Fluorinated metal-organic frameworks (MOFs), comprising a wheel-shaped ligand with geminal rotating fluorine atoms, produced benchmark mobility of correlated dipolar rotors at 2 K, with practically null activation energy (Ea=17 cal/mol). 1H T1 NMR revealed multiple relaxation phenomena due to the exchange among correlated dipole-rotor configurations. Synchrotron radiation X-ray diffraction at 4 K, Density Functional Theory, Molecular Dynamics and phonon calculations showed the fluid landscape and pointed out a cascade mechanism converting dipole configurations into each other. Gas accessibility, shown by hyperpolarized-Xe NMR, allowed for chemical stimuli intervention: CO2 triggered dipole reorientation, reducing their collective dynamics and stimulating a dipole configuration change in the crystal. Dynamic materials under limited thermal noise and high responsiveness enable the fabrication of molecular machines with low energy dissipation and controllable dynamics.

Benchmark dynamics of dipolar molecular rotors in fluorinated metal-organic frameworks

Giacomo Prando
;
Pietro Carretta;
2023-01-01

Abstract

Fluorinated metal-organic frameworks (MOFs), comprising a wheel-shaped ligand with geminal rotating fluorine atoms, produced benchmark mobility of correlated dipolar rotors at 2 K, with practically null activation energy (Ea=17 cal/mol). 1H T1 NMR revealed multiple relaxation phenomena due to the exchange among correlated dipole-rotor configurations. Synchrotron radiation X-ray diffraction at 4 K, Density Functional Theory, Molecular Dynamics and phonon calculations showed the fluid landscape and pointed out a cascade mechanism converting dipole configurations into each other. Gas accessibility, shown by hyperpolarized-Xe NMR, allowed for chemical stimuli intervention: CO2 triggered dipole reorientation, reducing their collective dynamics and stimulating a dipole configuration change in the crystal. Dynamic materials under limited thermal noise and high responsiveness enable the fabrication of molecular machines with low energy dissipation and controllable dynamics.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/1470915
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