Cristais líquidos iônicos diméricos com propriedades luminescentes e gelificantes
In this master’s work, 5 new dimeric ionic molecules containing the 2,5-disubstituted 1,3,4-oxadiazole heterocycle were synthesized, purified and characterized by structural, thermal and photophysical analyses. Structural analyzes were investigated by 1H NMR spectroscopy. Thermal and liquid-crystall...
| Autor principal: | Kutz, Monike da Silva |
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| Formato: | Dissertação |
| Idioma: | Português |
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Universidade Tecnológica Federal do Paraná
2022
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riut-1-278142022-04-05T06:08:19Z Cristais líquidos iônicos diméricos com propriedades luminescentes e gelificantes Dimeric ionic liquid crystals with luminescence and gelling properties Kutz, Monike da Silva Westphal, Eduard https://orcid.org/0000-0002-5711-5365 http://lattes.cnpq.br/2302116915931540 Molin, Fernando https://orcid.org/ 0000-0002-8219-7657 http://lattes.cnpq.br/8095241401362784 Merlo, Aloir Antonio https://orcid.org/0000-0002-8071-5297 http://lattes.cnpq.br/7385210507816401 Pilissao, Cristiane https://orcid.org/ 0000-0002-5410-3481 http://lattes.cnpq.br/3467686744800483 Westphal, Eduard https://orcid.org/0000-0002-5711-5365 http://lattes.cnpq.br/2302116915931540 Molin, Fernando https://orcid.org/ 0000-0002-8219-7657 http://lattes.cnpq.br/8095241401362784 Cristais líquidos Luminescência Energia - transferência Fluorescência Liquid crystals Luminescence Energy transfer Fluorescence CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ORGANICA Química In this master’s work, 5 new dimeric ionic molecules containing the 2,5-disubstituted 1,3,4-oxadiazole heterocycle were synthesized, purified and characterized by structural, thermal and photophysical analyses. Structural analyzes were investigated by 1H NMR spectroscopy. Thermal and liquid-crystalline analyzes were performed later using POM, DSC and TGA techniques. In parallel, all compounds had their photophysical properties analyzed in solution using the UV-vis absorption and fluorescence emission technique. All 5 target molecules of the project showed liquid-crystalline properties, with the formation and stabilization of smectic A mesophase in the heating and cooling of the samples. The phase transition temperatures of the compounds were high, thus causing thermal decomposition of the materials during POM and DSC analyses. A procedure adopted to overcome this problem was the increase of the spacer between the mesogenic units of the dimers and the change of counterion of the final molecules, from bromide (Br-) to the tetrafluoroborate anion (BF4-), being the mesomorphic properties of the molecules with bromide anion not investigated in this work. Changing the counter-ion to a more voluminous one did not generate satisfactory results, but the increase in the spacer caused a gradual decrease in the isotropization temperatures of the materials, facilitating the performance of thermal analyzes and guaranteeing their reproducibility. On the other hand, photophysical analyzes were carried out on molecules containing the bromide counter-ion and then with the tetrafluoroborate counter-ion, in order to investigate the influence that the counter-ion would have on absorption and fluorescence emission regions of the materials. In addition, optical studies of intermediate molecules were carried out in order to better understand the complex spectroscopic properties of the final compounds. Thus, it was verified that the final molecules present a double photophysical behavior, which combines the optical properties of the two mesogenic units that give rise to them. Furthermore, all molecules exhibit the phenomenon of Förster resonant energy transfer (FRET), with the materials absorbing in the regions of 282 and 379 nm, and emitting at 357 and 548 nm, thus causing an overlap between one of the absorption bands with an emission band. In addition to the formation of liquid-crystalline mesophases for all materials, it was also observed the formation of gels within a few minutes when the materials were dissolved in DMSO and in chloroform, for molecules with bromide and tetrafluoroborate counter-ion. Conselho Nacional do Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Neste trabalho de mestrado, 5 moléculas inéditas iônicas diméricas contendo o heterociclo 1,3,4-oxadiazol 2,5-dissubstituído foram sintetizadas, purificadas e caracterizadas por meio de análises estruturais, térmicas e fotofísicas. As análises estruturais foram investigadas através de espectroscopia no IV e 1H RMN. Já as análises térmicas e líquido cristalinas foram realizadas posteriormente através das técnicas de MOLP, DSC e TGA. Em paralelo, todos os compostos tiveram suas propriedades fotofísicas analisadas em solução através da técnica de absorção no UV-vis e emissão por fluorescência. Todas as 5 moléculas alvo do projeto apresentaram propriedades líquido-cristalinas, com a formação e estabilização de mesofase do tipo esmética A no aquecimento e no resfriamento das amostras. As temperaturas de transição de fase dos compostos mostraram-se altas, ocasionando assim decomposição térmica dos materiais durante as análises de MOLP e DSC. Um procedimento adotado para contornar este problema foi o aumento do espaçador entre as unidades mesogênicas dos dímeros e a mudança de contra-íon das moléculas finais, de brometo (Br-) para o ânion tetrafluoroborato (BF4-), sendo as propriedades mesomórficas das moléculas com ânion brometo não investigadas neste trabalho. A alteração do contra-íon para outro mais volumoso não gerou resultados satisfatórios, porém o aumento no espaçador ocasionou a diminuição gradativa das temperaturas de isotropização dos materiais, facilitando a realização das análises térmicas e garantindo sua reprodutibilidade. Já as análises fotofísicas foram realizadas das moléculas contendo o