Related Experiment Video
Updated: Sep 11, 2025
10:37
Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
9.1K
Linear-cyclic isomer competition in protonated ethanol-methanol clusters probed by infrared spectroscopy and
Po-Jen Hsu1, Atsuya Mizuide2, Jer-Lai Kuo1
1Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan. jlkuo@pub.iams.sinica.edu.tw.
Physical Chemistry Chemical Physics : PCCP
|August 15, 2025
Summary
Protonated ethanol tetramers show a preference for linear structures over cyclic ones. The choice of tag species significantly impacts isomer stability and the energy needed for structural changes.
Area of Science:
- Physical Chemistry
- Computational Chemistry
- Spectroscopy
Background:
- Protonated clusters are crucial in understanding chemical reactions.
- Ethanol clusters are model systems for studying hydrogen bonding and proton transfer.
- Isomerization dynamics in molecular clusters are complex and influenced by various factors.
Purpose of the Study:
- To investigate the competition between linear and cyclic isomers in protonated ethanol tetramers.
- To determine the global minimum structure of protonated ethanol tetramers.
- To understand the influence of mixing ratios and tag species on isomer stability.
Main Methods:
- Infrared spectroscopy of protonated ethanol-methanol mixed tetramers using inert gas tagging.
- Structure searches using the parallelized Basin-Hopping algorithm with neural network potentials.
- Spectral simulations via density functional theory (DFT) and molecular dynamics (MD) with neural network potentials.
Main Results:
- Infrared spectroscopy revealed significant dependence on mixing ratio and tag species.
- Theoretical calculations identified a linear structure as the global minimum for protonated ethanol tetramers.
- Tag species were found to influence the relative stability of linear and cyclic isomers and the isomerization barrier.
Conclusions:
- The global minimum structure of protonated ethanol tetramers is linear.
- Tag species play a critical role in determining isomer distribution and isomerization dynamics.
- Combined spectroscopic and theoretical approaches are effective for studying isomer competition in molecular clusters.
Related Concept Videos
01:10¹H NMR of Labile Protons: Temporal Resolution
1.2K
Protons bonded to heteroatoms such as nitrogen and oxygen exhibit a range of chemical shift values. This is due to the varying degree of hydrogen bonding between the proton and the heteroatom in other molecules. The extent of hydrogen bonding affects the electron density around the proton, thereby giving different chemical shift values for the protons in the proton NMR spectrum.
The –OH proton in alcohols typically appears in the range of δ 2 to 5 ppm but can vary depending on the specific...
The –OH proton in alcohols typically appears in the range of δ 2 to 5 ppm but can vary depending on the specific...
1.2K
00:58¹H NMR Chemical Shift Equivalence: Enantiotopic and Diastereotopic Protons
2.0K
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...
2.0K
02:18Conformations of Ethane and Propane
14.5K
In an organic molecule, free rotation about the carbon-carbon single bond results in energetically different conformers of the molecule. Due to this rotation, called the internal rotation, ethane has two major conformations — staggered and eclipsed.
Staggered conformation is a low energy and more stable conformation with the C-H bonds on the front carbon placed at 60°dihedral angles relative to the C-H bonds on the back carbon, leading to a reduced torsional strain. In staggered...
Staggered conformation is a low energy and more stable conformation with the C-H bonds on the front carbon placed at 60°dihedral angles relative to the C-H bonds on the back carbon, leading to a reduced torsional strain. In staggered...
14.5K
02:33Stereoisomerism of Cyclic Compounds
9.2K
In this lesson, we delve into the role of ring conformation and its stability, which determines the spatial arrangement and, consequently, the molecular symmetry and stereoisomerism of cyclic compounds. 1,2-Dimethylcyclohexane is used as a case study to evaluate the possible number of stereoisomers. Here, given the multiple (n = 2) chiral centers, there are 2n = 4 possible configurations that lack a plane of symmetry, as the ring skeleton exists in a non-planar chair conformation. In addition,...
9.2K
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
917
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...
917
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
8.6K
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.
8.6K