11 documents found, page 1 of 2
Effects of Charge Density on Photophysics and Aggregation Behavior of Anionic F...
Martelo, Liliana M.; Fonseca, Sofia M.; Marques, Ana T.; Burrows, Hugh D.; Valente, Artur J. M.; Justino, Licínia L. G.; Scherf, UllrichThree anionic fluorene-based alternating conjugated polyelectrolytes (CPEs) have been synthesized that have 9,9-bis(4-phenoxy-butylsulfonate) fluorene-2,7-diyl and 1,4-phenylene (PBS-PFP), 4,4'-biphenylene (PBS-PFP2), or 4,4″-p-terphenylene (PBS-PFP3) groups, and the effect of the length of the oligophenylene spacer on their aggregation and photophysics has been studied. All form metastable dispersions in water...
Photophysical Characterization and in Vitro Phototoxicity Evaluation of 5,10,15...
Costa, Letícia D.; Silva, Joana de A. e; Fonseca, Sofia M.; Arranja, Cláudia T.; Urbano, Ana M.; Sobral, Abílio J. F. N.Photodynamic therapy (PDT) is a selective and minimally invasive therapeutic approach, involving the combination of a light-sensitive compound, called a photosensitizer (PS), visible light and molecular oxygen. The interaction of these per se harmless agents results in the production of reactive species. This triggers a series of cellular events that culminate in the selective destruction of cancer cells, insid...
Theoretical and experimental insights into the complexation of 8-hydroxyquinoli...
Ramos, M. Luísa; Justino, Licínia L. G.; Branco, Adriana; Fonseca, Sofia M.; Burrows, Hugh D.The complexation of 8-hydroxyquinoline-5-sulfonic acid with cadmium(II) and mercury(II) has been studied in aqueous solutions using UV/visible absorption, fluorescence and 1H NMR spectroscopy, accompanied by DFT calculations. Results are compared with the behavior of zinc(II) and show in all cases the dominant formation of a 1:2 (metal:ligand) complex. DFT calculations under PCM (water) conditions indicate a pr...
Synthesis, spectroscopy, photophysics and thermal behaviour of stilbene-based t...
Gigante, Bárbara; Esteves, M. Alexandra; Pires, N.; Davies, Matthew L.; Douglas, Peter; Fonseca, Sofia M.; Burrows, Hugh D.; Pina, JoãoNovel stilbene-based triarylamines with dehydroabietic acid methyl ester moieties have been synthesised by palladium catalysed C–N coupling reactions. The presence of the bulky dehydroabietic acid group increases solubility, hinders crystallisation and permits their sublimation while preserving their electronic and optical characteristics. This makes them good candidates for various molecular electronic applica...
Solubilization of Poly{1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)] fluore...
Burrows, Hugh D.; Tapia, María J.; Fonseca, Sofia M.; Pradhan, Swapna; Scherf, Ullrich; Silva, Cláudia L.; Pais, Alberto A. C. C.; Valente, Artur J. M.In the presence of the nonionic alkyloxyethylene surfactant n-dodecylpentaoxyethylene glycol ether (C12E5), the anionic conjugated polyelectrolyte (CPE) poly{1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl} (PBS-PFP) dissolves in water, leading to a blue shift in fluorescence and dramatic increases in fluorescence quantum yields above the surfactant critical micelle concentration (cmc). No si...
Synthesis, spectroscopy, photophysics and thermal behaviour of stilbene-based t...
Gigante, Bárbara; Esteves, M. Alexandra; Pires, N.; Davies, Matthew L.; Douglas, Peter; Fonseca, Sofia M.; Burrows, Hugh D.; Pina, JoãoNovel stilbene-based triarylamines with dehydroabietic acid methyl ester moieties have been synthesised by palladium catalysed C–N coupling reactions. The presence of the bulky dehydroabietic acid group increases solubility, hinders crystallisation and permits their sublimation while preserving their electronic and optical characteristics. This makes them good candidates for various molecular electronic applica...
Interplay of Electrostatic and Hydrophobic Effects with Binding of Cationic Gem...
Burrows, Hugh D.; Tapia, María J.; Silva, Cláudia L.; Pais, Alberto A. C. C.; Fonseca, Sofia M.; Pina, João; Melo, J. Seixas de; Wang, YujieUnderstanding factors responsible for the fluorescence behavior of conjugated polyelectrolytes and modulation of their behavior are important for their application as functional materials. The interaction between the anionic poly{1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl}copolymer (PBS−PFP) and cationic gemini surfactants α,ω-(CmH2m+1N+(CH3)2)2(CH2)s(Br-)2 (m-s-m; m = 12, s = 2, 3, 5, 6...
Opto-Electronic Properties of Fluorene-Based Derivatives as Precursors for Ligh...
Fratiloiu, Silvia; Fonseca, Sofia M.; Grozema, Ferdinand C.; Burrows, Hugh D.; Costa, Maria L.; Charas, Ana; Morgado, Jorge; Siebbeles, Laurens D. A.This paper reports optical absorption spectra of oxidized fluorene copolymers obtained by chemical oxidation with Ce(IV) and by pulse radiolysis experiments in chlorinated solvents. Comparison of the results observed by the two techniques is used to provide spectral data on the copolymer radical ions and information on stability of the oxidized species. In addition, a detailed quantum chemical characterization ...
Interactions between hairy rod anionic conjugated polyelectrolytes and nonionic...
Fonseca, Sofia M.; Eusébio, M. Ermelinda; Castro, Ricardo; Burrows, Hugh D.; Tapia, Maria José; Olsson, UlfThe effect of three anionic, hairy-rod fluorene based conjugated polyelectrolytes on the cloud points of the alkyloxyethylene surfactants C10E3, C12E4, C12E5, and C12E6 has been studied in aqueous solution. Although the association behaviour of these rigid polymers with surfactants is different from that of more flexible polyelectrolytes, both types of polymers are seen to increase the cloud points, probably as...
On the photophysical behaviour of 4-halo-5-phenylisoxazoles
Fonseca, Sofia M.; Burrows, Hugh D.; Nunes, Cláudio M.; Melo, Teresa M. V. D. Pinho e; Gonsalves, António M. d'A. RochaDetailed spectral and photophysical properties of 4-halo-5-phenylisoxazoles in cyclohexane solutions are presented, including measurements of energies of lowest excited singlet and triplet states, fluorescence quantum yields, lifetimes, phosphorescence and triplet-singlet difference absorption spectra. Upon addition of ethanol, loss of vibrational structure is observed in fluorescence spectra and attributed to ...