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Fast pirouetting motion in a pyridine bisamine-containing copper-complexed rotaxane
Eugenio Coronado1, Pablo Gaviña, Julia Ponce
1Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, C/Catedrático José Beltrán 2, 46980 Paterna (Spain).
This study introduces a novel copper rotaxane using pyridine bisamine ligands, enabling faster switching speeds in dynamic systems. This breakthrough simplifies synthesis and enhances the stability and responsiveness of switchable interlocked molecules.
Area of Science:
- Supramolecular Chemistry
- Coordination Chemistry
- Materials Science
Background:
- Dynamic covalent chemistry is crucial for creating switchable interlocked systems.
- Copper-rotaxanes offer unique properties for molecular machines.
- Traditional terpyridine ligands present limitations in stabilizing copper coordination sites.
Purpose of the Study:
- To synthesize and characterize a novel pirouetting copper rotaxane incorporating pyridine bisamine terdentate ligands.
- To investigate the impact of ligand modification on the stabilization and lability of copper coordination sites.
- To explore the potential for accelerated switching dynamics in switchable copper-complexed interlocked systems.
Main Methods:
- Synthesis of rotaxane 2[PF6] utilizing imine-based dynamic covalent chemistry.
- Electron Paramagnetic Resonance (EPR) spectroscopy to study the pentacoordinated copper site.
- Cyclic voltammetry to analyze redox properties and coordination sphere reorganization.
- Structural modifications including ethynyl-3,8-substitution and 2,9-diphenyl-1,10-phenanthroline (dpp) incorporation.
Main Results:
- The pyridine bisamine ligand significantly stabilizes the pentacoordinated copper site, evidenced by EPR and cyclic voltammetry.
- Reduced congestion around the tetracoordinated copper site accelerates reorganization processes.
- Optimized ligands create a stable yet oxidatively labile coordination environment for Cu(I).
- Rotaxane 2[PF6] exhibits bistable behavior with enhanced energetic separation between states.
Conclusions:
- The incorporation of pyridine bisamine terdentate ligands and optimized axle ligands simplifies synthesis and enhances rotaxane performance.
- Rotaxane 2[PF6] demonstrates the fastest switching cycle reported for copper-interlocked dynamic systems.
- This work paves the way for more efficient and responsive molecular machines and switchable materials.
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