1H NMR study of bacteriochlorophyll a radical anion: Use of difference spectra

The radical anion of bacteriochlorophyll a has been monitored by observing differential electron transfer broadening in the 1H NMR spectrum of diamagnetic bacteriochlorophyll in the presence of a small amount of chemically produced anion. The use of NMR difference spectra clearly indicates which sites in the anion have greatest spin density; these data are compared with other studies on the cation and anion.