Dear Sasha,

There are numerous HSQC pulse programs, some of them are called "Multiplicity edited", indicated with a two letters code "ed" in their name. All the letters in addition to those of the actual experiment name (HSQC in this case) are associated with a special feature in the pulse program (ed = Multiplicity edited , ph = phase sensitive, pr= presaturation,...etc).

With 2D multiplicity edited experiments, the signals will appear in different color (= different phase, i.e positive or negative) according to their multiplicity. For 2D [1H-13C]-HSQC experiment, CH and CH3 will appear in a certain color (have the same phase) and CH2 groups will appear in another color (have a different phase). So, yes those blue and green colors give you additional information about the strucure of your compound.

The HSQC spectrum provides information on the proton-carbon one-bond bond. The positive signal indicates methyl and methine groups, the negative signal indicates methylene groups. Quaternary carbons do not appear. Jun.

CH2 groups will be one color, and CH+CH3 groups another color.

That's the clear answer. Jun

Dear Sasha,

all said above is correct if the spectrum is phased correctly....sometimes (also dependent on the processing automation in use) spectra may be phased wrong by 180° - in this case signs/colors are the opposite (but Jespers Answer is ALWAYS true).

If I see a spectrum where coloring is not clear I take the color of aromatic signals as reference for other methins/methyls.

Kind regards

Alfred