The control of peroxyoxalate chemiluminescence (PO-CL) by the coordination of nitrogen- containing ligands and metal cations was investigated. Turning the CL off and on was done by PO-CL using 15-monoazacrown-5-tethered anthracene and alkali metal ions. CL quenching and regeneration was also observed in the separated molecular system of 15- monoazacrown-5 and the fluorophores. CL quenching by a number of ligands bearing ...