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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...
Cores e corantes dos bordados de Castelo Branco : interação de contextos formai...
Paixão, Fátima; Pereira, Mariette; Cachapuz, AntónioOs coloridos bordados de Castelo Branco (Portugal) constituíram o mote para o desenvolvimento de um projeto que valoriza a relação entre os contextos formais e não formais na educação em química e na formação de professores e animadores culturais. A questão central prende-se com a possibilidade de identificar e obter os corantes antigos e atuais usados para tingir a seda. Apresentam-se duas atividades experimen...
Palladium-catalysed reactions of 8-hydroxy- and 8-benzyloxy-5,7-diiodoquinoline...
Takács, Attila; Szilágyi, Antal; Ács, Péter; Márk, László; Peixoto, Andreia F.; Pereira, Mariette M.; Kollár, LászlóVarious 5-carboxamido-7-iodo-8-benzyloxyquinolines were synthesised via selective aminocarbonylation of 5,7-diiodo-8-benzyloxyquinoline in the presence of ‘in situ’ generated palladium(0) catalysts. Under similar conditions (50 °C, 80 bar CO), 5,7-bis(N-tert-butyl-glyoxylamido)-8-hydroxyquinoline was obtained using tert-butylamine as N-nucleophile. The unprotected 5,7-diiodo-8-hydroxyquinoline underwent dehydro...
Superação do vitalismo e o imparável desenvolvimento da síntese orgânica
Paixão, Fátima; Pereira, MarietteA síntese orgânica representou um marco capital no História do Química, conduzindo ao fim da filosofia vitalista que considerava que as substâncias constitutivas dos animais e das plantas eram de natureza diferente dos corpos minerais, não obedecendo as mesmas leis, nem podendo ser feitas em laboratório. Quase dois séculos volvidos, a filosofia emergente e, agora, a de uma síntese verde, ambientalmente mais sus...
Argilas como catalisadores verdes na esterificação do colesterol: caracterizaçã...
Maria,Teresa M. R.; Nunes,Rui M. D.; Pereira,Mariette M.; Eusébio,M. Ermelinda S.A laboratory experiment that enables the professor to introduce the problematic of sustainable development in pharmaceutical chemistry to undergraduate students is proposed, using a simple synthetic procedure. Cholesteryl acetate is prepared by the esterification of cholesterol using Montmorillonite K10 as heterogeneous catalyst. Cholesterol and cholesteryl acetate are characterized by spectroscopic (¹H RMN, 13...
Rhodium catalyzed hydroformylation of kaurane derivatives: A route to new diter...
Peixoto, Andreia F.; Melo, Daniela S. de; Fernandes, Tânia F.; Fonseca, Yuraima; Gusevskaya, Elena V.; Silva, Artur M. S.; Contreras, Ricardo R.Kaurenic and grandiflorenic acids are naturally occurring diterpenes whose biological activity has been described. Both acids contain an exocyclic methylenic double bond that allows further functionalization on their structure. In an attempt to expand the number of derivatives of these two natural products, we have undertaken a study on the hydroformylation of the methyl esters of the two acids and the trimethy...
Synthesis of amphiphilic sulfonamide halogenated porphyrins: MALDI-TOFMS charac...
Monteiro, Carlos J. P.; Pereira, Mariette M.; Pinto, Sara M. A.; Simões, Ana V. C.; Sá, Gonçalo F. F.; Arnaut, Luís G.; Formosinho, Sebastião J.Porphyrins are key precursors for development of photosensitizers for photodynamic therapy. A new series of ortho-halogenated tetraarylporphyrins with sulfonamide substituents have been synthesized via chlorosulfonation reaction and characterized by MALDI-TOFMS. To predict their partition properties, log KOW of a selected range of the synthesized halogenated amphiphilic porphyrins is described. A significant ef...
Photoacoustic Measurement of Electron Injection Efficiencies and Energies from ...
Serpa, Carlos; Schabauer, Johann; Piedade, Ana P.; Monteiro, Carlos J. P.; Pereira, Mariette M.; Douglas, Peter; Burrows, Hugh D.; Arnaut, Luís G.Time-resolved photoacoustic calorimetry is used to measure the energy released upon injection of an electron from an electronically excited dye adsorbed to nanocrystalline TiO2 into the conduction band of this material. More energy is released when the environment of the dye is made less polar, because the energy of the dye-oxidized state has a more pronounced solvent dependence than the edge of the conduction ...
Photodegradation of atrazine and ametryn with visible light using water soluble...
Rebelo, Susana; Melo, A.; Coimbra, R.; Azenha, M.; Pereira, Mariette; Burrows, Hugh; Sarakha, MohamedAbstract The photodegradation of the herbicides atrazine and ametryn with visible light in aerated neutral aqueous solutions and 5, 10, 15, 20-tetrakis (2,6-dichloro-3-sulfophenyl) porphyrin or 5, 10, 15, 20-tetrakis (4-sulfophenyl) porphyrin as sensitizers are reported for the first time. Our findings show that the degradation percentage reached 30% for atrazine and 63% for ametryn. The final photoproducts we...
Corantes, cor e luz : recursos didácticos para um projecto com orientação ciênc...
Paixão, Fátima; Pereira, Mariette; Cachapuz, AntónioApresentam-se a fundamentação, os recursos didácticos e a avaliação pelos intervenientes de um projecto de educação CTS, centrado nas cores e corantes usados ancestralmente e actualmente nos bordados de Castelo Branco.
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