95 documents found, page 1 of 10
Novel organotin-PTA complexes supported on mesoporous carbon materials as recyc...
Mahmoud, Abdallah G.; Librando, Ivy L.; Paul, Anup; Carabineiro, Sónia A. C.; Ferraria, Ana Maria; Botelho do Rego, Ana MariaNew organotin compounds with general formula [(PTA-CH2-C6H4-p-COO)SnR3]Br (where R is Me for 3 and Ph for 4; PTA = 1,3,5-triaza-7-phosphaadamantane), bearing the methylene benzoate PTA derivative, were synthesized through a mild two-step process. The compounds were characterized by Fourier transform infrared spectroscopy, electrospray ionization mass spectrometry, elemental analysis and nuclear magnetic resonan...
Contribution of non-ionic interactions on bile salt sequestration by chitooligo...
Coreta-Gomes, Filipe Manuel; Silva, Inês M. V.; Nunes, Cláudia; Marin-Montesinos, Ildefonso; Evtuguin, Dmitry Victorovitch; Geraldes, Carlos F. G. C.Chitooligosaccharides have been suggested as cholesterol reducing ingredients mostly due to their ability to sequestrate bile salts. The nature of the chitooligosaccharides-bile salts binding is usually linked with the ionic interaction. However, at physiological intestinal pH range (6.4 to 7.4) and considering chitooligosaccharides pKa, they should be mostly uncharged. This highlights that other type of intera...
Elucidating the Nature of the External Acid Sites of ZSM-5 Zeolites Using NMR P...
Bornes, Carlos; Stosic, Dusan; Geraldes, Carlos F. G. C.; Mintova, Svetlana; Rocha, João; Mafra, LuísThe identification of acid and nonacid species at the external surface of zeolites remains a major challenge, in contrast to the extensively-studied internal acid sites. Here, it is shown that the synthesis of zeolite ZSM-5 samples with distinct particle sizes, combined with solid-state NMR and computational studies of trimethylphosphine oxide (TMPO) adsorption, provides insight into the chemical species on the...
Heterogeneous Gold Nanoparticle-Based Catalysts for the Synthesis of Click-Deri...
Librando, Ivy L.; Mahmoud, Abdallah G.; Carabineiro, Sónia A. C.; Guedes da Silva, M. Fátima C.; Maldonado-Hódar, Francisco J.A supported gold nanoparticle-catalyzed strategy has been utilized to promote a click chemistry reaction for the synthesis of 1,2,3-triazoles via the azide-alkyne cycloaddition (AAC) reaction. While the advent of effective non-copper catalysts (i.e., Ru, Ag, Ir) has demonstrated the catalysis of the AAC reaction, additional robust catalytic systems complementary to the copper catalyzed AAC remain in high demand...
Complexes of Bifunctional DO3A-N-(α-amino)propinate Ligands with Mg(II), Ca(II)...
Garda, Zoltán; Kócs, Tamara; Bányai, István; Martins, José A.; Kálmán, Ferenc Krisztián; Tóth, Imre; Geraldes, Carlos F. G. C.; Tircsó, GyulaThe thermodynamic, kinetic, and structural properties of Ln3+ complexes with the bifunctional DO3A-ACE4- ligand and its amide derivative DO3A-BACE4- (modelling the case where DO3A-ACE4- ligand binds to vector molecules) have been studied in order to confirm the usefulness of the corresponding Gd3+ complexes as relaxation labels of targeted MRI contrast agents. The stability constants of the Mg2+ and Ca2+ comple...
Synthesis of a Novel Series of Cu(I) Complexes Bearing Alkylated 1,3,5-Triaza-7...
Librando, Ivy L.; Mahmoud, Abdallah G.; Carabineiro, Sónia A. C.; Guedes da Silva, M Fátima C.; Geraldes, Carlos F. G. C.; Pombeiro, Armando J. L.The N-alkylation of 1,3,5-triaza-7-phosphaadamantane (PTA) with ortho-, meta- and para-substituted nitrobenzyl bromide under mild conditions afforded three hydrophilic PTA ammonium salts, which were used to obtain a new set of seven water-soluble copper(I) complexes. The new compounds were fully characterized and their catalytic activity was investigated for the low power microwave assisted one-pot azide-alkyne...
The Catalytic Activity of Carbon-Supported Cu(I)-Phosphine Complexes for the Mi...
Librando, Ivy L.; Mahmoud, Abdallah G.; Carabineiro, Sónia A. C.; Guedes da Silva, M. Fátima C.; Geraldes, Carlos F. G. C.; Pombeiro, Armando J. L.A set of Cu(I) complexes with 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo-[3.3.1]nonane (DAPTA) phosphine ligands viz. [CuX( P-DAPTA)3] (1: X = Br; 2: X = I) and [Cu( -X)( P-DAPTA)2]2 (3: X = Br; 4: X = I) were immobilized on activated carbon (AC) and multi-walled carbon nanotubes (CNT), as well as on these materials after surface functionalization. The immobilized copper(I) complexes have shown favorable cataly...
Complexes of bifunctional DO3A-N-(α-amino)propinate ligands with Mg(II), Ca(II)...
Garda, Zoltán; Kócs, Tamara; Bányai, István; Martins, J. A. R.; Kálmán, Ferenc Krisztián; Tóth, Imre; Geraldes, Carlos F. G. C.; Tircsó, GyulaThe thermodynamic, kinetic, and structural properties of Ln<sup>3+</sup> complexes with the bifunctional DO3A-ACE<sup>4−</sup> ligand and its amide derivative DO3A-BACE<sup>4−</sup> (modelling the case where DO3A-ACE<sup>4−</sup> ligand binds to vector molecules) have been studied in order to confirm the usefulness of the corresponding Gd<sup>3+</sup> complexes as relaxation labels of targeted MRI contrast agen...
What is being measured with p-bearing nmr probe molecules adsorbed on zeolites?
Bornes, Carlos; Fischer, Michael; Amelse, Jeffrey A.; Geraldes, Carlos F. G. C.; Rocha, João; Mafra, LuísElucidating the nature, strength, and siting of acid sites in zeolites is fundamental to fathom their reactivity and catalytic behavior. Despite decades of research, this endeavor remains a major challenge. Trimethylphosphine oxide (TMPO) has been proposed as a reliable probe molecule to study the acid properties of solid acid catalysts, allowing the identification of distinct Brønsted and Lewis acid sites and ...
Multifunctionalization of cyanuric chloride for the stepwise synthesis of poten...
Calvete, Mário J. F.; Pinto, Sara M. A.; Burrows, Hugh D.; Castro, M. Margarida C. A.; Geraldes, Carlos F. G. C.; Pereira, Mariette M.We report a synthetic strategy to combine different moieties in a single structure using cyanuric chloride (2,4,6-trichlorotriazine) as a starting platform for preparing potential bioimaging agents. This reacted with macrocycles of the porphyrin family and DOTA type metal chelators through mono-, di- and tri- substitution of its chlorine atoms by appropriate nucleophiles, control- ling the stepwise by temperatu...