Encontrados 13 documentos, a visualizar página 1 de 2
Circular dichroism of anthocyanidin 3-glucoside self-aggregates
Gavara, Raquel; Petrov, Vesselin; Quintas, Alexandre; Pina, Fernando"Self-association constants for the flavylium cations of the six most common anthocyanidin 3-glucosides were determined by circular dichroism (CD) and UV–Vis spectroscopy. Along with previous 1H NMR results, all measurements were consistent with a monomer–dimer model. The CD spectra of the antho-cyanidin 3-glucosides were similar to the analogues 3,5-diglucosides. All dimers of the anthocyanidin 3-glucosides ex...
Anatase as an alternative application for preventing biodeterioration of mortar...
Macedo, Maria Filomena; Fonseca, Ana Josina; Pina, Fernando; Leal, NunoInternational Biodeterioration & Biodegradation 64(2010)388 e 396 ; The aim of this study is the comparison between different treatments(anatase and two conventional biocides:Biotin T and Anios)for preventing biodeterioration of mortars.The treatments were applied both in the laboratory on mortar slabs and in situ on walls of Palácio Nacional da Pena(Sintra,Portugal). Mortar slabs treated with anatase (pure an...
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 and photophysical properties of dansyl-based polyamine ligands and th...
Parola, A. Jorge; Lima, João Carlos; Pina, Fernando; Pina, João; Melo, João Seixas de; Soriano, Conxa; García-España, Enrique; Aucejo, RicardoThe synthesis, potentiometric studies and photophysical properties of two new polyamine ligands (L1 and L2) possessing the dansyl chromophore were studied in aqueous 0.15 M NaCl. The compounds show the absorption and emissions bands characteristic of the dansylamide fluorophore and both present intramolecular excited state proton transfer at intermediate pH ranges. One of the ligands (L2) strongly coordinates Z...
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...
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...
Spectroscopy and Coordination Chemistry of a New Bisnaphthalene−Bisphenanthroli...
Pina, João; Melo, J. Seixas de; Pina, Fernando; Lodeiro, Carlos; Lima, J. C.; Parola, A. Jorge; Soriano, Conxa; Paz Clares, M.; Albelda, M. TeresaA new fluorescent macrocyclic structure (L1) bearing two naphthalene units at both ends of a cyclic polyaminic chain containing two phenanthroline units was investigated with potentiometric and fluorescence (steady-state and time-resolved) techniques. The fluorescence emission spectra show the simultaneous presence of three bands: a short wavelength emission band (naphthalene monomer), a middle emission band (...
A New ZnIITweezer Pyridine-Naphthalene System - An Off-On-Off System Working in...
Aucejo, Ricardo; Alarcón, Javier; García-España, Enrique; Llinares, José M.; Marchin, Katherine L.; Soriano, Conxa; Lodeiro, CarlosThe synthesis, protonation behaviour and Zn2+ coordination chemistry of a new photoactive polyamine exhibiting ldquooff-on-offrdquo fluorescence is presented. Addition of Zn2+ reduces the width of the fluorescence window, which is centred around physiological pH, and sharply enhances the emission intensity. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) ; http://dx.doi.org/10.1002/ejic.2...
Synthesis and H+, Cu2+, and Zn2+ Coordination Behavior of a Bis(fluorophoric) B...
Clares, M. Paz; Aguilar, Juan; Aucejo, Ricardo; Lodeiro, Carlos; Albelda, M. Teresa; Pina, Fernando; Lima, J. C.; Parola, A. Jorge; Pina, JoãoThe synthesis, protonation behavior, and Cu2+ and Zn2+ coordination chemistry of the novel bibrachial aza lariat ether (naphthalen-1-ylmethyl)[2-(20-2-[(naphthalen-1-ylmethyl)amino]ethyl-3,6,9,17,20,23,29,30-octaazatricyclo[23.3.1.1*11,15*]triaconta-1(29),11(30),12,14,25,27-hexaen-6-yl)ethyl]amine (L) are discussed. The macrocycle, which has two aminoethyl naphthyl moieties symmetrically appended to a 2:2 azapy...
Intramolecular Excimer Formation in a Tripodal Polyamine Receptor Containing Th...
Albelda, M. Teresa; García-España, Enrique; Gil, Laura; Lima, João C.; Lodeiro, Carlos; Melo, J. Seixas de; Melo, M. João; Parola, A. JorgeA comprehensive investigation on the energetics and dynamics of a new fluorescent sensor constituted by a tripodal polyamine receptor containing three naphthalene fluorophores, compound L, is reported. The influence of external factors such as the solvent, hydrogen ion concentration, and temperature in the photophysics of the sensor is discussed. The temperature dependence of monomer/excimer interconversion of ...
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