Photocatalytic activity of pyrazinoporphyrin in the presence of gold nanoparticles and nanoclusters

The effect of gold nanoparticles and nanoclusters on the catalytic activity of dicarboxy-substituted pyrazinoporphyrin was studied using the photooxidation reaction of 1,5-dihydr-oxynaphthalene as an example. Annelation of the pyrazine heterocycle at β-positions of porphyrin leads to an increased photocatalytic activity compared to that of tetrakis-(4-butoxyphenyl)-porphyrin, a similar unmodified macroheterocyclic photosensitizer. The presence of gold nanoparticles in the catalytic system leads to an increased rate of photocatalyzed oxidation of 1,5-dihydroxynaphthalene, while this effect is not observed in the case of gold nanoclusters. Analysis of the luminescence spectra of the obtained porphyrin in the presence of gold nanoparticles showed that an increase in the concentration of nanoparticles results in the quenching of luminescence, which indicates an electron interaction between the nanoparticles and the photosensitizer. At the same time, no quenching is observed in the presence of porphyrin for gold nanoclusters with intrinsic luminescence, which indirectly indicates the absence of this interaction. The obtained spectral data are consistent with those of earlier studies on the effect of gold nanoparticles and nanoclusters on the photocatalytic activity of porphyrins.