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Example 1 H NMR spectrum (1-dimensional) of a mixture of menthol enantiomers plotted as signal intensity (vertical axis) vs. chemical shift (in ppm on the horizontal axis). Signals from spectrum have been assigned hydrogen atom groups (a through j) from the structure shown at upper left.
A database that was developed and maintained by the publisher John Wiley & Sons. This database included more than 700,000 NMR, IR and MS Spectra, statistics specific to the NMR spectra are not listed. The NMR data includes 1 H, 13 C, 11 B, 15 N, 17 O, 19 F, 29 Si, and 31 P. The data were in the form of graphically displayed line lists.
The types of data accepted include: NMR spectral parameters, relaxation data, and kinetic and thermodynamic data. Data must be entered in the NMR-STAR format, conversion from other common formats can be carried out using the STARch file converter provided at the site. [13] The site also contains an NMR-STAR template generator which produces ...
A 900 MHz NMR instrument with a 21.1 T magnet at HWB-NMR, Birmingham, UK Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy or magnetic resonance spectroscopy (MRS), is a spectroscopic technique based on re-orientation of atomic nuclei with non-zero nuclear spins in an external magnetic field.
Hydrogen is highly abundant, especially in biological systems. It is the nucleus providing the strongest NMR signal (apart from 3 H, which is not commonly used due to its instability and radioactivity). Proton NMR has a narrow chemical-shift range but gives sharp signals in solution state. Fast acquisition of quantitative spectra (with peak ...
If a spectrum of an unknown chemical compound is available, a reverse search can be carried out by entering the values of the chemical shift, frequency or mass of the peaks in the NMR, FT-IR or EI-MS spectrum respectively. This type of search affords all the chemical compounds in the database that have the entered spectral characteristics. [6]
The data are then processed through Fourier transformation along both the t 1 and t 2 axes, creating a 2D spectrum with peaks plotted along the diagonal and off-diagonal. When interpreting the COSY spectrum, diagonal peaks correspond to the 1D chemical shifts of individual nuclei, similar to the standard peaks in a 1D NMR spectrum.
Paramagnetism diminishes the resolution of an NMR spectrum to the extent that coupling is rarely resolved. Nonetheless spectra of paramagnetic compounds provide insight into the bonding and structure of the sample. For example, the broadening of signals is compensated in part by the wide chemical shift range (often 200 ppm in 1 H NMR).