Orientadora: Profa. Dra. Káthia Maria Honório / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência & Tecnologia - Química, 2014. / Polimeros de impressao molecular (MIPs) sao materiais sinteticos que possuem sitios de reconhecimento molecular especificos para determinado analito de interesse (molecula molde), e tem sido empregados para a pre-concentracao e extracao em amostras complexas, considerando a maior seletividade em relacao aos sorventes convencionais empregados na extracao em fase solida. A escolha dos reagentes utilizados na sintese de um MIP deve ser criteriosa, a fim de que sejam criados sitios de ligacoes especificos. Metodos computacionais de Quimica Teorica podem ser empregados para racionalizar o planejamento de MIPs, por intermedio do estudo de parametros fisico-quimicos das moleculas envolvidas e as interacoes que ocorrem no sistema de pre-polimerizacao. Com a utilizacao de metodos de quimica quantica, foi objetivo desse trabalho o estudo previo das interacoes entre as moleculas moldes e os possiveis reagentes empregados na sintese de MIPs, como forma de predicao das melhores interacoes que promovam um MIP de desempenho ideal. O estudo teorico foi direcionado para a molecula de ¿¢9-tetrahidrocanabinol (¿¢9-THC), substancia presente na planta Cannabis sativa e que e a substancia ilicita mais produzida e consumida mundialmente, e seu principal metabolito de excrecao urinario, o 11-nor-9-carboxi-¿¢9-THC (THC-COOH). A simulacao computacional foi realizada utilizando a Teoria do Funcional da Densidade (DFT), e a metodologia envolveu a comparacao das energias de interacao (¿¢E) dos adutos de pre-polimerizacao entre a molecula molde e os reagentes de sintese. Com os resultados das simulacoes, verificou-se que as melhores interacoes ocorrem quando o monomero utilizado tem caracteristica acida, como o acido acrilico e o acido metacrilico; e que o solvente mais adequado para a sintese sao os que apresentam baixa constante dieletrica, como o cloroformio e o tolueno, por interferirem menos na formacao do complexo de interacao entre a molecula molde e o monomero na etapa de pre-polimerizacao. Detalhes das interacoes existentes entre as moleculas do meio reacional tambem foram analisadas e forneceram informacoes sobre a possivel competicao entre as moleculas no acesso aos sitios de interacao das moleculas moldes, informacao crucial para obtencao de MIPs seletivos e de grande afinidade a molecula molde desejada. A partir das predicoes do estudo computacional, os MIPs de THC-COOH foram sintetizados com os monomeros indicados, juntamente com o polimero nao impresso (NIP), em alguns dos solventes simulados (agua, acetonitrila, metanol e agua), para avaliacao da interferencia do solvente na eficiencia do MIP obtido. Foi realizada a analise dos MIPs por espectroscopia vibracional na regiao do infravermelho, e avaliada as bandas de absorcao nas regioes dos grupos C=O e O-H, para analise da formacao de interacoes por ligacao de hidrogenio. Concluiu-se, portanto, que sem substituir os ensaios experimentais, a abordagem computacional pode ser utilizada como uma ferramenta preliminar e complementar a selecao experimental. / Molecularly imprinted polymers (MIPs) are synthetic materials with specific sites of molecular recognition for a given analyte of interest (template molecule), and have been used for the extraction and pre-concentration in complex samples, considering the higher selectivity presented in relation to the sorbent employed in conventional solid phase extraction. The choice of the reagents used in the synthesis of a MIP must be chosen carefully, so that site-specific linkages are created. Computational methods in Theoretical Chemistry can be used to rationalize the planning of MIPs through the study of physico-chemical parameters of the molecules involved and the interactions that occur in the pre-polymerization system. Using quantum chemical methods, the aim of this study was a preliminary investigation of the interactions between the template molecules and the possible reagents used in the synthesis of MIPs, as a way to predict the best interactions that promote MIPs with optimal performance. The theoretical study was directed to the molecule of Ä9-tetrahydrocannabinol (Ä9-THC), present in the plant Cannabis sativa, and that is the illicit substance most widely produced and consumed globally, as well as its major metabolite urinary excretion, 11 -nor-9-carboxy-Ä9-THC (THC-COOH). The computational simulation was performed using the Density Functional Theory (DFT), and the methodology involved the comparison of the interaction energies (ÄE) of adducts in pre-polymerization between the template molecule and reagents for synthesis. From the results of the simulations, it was found that the best interactions occur when the monomer has acid characteristic, such as acrylic acid and methacrylic acid; and that the most suitable solvent for synthesis are those with low dielectric constant such as toluene and chloroform, by interfering less in the formation of complex interaction between the template molecule and monomer in the pre-polymerization step. Details of the existing interactions between the molecules of the reactional medium were analyzed and provided information about the possible competition between the molecules in the access to the interaction sites of the template molecules, which is a crucial information for obtaining selective MIPs and with high affinity to the template molecule desired. From the computational predictions obtainde in this study, the MIPs of THC-COOH was synthesized with the indicated monomers, and also a non-imprinted polymer (NIP), considering some of simulated solvents (water, acetonitrile, methanol and water) for evaluation of the interference of solvent in the efficiency of the MIP obtained. Analyses on the formed MIPs were performed by spectroscopy in the infrared region, and the absorption bands in the regions of the groups C=O and OH were evaluated with the aim of analysing the formation of hydrogen bond interactions. Therefore, it is possible to conclude that, without replacing the experimental trials, the computational approach can be used as a preliminary and complementary tool to experimental selection.
| Identifer | oai:union.ndltd.org:IBICT/oai:BDTD:76580 |
| Date | January 2014 |
| Creators | Fernandes, Luciana Sarmento |
| Contributors | Honório, Káthia Maria, Coutinho Neto, Maurício Domingues, Silva, Alberico Borges Ferreira da, Mello, Paula Homem de, Trossini, Gustavo Henrique Goulart |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf, 120 f. : il. |
| Source | reponame:Repositório Institucional da UFABC, instname:Universidade Federal do ABC, instacron:UFABC |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | http://biblioteca.ufabc.edu.br/index.php?codigo_sophia=76580&midiaext=69715, http://biblioteca.ufabc.edu.br/index.php?codigo_sophia=76580&midiaext=69716, Cover: http://biblioteca.ufabc.edu.brphp/capa.php?obra=76580 |
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