Banca de DEFESA: VERÔNICA DA SILVA OLIVEIRA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : VERÔNICA DA SILVA OLIVEIRA
DATA : 28/02/2018
HORA: 14:00
LOCAL: Sala 3G4
TÍTULO:

Study of the ferro-cyclam system and characterization of the [Fe(cyclam)ox]PF₆ complex: crossover spin, photochemistry and antibacterial activity

PALAVRAS-CHAVES:

Complexes, Cyclam, Photochemistry, Antibacterial Activity

PÁGINAS: 124
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Inorgânica
ESPECIALIDADE: Campos de Coordenação
RESUMO:

The aim of this work is to synthesize complexes of the iron-cyclam system with the phthalate (ph), salicylate (sa) and oxalate (ox) ligands, to obtain the complexes [Fe(cyclam)ph]Cl (1), [Fe(cyclam)sa]PF₆ (2) and [Fe(cyclam)ox]PF₆ (3), respectively. The characterization of the complexes was performed using spectroscopic techniques (IV, Uv-vis) and electrochemical (CV and DPV). The IR spectra showed vibrational modes in the range of 3443-2878 cm^-1, for the N-H group and C-H stretches of the cyclam macrocyclic ligand, as well as vibrational modes in the region of 1706-1550 cm^-1 and 1375-1343 cm^-1, corresponding to the n_as(O-C-O) and n_s(O-C-O), attributed to bidentate coordinated oxygenated binders. The electronic spectra of the complexes in aqueous medium presented intraligant transitions in more energetic regions, while the LMCT transitions were observed at higher wavelengths, observed at 325 nm (1), 527 nm (2) and 292 and 355 nm (3). And the cyclic voltammetry of the complexes exhibited a nearly reversible Fe^3+/2+ redox pair, with E_1/2 = 25.5 mV (1), 209 mV (2) and -41.9 mV (3). In addition, the complex (3) was characterized by Mössbauer spectroscopy, and also had its investigated photochemical and antibacterial activity. The mössbauer spectrum in 300K showed a doublet (D1) with d= 0.30 mm/s and ΔE_Q = 0.40mm/s, typical of Fe³⁺ with high spin configuration. However, with the lowering of the temperature, it was observed the gradual reduction of the intensity of D1 and the appearance of a second doublet (D2), with d= 0.19 mm/s and ΔE_Q = 1.73 mm/s to 12 K, typical Fe³⁺ low spin. Characterizing the existence of a temperature dependent spin state transition process. The photochemical reactivity evaluated by IR with exposure to white light evidenced the degradation of the oxalate ligand coordinated to the metal, being relevant in the synthesis of new complexes of the Fe-cyclam system and in the antibacterial activation. Through the photochemical reaction of the compound the binuclear [((cyclam)Fe)₂(μ-SO₄)](PF₆)2.H₂O was obtained, whose structure was identified by X-ray diffraction of monocrystal. The antibacterial activity of the complex (3) was evaluated against Pseudomonas aeruginosa (ATCC 9027), Staphylococcus aureus (ATCC 29213) and Escherichia coli (ATCC 25922). The best results were obtained for Pseudomonas, with minimum inhibitory concentration (MIC) of 293.5 μM. However, exposure of the compound to white or blue light for 90 min, potentiated the inhibitory activity of the complex by around 59% against Pseudomonas, reducing MIC values to 118.6 μM (white light) and 119.5 μM (blue light). When submitted to 240 min of exposure, the activity was potentiated in 79.5% (white light) and 77.4% (blue light). Therefore, the photochemical activity of the complex (3) represents a promising alternative in bacterial combat.

MEMBROS DA BANCA:
Externo à Instituição - ANA CAROLINA MORAIS APOLONIO - UFJF
Externo ao Programa - 1715109 - DANIEL DE LIMA PONTES
Externo à Instituição - EDUARDO HENRIQUE SILVA DE SOUSA - UFC
Interno - 1945343 - FRANCISCO ORDELEI NASCIMENTO DA SILVA
Externo ao Programa - 1674707 - MARCO ANTONIO MORALES TORRES