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Updated: May 9, 2026
11:45
Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
Triple ring contraction of a [2+2] macrocyclic ligand
Matthew Knapton1, Vickie McKee
1Chemistry Department, Loughborough University, Loughborough LE11 3TU, England.
Summary
This study details the synthesis of a novel macrocycle via Schiff base condensation, which then undergoes ring contraction upon transmetallation with copper(II) ions, resulting in a smaller macrocyclic complex.
Area of Science:
- Coordination Chemistry
- Supramolecular Chemistry
- Organic Synthesis
Background:
- Schiff base condensation is a versatile method for constructing complex organic ligands.
- Macrocyclic ligands are crucial in coordination chemistry for templating metal ions and creating unique structures.
- Template-assisted synthesis allows for the controlled formation of specific macrocyclic architectures.
Purpose of the Study:
- To synthesize a [2+2] macrocycle using 2,6-diformylpyridine and 1,3-diaminopropan-2-ol with a Ba(II) template.
- To investigate the structural transformation of the synthesized macrocycle upon transmetallation with Cu(II) ions.
- To characterize the resulting copper(II) complex and analyze the macrocycle's ring contraction.
Main Methods:
- Schiff base condensation reaction.
- Template ion synthesis utilizing Ba(II).
- Transmetallation reaction with Cu(II) salts.
- X-ray crystallography for structural determination.
Main Results:
- Formation of a [2+2] macrocyclic complex, [Ba₂(μ1,2-ClO₄)₂(H₂L1)₂], templated by Ba(II).
- Observed three successive ring contractions of the macrocycle upon transmetallation with Cu(II).
- Isolation and characterization of a novel 16-membered macrocyclic copper(II) complex, [Cu(CH₃COO)(L2)]ClO₄.
Conclusions:
- The Ba(II) template effectively directs the formation of the larger [2+2] macrocycle.
- Transmetallation with Cu(II) induces a significant ring contraction, altering the macrocycle's size and structure.
- The study demonstrates a novel pathway for macrocycle size modification through metal-templated reactions.
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