Investigating the interaction of a nitrobenzoxadiazole derivative with metal ions: Photophysical and theoretical (DFT) study

Photophysical and density functional studies on a nitrobenzoxadiazole-based system, 4-(2-diphenylphosphinoethylamino)-7-nitro-2,1,3-benzoxadiazole (1), have been carried out in acetonitrile medium to determine the nature of interaction between 1 and different biologically and environmentally relevant metal ions. Quantum mechanical calculations have been carried out to find out the molecular origin of fluorophore–metal interactions. Higher fluorescence enhancement values of the system in presence of Fe(III) and Cr(III) has been attributed to the stabilization interactions between the P-atom of the receptor with M(III) as well as the π-overlapping of the aromatic rings (through the formation of η6 complexes).