Banca de DEFESA: MAGNO KLEBSON AUGUSTINHO SENA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : MAGNO KLEBSON AUGUSTINHO SENA
DATE: 29/07/2022
TIME: 08:30
LOCAL: videoconferência
TITLE:

Synthesis, spectroscopic and electrochemical characterization of new cobalt (III) complexes with nitrogenous ligands.

KEY WORDS:

Cobalt (III). coumarins. Tumor hypoxia. Pro-drugs.

PAGES: 134
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SPECIALTY: Química Bio-Inorgânica
SUMMARY:

Tumor hypoxia regions are currently one of the main therapeutic targets for anticancer therapy, because these regions are related to the increase of mortality and metastasis, therefore, today in bioinorganic research seeks to develop metal complexes that can act as hypoxia-activated pro-drugs (HAPs). Cobalt (III) complexes are widely studied as HAPs because they are inert, and then when reduced to Co (II) present a lability (reactivity) and release a drug into the tumor environment. In this context, the present work aims to synthesize new cobalt complexes with the auxiliary ligand o- phenanthroline (phen), and the ligands imidazole (imd), 4-aminopriridin (4apy) and 7-hydroxy-4-imidazolylmethylcoumarin (S1) as pro-drugs. Thus, cis-[Co(phen)2L2]n+ complexes were synthesized, l being the ligands Cl-, imd, 4apy and S1, and n equal to 1+ or 3+. The S1 ligand was synthesized from a methodology reported in the literature and characterized by spectroscopic techniques (UV-vis, fluorescence, IR, NMR), while the synthesized complexes were characterized by spectroscopic and electrochemical techniques.   From the vibrational and NMR spectra, it was possible to confirm the structure of the S1 ligand, it is through the data of absorption and fluorescence to identify pKa of approximately 7.5 for the ligand, besides the fluorescence having a strong dependence on pH and solvent. The IR spectra for the complexes confirmed the coordination of the ligands by presenting characteristic stretches from phen (C=N), imd (N-H), 4apy (N-H) and S1 (C=O). The electronic spectra in DMSO presented intraligands bands in the region from 200 to 400 nm and the d-d transitions in 534 and 612, 487, 462 and 530, 475 nm for the cis-[Co(phen)2L2]n+ complexes with L =chlorides, imd, S1 and 4apy, respectively. In addition, it was observed the order Cl-< S1 < imd < 4apy for the crystal field splitting. From the fluorescence of the complex containing the S1 ligand, it was possible to observe an emission band at about 472 nm. Additionally, the cyclic voltammograms of the cis-[Co(phen)2L2]n+ complexes presented  two redox pairs for the metal, CoIII/II and CoII/I, with potentials of E1/2  between 380 and 460 mV for CoIII/II and -860 to -750 mV for CoII/I, presenting redox process within the biological medium range for generation of reactive oxygen species.

COMMITTEE MEMBERS:
Presidente - 348475 - DJALMA RIBEIRO DA SILVA
Interno - 1086214 - ANDERSON DOS REIS ALBUQUERQUE
Externo ao Programa - 1715109 - DANIEL DE LIMA PONTES - UFRNExterna à Instituição - WENDY MARINA TOSCANO QUEIROZ DE MEDEIROS - IFRN