Related Experiment Video
Updated: Jun 6, 2026
09:35
Preparation of a Corannulene-functionalized Hexahelicene by Copper(I)-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
Surface modification induced shielding effects on electron orbital coupling in metallofullerene.
Shukuan Wang1, Baoyun Sun, Dongmei Yue
1CAS Key Lab for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, and National Center for Nanoscience and Technology of China, Beijing 100049, China.
Journal of Nanoscience and Nanotechnology
|December 3, 2010
Summary
We observed a new electronic signal in lanthanum metallofullerenes (La@C82) linked to metal-cage orbital coupling. Surface modifications with hydroxyl groups shield this electronic interaction in metallofullerenols.
Area of Science:
- Physical Chemistry
- Materials Science
- Nanotechnology
Background:
- Metallofullerenes, such as lanthanum confined within fullerene cages (La@C82), exhibit unique electronic properties.
- Understanding the interaction between the encapsulated metal atom and the fullerene cage is crucial for their application.
Purpose of the Study:
- To investigate the electronic properties of La@C82 and its hydroxylated derivatives (metallofullerenols).
- To identify and characterize the electronic coupling between the lanthanum atom and the C82 nanocage.
Main Methods:
- Synchrotron radiation photoelectron emission spectroscopy (PES) was employed.
- Density Functional Theory (DFT) calculations were used for theoretical support.
Main Results:
- A novel emission peak at 13.9 eV, attributed to La 5d orbital coupling with nanocage orbitals, was observed in La@C82 for the first time.
- This specific electronic coupling signal diminished upon surface modification with hydroxyl (-OH) groups on the fullerene cage.
Conclusions:
- The study confirms the direct electronic orbital coupling between the inner lanthanum atom and the outer C82 nanocage in La@C82.
- Surface functionalization of metallofullerenes can effectively shield or modulate these crucial electronic interactions.
Related Concept Videos
01:27π Electron Effects on Chemical Shift: Overview
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, resulting in...
01:14Diamagnetic Shielding of Nuclei: Local Diamagnetic Current
An applied magnetic field causes the electrons present in the molecule to circulate, setting up a local diamagnetic current within the molecule. The local diamagnetic current arising from circulating sigma-bonding electrons induces a magnetic field, Blocal that opposes the applied magnetic field, B0. The effective magnetic field experienced by these nuclei is given by the difference between the applied and local magnetic fields in a phenomenon called local diamagnetic shielding. Essentially,...
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...
01:27¹H NMR: Long-Range Coupling
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 π orbitals.
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 π orbitals.
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
01:24Metal-Semiconductor Junctions
The contact of metal and semiconductor can lead to the formation of a junction with either Schottky or Ohmic behavior.
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...