| Autor: |
Vaz Serra V; Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa , Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal.; Unidade de Química Orgânica e Produtos Naturais, Departamento de Química, Universidade de Aveiro , 3810-193 Aveiro, Portugal., Neto NGB; Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa , Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal., Andrade SM; Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa , Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal., Costa SMB; Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa , Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal. |
| Abstrakt: |
A strategy assisted by an inorganic template was developed to promote the organized self-assembly of meso-(tetrakis)-(p-sulfonatophenyl)porphyrin (TPPS) on pH-sensitive core-shell polyelectrolyte microcapsules (PECs) of poly(styrenesulfonate) (PSS) and poly(allylamine hydrochloride) (PAH). A key feature of this strategy is the use of template CaCO 3 microparticles as a nucleation site endorsing inside-outside directional growth of porphyrin aggregates. Using this approach, TPPS self-assembly in positively charged PECs with CaCO 3 (PAH/PSS) 2 PAH as a sequence of layers was successfully achieved using mild pH conditions (pH 3). Evidence for porphyrin aggregation was obtained by UV-vis with the characteristic absorption bands in PECs functionalized with porphyrins. Fluorescence lifetime imaging microscopy (FLIM) of the polyelectrolyte core-shell confirmed the presence of radially distributed needlelike structures sticking out from polyelectrolyte shells. Microscopic images also revealed a sequential process (adsorption, redistribution, and aggregation) for the directional growth (inside/outside) of TPPS aggregates, which highlights the importance of the core in the aggregation induction. Removing the CaCO 3 core alters the porphyrin interaction in the PEC environment, and aggregate growth is no longer favored. |
