1D TOCSY spectra
A dramatic spectral simplification can be achieved by editing 1H NMR spectrum into a set of simpler subspectra by the use of the one-dimensional total correlation spectroscopy (1D TOCSY) experiment. This method can result in phase and intensity distortions of the multiplets in the subspectra, but when combined with the z-filtering technique pure phase subspectra are possible. This method of spectral simplification requires at least one spin multiplet to be sufficiently isolated that it alone can be inverted by a selective 180o pulse.
The magnetization of this inverted spin then propagates through the network of spins coupled to it. A difference spectrum (with the decoupler switched off during the selective pulse interval) then yields a subspectrum of all hydrogens directly or indirectly scalar coupled to the inverted 1H resonance. This method was used to obtain pure phase subspectra to separate out the spectrum of each ring. For identifying of the spin network corresponding to each ring in the molecule, the 1D TOCSY experiment was performed with a mixing time of 80 ms.
The 1D TOCSY experiment is analogue of the 2D HOHAHA (TOCSY) experiment and can have significant advantages over the 2D TOCSY because of shorter minimum measuring time over reduced data storage requirements, and improved digital resolution.
Address:
C. Eugene Bennett
Department of Chemistry
406 Clark Hall
Prospect Street
P.O. Box 6045
West Virginia University
Morgantown, WV 26506
Phone:
(304) 293-3435 X6439
Fax:
(304) 293-4904
Email:
Chemistry@mail.wvu.edu
