Switch-Off fluorescence of 5-amino-2-mercapto benzimidazole with Ag3O4 nanoparticles: Experimental and theoretical investigations

•Binding interaction of 5-amino-2-mercapto benzimidazole with Ag3O4 have been studied.•AMB acts as a new host for Ag3O4 nanoparticles which quenches its fluorescence.•Interaction between AMB and Ag3O4 occurs through static quenching mechanism.•The apparent association constant (Kapp=2.0×105M−1) has been obtained.•Binding site is supported by molecular electrostatic potential (MEP). The binding interaction of 5-amino-2-mercaptobenzimidazole (AMB) with Ag3O4 nanoparticles was studied. AMB adsorbs strongly on the surfaces of nano semiconductor. The interaction of AMB with Ag3O4 was studied by absorption, fluorescence, FT-IR, SEM and EDX spectral studies. The Ag3O4 nanoparticles were synthesized by chemical route and was characterized by XRD study. Excellent results observed were due to electron transfer between AMB and Ag3O4 nanoparticles. To confirm the binding site of Ag3O4 with AMB, molecular electrostatic potential (MEP) study was carried out theoretically. It confirmed the higher electron density at azomethine nitrogen atom. Photo-induced electron transfer is responsible for fluorescence quenching of AMB. The interaction between AMB and Ag3O4 occurs through static quenching mechanism. The apparent association constant (Kapp=2.0×105M−1) was obtained from the fluorescence quenching data.