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Self-aggregation of free base porphyrins in aqueous solution and in DMPC vesicles
Andrade, Suzana M.; Teixeira, Raquel; Costa, Sílvia M.B.; Sobral, Abílio J.F.N.Free base porphyrin (PPhe), derivatized with aminosulfonyl groups linked to the aromatic amino acid phenylalanine at the meso-positions, was mixed with DMPC vesicles. The resulting interaction was studied by absorption, steady-state and transient state fluorescence, at different pHs. ; http://www.sciencedirect.com/science/article/B6TFB-4R68NKV-2/1/aca6e255f297903981898ccea264a386
Synthesis of flexible dimeric meso-tetrakis-porphyrins
Sobral, Abilio J.F.N.; Melo, Susana M.; Ramos, M. Luísa; Teixeira, Raquel; Andrade, Susana M.; Costa, Silvia M.B.Monofunctionalisation of meso-tetrakis-porphyrins through introduction of a carboxylic group in the meso position of the phenyl group confers the necessary characteristics to anchor them through stable amide bonds to functionalised supports or to molecules. In this Letter we describe the synthesis, characterisation and photophysical evaluation of such a functionalised flexible dimeric porphyrin, bis-(meso-tetra...
Self-association of free base porphyrins with aminoacid substituents in AOT rev...
Andrade, Suzana M.; Teixeira, Catarina; Togashi, Denisio M.; Costa, Sílvia M.B.; Sobral, Abílio J.F.N.The aggregation properties of aminosulfonyl porphyrins with aminoacid substituents: methionine with the acid function methylated, PMetCH3; phenylalanine, PPhe; attached to the para positions of the meso phenyls of the porphyrin, was followed in organic solvents, water-dioxane mixtures and in reverse micelles of aerosol OT (AOT RM), using absorption, steady-state and time-resolved fluorescence. In AOT RM in the ...
Electric polarization effects on the electronic spectral shift of centrosymmetr...
Togashi, Denisio M.; Costa, Sílvia M. B.; Sobral, Abílio J. F. N.; Gonsalves, A. M. d'A. R.The classic dielectric dipolar Onsager model was extended to include quadrupolar interactions between solute molecules and solvents with different polarities. A multiparametric solvatochromic expression, based on the point quadrupole moment inside a spherical cavity embedded in a dielectric continuum, is applied to centrosymmetric sulfonamide porphyrins, zinc tetraphenyl porphyrin, squaraine and 9,10-dicyanoant...
Self-Aggregation of Lipophilic Porphyrins in Reverse Micelles of Aerosol OT
Togashi, Denisio M.; Costa, Sílvia M. B.; Sobral, Abílio J. F. N.; Gonçalves, A. M. d'A. R.The aggregation process of meso-tetra(4-aminosulfonylphenyl)porphyrin (PC0), of butyl and dodecyl derivatives (PC4 and PC12, respectively) in the presence of aerosol-OT (AOT) reversed micelles with different values of ω0 = [water]/[AOT] was investigated using steady-state extinction, fluorescence, and resonance light scattering (RLS) techniques. The scattering has been accounted for and the absorption spectra c...
Effective distances of exothermic charge-transfer reactions in the excited state
Costa, Sílvia M. B.; Maçanita, A. L.; Formosinho, S. J.A study of intermolecular, exothermic charge-transfer interactions is described. A distance dependence on the unimolecular charge-transfer rate constant k,,(R) is observed in viscous solvents where transfer at longer distances than the collisional one can compete with dissociation of an encounter complex. A comparative study of the quenching phenomena, occurring in a family of redox partners of aromatic esters ...
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