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Towards redox-switchable organocatalysts based on bidentate halogen bond donors
E Engelage1, H Hijazi2, M Gartmann1
1Fakultät für Chemie und Biochemie, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801 Bochum, Germany. stefan.m.huber@rub.de.
Physical Chemistry Chemical Physics : PCCP
|February 15, 2021
Summary
New redox-active bidentate halogen bond donors were synthesized. These compounds function as Lewis acidic organocatalysts, showing strong binding to halides without oxidizing them.
Area of Science:
- Supramolecular Chemistry
- Organic Chemistry
- Electrochemistry
Background:
- Halogen bonding is a key non-covalent interaction.
- Developing tunable halogen bond donors is crucial for various applications.
- Redox-tunable Lewis acids offer unique reactivity profiles.
Purpose of the Study:
- Synthesize novel redox-active bidentate halogen bond donors.
- Investigate their structural, electrochemical, and binding properties.
- Evaluate their performance as organocatalysts in halide abstraction reactions.
Main Methods:
- Synthesis of halopyridinium-based bidentate compounds.
- X-ray diffraction for structural elucidation.
- Density Functional Theory (DFT) calculations.
- Electrochemical methods including cyclic voltammetry (CV).
- UV-vis and Nuclear Magnetic Resonance (NMR) titrations for binding studies.
Main Results:
- Successful synthesis and structural characterization of dicationic halopyridinium halogen bond donors.
- Demonstrated reversible twofold reduction to neutral, weaker Lewis acidic species.
- Quantified binding affinities to halides, with chloride showing the strongest interaction.
- Ethylene-linked variants did not oxidize halides, unlike previous analogues.
- Achieved performance comparable to established catalysts in halide abstraction reactions.
Conclusions:
- Novel redox-active bidentate halogen bond donors with tunable Lewis acidity have been developed.
- These compounds exhibit strong halide binding capabilities.
- Their stability towards halide oxidation and catalytic activity make them promising Lewis acidic organocatalysts.
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