A novel fluorescent 2,2 '-bipyridine derivative prepared by coupling to a fluorescent aminophenazine-fluorescence properties and response toward various cations

2,2'-Bipyridine (bpy), a non-fluorescent but good metal-chelating unit, and 2-aminophenazine (2-aphz), a good fluorescent unit, are integrated to give 7-aminodipyrido[3,2-a:2',3'-c]phenazine (7-amino-dppz) 1. Compound 1 exhib its an efficient fluorescence at 517 nm (Phi = 0.24, dichloromethane), whic h is similar to the parent 2-aphz. It is suggested that the orbitals involv ed in the photoexcitation process are mostly localized on the phenazine uni t. However, addition of divalent metal ions such as Mg2+, Ca2+ and Cu2+ cau ses a noticeable fluorescence response, which is attributed to coordination of these cations to the bpy chelation site of 1. This behaviour indicates that sufficient electronic communication exists between the bpy chelation s ite and the phenazine fluorophore. 7-(4-tert-Butylbenzoylamino)dppz 2 also showed a fluorescence response towards divalent metal ions.