Banca de QUALIFICAÇÃO: GUTTO RAFFYSON SILVA DE FREITAS
Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.DISCENTE : GUTTO RAFFYSON SILVA DE FREITAS
DATA : 10/03/2017
HORA: 14:00
LOCAL: Auditório do química 3
TÍTULO:
COMPUTATIONAL CHEMISTRY APPLIED TO THE STUDY OF STRUCTURE AND REACTIVITY OF BIOLOGICALLY RELEVANT QUINOXALINE DERIVATIVES
PALAVRAS-CHAVES:
Computational Chemistry; DFT; Quinoxaline; Structural Aspects; Electronic Properties; Thermodynamic Parameters; Reactivity.
PÁGINAS: 120
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Físico-Química
ESPECIALIDADE: Química Teórica
RESUMO:
Organic molecules bearing heterocyclic unities are found presenting applications in many fields, and in this context, the study of quinoxaline derivatives plays a relevant role to the heterocyclcic chemistry. Nowadays, the computational chemistry have been demonstrated to be a relevant tool for the study of structural, electronic and thermodynamic properties of many heterocylcic compounds, including biologically relevant quinoxaline derivatives. In this work, they are presented three approaches for the study of some interesting quinoxaline derivatives by means of theoretical methods based on desnsity functional Theory (DFT). The fisrt part of the work presents the structural, electronic and energetic aspects of 6,7-dinitro-1,4-dihydriquinoxaline-2,3-dione (DNQX), which is a biologically relevant compound due its role as antagonist of the iGluR2 glutamatergic systems which is directly associated to memory and learning capacity. More specifically, several computational methods were applied to evaluate the possible tautomers of DNQX as well their mono- and di-anionic forms. They were found that the dicarbonyl tautomer is the more stable form of DNQX and pKa values for the first and second deprotonation in water vary from approximetly 6-8 and 10-12, respectively, depending on the applied method. The next chapter proposes the study of the nucleophilic heteroaromatic substitution involving the substrate 2,3-dichloroquinoxaline (DCQX) and the aminolacohols ethanolamine and diethanolamine, in DMF, in terms of thermodynamic and kinetic aspects for both mono- and di-chlorine-displacement by the nucleophilic species. Results showed that these reactions proceed via concerted mechanisms instead a stepwise processes involving reactive intermeadites. In both cases, cyclization processes are ernergically favorable, which is in agreement with experimental results only for reaction of DCQX with diethanolmine. In attemp to provied better understanding of these systems, the were evalued the reactions of 2-chloropyiridine and 2-fluorpyriodine with methoxyde anion and metanol. Lastly, a extensive study on the interactions of the chemosensor N-(2-aminophenil)-3-[(1S,2S)-1,2,3-trihydroxipropyl]quinoxalin2-2-carboxamide (AAQX) with Cu(II) was performed in attempt to understand the sensing mechanism of this quinoxaline derivative, incluindo 1:1 and 1:2 ligand-metal coordination complexes. Due the complexity of the systems, they were applied DTF and semi-empirical combined methods. Results suggest at least two main features: i) tetrahedral complexes are favorable in these systems; ii) substituion of chloride by water is unfavorable. In summary, the development of the presente work allowed to be obtained interesting results associated to structural, electronic, enegetic and reactivity aspects for some relevant quinoxaline derivatives by means of theoretical chemistry.
MEMBROS DA BANCA:
Interno - 1959889 - DAVI SERRADELLA VIEIRA
Presidente - 1803692 - FABRICIO GAVA MENEZES
Interno - 2140775 - LIVIA NUNES CAVALCANTI
Interno - 1859346 - MIGUEL ANGELO FONSECA DE SOUZA