Spectral investigations on the influence of silver nanoparticles on the fluorescence quenching of 1,4-dimethoxy-2,3-dibromomethylanthracene-9,10-dione

Abstract

Silver nanoparticles (Ag NPs) of different sizes from 9 to 17 nm were synthesized by Creighton method and characterized using UV-vis spectroscopy and high resolution transmission electron microscopy (HRTEM). Fluorescence quenching of 1,4-dimethoxy-2,3-dibromomethylanthracene-9,10-dione (DMDBMAD) in methanol has been studied by fluorescence spectroscopy combined with UV-vis absorption spectroscopic techniques. It has been observed that the fluorescence intensity of DMDBMAD decrease with increase in the size of the Ag NPs. The quenching rate constant and association constant were determined using Stern-Volmer and Benesi-Hildebrand plots. The Stern-Volmer plot suggested that the quenching of DMDBMAD fluorescence by silver NPs was a dynamic process. The obtained value of the association constant infers that there is an association between DMDBMAD and the Ag NPs. Using Forster resonance energy transfer (FRET) theory, the distance between the donor (DMDBMAD) to acceptor (Ag NPs) and the critical energy transfer distance were obtained. Long range dipole-dipole interaction between the excited donor and ground state acceptor molecules is the dominant mechanism responsible for the energy transfer.