Fast motion of molecular rotors in metal–organic framework struts at very low temperatures
| Autor: | Giacomo Prando, Charl X. Bezuidenhout, J Perego, Angiolina Comotti, M Negroni, Silvia Bracco, Piero Sozzani, Pietro Carretta |
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| Přispěvatelé: | Perego, J, Bracco, S, Negroni, M, Bezuidenhout, C, Prando, G, Carretta, P, Comotti, A, Sozzani, P |
| Rok vydání: | 2020 |
| Předmět: |
Bicyclic molecule
010405 organic chemistry General Chemical Engineering Supramolecular chemistry General Chemistry Cubic crystal system CHIM/04 - CHIMICA INDUSTRIALE 010402 general chemistry Rotation Crystal engineering 01 natural sciences Molecular machine 0104 chemical sciences CHIM/02 - CHIMICA FISICA chemistry.chemical_compound Crystallography chemistry molecular rotors molecular dynamics MOFs solid state NMR spin–lattice relaxation times energy barrier Metal-organic framework Carboxylate |
| Zdroj: | Nature Chemistry. 12:845-851 |
| ISSN: | 1755-4349 1755-4330 |
| DOI: | 10.1038/s41557-020-0495-3 |
| Popis: | The solid state is typically not well suited to sustaining fast molecular motion, but in recent years a variety of molecular machines, switches and rotors have been successfully engineered within porous crystals and on surfaces. Here we show a fast-rotating molecular rotor within the bicyclopentane–dicarboxylate struts of a zinc-based metal–organic framework—the carboxylate groups anchored to the metal clusters act as an axle while the bicyclic unit is free to rotate. The three-fold bipyramidal symmetry of the rotator conflicts with the four-fold symmetry of the struts within the cubic crystal cell of the zinc metal–organic framework. This frustrates the formation of stable conformations, allowing for the continuous, unidirectional, hyperfast rotation of the bicyclic units with an energy barrier of 6.2 cal mol−1 and a high frequency persistent for several turns even at very low temperatures (1010 Hz below 2 K). Using zirconium instead of zinc led to a different metal cluster–carboxylate coordination arrangement in the resulting metal–organic framework, and much slower rotation of the bicyclic units. Molecular rotors have been engineered within the bicyclopentane–dicarboxylate struts of a metal–organic framework—the bicyclic unit is the rotator and the carboxylate groups serve as the stator. In a zinc-based metal–organic framework, the crossed conformation of the strut–metal nodes enables fast rotation of the bicyclic moiety, but in the corresponding zirconium metal–organic framework a change in the conformation results in much slower rotation. |
| Databáze: | OpenAIRE |
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