Related Experiment Video
Updated: May 23, 2025
06:48
CD Spectroscopy to Study DNA-Protein Interactions
Published on: February 10, 2022
6.6K
Photoelectron circular dichroism of aqueous-phase alanine
Dominik Stemer1, Stephan Thürmer2, Florian Trinter1
1Fritz-Haber-Institut der Max-Planck-Gesellschaft Berlin 14195 Germany dstemer@fhi-berlin.mpg.de winter@fhi-berlin.mpg.de.
Chemical Science
|April 21, 2025
Summary
Photoelectron circular dichroism (PECD) can now probe chiral molecules in water. This new method reveals details about alanine
Area of Science:
- Biochemistry
- Physical Chemistry
- Spectroscopy
Background:
- Chiral molecules are vital in biochemistry.
- Studying chiral molecules in aqueous solutions is essential for understanding their in vivo behavior.
- Photoelectron circular dichroism (PECD) is a sensitive probe for chiral molecules, but its application in aqueous solutions was unproven.
Purpose of the Study:
- To demonstrate the suitability of PECD for studying chiral molecules in aqueous solutions.
- To measure the PECD response of alanine in water.
- To investigate the sensitivity of PECD to molecular structure and pH-dependent protonation states.
Main Methods:
- Photoelectron circular dichroism (PECD) measurements.
- Aqueous-phase alanine solutions.
- C 1s photoionization of alanine's carboxylic acid group.
Main Results:
- PECD measurements of aqueous-phase alanine were successfully performed.
- The PECD response varied for different carbon atoms in alanine.
- PECD signals were sensitive to changes in alanine's protonation states with solution pH.
- The magnitude of PECD for C 1s photoionization of alanine's carboxylic acid group was comparable to gas-phase measurements.
Conclusions:
- Liquid-phase PECD is a viable and powerful tool for studying aqueous-phase chiral molecules.
- PECD can provide insights into solution-specific phenomena, including solvation shells.
- This technique opens new avenues for investigating biologically relevant chiral molecules in water.
Related Concept Videos
01:27π Electron Effects on Chemical Shift: Overview
1.0K
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0,...
1.0K
00:58¹H NMR Chemical Shift Equivalence: Enantiotopic and Diastereotopic Protons
1.4K
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...
1.4K
01:29IR and UV–Vis Spectroscopy of Aldehydes and Ketones
5.2K
Infrared spectroscopy, also known as vibrational spectroscopy, is mainly used to determine the types of bonds and functional groups in molecules. In aldehydes and ketones, the carbonyl (C=O) bond shows an absorption around 1710 cm-1. The C=O bond vibration of an aldehyde occurs at lower frequencies than that of a ketone. In addition to the C=O absorption in an aldehyde, the aldehydic C–H bond also gives two peaks in the 2700–2800 cm-1 range. This absorption, coupled with the...
5.2K
02:24Properties of Enantiomers and Optical Activity
16.6K
It is essential to understand the difference between chiral and achiral interactions and the implications thereof in optical activity and their applications. Just as our feet, which are chiral, interact uniquely with chiral objects, such as a pair of shoes, but identically with achiral socks, enantiomers of a molecule exhibit different properties only when they interact with other chiral media. An example of a significant implication from this facet is the phenomenon known as optical activity,...
16.6K
01:19NMR Spectroscopy Of Amines
8.4K
In proton NMR spectroscopy, primary amines and secondary amines showcase their N–H protons as a broad signal in the chemical shift range between δ 0.5 and 5 ppm. The exact position in this range depends on several factors, including sample concentration, hydrogen bonding, and the type of solvent used. Since amine protons undergo fast proton exchange in solution, the protons are labile and therefore do not participate in any splitting with adjacent protons. Thus, the observed peak is...
8.4K
02:38Electrophilic Addition to Alkynes: Halogenation
8.1K
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
8.1K