Banca de DEFESA: DAYANA PATRICIA DA SILVA PENHA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : DAYANA PATRICIA DA SILVA PENHA
DATA : 30/01/2018
HORA: 14:00
LOCAL: SALA DE AULA DO QUÍMICA I
TÍTULO:

SYNTHESIS, CHARACTERIZATION, REACTIVITY AND ANTIBACTERIAL EVALUATION OF RUTHENIUM NITROSYL COMPLEXES

PALAVRAS-CHAVES:

Nitrosyl complexes. Ruthenium. Pseudomonas aeruginosa.

PÁGINAS: 135
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Inorgânica
ESPECIALIDADE: Campos de Coordenação
RESUMO:

The biological significance of nitric oxide in cardiovascular control, in neurotransmission and in defense mechanisms against microbes and tumor cells has strong interest in the coordination chemistry to develop complex capable of releasing NO in the organism. In this context, ruthenium nitrosyl complexes present a biological potential in releasing the NO molecule in a selective and controlled manner, because they are thermodynamically stable and photochemically active compounds. Thus, the synthesis, characterization, reactivity and antibacterial test of complex of the type cis-[Ru(bpy)(phen)L(NO)](PF6)_n, where L are the imidazole and sulfite ligands, bpy = 2,2’- bipyridine and phen = 1,10'-phenanthroline. Complex nitrosyls were obtained by dissolving the nitro complexes in methanol and adding trifluoroacetic acid with stirring. Through electronic spectroscopy in aqueous media, it was possible to identify as intraligant bands of bipyridine and phenanthroline ligands as well as metal charge transfer bands for both the polypyridine ligands in the region of 330 nm and for the nitrosyl ligand around 476 nm. The vibrational spectra in KBr pellets showed NO⁺ stretching at high frequencies in the 1900 cm^-1 region indicating that nitric oxide is found coordinated to the metal center. When analyzing the cyclic voltammograms, in NaTFA 0,1 mol L^-1, of the nitrosyl complex, a single almost reversible process with respect to the NO^+/0 redox pair was observed. Regarding the reactivity was done the acid-base equilibrium, noting that pH 6.3 and 8.9 occurs the conversion of nitrosyl to nitrite to the complexes with imidazole and sulfite, respectively. In order to verify the release of nitric oxide by square-wave voltammetry, kinetics with biological reductant and photochemical study with white light, it was inferred that the release of NO occurs by a chemical reaction in which the ligand is reduced in the NO⁺ to NO⁰, this is released due to the weakening of the link Ru^II - NO⁰ and in its position coordinates itself to the molecule of water, forming the aqua complex. The antibacterial activity of the nitrosyl complexes was tested on the bacterium Pseudomonas aeruginosa ATCC 9027 using the broth microdilution method. Thus, observed through MIC, the complexes are able to inhibit bacterial growth in minimum concentrations of 57.23 mM for the complex with imidazole and 200.8 mM with sulfite.

MEMBROS DA BANCA:
Presidente - 1945343 - FRANCISCO ORDELEI NASCIMENTO DA SILVA
Interno - 2203888 - MARCIA RODRIGUES PEREIRA
Externo ao Programa - 1715109 - DANIEL DE LIMA PONTES
Externo à Instituição - LUIZ GONZAGA DE FRANÇA LOPES - UFC