Nuclear Magnetic Resonance (NMR) Analysis

Nuclear Magnetic Resonance (NMR) spectroscopy has become the primary analytical technique for obtaining structural information on organic compounds and biomacromolecules, as it can provide valuable structural information for entire molecules through a series of analytical tests in many cases.

NMR

Nuclear magnetic resonance is a property of atomic nuclei, related to nuclear spin (I). Although isotopes have various I values (including zero), NMR spectroscopy typically operates on nuclei with I = 1/2, including 1H, 13C, 19F, and 31P, which helps in the structural determination of the most common elements in organic chemistry.

When a nucleus with I = 1/2 is placed in an external high-frequency magnetic field, it can align itself with the field (lower energy) or against the field (higher energy). If a radio frequency pulse is applied, the nucleus in the lower energy state can absorb energy and transition to the higher energy state, then return to the lower energy state as the applied magnetic field disappears. NMR spectroscopy can detect the absorption and subsequent release of energy.

NMR spectroscopy can be used for various studies, including: 1. Structural information of synthesized molecules; 2. Interactions between various molecules; 3. Kinetics or molecular dynamics analysis; 4. Composition of chemical mixtures; 5. Quantitative analysis of specific chemicals.

The range of analytes for NMR spectroscopy spans from small organic molecules or metabolites to medium-sized peptides or natural products, and to biomacromolecules and synthetic high molecular weight polymers. As a powerful analytical platform, NMR spectroscopy can serve as an alternative to other techniques (such as X-ray crystallography and mass spectrometry) to obtain structural information. NMR spectroscopy can be used for non-destructive, qualitative, and quantitative studies of both solution-phase and solid-state molecules.