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Updated: May 20, 2026

Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks (MOFs)
Published on: January 17, 2020
A regioselective Huisgen reaction inside a Keplerate polyoxomolybdate nanoreactor
Claire Besson1, Sebastian Schmitz, Kimberly M Capella
1Institut für Anorganische Chemie, RWTH Aachen University, 52074 Aachen, Germany.
A quantitative cycloaddition reaction within a {Mo(132)}-type Keplerate yields a 2:1 ratio of 1,4- and 1,5-triazoles from propiolic acid and azide guests. This demonstrates controlled synthesis of triazole isomers inside a molecular cage.
Area of Science:
- Supramolecular Chemistry
- Organic Synthesis
- Materials Science
Background:
- Keplerates are large, polyoxometalate cages with internal cavities suitable for hosting guest molecules.
- 1,3-Dipolar cycloaddition reactions are versatile tools for constructing heterocyclic compounds like triazoles.
- Controlling the regioselectivity of cycloaddition reactions within confined spaces is a significant challenge.
Purpose of the Study:
- To investigate the regioselectivity of 1,3-dipolar cycloaddition reactions within the cavity of a {Mo(132)}-type Keplerate.
- To explore the quantitative formation of triazole isomers using propiolic acid and azide functionalities.
- To demonstrate the utility of Keplerates as nanoreactors for controlled organic synthesis.
Main Methods:
- Encapsulation of azide-functionalized linkers within the {Mo(132)}-type Keplerate.
- Reaction of the encapsulated azide with propiolic acid (guest molecule).
- Characterization of the resulting triazole products using spectroscopic techniques and X-ray crystallography.
Main Results:
- The cycloaddition reaction proceeded quantitatively, yielding triazoles with high efficiency.
- A reproducible 2:1 ratio of 1,4- to 1,5-triazoles was obtained.
- The Keplerate cavity directed the regioselectivity of the cycloaddition reaction.
Conclusions:
- The {Mo(132)}-type Keplerate acts as a successful nanoreactor, enabling regioselective synthesis of triazoles.
- This study highlights the potential of polyoxometalate cages for controlled guest-host chemistry and molecular assembly.
- The findings open avenues for designing functional materials and catalysts using Keplerate structures.
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