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Vernier template synthesis of molecular knots
Zoe Ashbridge1, Elisabeth Kreidt1, Lucian Pirvu1
1Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
Science (New York, N.Y.)
|March 3, 2022
Summary
Synthesizing complex molecular knots is now more efficient using coordinatively mismatching ligands and metal ions with Vernier templating. This method enables the creation of larger, precisely structured molecular knots, including intricate triskelion architectures.
Area of Science:
- Supramolecular Chemistry
- Organic Synthesis
- Coordination Chemistry
Background:
- Traditional methods for synthesizing molecular knots often rely on metal helicates.
- Achieving larger and more complex molecular knots has been a significant challenge in supramolecular chemistry.
Purpose of the Study:
- To develop a more effective strategy for synthesizing larger molecular knots.
- To explore the use of Vernier templating with coordinatively mismatching components.
Main Methods:
- Utilized coordinatively mismatching oligodentate ligands and metal ions for Vernier templating.
- Employed tridentate 2,6-pyridinedicarboxamide strands that fold around nine-coordinate lanthanide(III) ions.
- Completed knot formation using ring-closing olefin metathesis.
Main Results:
- A 3:2 (ditopic strand:metal) Vernier assembly successfully produced +31#+31 and -31#-31 granny knots.
- A 3:4 (tetratopic strand:metal) stoichiometry selectively formed a 378-atom trefoil-of-trefoils triskelion knot with 12 alternating strand crossings.
- By altering strand stereochemistry, an inverted-core triskelion knot with mixed alternating and nonalternating crossings was synthesized.
Conclusions:
- Coordinatively mismatching ligands and metal ions offer a superior approach for synthesizing larger molecular knots via Vernier templating.
- This methodology allows for precise control over knot topology and complexity, including the formation of intricate poly-noded knots.
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