Related Experiment Video
Updated: Aug 5, 2026
09:42
Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
Published on: January 16, 2016
Environment Rearrangement Slows Down the Tunneling Rates of Proton Transfer in Sandwich-Like Molecular Clusters
Jingling Hong1, Ziye Qi1, Yao Wang2
1Department of Chemistry, State Key Laboratory of Porous Materials for Separation and Conversion, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Songhu Rd. 2005, 200438Shanghai, China.
The Journal of Physical Chemistry Letters
|July 31, 2026
Summary
Proton tunneling splitting in complex molecular clusters was measured. Adding molecular layers and helium tagging significantly suppressed proton transfer rates, offering insights into quantum dynamics.
Area of Science:
- Quantum Chemistry
- Molecular Spectroscopy
- Chemical Physics
Background:
- Double proton transfer is a fundamental process in chemistry.
- Understanding proton tunneling dynamics is crucial for various chemical and biological systems.
- Environmental effects on quantum phenomena are of significant interest.
Purpose of the Study:
- To measure tunneling splitting for double proton transfer in complex molecular systems.
- To investigate the influence of molecular environment on proton tunneling rates.
- To compare experimental findings with theoretical models.
Main Methods:
- Rotational spectroscopy was employed to measure tunneling splitting.
- Systematic comparison of tunneling splittings in various carboxylic acid dimers and clusters.
- Theoretical calculations using ring-polymer instanton theory and Schrödinger equation models.
Main Results:
- A consistent trend of suppressed tunneling rates with increasing environmental complexity was observed.
- The ternary FA-PA@PhF cluster showed a reduced splitting (50.89 MHz) compared to the bare dimer (291.43 MHz).
- Helium tagging further decreased the splitting to 47.58 MHz, consistent with theoretical predictions.
Conclusions:
- The molecular environment acts as a penalty on proton transfer, aligning with the Marcus-type environment reorganization model.
- This study presents the most complex system to date with resolved proton tunneling.
- Findings provide a framework for engineering quantum proton dynamics in tailored environments.
Related Concept Videos
02:26SN2 Reaction: Transition State
An SN2 reaction of an alkyl halide is a single-step process in which bond formation between the nucleophile and the substrate and bond breaking between the substrate and the halide occurs simultaneously through a transition state without forming an intermediate.
When the nucleophile approaches the electrophilic carbon with its lone pairs, the halide acts as a leaving group and moves away with the electron-pair bonded to the carbon. Dotted partial bonds represent the bonds being formed or broken...
When the nucleophile approaches the electrophilic carbon with its lone pairs, the halide acts as a leaving group and moves away with the electron-pair bonded to the carbon. Dotted partial bonds represent the bonds being formed or broken...
01:16Thermal Sigmatropic Reactions: Overview
Sigmatropic rearrangements are a class of pericyclic reactions in which a σ bond migrates from one part of a π system to another. These are intramolecular rearrangements where the total number of σ and π bonds remain unchanged.
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in 1,5-hexadiene, referred to as...
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in 1,5-hexadiene, referred to as...
![[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12422.jpg&w=3840&q=75)
01:21[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
The Cope rearrangement is classified as a [3,3] sigmatropic shift in 1,5-dienes, leading to a more stable, isomeric 1,5-diene. The reaction involves a concerted movement of six electrons, four from two π bonds and two from a σ bond, via an energetically favorable chair-like transition state.
01:24Protein Diffusion in the Membrane
Proteins show rotational as well as lateral diffusion across the membrane. The lateral diffusion of proteins was confirmed through the cell fusion experiment where mouse and human cells were fused, resulting in hybrid cells. When the human and mouse cells fused, the specific membrane proteins on human and mouse cells were marked with the red and green-fluorescent markers, respectively. Initially, the red and green fluorescence was located on the respective hemisphere of the cell. As time...
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
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...
01:14π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
In aromatic compounds, such as benzene, the circulation of (4n + 2) π-electrons sets up a diamagnetic or diatropic ring current around the perimeter of the molecule. This current induces a magnetic field that opposes the external field inside the ring and reinforces it on the outside. The protons in benzene are deshielded and exhibit high chemical shifts in the range 6.5–8.5 ppm. The shielding effect at the center of the ring is evident in complex aromatic molecules, such as annulenes. In...