contra-íon brometo e, em seguida, com o contra-íon tetrafluoroborato, a fim de investigar a influência que o contra-íon teria nas regiões de absorção e emissão por fluorescência dos materiais. Além disto, foram realizados estudos ópticos de moléculas intermediárias, a fim de melhor compreender as propriedades espectroscópicas complexas dos compostos finais. Com isso, verificou-se que as moléculas finais apresentam um comportamento fotofísico duplo, que combina as propriedades ópticas das duas unidades mesogênicas que as dão origem, além de apresentarem o fenômeno de transferência de energia ressonante de Förster (FRET), com os materiais absorvendo nas regiões de 282 e 379 nm, e emitindo em 357 e em 548 nm, ocasionando assim uma sobreposição entre uma das bandas de absorção com uma banda de emissão. Somada à formação das mesofases líquido-cristalinas para todos os materiais, observou-se também a formação de géis dentro de poucos minutos quando os materiais eram dissolvidos em DMSO e em clorofórmio, para as moléculas com contra-íon brometo e tetrafluoroborato. 2022-04-04T17:49:26Z 2022-04-04T17:49:26Z 2022-03-11 masterThesis KUTZ, Monike da Silva. Cristais líquidos iônicos diméricos com propriedades luminescentes e gelificantes. 2022. Dissertação (Mestrado em Químíca) - Universidade Tecnológica Federal do Paraná, Curitiba, 2022. http://repositorio.utfpr.edu.br/jspui/handle/1/27814 por openAccess http://creativecommons.org/licenses/by/4.0/ application/pdf Universidade Tecnológica Federal do Paraná Curitiba Brasil Programa de Pós-Graduação em Químíca UTFPR |
| institution |
Universidade Tecnológica Federal do Paraná |
| collection |
RIUT |
| language |
Português |
| topic |
Cristais líquidos Luminescência Energia - transferência Fluorescência Liquid crystals Luminescence Energy transfer Fluorescence CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ORGANICA Química |
| spellingShingle |
Cristais líquidos Luminescência Energia - transferência Fluorescência Liquid crystals Luminescence Energy transfer Fluorescence CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ORGANICA Química Kutz, Monike da Silva Cristais líquidos iônicos diméricos com propriedades luminescentes e gelificantes |
| description |
In this master’s work, 5 new dimeric ionic molecules containing the 2,5-disubstituted 1,3,4-oxadiazole heterocycle were synthesized, purified and characterized by structural, thermal and photophysical analyses. Structural analyzes were investigated by 1H NMR spectroscopy. Thermal and liquid-crystalline analyzes were performed later using POM, DSC and TGA techniques. In parallel, all compounds had their photophysical properties analyzed in solution using the UV-vis absorption and fluorescence emission technique. All 5 target molecules of the project showed liquid-crystalline properties, with the formation and stabilization of smectic A mesophase in the heating and cooling of the samples. The phase transition temperatures of the compounds were high, thus causing thermal decomposition of the materials during POM and DSC analyses. A procedure adopted to overcome this problem was the increase of the spacer between the mesogenic units of the dimers and the change of counterion of the final molecules, from bromide (Br-) to the tetrafluoroborate anion (BF4-), being the mesomorphic properties of the molecules with bromide anion not investigated in this work. Changing the counter-ion to a more voluminous one did not generate satisfactory results, but the increase in the spacer caused a gradual decrease in the isotropization temperatures of the materials, facilitating the performance of thermal analyzes and guaranteeing their reproducibility. On the other hand, photophysical analyzes were carried out on molecules containing the bromide counter-ion and then with the tetrafluoroborate counter-ion, in order to investigate the influence that the counter-ion would have on absorption and fluorescence emission regions of the materials. In addition, optical studies of intermediate molecules were carried out in order to better understand the complex spectroscopic properties of the final compounds. Thus, it was verified that the final molecules present a double photophysical behavior, which combines the optical properties of the two mesogenic units that give rise to them. Furthermore, all molecules exhibit the phenomenon of Förster resonant energy transfer (FRET), with the materials absorbing in the regions of 282 and 379 nm, and emitting at 357 and 548 nm, thus causing an overlap between one of the absorption bands with an emission band. In addition to the formation of liquid-crystalline mesophases for all materials, it was also observed the formation of gels within a few minutes when the materials were dissolved in DMSO and in chloroform, for molecules with bromide and tetrafluoroborate counter-ion. |
| format |
Dissertação |
| author |
Kutz, Monike da Silva |
| author_sort |
Kutz, Monike da Silva |
| title |
Cristais líquidos iônicos diméricos com propriedades luminescentes e gelificantes |
| title_short |
Cristais líquidos iônicos diméricos com propriedades luminescentes e gelificantes |
| title_full |
Cristais líquidos iônicos diméricos com propriedades luminescentes e gelificantes |
| title_fullStr |
Cristais líquidos iônicos diméricos com propriedades luminescentes e gelificantes |
| title_full_unstemmed |
Cristais líquidos iônicos diméricos com propriedades luminescentes e gelificantes |
| title_sort |
cristais líquidos iônicos diméricos com propriedades luminescentes e gelificantes |
| publisher |
Universidade Tecnológica Federal do Paraná |
| publishDate |
2022 |
| citation |
KUTZ, Monike da Silva. Cristais líquidos iônicos diméricos com propriedades luminescentes e gelificantes. 2022. Dissertação (Mestrado em Químíca) - Universidade Tecnológica Federal do Paraná, Curitiba, 2022. |
| url |
http://repositorio.utfpr.edu.br/jspui/handle/1/27814 |
| _version_ |
1805305529573048320 |
| score |
10,814766 |