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Toward multistation rotaxanes using metalloporphyrin coordination templating
Kathleen M Mullen1, Maxwell J Gunter
1Department of Chemistry, University of New England, Armidale, NSW, Australia.
The Journal of Organic Chemistry
|April 9, 2008
Summary
This study explored templated synthesis of rotaxanes using strapped metalloporphyrins. A click chemistry approach successfully created porphyrinic and crown ether rotaxanes with functionalized threads.
Area of Science:
- Supramolecular Chemistry
- Organic Synthesis
- Coordination Chemistry
Background:
- Rotaxanes are mechanically interlocked molecules with potential applications in molecular machines.
- Metalloporphyrins offer unique electronic and structural properties for supramolecular assemblies.
- Templated synthesis is crucial for constructing complex molecular architectures like rotaxanes.
Purpose of the Study:
- To develop efficient methods for the templated synthesis of rotaxanes incorporating strapped metalloporphyrins.
- To investigate the influence of pyridine moieties as templates and binding sites.
- To explore the molecular motion of the synthesized rotaxanes in response to external stimuli.
Main Methods:
- Templated synthesis utilizing pyridine derivatives and strapped metalloporphyrins.
- Stoppering approach with pyridine esters and rhodium(III) chloride porphyrins.
- 1,3-dipolar cycloaddition (click reaction) for constructing triazole linkers in rotaxanes.
Main Results:
- The stoppering approach with pyridine esters and Rh(III)-strapped porphyrins yielded unlinked components.
- Click chemistry successfully produced porphyrinic (Zn, free base, Rh(III)) and crown ether rotaxanes.
- Multifunctional threads containing triazole and naphthodiimide units were synthesized.
- Limited molecular motion was observed in response to acid, solvent, or competing ligands.
Conclusions:
- The click chemistry approach is more effective for synthesizing rotaxanes with strapped metalloporphyrins compared to the initial stoppering strategy.
- The flexibility of the strap in some porphyrin systems hindered successful interlocking.
- Further optimization is needed to achieve controlled molecular motion in these systems.
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