Monitoring ion pairing/ion separation using green-red FRET. Dissociation of close ion pairs in solution leads to spatial separation of the respective anions and cations. It should be possible to monitor this process via FRET if appropriate fluorescent labels are used. We have recently studied ion pairing/dissociation processes based on changes in fluorescence of the anion, but this approach only works in a specific setting because it relies on the quenching effect of the transition metal (iridium) cation towards the anionic Bodipysulfonate (bdpSO3 -). Consequently, close ion pairs are characterized by weak fluorescence and separated ion pairs by strong fluorescence. Here we will present a general approach independent of specific properties of metals, in which both the anion and the cation are labeled with red and green fluorescent dyes, respectively. This should lead to a pronounced FRET signal for close ion pairs. A salt consisting of a Bodipy-labeled NHC gold cation and a