Characterization of the magneto-optical properties of eosin Y and erythrosin

We report the results of a study of the properties of the paramagnetic triplet state of eosin Y and erythrosin. This information is a prerequisite for their use as EPR probes. The magnetic anisotropy in both molecules is found to be suitable for monitoring slow rotational dynamics. Interestingly, the magnetic interactions in eosin show a large anisotropy in the x−y plane (E is roughly equal to D/3) of the Magnetic frame. Erythrosin on the other hand, has a virtually isotropic interaction in that plane (E small compared to D/3).