Interaction of porphyrin nanostructures with hard templates

MARIANA HAMER; PETER J. EATON; CRAIG MEDFORTH

Munich

Congreso; International Conference on Porphyrins and Phthalocyanines (ICPP); 2018

Friedrich-Alexander-Universitaet Erlangen-Nuernberg

Porphyrins and metalloporphyrins are one of the most widely studied platforms for the construction of supramolecular structures. The aromatic system of these compounds is optimal for the occurrence of π-π stacking interactions, which, together with the hydrogen bonds, the formation of inter-metallic complexes and the electrostatic forces offer a versatile platform to control the aggregation mechanism (1). In this work, we present the study of the formation of nanostructures by spontaneous aggregation of water-soluble porphyrins (TPPSH2 & TMPyPH2) in the presence of hard nanotemplates (silica, gold, and polystyrene nanoparticles (NPs)). The nanostructures obtained were characterized by UV-vis, fluorescence spectroscopy, Raman, SEM, TEM and AFM. The spectroscopic analysis revealed the presence of porphyrin nanostructures. However, the results were variable depending on the nature of the NP template used and the porphyrin concentration. At concentrations of porphyrin greater than 10 μM, the nanostructures could not be deposited on the surfaces of the NPs under the conditions implemented such as a) direct mixing of the porphyrins of opposite charge in the presence of the template, or b) by layer by layer self-assembly. This is mainly due to the fact that aggregation by stacking π-π, face (H aggregates) or edge with edge (J aggregates), of the porphyrin molecules is more stable than accommodation on the surfaces studied (gold, silica and polystyrene). It should be noted that in the case of silica NPs at concentrations lower than 10 μM, it was observed that there is a change in the texture of the surface and an increase in the diameter of the nanoparticles. Figure shows the differences observed by AFM and SEM.