Plasmon enhanced fluorescence of a bisphthalonitrile-based dye via a dopamine mediated interfacial crosslinking reaction on silver nanoparticles

Abstract

A fluorescent dye of a phenolphthalein derivative containing bisphthalonitrile groups was synthesized and subsequently chemically grafted onto dopamine modified silver nanoparticles via the interfacial crosslinking reaction, leading to enhanced fluorescent emission of dye molecules in a solution phase. Specifically, the non-fluorescent phenolphthalein (PP) molecule was end-capped with bisphthalonitrile (BPH) groups through nucleophilic substitution to obtain a violet/blue-emitting fluorescent dye PP-BPH due to the restriction of inter-molecular rotation. Furthermore, the PP-BPH dye can be immobilized on the surface of the dopamine modified silver nanoparticles, given the fact that bisphthalonitrile based monomers can be readily crosslinked in the presence of aromatic amine or phenol compounds (i.e. dopamine). Consequently, the fluorescent emission of the PP-BPH dye can be further enhanced via the plasmonic enhancement effects of silver nanoparticles. The preliminary results obtained in this communication will pave the way for the plasmon controlled photonic properties of PP-BPH based multifunctional polymers.