Publications

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2012
Pina, F, Melo MJ, Laia CAT, Parola JA, Lima JC.  2012.  Chemistry and applications of flavylium compounds: a handful of colours. Chemical Society Reviews. 41:869-908., Number 2 Abstract
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Otero, V, Carlyle L, Vilarigues M, Melo MJ.  2012.  Chrome yellow in nineteenth century art: historic reconstructions of an artists' pigment. Rsc Advances. 2:1798-1805., Number 5 Abstract
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Miguel, C, Lopes JA, Clarke M, Melo MJ.  2012.  Combining infrared spectroscopy with chemometric analysis for the characterization of proteinaceous binders in medieval paints. Chemometrics and Intelligent Laboratory Systems. 119:32-38. Abstract
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Rodriguez, L, Ferrer M, Crehuet R, Anglada J, Lima JC.  2012.  Correlation between Photophysical Parameters and Gold-Gold Distances in Gold(I) (4-Pyridyl)ethynyl Complexes. Inorganic Chemistry. 51:7636-7641., Number 14 Abstract
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2011
Oliveira, J, Petrov V, Parola AJ, Pina F, Azevedo J, Teixeira N, Bras NF, Fernandes PA, Mateus N, Ramos MJ, de Freitas V.  2011.  Chemical Behavior of Methylpyranomalvidin-3-O-glucoside in Aqueous Solution Studied by NMR and UV-Visible Spectroscopy, 2011. Journal of Physical Chemistry B. 115:1538-1545. Abstract

In the present work, the proton-transfer reactions of the methylpyranomalvidin-3-O-glucoside pigment in water with different pH values was studied by NMR and UV-visible spectroscopies. The results showed four equilibrium forms: the methylpyranomalvidin-3-O-glucoside cation, the neutral quinoidal base, the respective anionic quinoidal base, and a dianionic base unprotonated at the methyl group. According to the NMR data, it seems that for methylpyranomalvidin-3-O-glucoside besides the acid base equilibrium between the pyranoflavylium cation and the neutral quinoidal base, a new species is formed at pD 4.88-6.10. This is corroborated by the appearance of a new set of signals in the NMR spectrum that may be assigned to the formation of hemiketal/cis-chalcone species to a small extent. The two ionization constants (pK(a1) and pK(a2)) obtained by both methods (NMR and UV-visible) for methylpyranomalvidin-3-O-glucoside are in agreement (pK(a1) = 5.17 +/- 0.03; pK(a2) = 8.85 +/- 0.08; and pK(a1) = 4.57 +/- 0.07; pK(a2) = 8.23 +/- 0.04 obtained by NMR and UV-visible spectroscopies, respectively). Moreover, the fully dianionic unprotonated form (at the methyl group) of the methylpyranomalvidin-3-O-glucoside is converted slowly into a new structure that displays a yellow color at basic pH. On the basis of the results obtained through LC-MS and NMR, the proposed structure was found to correspond to the flavonol syringetin-3-glucoside.

