7 documents found, page 1 of 1
A photoswitchable “host-guest¿? approach for the selective enrichment of dimeth...
Garcia, Raquel; Carreiro, Elisabete P.; Prates Ramalho, João P.; Burke, Anthony J.; Lima, João C.; Gomes da Silva, Marco D.R.; Costa Freitas, Ana MariaThis work describes the development of a new selective photocontrollable molecularly imprinted-based sorbent for the selective enrichment/pre-concentration of dimethoate from spiked olive oil samples. To achieve this goal an improved molecularly imprinted strategy relying on the embedding of a functional monomer containing an azobenzene chromophore as light-responsive element, on the crosslinked tridimensional ...
Elucidation of the multiple equilibria of malvin in aqueous solution by One- an...
Santos, Helena; Turner, David L.; Lima, João C.; Figueiredo, Paulo; Pina, Fernando S.; Maçanita, António L.One- and two-dimensional NMR were used to characterize the several forms of malvin present in aqueous solution in the pH range 0.3–4.5 and to determine their molar fractions as a function of pH. In addition to the flavylium cation, two hemiacetal forms and both the cis and trans forms of chalcone were firmly identified. The pathways for the interconversion of the different forms were derived and the molar absor...
Photochromism of the Synthetic 4',7-Dihydroxyflavylium Chloride
Figueiredo, Paulo; Lima, João C.; Santos, Helena; Wigand, Marie Claude; Brouillard, Raymond; Maçanita, António L.; Pina, FernandoThe synthetic compound 4',7-dihydroxyflavylium chloride shows an interesting photochromic effect at moderately acidic pH values. Pale yellow solutions of this compound, equilibrated in the dark at pH 3.4, become bright yellow upon irradiation with 313-nm light. Switching off the light, gives back the initial pale yellow solution. Photochemical methods, *H NMR, and molecular orbital calculations were used to elu...
Characterization of antiproliferative potential and biological targets of a cop...
Mendo, Ana Soraia; Figueiredo, Sara; Roma-Rodrigues, Catarina; Videira, Paula A.; Ma, Zhen; Diniz, Mário; Larguinho, Miguel; Costa, Pedro M.Several copper complexes have been assessed as anti-tumor agents against cancer cells. In this work, a copper compound [Cu(H2O){OS(CH3)2}L](NO3)2 incorporating the ligand 4′-phenyl-terpyridine antiproliferative activity against human colorectal, hepatocellular carcinomas and breast adenocarcinoma cell lines was determined, demonstrating high cytotoxicity. The compound is able to induce apoptosis and a slight de...
A Family of Styrylcoumarins: Synthesis, Spectroscopic, Photophysical and Photoc...
Avó, João; Martins, Sérgio; Parola, A. Jorge; Lima, João C.; Branco, Paula S.; Prates Ramalho, João P.; Pereira, AntónioPhotochromism, which is the reversible transformation between two molecular forms with different absorption spectra, resulting from photoirradiation, has applicability in several fields, including light modulation materials, optical recording materials, optical switches and photochromic inks.[1] The switching from one molecular state to another is dependent upon the efficiency of light absorption by the input c...
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. Jorge; PiA 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 ...
Switching from intramolecular energy transfer to intramolecular electron transf...
Albelda, M. Teresa; Díaz, Pilar; García-España, Enrique; Lima, João C.; Lodeiro, Carlos; Seixas de Melo, J.; Jorge Parola, A.; Pina, Fernandohttp://www.sciencedirect.com/science/article/B6TFN-44SKJK4-4/1/7cd5958d3acd1757d2b3a88517f1d557