Spectrus: Evaluating coupling constants (J) from multiplet patterns in NMR spectra

Description
Coupling constants (J) provide information about connectivity and spatial relationships (e.g., vicinal vs long‑range couplings). Spectrus can measure J values directly from resolved multiplets.

Solution

1. Load the processed NMR spectrum with properly phased and baseline‑corrected peaks.
2. Zoom in on a multiplet of interest (e.g., doublet, triplet, doublet of doublets).
3. Use Spectrus tools to:
   • Pickpeak positions within the multiplet.
   • Calculate Δν in Hz between relevant lines. By assigning as a multiplet, the J coupling constants are generated automatically based on its multiplicity. Click a peak and drag to another peak to manually measure the J coupling constant.
4. Assign each measured J to the corresponding coupling (e.g., vicinal, geminal, long‑range) using structure context and 2D data as needed.
5. Compare J values to expected ranges (e.g., typical vicinal ³J_HH values) to:
   • Support stereochemical assignments.
   • Distinguish between conformers or isomers.
6. Include key J values with multiplet annotations in reports.