Tunable-photophysical processes of porphyrin macrocycles on the surface of ZnO nanoparticles

Tunable-photophysical processes of porphyrin macrocycles on the surface of ZnO nanoparticles

Tunable-photophysical processes of porphyrin macrocycles on the surface of ZnO nanoparticles
Manas R. Parida, Shawkat M. Aly, Erkki Alarousu, and Omar F. Mohammed
J. Phys. Chem. C, 119 (5), pp 2614–2621, (2015)
Manas R. Parida, Shawkat M. Aly, Erkki Alarousu, and Omar F. Mohammed
Tunable-photophysical processes, Porphyrin macrocycles
2015
We investigated the impact of the molecular structure of cationic porphyrins on the degree of electrostatic interactions with zinc oxide nanoparticles (ZnO NPs) using steady-state and time-resolved fluorescence and transient absorption spectroscopy. Our results demonstrate that the number of cationic pyridinium units have a crucial impact on the photophysics of the porphyrin macrocycle. Fluorescence enhancement, relative to initial free porphyrin fluorescence, was found to be tuned from 3.4 to 1.3 times higher by reducing the number of cationic substituents on the porphyrin from 4 to 2. The resulting enhancement of the intensity of the fluorescence is attributed to the decrease in the intramolecular charge transfer (ICT) character between the porphyrin cavity and its meso substituent. The novel findings reported in this work provide an understanding of the key variables involved in nanoassembly, paving the way toward optimizing the interfacial chemistry of porphyrin-ZnO NP assembly for photodynamic therapy and energy conversion.



DOI: 10.1021/jp511740t