Navegando por Autor "Lima, Benedicto Augusto Vieira"
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Item Assessment of the biological potential of diaryltriazene-derived triazene compounds.(2021) Figueirêdo, Patricia de Maria Silva; Sampaio Filho, José Costa; Sodré, Alzirene de Jesus Sales; Castro Júnior, José Ribamar de; Gonçalves, Ingrid Santos; Blasques, Rodrigo Vieira; Correa, Rodrigo de Souza; Lima, Benedicto Augusto Vieira; Marques, Larissa dos Anjos; Coutinho, Denise Fernandes; Santos, Ana Paula Silva de Azevedo dos; Luz, Tássio Rômulo Silva Araújo; Miranda, Rita de Cassia Mendonça de; Santos, Julliana Ribeiro Alves dos; Doriguetto, Antônio Carlos; Pividori, María Isabel; Hörner, Manfredo; Villis, Paulo Cesar MendesIn the present study, novel, 1,3-diaryltriazene-derived triazene compounds were synthesized and tested. Triazenes are versatile and belong to a group of alkylating agents with interesting physicochemical properties and proven biological activities. This study describes the synthesis, molecular and crystalline structure, biological activity evaluation, and antifungal and antimicrobial potentials of 1,3-bis(X-methoxy-Y-nitrophenyl)triazenes [X= 2 and 5; Y= 4 and 5]. The antimicrobial and antifungal activities of the compounds were tested by evaluating the sensitivity of bacteria (American Type Culture Collection, ATCC) and clinical isolates to their solutions using standardized microbiological assays, cytotoxicity evaluation, and ecotoxicity tests. The antimicrobial potentials of triazenes were determined according to their minimum inhibitory concentrations (MICs); these compounds were active against gram-positive and gram-negative bacteria, with low MIC values. The most surprising result was obtained for T3 having the efective MIC of 9.937 µg/mL and antifungal activity against Candida albicans ATCC 90028, C. parapsilosis ATCC 22019, and C. tropicallis IC. To the best of our knowledge, this study is the frst to report promising activities of triazene compounds against yeast and flamentous fungi. The results showed the potential utility of triazenes as agents afecting selected resistant bacterial and fungal strains.Item Influence of gold nanoparticles applied to catalytic hydrogenation of acetophenone with cationic complexes containing ruthenium.(2016) Souza, Lanarck Cristina Moro; Santos, Thiago A.; Prado, Cássio Roberto Arantes do; Lima, Benedicto Augusto Vieira; Correa, Rodrigo de Souza; Batista, Alzir Azevedo; Otubo, Larissa; Ellena, Javier Alcides; Ueno, Leonardo Tsuyoshi; Dinelli, Luís Rogério; Bogado, André LuizHerein the catalytic activity of cationic ruthenium(II) complexes [Ru]+ is described in the presence of gold nanoparticles (AuNPsn ) in the transfer hydrogenation of acetophenone, to produce phenylethanol. The catalytic activity of the complexes, with a general formula cis-[RuCl(CH3OH)(P–P)(N–N)]+ or cis- [RuCl(CH3OH)(P)2(N–N)]+ {where: P ¼ triphenylphosphine (PPh3); P–P ¼ 1,1-bis(diphenylphosphino) methane (dppm); 1,2-bis(diphenylphosphino)ethane (dppe); 1,3-bis(diphenylphosphino)propane (dppp), 1,4-bis(diphenylphosphino)butane (dppb); N–N ¼ 2,20-bipyridine; 4,40-dimethyl-2,20-bipyridine} was investigated in the presence of AuNPsn . The interaction between [Ru]+ and AuNPsn citrate capped is an electrostatic interaction, by a self-assembly processes, to produce a supramolecular species, labeled as [Ru]+/AuNPsn . This non-covalent interaction has no effect over the chemical and physical chemical parameters of the complexes, which provides a good point of comparison in the presence and absence of AuNPsn . The AuNPsn alone have no catalytic activity in the transfer hydrogenation of acetophenone within 24 h of reaction. However, the AuNPsn have improved the catalytic activity of the complexes that have biphosphines with tensioned or large bite angle, while for the complexes that have biphosphines with a strong chelate effect a decrease in the catalytic activity was observed. The evidence is supported by experimental values of the yields of the hydrogenated product and DFT calculations of the “RuP–P” intermediates. Suitable crystals of cis-[RuCl2(dppe)(bipy)], cis-[RuCl2(dppp)(bipy)] and cis- [RuCl(CH3OH)(dppb)(bipy)](PF6) were obtained and the X-ray structures are presented here.Item Molecular structure of Ru(II)/diphosphine/4,6-dimethyl-2-pyrimidinethiol complexes : a combined experimental and density functional theory study.