Related Experiment Video
Updated: Oct 21, 2025
11:27
Single-Molecule Förster Resonance Energy Transfer Methods for Real-Time Investigation of the Holliday Junction Resolution by GEN1
Published on: September 18, 2019
9.6K
Heteroatom Effects on Quantum Interference in Molecular Junctions: Modulating Antiresonances by Molecular Design
Luke J O'Driscoll1, Sara Sangtarash2, Wei Xu3
1Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K.
The Journal of Physical Chemistry. C, Nanomaterials and Interfaces
|September 3, 2021
Summary
Researchers used scanning tunneling microscopy and computational methods to study charge transport in molecular wires. They found that nitrogen atoms in molecular junctions significantly influence quantum interference, validating new predictive rules for molecular electronics.
Area of Science:
- Single-molecule electronics
- Quantum interference (QI) in molecular junctions
- Molecular conductance properties
Background:
- Controlling charge transport via quantum interference (QI) is crucial in molecular electronics.
- Predicting QI behavior in molecular junctions is an active research area.
Purpose of the Study:
- Investigate single-molecule conductance of novel 1-phenylpyrrole derivatives.
- Test extended curly arrow rules (ECARs) for predicting QI.
- Explore the influence of a nitrogen heteroatom in the conductance pathway.
Main Methods:
- Scanning tunneling microscopy-break junction techniques
- Density functional theory calculations
- Experimental and computational investigation of molecular conductance
Main Results:
- The presence of a nitrogen atom in the conductance pathway enhances the effect of anchoring group position (para vs. meta).
- Destructive QI and shifted DQI were observed in meta- and para-connected pyrrole isomers, respectively.
- Experimental and computational data validate ECARs for predicting QI behavior.
Conclusions:
- Molecular design can effectively modulate antiresonances in molecular junctions.
- ECARs provide a simple, reliable method for predicting QI.
- Findings offer fundamental insights into structure-property relationships for molecular electronics applications.
More Related Videos
Related Concept Videos
01:14π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
1.4K
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...
1.4K
01:08NMR Spectroscopy: Spin–Spin Coupling
2.0K
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved...
2.0K
01:27π Electron Effects on Chemical Shift: Overview
1.3K
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,...
1.3K
01:27¹H NMR: Long-Range Coupling
2.1K
The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
2.1K
01:25Atomic Absorption Spectroscopy: Interference
1.4K
Interference leads to systematic error in atomic absorption (AA) measurements by enhancing or diminishing the analytical signal or the background. These interferences can be grouped into three main categories: spectral interference, chemical interference, and physical interference.
Spectral interference occurs when signals from other elements or molecules overlap with the analyte signal, falsely elevating or masking the analyte's absorbance. This interference can be corrected using Zeeman,...
Spectral interference occurs when signals from other elements or molecules overlap with the analyte signal, falsely elevating or masking the analyte's absorbance. This interference can be corrected using Zeeman,...
1.4K
01:27Inductive Effects on Chemical Shift: Overview
1.6K
The protons in unsubstituted alkanes are strongly shielded with chemical shifts below 1.8 ppm. Methine, methylene, and methyl protons appear at approximately 1.7, 1.2 and 0.7 ppm, while the proton signal from methane appears at 0.23 ppm. An electronegative substituent, such as chlorine, withdraws the electron density from the protons, increasing their chemical shift. Progressive substitution of the hydrogens in methane by chlorine shifts the proton signals increasingly downfield, to 3.05 ppm in...
1.6K