Spectrus: Using 2D TOCSY to define spin systems in crowded spectra

Description
TOCSY (Total Correlation Spectroscopy) helps identify complete spin systems by showing through-bond correlations across a network of coupled protons. In crowded 1H spectra, this can clarify which peaks belong to which substructures.

Solution

1. Acquire a TOCSY spectrum for the sample under appropriate mixing conditions.
2. Import the TOCSY and 1H spectra into Spectrus.
3. In Spectrus:
   • Process TOCSY (phase, baseline).
   • Use crosshair tools to explore cross-peak patterns.
4. Identify clusters of TOCSY cross-peaks:
   • Each cluster corresponds to a spin system (e.g., one side chain or fragment).
5. Map each spin system back to the structure:
   • Assign 1H resonances within a system to the corresponding atoms.
   • Use comments or system labels in the assignment table.
6. Use these spin systems to support overall assignment and to help disentangle overlapping multiplets in crowded regions.