Fig. 1. Structures and MR binding data of the reported fluorescent probes 1–5, being non-selective MR ligands (1–4) or showing a slight preference for the M₁R (2),33 and structures and MR affinities of the M₂R preferring dibenzodiazepinone-type MR ligands DIBA and the DIBA-derived fluorescent probes 7 and 8.47 (Note: binding data for all MR subtypes were not reported in all cases). ^a Tahtaoui et al. (the reported K_i value was converted to a pK_i value);32^b Jones et al. (reported K_i values were converted to pK_i values);33^c Hern et al. (reported K_i values were converted to pK_i values);34^d Nenasheva et al.;35^e Daval et al.;37^f Gitler et al. (reported K_i values were converted to pK_i values);42^g She et al.47.