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Absolute Configuration Assignment From a Single Reflection Using Resonant X-Ray Diffraction
Anmol Andotra1,2, Fabian Gasser1, Ferdinando Malagreca2
1Institute of Solid-State Physics, Graz University of Technology, Graz, Austria.
Chirality
|August 4, 2026
Summary
Determining the absolute configuration of chiral molecules is crucial. A new method uses the energy-dependent intensity of a single X-ray diffraction peak to reliably assign chirality, even with limited data.
Area of Science:
- Crystallography
- Chirality Studies
- Materials Science
Background:
- Absolute configuration of chiral molecules dictates crucial properties.
- Single crystal X-ray diffraction is the standard, but often requires extensive data.
- Conventional methods like Flack parameter analysis can be unreliable with limited reflections.
Purpose of the Study:
- Introduce a novel, simpler method for determining absolute configuration.
- Utilize X-ray energy-dependent intensity of a single Bragg reflection.
- Provide an unambiguous probe of chirality for known crystal structures.
Main Methods:
- Focus on the X-ray energy-dependent intensity variation of a single Bragg reflection.
- Monitor Bragg peak intensity changes across an absorption edge.
- Demonstrated using the 211 reflection of a 2-(3-bromophenyl)-N,N-diisopropyl-2-oxoacetamide single crystal.
Main Results:
- Successfully determined the absolute configuration from a single reflection.
- The method provides an unambiguous probe of chirality.
- X-ray energy dependence of additional peaks confirmed chirality assignment and assessed limitations.
Conclusions:
- A new, reliable method for absolute configuration determination is presented.
- This approach is particularly beneficial for systems with limited accessible reflections.
- Offers an advantageous alternative to conventional statistical methods.
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