ZnO-Porphyrin Composite Nanostructures as Discriminating Adducts for Metallic Ions in Aqueous Matrices

摘要

Tetrapyrrolic macrocycles are largely used in the sensing of vari- ous analytes both in liquid and in gaseous phase, but the strong electronic delocalization of this class of molecules makes difficult to realize a selective active layer. To overcome this problem, in the present work it is proposed the synthesis of a supramolecular adduct of zinc oxide nanostructure and a free- base tetra- pyridyl substituted porphyrin. The electronic struc- ture of the two organic/inorganic compounds allows to ob- serve a surface-enhanced Raman scattering (SERS) of the por- phyrin vibrational bands. This phenomenon is quenched by the presence of mercuric and cupric ions according to two different mechanisms monitored and explained by means of time re- solved fluorescence spectroscopy. It was demonstrated that other substances in complex matrices, such as the food ex- tracts, do not affect the electronic communication between ZnO and porphyrin preserving the SERS effect and minimizing the effect of interfering compounds.