Two molecules of a laterally non-symmetric aza cryptand have been attached to 9,10-dimethylanthracene to obtain a multi-receptor fluorescent signalling system in the “receptor-spacer-fluorophore-spacer-receptor” format. In the absence of a metal ion, weak fluorescence is observed upon excitation of the anthryl group owing to efficient photo-induced electron transfer (PET) of the lone pair of N attached to the anthryl group. However, when a metal salt is added, the lone pair is engaged, thus in blocking of the PET and leading to recovery of fluorescence to different extents depending upon the nature of the metal ion.
