source X-ray diffraction. Moreover, identifying rotor conformations, occupation of specific sites and symmetry changes as a function of temperature will help explain unprecedented mobility and the mechanism of motion in the solid-state.