Banca de QUALIFICAÇÃO: BEATRIZ AZEVEDO GALVÃO DE LIMA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : BEATRIZ AZEVEDO GALVÃO DE LIMA
DATE: 21/01/2022
TIME: 14:00
LOCAL: VIDEOCONFERÊNCIA
TITLE:

Development of phenanthroline complexes of manganese, cobalt and zinc (II) with kojic acid: synthesis, spectroscopic and electrochemical study.


KEY WORDS:

Bioinorganic. Cobalt complexes. Manganese complexes. Zinc complexes. Kojic acid.


PAGES: 85
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SPECIALTY: Química Bio-Inorgânica
SUMMARY:

Among the various applications of metallic complexes, one of the most outstanding is its biological potential, evidenced after the discovery of antitumor properties of cisplatin in 1844, a drug widely used in the treatment of different types of cancer. However, the discovery of the toxicity of this chemotherapeutic has opened doors for the development of new coordination compounds, aiming at similar or superior efficacy allied to a low metal-to-metal toxicity in the biological environment. In this context, manganese, cobalt and zinc complex stand out in the literature as promising in the treatment of cancer, both for their low toxicity, in particular associated with the fact that they are trace elements present in our body and crucial in the performance of vital functions, as well as for magnetic and electrochemical properties. Additionally, there is also a search for systems with bioactive ligands, for example kojic acid, a naturally occurring molecule with applications, active and biological properties that, together with the metal, can originate optimized structures favorable to the field of medicinal bioinorganic chemistry. Therefore, this work is presented, with the objective of contributing to the inorganic chemistry of Mn (II), Co (II) and Zn (II) systems, the synthesis and spectroscopic and electrochemical characterization of new complexes with phenanthroline ligand and Kojic acid of the type [M(phen)(koj)2], where M = Mn (II), Co (II) and Zn (II), phen corresponds to 1,10-phenanthroline and hkoj to 5-hydroxy-2- (hydroxymethyl)-4H-pyran-4-one (kojic acid). All complexes were synthesized supplying the ligand hkoj to the complex precursors [M(phen)Cl2], with M = Mn (II), Co (II) and Zn (II), in a 1:2 ratio of precursor to ligand, using water as solvent and basifying the medium with the addition of potassium hydroxide. The kojic acid ligand was adapted by the technique of vibrational spectroscopy in the infrared region (IR), electronic absorption spectroscopy in the UV and visible region (UV-vis) and cyclic voltammetry (CV). Analyzing the vibrational spectra obtained in KBr pellets, in the systems [M(phen)(koj)2], the presence of phenanthroline bands in the complexes close to the 1427, 844 and 727 cm-1 region, in addition to the ligand bands kojic acid, with stretch values at 1630, 1611, 1581, 877 and 548 cm-1. The electronic spectra of the complexes [M(phen)(koj)2] capture in aqueous medium dissipates intra-ligand bands, in the ultraviolet region, which is preferable to electronic transitions of phenanthroline with absorption at approximately 222, 268 and 291 nm. Kojic acid absorbs in the same region, however, the molar absorptivity of phenanthroline is higher and causes the overlapping of the electronic transitions of the other ligand, making it possible to visualize only one band at 320 nm characteristic of the kojic ion (koj-). The d-d bands were observed only for the Co and Mn (II) complexes. Cyclic voltammograms of Co and Mn (II) complexes were captured in 0.1 M KCl, pH = 7.0, appearing almost reversible processes for both metals. For cobalt there is the process Co1+/Co2+ and for manganese Mn2+/Mn3+ in the systems [M(phen)(koj)2], in addition to the irreversible oxidation process of the ligand hkoj.


BANKING MEMBERS:
Externo ao Programa - 1715109 - DANIEL DE LIMA PONTES
Externo ao Programa - 1945343 - FRANCISCO ORDELEI NASCIMENTO DA SILVA
Presidente - 2413537 - POLLYANA SOUZA CASTRO
Notícia cadastrada em: 10/01/2022 10:58
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