Seixas de Melo, SJ, Cabral C, Lima JC, Macanita AL.  2011.  Characterization of the Singlet and Triplet Excited States of 3-Chloro-4-methylumbelliferone. Journal of Physical Chemistry a. 115:8392-8398., Number 30 Abstract
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Oliveira, J, Petrov V, Parola JA, Pina F, Azevedo J, Teixeira N, Bras NF, Fernandes PA, Mateus N, Ramos MJ, de Freitas V.  2011.  Chemical Behavior of Methylpyranomalvidin-3-O-glucoside in Aqueous Solution Studied by NMR and UV-Visible Spectroscopy. Journal of Physical Chemistry B. 115:1538-1545., Number 6 Abstract
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Branco, LC, Serbanovic A, da Ponte MN, Afonso CAM.  2011.  Chiral Guanidinium Ionic Liquids for Asymmetric Dihydroxylation of Olefins with Recycling of the Catalytic System by Supercritical CO2. Acs Catalysis. 1:1408-1413., Number 10 Abstract
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Gordo, J, Avo J, Parola JA, Lima JC, Pereira A, Branco PS.  2011.  Convenient Synthesis of 3-Vinyl and 3-Styryl Coumarins. Organic Letters. 13:5112-5115., Number 19 Abstract
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Giestas, L, Lima JC, Baptista PV.  2011.  Coupling single base extension to a spectral codification tool for increased throughput screening. Journal of Biotechnology. 154:199-204., Number 4 Abstract
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2010
Gago, S, Balula SS, Figueiredo S, Lopes AD, Valente AA, Pillinger M, Goncalves IS.  2010.  Catalytic olefin epoxidation with cationic molybdenum(VI) cis-dioxo complexes and ionic liquids. Applied Catalysis a-General. 372:67-72., Number 1 Abstract
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Gavara, R, Petrov V, Pina F.  2010.  Characterization of the 4 '-hydroxynaphthoflavylium network of chemical reactions. Photochemical & Photobiological Sciences. 9:298-303., Number 3 Abstract
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Monteiro, B, Cunha-Silva L, Gago S, Klinowski J, Almeida Paz FA, Rocha J, Goncalves IS, Pillinger M.  2010.  Crystal and supramolecular structures of dioxomolybdenum(VI) and dioxotungsten(VI) complexes of dihydroxybenzoic acids. Polyhedron. 29:719-730., Number 2 Abstract
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Neves, P, Pereira CCL, Paz FAA, Gago S, Pillinger M, Silva CM, Valente AA, Romao CC, Goncalves IS.  2010.  Cyclopentadienyl molybdenum dicarbonyl eta(3)-allyl complexes as catalyst precursors for olefin epoxidation. Crystal structures of Cp ' Mo(CO)(2)(eta(3)-C3H5) (Cp ' = eta(5)-C5H4Me, eta(5)-C5Me5). Journal of Organometallic Chemistry. 695:2311-2319., Number 21 Abstract
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2009
Neves, P, Gago S, Pereira CCL, Figueiredo S, Lemos A, Lopes AD, Goncalves IS, Pillinger M, Silva CM, Valente AA.  2009.  Catalytic Epoxidation and Sulfoxidation Activity of a Dioxomolybdenum(VI) Complex Bearing a Chiral Tetradentate Oxazoline Ligand. Catalysis Letters. 132:94-103., Number 1-2 Abstract
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Monteiro, B, Balula SS, Gago S, Grosso C, Figueiredo S, Lopes AD, Valente AA, Pillinger M, Lourenco JP, Goncalves IS.  2009.  Comparison of liquid-phase olefin epoxidation catalysed by dichlorobis-(dimethylformamide)dioxomolybdenum(VI) in homogeneous phase and grafted onto MCM-41. Journal of Molecular Catalysis a-Chemical. 297:110-117., Number 2 Abstract
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2008
Kulkarni, PS, Branco LC, Crespo JG, Afonso CAM.  2008.  Capture of Dioxins by ionic liquids. Environmental Science & Technology. 42:2570-2574., Number 7 Abstract
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2007
Jimenez, A, Pinheiro C, Parola AJ, Maestri M, Pina F.  2007.  The chemistry of 6-hydroxyflavylium: zwitterionic base and p-quinoidal chalcones. A multiswitchable system operated by proton, electron and photon inputs, 2007. Photochemical & Photobiological Sciences. 6:372-380. Abstract

The complex network of chemical reactions of the compound 6-hydroxyflavylium perchlorate was studied by different techniques including UV-vis absorption spectrophotometry, stopped-flow, electrochemistry, and photochemistry. The network is characterized by the formation of a very reactive zwitterionic base as well as by p-quinoidal chalcones. The trans-chalcone is metastable in very acidic solutions and exhibits reversible redox reactions, allowing to introduce for the first time in the flavylium network an electrochemical input.

Kulkarni, PS, Branco LC, Crespo JG, Afonso CAM.  2007.  A comparative study on absorption and selectivity of organic vapors by using ionic liquids based on imidazolium, quaternary ammonium, and guanidinium cations. Chemistry-a European Journal. 13:8470-8477., Number 30 Abstract
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Kulkarni, PS, Branco LC, Crespo JG, Nunes CM, Raymundo A, Afonso CAM.  2007.  Comparison of physicochemical properties of new ionic liquids based on imidazolium, quaternary ammonium, and guanidinium cations. Chemistry-a European Journal. 13:8478-8488., Number 30 Abstract
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2006
Bazzicalupi, C, Bencini A, Bianchi A, Borsari L, Danesi A, Giorgi C, Mariani P, Pina F, Santarelli S, Valtancoli B.  2006.  Coordination features of a terpyridine-containing polyamine receptor. Effect of protonation on the photophysical properties of the complexes. Dalton Transactions. :5743-5752., Number 48 Abstract
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2005
Kuhn, FE, Zhao J, Abrantes M, Sun W, Afonso CAM, Branco LC, Goncalves IS, Pillinger M, Romao CC.  2005.  Catalytic olefin epoxidation with cyclopentadienyl-molybdenum complexes in room temperature ionic liquids. Tetrahedron Letters. 46:47-52., Number 1 Abstract
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da Silva, PF, Lima JC, Freitas AA, Shimizu K, Macanita AL, Quina FH.  2005.  Charge-transfer complexation as a general phenomenon in the copigmentation of anthocyanins. Journal of Physical Chemistry a. 109:7329-7338., Number 32 Abstract
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