Rotors, motors and switches in the solid state find a favorable playground in the solid state, especially in porous frameworks, thanks to their large free volume, which allows for fast dynamics. We have realized a fast molecular rotor in a Zn-MOF whose rotation speed approaches that of unhindered rotations in organic moieties even 2 K[1,2]. The three-fold bipyramidal symmetry of the rotator conflicting with the four-fold symmetry of the strut frustrates the formation of stable conformations and allows for the hyperfast rotation of the rotator persistent for several continuous turns, with an energy barrier of 6.2 calmol−1 and a high frequency of 1010 Hz at 2K. Geared molecular rotors with negligible energy-requirements in MOFs enabled fast yet controllable and correlated rotary motion [3]. The rotors inserted in a MOF exhibited fast motion (107 Hz), even at extremely cold temperatures and explored multiple configurations of conrotary/disrotary relationships, switched on and off by thermal energy, a cascade mechanism modulated by distinct energy barriers as supported by 2H, 1H(T1) relaxation NMR and DFT modeling. Chemical stimuli such as CO2 diffused through the open pores changed dramatically the rotation mechanism and rotor speed. Furthermore, motors were inserted into porous frameworks and metal-organic frameworks wherein two distinct linkers with complementary light absorption-emission properties were integrated into the same material. Unidirectional motion was achieved by exposure to sunlight of the solid particles, which behave as autonomous nanodevices.[4] Visible light-driven rotation of a molecular switch was proved to be in the solid state at rates similar to those observed in solution.[5] [1] A. Comotti, P. Sozzani et al Nat.Chem.2020,12,845. [2] G. Prando et al Nanoletters 2020,20,7613. [3] A. Comotti, P. Sozzani et al J.Am.Chem.Soc. 2021,143,13082. [4] A. Comotti, B. Feringa et al Nat.Chem. 2020,12,595. [5] B. Feringa et al J.Am.Chem.Soc. 2020,142,9048.
Comotti, A., Bracco, S., Perego, J., Bezuidenhout, C., Prando, G., Piva, S., et al. (2022). Hyperfast rotors at liquid He temperature and light-driven switches in porous frameworks. In Book of Abstracts_Genova Hyma 2022 (pp.1-1).
Hyperfast rotors at liquid He temperature and light-driven switches in porous frameworks
Comotti, A
;Bracco, S;Perego, J;Bezuidenhout, C;Piva, S;Sozzani, P
2022
Abstract
Rotors, motors and switches in the solid state find a favorable playground in the solid state, especially in porous frameworks, thanks to their large free volume, which allows for fast dynamics. We have realized a fast molecular rotor in a Zn-MOF whose rotation speed approaches that of unhindered rotations in organic moieties even 2 K[1,2]. The three-fold bipyramidal symmetry of the rotator conflicting with the four-fold symmetry of the strut frustrates the formation of stable conformations and allows for the hyperfast rotation of the rotator persistent for several continuous turns, with an energy barrier of 6.2 calmol−1 and a high frequency of 1010 Hz at 2K. Geared molecular rotors with negligible energy-requirements in MOFs enabled fast yet controllable and correlated rotary motion [3]. The rotors inserted in a MOF exhibited fast motion (107 Hz), even at extremely cold temperatures and explored multiple configurations of conrotary/disrotary relationships, switched on and off by thermal energy, a cascade mechanism modulated by distinct energy barriers as supported by 2H, 1H(T1) relaxation NMR and DFT modeling. Chemical stimuli such as CO2 diffused through the open pores changed dramatically the rotation mechanism and rotor speed. Furthermore, motors were inserted into porous frameworks and metal-organic frameworks wherein two distinct linkers with complementary light absorption-emission properties were integrated into the same material. Unidirectional motion was achieved by exposure to sunlight of the solid particles, which behave as autonomous nanodevices.[4] Visible light-driven rotation of a molecular switch was proved to be in the solid state at rates similar to those observed in solution.[5] [1] A. Comotti, P. Sozzani et al Nat.Chem.2020,12,845. [2] G. Prando et al Nanoletters 2020,20,7613. [3] A. Comotti, P. Sozzani et al J.Am.Chem.Soc. 2021,143,13082. [4] A. Comotti, B. Feringa et al Nat.Chem. 2020,12,595. [5] B. Feringa et al J.Am.Chem.Soc. 2020,142,9048.
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