Encontrados 17 documentos, a visualizar página 1 de 2
Energy Transfer from Fluorene Based Conjugated Polyelectrolytes to Onchain and ...
Marques, Ana T.; Pinto, Sara M. A.; Monteiro, Carlos J. P.; Melo, J. Sérgio Seixas de; Burrows, Hugh D.; Scherf, Ullrich; Calvete, Mário J. F.A new water soluble fluorene-based polyelectrolyte containing on-chain porphyrin units has been synthesized via Suzuki coupling, for use in optoelectronic devices. The material consist of a random copolymer of poly{1,4-phenylene-[9,9-bis(4-phenoxy butylsulfonate)]fluorene-2,7-diyl} (PBS-PFP) and a 5,15-diphenylporphyrin (DPP). The energy transfer process between the PBS-PFP units and the porphyrin has been inve...
Synthesis and characterization of the ground and excited states of tripodal-lik...
Pina, João; Melo, J. Sérgio Seixas de; Batista, Rosa M. F.; Costa, Susana P. G.; Raposo, M. Manuela M.Six new thiophene oligomers, here designated as tripodal-like oligothienyl imidazoles, were synthesized and have been investigated in ethanol solution at room and low temperature. The oligomers bear a common core where two or more thiophenes are linked to one or more imidazole unit which further links through its alpha position to a different number of incremental thiophene units. The study involves a comprehen...
The influence of the relative position of the thiophene and pyrrole rings in do...
Pina, João; Melo, J. Sérgio Seixas de; Batista, Rosa M. F.; Costa, Susana P. G.; Raposo, M. Manuela M.A detailed spectroscopic and photophysical study has been carried out on a series of heterocyclic compounds -known to display nonlinear optical properties- consisting on one electron donating thienylpyrrolyl π-conjugated system functionalized with an electron acceptor benzothiazole moiety. The absorption, emission and triplet-triplet absorption together with all relevant quantum yields (fluorescence, intersyste...
The use of microspectrofluorimetry for the characterization of lake pigments
Claro, Ana; Melo, Maria J.; Schäfer, Stephan; Melo, J. Sérgio Seixas de; Pina, Fernando; Berg, Klaas Jan van den; Burnstock, AvivaIn this paper, the potential of confocal microfluorescence spectroscopy is explored for the characterization of selected red lake pigments and paints based on alizarin, purpurin and eosin (weak, medium and strong emitters). The anthraquinone pigments have been used since ancient times by artists, and eosin lakes were used by impressionist painters. Reconstructions of artists paints based on 19th century recipes...
Synthesis, Structural and Photophysical Evaluations of Urea Based Fluorescent P...
Santos, Cidália M. G. Dos; Glynn, Mark; Mccabe, Tomas; Melo, J. Sérgio Seixas de; Burrows, Hugh D.; Gunnlaugsson, ThorfinnurThe design, synthesis and photophysical evaluation of four anthracene based photoinduced electron transfer (PET) sensors (3a–d) for anions is described. The [4p+4p] photodimerization product, 4, was also obtained from 3b, by slow evaporation from DMSO solution and its X-ray crystal structure determined. The structure of 4 showed the classical dimerization at the 9,10-positions of anthracene. Sensors 3a–d are al...
A Study in Mauve: Unveiling Perkin's Dye in Historic Samples
Sousa, Micaela M.; Melo, Maria J.; Parola, A. Jorge; Morris, Peter J. T.; Rzepa, Henry S.; Melo, J. Sérgio Seixas deThe analysis of different historic mauve samples - mauve salts and dyed textiles - was undertaken to establish the exact nature of the iconic dye produced by W. H. Perkin in the nineteenth century. Fourteen samples from important museum collections were analyzed, and it was determined that, in contrast to the general wisdom that mauveine consists of C26 and C27 structures, Perkin's mauveine is a complex mixture...
A Study in Mauve: Unveiling Perkin's Dye in Historic Samples
Sousa, Micaela M.; Melo, Maria J.; Parola, A. Jorge; Morris, Peter J. T.; Rzepa, Henry S.; Melo, J. Sérgio Seixas deThe analysis of different historic mauve samples - mauve salts and dyed textiles - was undertaken to establish the exact nature of the iconic dye produced by W. H. Perkin in the nineteenth century. Fourteen samples from important museum collections were analyzed, and it was determined that, in contrast to the general wisdom that mauveine consists of C26 and C27 structures, Perkin's mauveine is a complex mixture...
Identification of 7,4prime-Dihydroxy-5-methoxyflavylium in ldquoDragon's Bloodr...
Melo, Maria J.; Sousa, Micaela; Parola, A. Jorge; Melo, J. Sérgio Seixas de; Catarino, Fernando; Marçalo, Joaquim; Pina, FernandoThe compound 7,4prime-dihydroxy-5-methoxyflavylium (dracoflavylium) was identified as the major red colorant in samples of the resin ldquodragon's bloodrdquo, extracted from the tree Dracaena draco. The complex network of reversible chemical reactions that dracoflavylium undergoes in aqueous solution is fully described; for the first time, all the equilibrium constants that enable a complete characterisation of...
Spectral and Photophysical Characterization of Donor-π-Acceptor Arylthienyl- an...
Pina, João; Melo, J. Sérgio Seixas de; Burrows, Hugh D.; Batista, Rosa M. F.; Costa, Susana P. G.; Raposo, M. Manuela M.A comprehensive study has been made in solution at room temperature (293 K), low temperature (77 K), and in thin films (Zeonex matrixes) of the spectral and photophysical properties of six arylthienyl- and bithienyl-benzothiazole derivatives functionalized with different donor groups. Similar experiments have been carried out with two related precursors (containing the arylthienyl and aryl-bithienyl conjugated ...
Fluorescence studies on the interaction between pyrene-labelled poly(acrylic ac...
Melo, J Sérgio Seixas de; Costa, Telma; Oliveira, Noémia; Schillén, KarinThe interactions, in aqueous media, between a pyrene-labelled polyelectrolyte poly(acrylic acid) (PAAMePy) with two different degrees of labelling and beta- and gamma-cyclodextrins (beta- and gamma-CD) were studied using absorption and fluorescence (steady-state and time-resolved) techniques. In addition to qualitative and quantitative parameters obtained from absorption and steady-state fluorescence spectra, t...
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