Banca de DEFESA: Carlos Xavier de Oliveira

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Carlos Xavier de Oliveira
DATE: 24/04/2023
TIME: 14:00
LOCAL: IF
TITLE:

Study of the Electronic Structure of Neutral and Ionized Organic Molecules, in the search for fragmentation routes.

KEY WORDS:

Keywords: Cysteine Amino Acid, Electronic Structure, QTAIM, DFT.

PAGES: 105
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUMMARY:

The study presented in this doctoral thesis work is important for us to understand the elec-tronic properties of a group of organic molecules, such as the amino acid cysteine and aromatic molecules (benzene, aniline, and o-, m-, and p-nitroaniline), in their forms of neutral and singly charged ions, which has great interest in the field of atomic molecular physics, quantum chemistry, pharmacy, biochemistry, and industrial chemistry. Five conformations of the cysteine amino acid (Cys01, Cys02, Cys03, Cys04, and Cys05) were calculated, with five neutral molecules and from these structures, five cationic conformations were calculated. The calculation results showed that there are structural modifications in the cysteine amino acid conformations, which are evident in the lengths of chemical bonds, bond orders (BOs), and charge distribution, when comparing the differ-ent singly charged conformations with the neutral ones. Our results indicate that the alpha carbon is the most favorable fragmentation point for the CH2SH and COOH radicals, after a single ionization of the cysteine molecule. The possibility of finding fragmentation routes, by theoretical methods, led us to compare molecular ions between neutral benzene, aniline, and o-, m-, and p-nitroaniline molecules, using Density Functional Theory (DFT), under an aug-cc-pVDZ basis set and a B3LYP ex-change correlation functional. After determining the structure and electronic energy of the neutral and doubly charged species, we also used the same methods used for the cysteine amino acid cal-culations such as: Wiberg bond indices and Bader's quantum theory of atoms in molecules (QTAIM). Where it was possible to observe the charge transfer and electronic distribution in each monomer, making it possible to observe possible locations for fragment formation in at least two pairs of car-bon-carbon (CC) atoms of the aromatic ring, which indicates the possible loss of the -CNH2 and -NO2 groups in the doubly charged aniline and nitroaniline molecules.

BANKING MEMBERS:
Presidente - 407633 - DAVID LIMA AZEVEDO
Interno - 3272139 - ALEXANDRE CAVALHEIRO DIAS
Interno - 1273560 - RICARDO GARGANO
Externo à Instituição - GUNAR VINGRE DA SILVA MOTA - UFPA
Externo à Instituição - ANTÔNIO MAIA DE JESUS CHAVES NETO - UFPA