| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 4.05 MB | Adobe PDF |
Authors
Advisor(s)
Abstract(s)
A presente dissertação teve como objetivo o desenvolvimento e caracterização de novos sistemas fluorescentes baseados em calix[4]areno seletivamente funcionalizados, possuindo cavidades intramoleculares ampliadas através da introdução de unidades fluorogénicas de carbazole no seu bordo superior, com potencial aplicação como sensores de moléculas de grandes dimensões (e.g. fulerenos).
A síntese dos novos bis-calixarenos foi realizada por acoplamento cruzado de Sonogashira-Hagihara entre derivados de calix[4]areno mono-iodados no bordo superior e monómeros de etinil-carbazole possuindo diferentes padrões de substituição, resultando em macromoléculas com estruturas e propriedades distintas.
Os compostos sintetizados foram caracterizados por espetroscopia de infravermelho com transformada de Fourier (FTIR), ressonância magnética nuclear de protão e carbono (RMN 1H e 13C), e, sempre que se justificou, RMN bidimensional.
As propriedades fotofísicas foram estudadas por espetroscopia de absorção de estado fundamental (UV-Vis) e de fluorescência de estado estacionário, com os sistemas sintetizados a exibirem rendimentos quânticos de fluorescência moderados e elevada estabilidade sob condições de irradiação contínua.
A magnitude da capacidade de formação de complexos supramoleculares entre os bis-calixarenos-carbazole e fulerenos (C60 e C70) foi avaliada através da determinação das constantes de associação por titulações fluorimétricas, revelando-se a configuração do tipo “cápsula” dos novos fluoróforos fundamental no processo de deteção.
A estequiometria dos complexos formados foi determinada recorrendo ao método de variações contínuas (método de Job), revelando estequiometrias de complexação similares para os diferentes pares analisados.
The objective of the current dissertation was the development and characterization of new fluorescent systems based in selectively functionalized calix[4]arenes, possessing amplified intramolecular cavities through the introduction of fluorogenic carbazole units on its upper rim, with potential application as sensors for large molecules (e.g. fullerenes). The synthesis of the new bis-calixarenes was achieved by Sonogashira-Hagihara cross-coupling of mono-iodized calix[4]arene derivates with ethynyl-carbazole monomers possessing different substitution patterns, resulting in macromolecules with different structures and properties. The synthesized compounds were characterized by Fourier transform infrared spectroscopy (FTIR), Proton and Carbon Nuclear Magnetic Resonance (NMR 1H and 13C) and, when appropriate, bidimensional NMR. The photophysical properties were studied by ground state absorption spectroscopy (UV-Vis) and steady-state fluorescence, with the developed systems exhibiting moderate fluorescence quantum yields and high stability under continuous irradiation conditions. The ability to form supramolecular complexes between bis-calixarenes-carbazole and fullerenes (C60 and C70) was assessed by association constants determination through fluorimetric titrations, with the “capsule”-like configuration of the new fluorophores being essential in the detection process. The stoichiometry of the formed complexes was determined using the method of continuous variations (Job’s Method), revealing similar complexations stoichiometries for the different pairs analyzed.
The objective of the current dissertation was the development and characterization of new fluorescent systems based in selectively functionalized calix[4]arenes, possessing amplified intramolecular cavities through the introduction of fluorogenic carbazole units on its upper rim, with potential application as sensors for large molecules (e.g. fullerenes). The synthesis of the new bis-calixarenes was achieved by Sonogashira-Hagihara cross-coupling of mono-iodized calix[4]arene derivates with ethynyl-carbazole monomers possessing different substitution patterns, resulting in macromolecules with different structures and properties. The synthesized compounds were characterized by Fourier transform infrared spectroscopy (FTIR), Proton and Carbon Nuclear Magnetic Resonance (NMR 1H and 13C) and, when appropriate, bidimensional NMR. The photophysical properties were studied by ground state absorption spectroscopy (UV-Vis) and steady-state fluorescence, with the developed systems exhibiting moderate fluorescence quantum yields and high stability under continuous irradiation conditions. The ability to form supramolecular complexes between bis-calixarenes-carbazole and fullerenes (C60 and C70) was assessed by association constants determination through fluorimetric titrations, with the “capsule”-like configuration of the new fluorophores being essential in the detection process. The stoichiometry of the formed complexes was determined using the method of continuous variations (Job’s Method), revealing similar complexations stoichiometries for the different pairs analyzed.
Description
Trabalho Final de Mestrado para obtenção do
Grau de Mestre em Engenharia Química e Biológica
Keywords
Bis-calixarenos Carbazole Cápsula Fulereno Sensores fluorescentes Bis-calixarenes Capsule Fullerene Fluorescent sensors
Citation
COSTA, Sérgio Fidalgo dos Santos – Síntese e avaliação sensorial de novos receptores fluorescentes baseados em calixarenos. Lisboa: Instituto Superior de Engenharia de Lisboa, 2021. Dissertação de Mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa