Prediction of nuclear magnetic resonance (NMR) spectra

Fast and accurate prediction of ¹³C and ¹H NMR spectra from the molecular structure plays an important role in structure validation and elucidation of molecules. The NMR predictor application is able to predict NMR spectra for standard organic molecules containing the most frequent atoms (H, C, N, O, F, Cl, Br, I, P, S). Chemical shifts are estimated by a linear model based on a topological description scheme and are in relation to the chemical shift of tetramethylsilane (δ(TMS)=0 ppm). ¹³C and ¹H chemical shift training data were retrieved from the NMRShift Database.

Basic features

• Prediction of ¹³C and ¹H NMR chemical shifts;
• Spin-spin couplings are taken into account according to the first order approximation;
• Vicinal proton-proton coupling constants computed by the Karplus equation in case of ¹H NMR.

The NMR Predictor graphical user interface incorporates the following features:

• Export spectrum to molfile, export and import JCAMP-DX (*.jdx) spectra;
• Create PDF file as report of your prediction, containing molecule structure, predicted spectrum, and related tables;
• Detached Copy to clipboard action for all predictor panels and tables is available;
• Toggle between decoupled and coupled NMR spectrum;
• Toggle between explicit and implicit hydrogen display;
• Select NMR measurement frequency from a predetermined list;
• Display realistic or line NMR spectra;
• Show integral curve to assign value to NMR spectrum signals;
• Display spectrum scale in ppm or Hz units;
• Add atom indices or chemical shift values to signals as spectrum labels;
• Show atom indices on molecule structure corresponding to the different multiplets;
• Choose multiplet selection mode: individual selection in case of overlapping multiplets is available;
• Set chart color uniquely;
• Use various modes of zoom in on spectrum.
• Find spectrum and molecule structure related information in Atom, Multiplet, and Coupling tables.

Atoms of the input molecule and multiplets of the NMR spectrum are linked together: Upon selection of an atom the corresponding multiplet is highlighted and vice versa.
A single NMR prediction is allowed to contain more molecules.

NMR predictor is integrated into MarvinSketch's Calculations menu, and contains the following three components to discover NMR spectra of molecules:

1. CNMR Prediction and
2. HNMR Prediction;
3. NMR Spectrum Viewer.

NMR Prediction is accessible via cxcalc as well (cxcalc nmr -h).

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