Having developed a system that exhibits distinct fluorescent properties at equilibrium and at the fueldriven steady state, it occurred to us that transient excimers such as Pyr2AcP could be of value for the advancement of systems chemistry. While optical readouts have been developed for biochemical investigations, parallel well plate screenings to report on the chemical state of a large number of chemical reaction networks are unexplored. For this reason, we isolated Pyr2AcP and used its transient excimer emission in an optical screening setup. In the context of this present study, the following experiments served the purpose to identify further catalysts for acylphosphate hydrolysis and thus gain a broader control over acylphosphate steady state kinetics (Figure ). Specifically, we loaded a 96position well plate with Pyr2AcP, as well as a wide range of catalysts and monitored the fluorescence intensity of the excimer (at 500 nm) by the aid of a microplate reader. Since excimer emission is a specific property of the transient dimeric species, the fluorescence signal at 500 nm gradually decreases while the concentration of Pyr2AcP diminishes. It is worth emphasizing that using a fluorescence-based response for this purpose offers two significant advantages. First, these measurements can be carried out in highly diluted media, which means that only minimal amounts of reactants are required for initial assessment. Second, and perhaps more importantly, when using a well plate setup, a large number of reactions can be monitored rapidly and continuously, because it only takes a few seconds (depending on the instrument; in our case 20 seconds) to scan the entire well plate (at 500 nm). In comparison to conventional analytical techniques commonly employed in systems chemistry such as HPLC and NMR, where a single measurement of one sample can take several minutes, a microplate reader allows measurements of the fluorescence intensity in dozens of samples within a few seconds.