How Does a Nuclear Magnetic Resonance Spectrometer Unveil Molecular Structures?
Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical technique that can be used to investigate structures of molecules, ranging from simple chemicals to macromolecular assemblies. NMR spectroscopy is also an ideal solution for obtaining insights into molecular dynamics and studying chemical reactions. This is all based on measuring the interaction of nuclear spins in a strong magnetic field. In this blog post, we will explain the principles of NMR spectroscopy, the information obtained from it, and how it is used to study molecular structures in various scientific fields.
Principles of NMR Spectroscopy
To obtain an NMR spectrum, samples are placed in a strong magnetic field generated by a superconducting magnet. The nuclei in the sample align with the magnetic field, which creates a net macroscopic magnetization. By using a secondary oscillating magnetic field, the macroscopic magnetization is manipulated and made to rotate into the horizontal or xy plane. As a result, the signals created from the rotation of that macroscopic magnetization are detected and used to analyze molecular structures.
Methods Used in NMR Spectroscopy
Several measurable parameters are used to obtain information through NMR spectroscopy, including chemical shift and spin-spin coupling. Both parameters are used to study the properties of molecules by observing the signals they emit once placed in a generated magnetic field. Chemical shift describes the shift in the position of NMR absorption due to electrons shielding or deshielding of nuclei. In contrast, the coupling constant refers to the interaction between a pair of nuclear spins.
NMR spectroscopy provides valuable information about the properties of molecules through chemical shift. The chemical shift of a nucleus is a resonant NMR frequency of that nucleus relative to some standard. The position of a signal in the NMR spectrum changes depending on the electronic environment of the atoms in a molecule. When nuclei are subjected to different electronic environments, this creates variations in their resonance frequencies.1
Spin-spin coupling (also called J-coupling or scalar coupling) provides insights into the neighboring atoms in a molecule. These interactions can cause a single peak to split into multiple peaks, and the pattern in which they split offers information about the neighboring protons and their molecular positions. Spin-spin coupling is a powerful NMR tool that provides valuable information about molecular structures.
Applications of NMR Spectroscopy
NMR Spectroscopy has several key applications across multiple scientific disciplines, and as technology advances, it is likely researchers will discover even more uses for this technique.
Molecular Structure Determination
NMR spectroscopy analyzes NMR spectra to understand chemical shifts, coupling constants, and other parameters to learn more about specific features within a molecule. This includes the arrangement, conformation, and connectivity of atoms within a molecule, which is observed at an atomic level.
Protein Structure Analysis
NMR is a very powerful tool used to study protein 3D structure, dynamics, and protein-ligand interactions. It is also possible to analyze the NMR spectra of amino acid residues, which enables researchers to identify their spatial arrangement and learn more about the 3D structure of proteins.
Biotechnology and Food Analysis
In biotechnology, NMR spectroscopy helps to analyze bio-solutions and study their molecular composition. Additionally, it can be used in food analysis to identify and quantify contaminants and nutritional components in food samples.
Nuclear Magnetic Resonance Spectrometers with JEOL, USA
Nuclear Magnetic Resonance (NMR) spectroscopy has dramatically changed how we study a wide range of applications in life sciences, biopharmaceuticals, and other fields. By utilizing the working methods of magnetic fields and studying the interactions of nuclear spins, NMR spectroscopy provides valuable insights into the composition, connectivity, and dynamics of molecules. Its multiple applications in scientific research, including protein structure analysis, showcase how important this technique is in advancing our understanding of molecular systems.
Where does JEOL, USA fit in? We have developed state-of-the-art NMR instruments designed to analyze specific atoms in molecules. Studying molecular structures through NMR enables researchers to identify inter-molecular interactions, high-order-structure, molecular dynamics, and more. The JNM-ECZL series FT NMR spectrometer
is suitable for high-field and solid-state NMR measurements by utilizing its integrated multi-frequency drive and smart transceiver systems.
- 1. https://www.sciencedirect.com/book/9780444518118/basic-1h-and-13c-nmr-spectroscopy