Rigidity and Flexibility in Rotaxanes and Their Relatives; On Being Stubborn and Easy-Going.
| Autor: | Fadler RE; Department of Chemistry, Indiana University, Bloomington, IN, United States., Flood AH; Department of Chemistry, Indiana University, Bloomington, IN, United States. |
|---|---|
| Jazyk: | angličtina |
| Zdroj: | Frontiers in chemistry [Front Chem] 2022 Apr 07; Vol. 10, pp. 856173. Date of Electronic Publication: 2022 Apr 07 (Print Publication: 2022). |
| DOI: | 10.3389/fchem.2022.856173 |
| Abstrakt: | Rotaxanes are an emerging class of molecules composed of two building blocks: macrocycles and threads. Rotaxanes, and their pseudorotaxane and polyrotaxane relatives, serve as prototypes for molecular-level switches and machines and as components in materials like elastic polymers and 3D printing inks. The rigidity and flexibility of these molecules is a characteristic feature of their design. However, the mechanical properties of the assembled rotaxane and its components are rarely examined directly, and the translation of these properties from molecules to bulk materials is understudied. In this Review , we consider the mechanical properties of rotaxanes by making use of concepts borrowed from physical organic chemistry. Rigid molecules have fewer accessible conformations with higher energy barriers while flexible molecules have more accessible conformations and lower energy barriers. The macrocycles and threads become rigidified when threaded together as rotaxanes in which the formation of intermolecular interactions and increased steric contacts collectively reduce the conformational space and raise barriers. Conversely, rotational and translational isomerism in rotaxanes adds novel modes of flexibility. We find that rigidification in rotaxanes is almost universal, but novel degrees of flexibility can be introduced. Both have roles to play in the function of rotaxanes. Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. (Copyright © 2022 Fadler and Flood.) |
| Databáze: | MEDLINE |
| Externí odkaz: |
|