NMR Spectrum Prediction

NMR Spectrum Prediction
Nuclear magnetic resonance (NMR) is a powerful tool for studying the absorption of
radio-frequency radiation by atomic nuclei. In a strong magnetic field, the nuclei and
electronic energy of certain elements are magnetic, so the nucleus will undergo energy level
splitting. When absorbing external electromagnetic radiation, it will split into two or more
quantized energy levels. When electromagnetic radiation of appropriate frequency is
absorbed, a transition can occur between the generated magnetically induced energy levels,
resulting in a NMR phenomenon. In a magnetic field, a nuclear magnetic molecule or
nucleus absorbs the energy of the transition from a low energy state to a high energy state
will produce a resonance spectrum, which can be used to determine the number, type and
relative position of certain atoms in the molecule. According to the object to be measured,
NMR spectrum can be classified into the following: 1 H-NMR spectrum, 13 C-NMR spectrum,
fluorine spectrum, phosphorus spectrum, nitrogen spectrum, etc. 1 H-NMR and 13 C-NMR
spectrum are commonly applied in the study of material structure and performance since
organic compounds and polymer materials are mainly composed of hydrocarbons.
Figure 1.
DFT analysis of the 125Te NMR Knight shifts in Bi2Te3 nanoplatelets. (Papawassiliou, W.; et
al. 2020)
Application of NMR Spectrum
Identification of the structure of organic compounds

Identify groups according to chemical shift, determine the way groups are connected by the
number of coupling splitting peaks and coupling constant, determine the proton ratio of each
group according to the integral area of the peak of each H atom.
NMR imaging technology of polymer materials
NMR technology has been successfully used to detect defects or damages in materials.
Scientists use it to study the pore size distribution in extruded or foamed materials,
adhesives, and porous materials. NMR technology can be applied to improve processing
conditions and product quality.
Multi-component material analysis
NMR technology can be used to measure the relaxation time of polymer blends, determine
their compatibility, and investigate the structural stability and performance of materials.
Polymer study
Study polymerization reaction mechanism, polymer sequence structure, qualitative
identification of unknown polymers, mechanical and physical properties analysis, etc.
Our NMR Spectrum Prediction Process
Structure optimization
Optimize the molecular structure to get the most stable conformation.

NMR calculation of sample molecule and reference molecule
Use a larger basis set to optimize molecule which is then used as the initial structure for
NMR calculation. The magnetic shielding value of the sample molecule can be obtained in
this step.
Calculation of chemical shifts of sample molecules
Subtract the magnetic shielding values of the same atomic nuclei in the sample molecule
from the magnetic shielding values of H and C atom in the reference, the chemical shift
value corresponding to the experimentally measured value can be obtained.
Our Services
At Alfa Chemistry, we mainly apply machine learning (ML) and density functional theory
(DFT) method for the NMR spectrum prediction, assisting in the follow-up chemical
characterization and identification. Our fast and high-quality services include the following:
Fully ML-based prediction of NMR spectra
We have developed deep neural networks for predicting single-atom properties of molecules
including NMR shifts. Our teams can predict multiple spectroscopic parameters for structure
elucidation such as indirect dipolar coupling (J-coupling) coefficients and nuclear
Overhauser-effect (NOE) couplings.
DFT-based prediction

At Alfa Chemistry, 1 H NMR chemical shifts and coupling constants for several aromatic and
aliphatic organic molecules have been calculated with DFT methods. Our experts have also
analyzed the performance of several functionals and basis sets. Moreover, various
contributions to spin-spin coupling (Fermi-contact, diamagnetic and paramagnetic spin-orbit)
have been evaluated.
NMR spectrum prediction provides complete prediction of the NMR spectrum of various
molecules for structural identification. Our NMR spectrum prediction services remarkably
reduce the cost, promote further experiments, and enhance the understanding of chemical
process for customers worldwide. Our personalized and all-around services will satisfy your
innovative study demands. If you are interested in our services, please don't hesitate
to contact us. We are glad to cooperate with you and witness your success!
Reference
Papawassiliou, W.; et al. Resolving Dirac electrons with broadband high-resolution
NMR. Nature Communications. 2020, 11(1).
NMR Spectrum Prediction - Alfa Chemistry (alfa-chemistry.com)