Banca de DEFESA: GUTTO RAFFYSON SILVA DE FREITAS
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.DISCENTE : GUTTO RAFFYSON SILVA DE FREITAS
DATA : 18/08/2017
HORA: 08:00
LOCAL: Auditório do Química 3
TÍTULO:
COMPUTATIONAL CHEMISTRY APPLIED TO THE STUDY OF STRUCTURE AND REACTIVITY OF BIOLOGICALLY RELEVANT QUINOXALINE DERIVATIVES
PALAVRAS-CHAVES:
Quinoxalines; DFT structural parameters; pKa; Aromatic nucleophilic substitution; chemosensor; DFT.
PÁGINAS: 98
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Físico-Química
ESPECIALIDADE: Química Teórica
RESUMO:
The quinoxalines make part of a class of nitrogen heterocycles compounds with a broad spectrum of applications in various areas. On this context, biological activities for different uses stand out. Nowadays, the computational chemistry methods have shown themselves as a relevant tool for the structural, electronic and thermodynamic properties of many heterocycles compounds investigations, including quinoxalines of biological interest. At this paper, these properties were look into in three different approaches, based on the Density Functional Theory (DFT). Firstly, an investigation were made on the structural, electronic and energetic properties of the compound 6,7-dinitro-1,4-dihidro-quinoxaline-2,3-dione (DNQX), an important antagonist of the glutamate neuroreceptor iGluR2, which has an important role in the processes related to learning and memory. More specifically, possible DNQX tautomers were made, proving that the diketone form possess less energy. Moreover, a study to determine the pKa values associated to the mono- and dianionics formations was made, in its gas and water forms, using different methodologies. In the next chapter, the Nucleophilic aromatic substitution reactions involving 6,7-dicloroquinoxalin-2,3-dione (DCQX) and the aminoalcohols ethanolamine e diethanolamine in DMF were studied. The energy variations associated to the formation of possible mono- and di-substitution products were calculated, as well as the transition state for its formation. The results were discussed considering the structural aspects, based on previous papers, from which it was possible to suggest that these reactions happen via concerted mechanism for a chlorine double substitution for ethanolamine, both by a nitrogen nucleophilic attack, and for diethanolamine, by a nitrogen and a an oxygen nucleophilic attack. Also, the ∆G value reaction and activation analyses suggest that the cyclized product formation is more favorable for both cases. Finally the structural and thermodynamic properties of various copper complexes (II) with a selective chemosensor N-(2-aminofenil)-3-[(1S,2S)-1,2,3-trihidroxi-propil] quinoxaline-2-carboxamide (AAQX) were evaluated, in order to understand the interaction of this quinoxaline as a 2:1 metal bonding complex. Due to the complex size, the calculations were made using a combination of DFT and semi-empirical methods to reduce the computational cost. The results suggest that complexes with a tetrahedron geometry are the most favorable and the chloride bond by water are not the most stable complexes. With the development of this work, satisfactory results associated to the use of DFT to the study of the different properties of these quinoxalines products were obtained
MEMBROS DA BANCA:
Interno - 1959889 - DAVI SERRADELLA VIEIRA
Presidente - 1803692 - FABRICIO GAVA MENEZES
Externo à Instituição - GERD BRUNO DA ROCHA - UFPB
Interno - 2140775 - LIVIA NUNES CAVALCANTI
Externo à Instituição - RODRIGO CRISTIANO - UFPB