Related Experiment Video
Updated: May 2, 2026
06:48
CD Spectroscopy to Study DNA-Protein Interactions
Published on: February 10, 2022
6.5K
Spectroscopy and Conformer-Selective Photoelectron Circular Dichroism of Chiral Molecules
Laurent Nahon1, Anne Zehnacker2
1Synchrotron SOLEIL, L'Orme des Merisiers, Gif sur Yvette, France.
Chemistry, an Asian Journal
|April 30, 2026
Summary
Photoelectron circular dichroism (PECD) now offers conformer-selective analysis for flexible chiral molecules. This advancement provides a direct link between molecular structure, chirality, and phenomena like molecular recognition.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Molecular Physics
Background:
- Chiroptical spectroscopy, including photoelectron circular dichroism (PECD), is sensitive to structural changes in chiral molecules.
- PECD measures forward-backward electron asymmetry during ionization by circularly polarized light, offering insights into molecular structure.
- Flexible chiral molecules in the gas phase present challenges for detailed structural analysis.
Purpose of the Study:
- To present recent advancements in PECD spectroscopy enabling conformer-selective analysis.
- To establish a direct connection between molecular conformation, chirality, and PECD signals.
- To demonstrate the utility of PECD for studying subtle structural variations and molecular recognition.
Main Methods:
- Utilizing one-photon PECD with partial population selection.
- Employing two-photon PECD with resonance-enhanced ionization for complete conformer selection.
- Conducting experiments under supersonic expansion (low temperature) with narrow-band nanosecond lasers.
Main Results:
- Developed conformer-selective PECD techniques.
- Achieved complete conformer selection using two-photon PECD for systems with near-UV electronic transitions.
- Successfully distinguished between conformers with similar structures, including ring-inversion and hydrogen-bonded forms.
Conclusions:
- PECD spectroscopy is a powerful tool for detailed structural characterization of flexible chiral molecules.
- The advancements allow for precise differentiation of conformers, crucial for understanding molecular recognition.
- PECD provides a direct link between chirality, conformation, and observable spectroscopic signals.
Related Concept Videos
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
992
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
992
02:30Chirality in Nature
13.5K
Chirality is the most intriguing yet essential facet of nature, governing life’s biochemical processes and precision. It can be observed from a snail shell pattern in a macroscopic world to an amino acid, the minutest building block of life. Most of the snails around the world have right-coiled shells because of the intrinsic chirality in their genes. All the amino acids present in the human body exist in an enantiomerically pure state, except for glycine - the sole achiral amino acid.
13.5K
01:32UV–Vis Spectroscopy of Conjugated Systems
5.9K
Organic compounds with conjugated double bonds show strong absorption features in the UV–visible region of the electromagnetic spectrum attributed to π → π* electronic excitations. Generally, a UV–vis absorption spectrum is recorded as a plot of absorbance vs wavelength. The wavelength of maximum absorbance, which manifests as a peak in the absorption spectrum, is denoted as λmax.
One of the factors influencing λmax is...
One of the factors influencing λmax is...
5.9K
02:05Prochirality
4.0K
The concept of prochirality leads to the nomenclature of the individual faces of a molecule and plays a crucial role in the enantioselective reaction. It is a concept where two or more achiral molecules react to produce chiral products. A typical process is the reaction of an achiral ketone to generate a chiral alcohol. Here, the achiral reactant reacts with an achiral reducing agent, sodium borohydride, to generate an equimolar mixture of the chiral enantiomers of the product. For example, an...
4.0K
00:58¹H NMR Chemical Shift Equivalence: Enantiotopic and Diastereotopic Protons
3.7K
Replacing each alpha-hydrogen in chloroethane by bromine (or a different functional group) yields a pair of enantiomers. Such protons are called prochiral or enantiotopic and are related by a mirror plane. Enantiotopic protons are chemically equivalent in an achiral environment. Because most proton NMR spectra are recorded using achiral solvents, enantiotopic hydrogens yield a single signal.
In chiral compounds such as 2-butanol, replacing the methylene hydrogens at C3 produces a pair of...
In chiral compounds such as 2-butanol, replacing the methylene hydrogens at C3 produces a pair of...
3.7K
02:25Chirality
23.4K
Chirality is a term that describes the lack of mirror symmetry in an object. In other words, chiral objects cannot be superposed on their mirror images. For example, our feet are chiral, as the mirror image of the left foot, the right foot, cannot be superposed on the left foot.
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
23.4K