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Stereochemical Control of Secondary Benzamide-based BODIPY Emitters
Sara M A Waly1, Andrew C Benniston1, Joshua K G Karlsson1
1Molecular Photonics Laboratory, Bedson Building School of Natural & Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|March 23, 2023
Summary
Aromatic amides enable light-harvesting materials. This study confirms a trans geometry for amide bonds in boron dipyrromethene derivatives, with minimal impact on optical properties.
Area of Science:
- Organic Chemistry
- Materials Science
- Photochemistry
Background:
- Aromatic amides are key building blocks for advanced materials.
- Boron dipyrromethene (BODIPY) derivatives are known for their optical properties.
- Understanding amide bond stereochemistry is crucial for material design.
Purpose of the Study:
- To synthesize and characterize novel boron dipyrromethene derivatives featuring an amide linkage.
- To investigate the stereochemistry of the amide bond in these compounds.
- To assess the influence of the amide linkage on photophysical properties.
Main Methods:
- Synthesis of boron dipyrromethene derivatives using standard coupling agents.
- Nuclear Magnetic Resonance (NMR) spectroscopy for structural analysis.
- Quantum chemical calculations to determine preferred conformations.
- X-ray crystallography for definitive structural determination.
Main Results:
- Near quantitative yield achieved in amide bond formation.
- X-ray crystallography confirmed a trans geometry for the amide bond in an N-cyclohexyl derivative.
- Quantum chemical calculations supported the trans conformation as the lowest energy state.
- Rotation around the C(sp2)-C(aryl) bond significantly impacts NMR spectra.
- The amide linkage showed minimal effect on photophysical properties.
Conclusions:
- The synthesis of amide-linked boron dipyrromethene derivatives is efficient.
- The trans amide geometry is stable and preferred in these systems.
- Structural features, particularly aryl ring inversion and rotation, influence spectroscopic properties.
- Amide linkages are suitable for constructing light-harvesting materials without compromising optical performance.
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