Pyrene-Functionalized Nanoparticles: Two Independent Sensors, the Excimer and the Monomer

The high surface-to-volume ratio of nanoparticles has been used to obtain a high local concentration of pyrene units on their periphery, making the formation of both pyrene emissive species possible using amazingly small pyrene concentrations. The sensing properties of model pyrene-functionalized nanoparticles was investigated by using different nitroaromatic compounds [<i>m</i>-nitroaniline and <i>p</i>-nitroaniline] and nitrobenzenes [nitrobenzene, <i>p</i>-nitrotoluene, 2,4-dinitrotoluene, and 2,6-dinitrotoluene]. The hybrid system acts as a dual-fluorescence sensor, in which the decrease of the pyrene emission, induced by the quencher, is hardly reflected in the pyrene excimer emission. The encapsulation capacity of the NPs also plays a key role in their sensitivity to the analyte