Ground and excited state behavior of 1,4-dimethoxy-3-methyl-anthracene-9,10-dione in silver nanoparticles: Spectral and computational investigations

Silver nanoparticles (Ag NPs) of various sizes have been successfully synthesized by the simple and convenient Creighton method using sodium borohydride as the reducing agent under microwave irradiation. Optical absorption and fluorescence emission spectroscopic techniques were employed to investigate the effect of silver nanoparticles on the ground and excited state of 1,4-dimethoxy-3-methylanthracene-9,10-dione (DMMAD). The surface plasmon resonance (SPR) peak of the prepared silver colloidal solution was observed at 400 nm. Fluorescence quenching of DMMAD by silver nanoparticles has been found to increase with increase in the size of Ag. The fluorescence quenching has been explained by Forster Resonance Energy Transfer (FRET) theory between DMMAD and silver nanoparticles. The Stern-Volmer quenching constant and Benesi-Hildebrand association constant for the above system were calculated. DFT calculations were also performed to study the charge distribution of DMMAD in Ag both in ground and excited states.