Coupling between plasmonic resonances in nanoparticles and porphyrins molecules.

A driving force for the growing interest in nanoassemblies is the use of nanoparticles linked to organic molecules. The goal of our research is to investigate the coupling of gold and silver nanoparticles (GNP and AgNP) with porphyrins molecules. We prepared water-soluble GNP and AgNP by reducing the noble metal complex salt with sodium citrate. The exchange of the initial ligand (citrate ions) with porphyrins formed hybrid nanostructures and change the electronic properties of GNP and AgNP. We highlighted the importance of the pH value to obtain the coupling of nanoparticles and porphyrins. We have shown that the absorption spectra of AgNP have a strong overlap with that of porphyrins. The effect of dye molecules on the plasmon properties of nanoparticles was demonstrated by UV-Vis, fluorescence and electrochemical spectroscopy (OTTLE cell). These new hybrid materials will be helpful for the design of light harvesting cells and sensors.