(2023) Lima, Benedicto Augusto Vieira; Varela Júnior, Jaldyr de Jesus Gomes; Ellena, Javier Alcides; Batista, Alzir Azevedo; Silva, Albérico Borges Ferreira da; Correa, Rodrigo de SouzaReactions of cis-[RuCl2(P-P)(bipy)] precursors with the SpymMe2 ligand (4,6-dimethyl-2- pyrimidinethiol) yielded complexes of the [Ru(SpymMe2)(P-P)(bipy)]PF6 type, where P-P = 1,2- bis(diphenylphosphino)ethane (dppe - for complex 1), 1,3-bis(diphenylphosphino)propane (dppp - for complex 2) and 1,1’-bis(diphenylphosphino)ferrocene (dppf - for complex 3) and bipy = 2,2’-bipyridine. The new compounds were obtained by displacing the chlorido ligands from the precursors and coordination of one monoanionic 4,6-dimethyl-2-pyrimidinethiol ligand. All complexes were characterized by spectroscopic, electrochemical and elemental analysis techniques, as well as single-crystal X-ray diffraction, where the structures of complexes 1, 2 and 3 showed that the SpymMe2 ligand coordinates to the ruthenium(II) center as bidentated, yielding complexes with the sulfur atom trans positioned to the nitrogen atom from the bipy ligand. A theoretical study of the structures of the complexes was performed using the DFT/B3LYP method. Distances and angles of optimized structures agree with X-ray experimental data. Furthermore, the calculated IR and UV-Vis spectra are compatible with experimental data. Charge decomposition analysis (CDA) and NBO (natural bond orbitals) charges showed that there was an overall charge transfer from bipy and P-P ligands to the ruthenium centers. Higher electrochemical stability and 1H and 31P{1H} NMR shifts of 1, 2 and 3 compared with precursors could be explained by the lower values of calculated molecular orbital energies, NBO charge on atoms and CDA data. Finally, the structure of the isomers of complexes 1, 2 and 3, considering the sulfur atom trans positioned to the phosphorus atom, were optimized, showing that they are slightly less stable, presenting total energy higher, 10.4, 31.5 and 60.5 kJ/mol than 1, 2 and 3, where nitrogen is trans to the phosphorus atom.Item New heteroleptic RuII/diphosphine complexes with cytotoxicity against human breast and murine ascitic sarcoma 180 tumor cells.(2020) Lima, Benedicto Augusto Vieira; Correa, Rodrigo de Souza; Graminha, Angelica Ellen; Varela Júnior, Jaldyr de Jesus Gomes; Silva, Albérico Borges Ferreira da; Ellena, Javier Alcides; Silva, Thales E. M.; Batista, Alzir AzevedoThe preparation, characterization, theoretical calculations and biological application of four RuII complexes with 2-picolinate (pic), 2,2’-bipyridine (bipy) and P-P as ligands [P-P = 1,1-bis(diphenylphosphino)methane (dppm-1), 1,2-bis(diphenylphosphino)ethane (dppe-2), 1,3-bis(diphenylphosphino)propane (dppp-3) or 1,1’-bis(diphenylphosphino)ferrocene (dppf-4)], is here presented. The complexes 1-4, with general formula [Ru(pic)(P-P)(bipy)]PF6, were characterized by elemental analysis and by infrared (IR), UV-Vis, nuclear magnetic resonance (NMR 1 H and 13P{1 H}) spectroscopies, cyclic voltammetry and X-ray crystallography technique. Additionally, preliminary in vitro tests against human breast (MDA-MB-231) and murine ascitic sarcoma 180 (S180) tumor cell lines were carried out, and compared with cisplatin, a reference drug. The drug concentration at which 50% of the cells are viable relative to the control (IC50) values found for complexes 1, 2, 3 and 4 against MDA-MB-231 tumor cells were around 14.6, 7.6, 3.3 and 0.4 μM, respectively, while against S180 tumor cells these complexes showed IC50 values of 71.9, 31.3, 11.2 and 3.5 μM, respectively. Therefore, the complexes were more active against MDA-MB-231 than S180.