Related Experiment Video
Updated: Apr 18, 2026
07:24
Hyperspectral Imaging as a Tool to Study Optical Anisotropy in Lanthanide-Based Molecular Single Crystals
Published on: April 14, 2020
19.0K
Nuclear quadrupole coupling parameters and structural nature of the nonlinear optical material Li2B4O7 by NMR
1Department of Science Education, Jeonju University, Jeonju 560-759, South Korea.
Solid State Nuclear Magnetic Resonance
|January 26, 2015
Summary
Nuclear magnetic resonance (NMR) reveals distinct boron atom environments in lithium diborate (Li2B4O7), explaining its nonlinear optical properties. This structural insight is crucial for understanding material behavior.
Area of Science:
- Solid-state chemistry
- Materials science
- Nuclear magnetic resonance spectroscopy
Background:
- Lithium diborate (Li2B4O7) exhibits significant nonlinear optical (NLO) properties.
- Understanding the atomic-level structure is key to optimizing NLO material performance.
- Nuclear magnetic resonance (NMR) is a powerful tool for probing local atomic environments.
Purpose of the Study:
- To elucidate the structural basis of Li2B4O7's NLO properties.
- To characterize the different boron sites within the Li2B4O7 crystal structure.
- To determine key parameters related to the electric field gradient at boron nuclei.
Main Methods:
- (11)B NMR spectroscopy was employed to study Li2B4O7.
- Rotation patterns of NMR spectra were analyzed.
- Data analysis focused on identifying distinct boron environments and their associated parameters.
Main Results:
- Sixteen unique (11)B NMR spectra were observed, indicating two distinct types of boron atoms.
- These boron types, 4-coordinated B(1) and 3-coordinated B(2), occupy chemically inequivalent sites.
- The quadrupole parameter and principal axis of the electric field gradient (EFG) tensor were determined for both B(1) and B(2) sites.
Conclusions:
- The structural heterogeneity of boron atoms in Li2B4O7 directly influences its NLO properties.
- NMR characterization provides detailed insights into the local coordination and electronic environment of boron.
- This study establishes a structure-property relationship for Li2B4O7 relevant to NLO applications.
More Related Videos
08:55Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
9.1K
08:42High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions
Published on: October 10, 2014
12.1K
Related Concept Videos
01:08Spin–Spin Coupling Constant: Overview
1.7K
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...
1.7K
01:13¹H NMR: Complex Splitting
2.2K
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...
2.2K
01:27¹H NMR: Long-Range Coupling
2.9K
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...
2.9K
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
2.0K
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
2.0K
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
1.8K
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...
1.8K
01:17Spin–Spin Coupling: One-Bond Coupling
1.6K
Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...
1.6K