Pontes, Ana Cristina Facundo de BritoOliveira, Verônica da Silva2018-08-162018-08-162018-02-28OLIVEIRA, Verônica da Silva. Estudo do sistema Fe-cyclam com ligantes carboxilatos e avaliação do efeito spin crossover e atividade antibacteriana do complexo (Fe(cyclam)ox)PF6. 2018. 166f. Tese (Doutorado em Química) - Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Natal, 2018.https://repositorio.ufrn.br/jspui/handle/123456789/25735The aim of the present work is to obtain complexes of the Fe-cyclam system with carboxylate ligands, such as salicylate (sal), phthalate (ph), benzoate (ben) and oxalate (ox), synthesized from cis-[Fe(cyclam)Cl2]Cl (1) to form the complexes [Fe(cyclam)sal]PF6 (2), [Fe(cyclam)ph]PF6 (3), cis-[Fe(cyclam)(ben)2]PF6 (4) e [Fe(cyclam)ox]PF6 (5). The characterization was performed using elemental, spectroscopic (IR and UV-Vis) and electrochemical analysis (CV and DPV). The IR spectrum of the compounds showed vibrational modes in the range of 3446-2869 cm-1 , referring to the N-H and C-H of the cyclam macrocyclic, as well as as(OCO) at 1705-1570 cm-1 , and s(OCO) at 1359-1348 cm-1 , attributed to the carboxylates acting as bidentate ligands, except for benzoate. However, the UV-Vis spectra in the aqueous medium presented IL transitions in the more energetic regions, whereas the LMCT transitions were observed at lower energies, verified in 520 (2), 320 (3), 326 (4) and 292 and 355 nm for the complex (5). The voltammograms exhibited a reduction in E1/2 (Fe3+/2+) compared to complex (1), being dependent on the nature of the oxygenated ligands. In addition, the complex (5) was evaluated by Mössbauer spectroscopy and its photochemical and antibacterial activity were investigated. The Mössbauer spectrum in 300K showed a doublet (D1) with =0.42 mm/s and ∆EQ=0.40 mm/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 =0.30 mm/s and ΔEQ=1.72 mm/s to 12 K, typical Fe3+ low spin. This behavior characterized the existence of the crossover spin effect dependent on the temperature. The photochemical reactivity of the complex (5) was shown to be relevant in the synthesis of new compounds of the Fe-cyclam system and in the antibacterial activation. Through the photochemical reaction of the complex the binuclear [((cyclam)Fe)2(μ-SO4)](PF6)2.H2O was obtained, whose structure was identified by X-ray diffraction and its voltammogram showed two redox processes, with E1/2 =169 mV and -10.5 mV, with Kc =1.1x103 . Antibacterial activity was evaluated against Pseudomonas aeruginosa (Pa), Staphylococcus aureus and Escherichia coli. The best results were obtained for Pa, with MIC of 294 μmol L-1 . However, exposure of the compound to white or blue light for 90 min, potentiated the inhibitory activity around 59% against Pa, reducing MIC values to 118.6 μmol L -1 (white light) and 119.5 μmol L-1 (blue light). Therefore, the photochemical activity of the complex under study represents a promising alternative in the combat of bacterialAcesso AbertoFerro-cyclamÍons carboxilatosFotoquímicaAtividade antibacterianadoctoralThesisCNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA