Selective 1D TOCSY

1D TOCSY (Total correlation spectroscopy), like 2D TOCSY gives correlations between all protons within a given spin system. In 1D TOCSY, one peak is selected and signal is transferred from it to to all J-coupled protons in a stepwise process. Instead of cross peaks, magnetization transfer is seen as increased multiplet intensity.

TOCSY spectra are especially useful for carbohydrates since each ring is a discrete spin system separated by oxygen. TOCSY transfer correlates protons within each ring. Shown below is a series of selective TOCSY spectra of sucrose where the anomeric proton (5.3 ppm) has been selected and the mixing time and thus, the number of transfers, has been changed. In the top spectrum (21 ms mixing) only 1-2 step transfer is seen. At longer mixing times, progressively more transfers are seen. The 1D version is especially useful since this whole series of spectra was taken in less than 10 minutes. (A 2D TOCSY with a single mixing time requires more than 1 hour.)

1D selective TOCSY spectrum of sucrose at 500 MHz