Related Experiment Video
Updated: Jun 3, 2025
11:22
Using Three-color Single-molecule FRET to Study the Correlation of Protein Interactions
Published on: January 30, 2018
10.0K
Comparative Computational Study of Frequency Shifts and Infrared Intensity Changes in Model Binary Complexes with
1Department of Biological and Chemical Sciences, The University of the West Indies, Cave Hill Campus, Wanstead P.O. Box 64, Barbados.
Molecules (Basel, Switzerland)
|January 11, 2025
Summary
This study computationally examines hydrogen-bonded complexes, revealing red- and blue-shifting tendencies in X-H···Y interactions. A perturbation theory model accurately predicts frequency shifts and infrared intensity changes at reduced computational cost.
Area of Science:
- Computational Chemistry
- Spectroscopy
- Quantum Mechanics
Background:
- Hydrogen bonding significantly influences molecular properties.
- Understanding X-H···Y complex behavior is crucial for various chemical applications.
- Proton donor and Lewis base interactions dictate spectral shifts.
Purpose of the Study:
- To computationally investigate the red- and blue-shifting behavior of X-H···Y binary hydrogen-bonded complexes.
- To analyze the factors contributing to frequency shifts and infrared intensity changes.
- To validate a perturbation theory model for predicting these spectral properties.
Main Methods:
- Computational study of three model X-H proton donors (FArH, F3CH, FH) with various Lewis bases (Y).
- Application of a perturbation theory model for frequency shifts.
- Analysis of interaction energy, X-H bond length changes, and dipole moment derivatives.
- Comparison with standard ab initio computations.
Main Results:
- FArH and F3CH exhibit blue-shifting tendencies, while FH shows red-shifting.
- The perturbation theory model accurately predicts frequency shifts and infrared intensity changes.
- The model provides insights into the contributions of interaction energy and bond length changes.
- Computational efficiency was significantly improved compared to standard ab initio methods.
Conclusions:
- The perturbation theory model is a reliable and computationally efficient tool for studying hydrogen-bonded complexes.
- The interplay between interaction energy and bond length dynamics governs spectral shifts.
- This work provides a deeper understanding of infrared spectral changes in hydrogen-bonded systems.
More Related Videos
10:03Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
Published on: June 27, 2014
17.9K
08:04Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
8.4K
Related Concept Videos
01:23IR Spectrum Peak Broadening: Hydrogen Bonding
834
The vibrational frequency of a bond is directly proportional to its bond strength. As a result, stronger bonds vibrate at higher frequencies, while weaker bonds vibrate at lower frequencies. The stretching vibration of the strong O–H bond in alcohols and phenols (very dilute solution or gas phase) appears as a sharp peak at 3600–3650 cm−1.
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular...
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular...
834
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
1.0K
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
1.0K
01:21IR Absorption Frequency: Hybridization
630
Hydrocarbons such as alkanes, alkenes, and alkynes show characteristic C–H stretching absorption bands. These IR stretching frequencies depend on the hybridization of the involved carbon atom and can be explained in terms of the s character of each hybridized atomic orbital.
Among the sp, sp2, and sp3 hybridized orbitals, sp orbitals have the maximum s character (50%). Consequently, the electrons are held more closely to the nucleus, resulting in stronger and shorter C–H bonds that...
Among the sp, sp2, and sp3 hybridized orbitals, sp orbitals have the maximum s character (50%). Consequently, the electrons are held more closely to the nucleus, resulting in stronger and shorter C–H bonds that...
630
01:08Spin–Spin Coupling Constant: Overview
872
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
872
01:13¹H NMR: Complex Splitting
1.2K
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
1.2K
01:24IR Frequency Region: X–H Stretching
908
In IR spectroscopy, signals produced by the X−H bonds (such as C−H, O−H, or N−H) can be observed in the frequency range of 2700–4000 cm–1. The C−H stretching vibration forms sharp bands in the region 2850–3000 cm–1. The presence of the O−H stretching vibration leads to the forming of an absorption band in the frequency range 3650–3200 cm−1. At the same time, N−H stretching can be confirmed by absorption bands in...
908