Perego Jacopo, Bezuidenhout Charl X, Bracco Silvia, Piva Sergio, Prando Giacomo, Aloisi Cristian, Carretta Pietro, Kaleta Jiří, Le Thi Phuong, Sozzani Piero, Daolio Andrea, Comotti Angiolina
Department of Materials Science, University of Milano - Bicocca, Via R. Cozzi 55, 20125, Milan, Italy.
Department of Physics, University of Pavia, Via Bassi 6, 27100, Pavia, Italy.
Angew Chem Int Ed Engl. 2023 Jan 26;62(5):e202215893. doi: 10.1002/anie.202215893. Epub 2022 Dec 20.
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 (E =17 cal mol ). H T 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: CO 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.
含偕二旋转氟原子的轮状配体构成的氟化金属有机框架（MOF），在2 K时产生了相关偶极转子的基准迁移率，其活化能几乎为零（E = 17 cal mol）。 H T NMR揭示了由于相关偶极 - 转子构型之间的交换而产生的多种弛豫现象。 4 K下的同步辐射X射线衍射、密度泛函理论、分子动力学和声子计算显示了流体态势，并指出了一种将偶极构型相互转换的级联机制。 超极化氙核磁共振显示的气体可及性允许化学刺激干预：CO触发偶极重新定向，降低其集体动力学并刺激晶体中的偶极构型变化。 在有限热噪声和高响应性下的动态材料能够制造出具有低能量耗散和可控动力学的分子机器。
