Líquidos iônicos arilfuncionalizados como potenciais ligantes fluorescentes de G-quadruplex

• Ano de defesa: 2025
• Autor(a) principal: Pereira, Victor dos Santos
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Santa Maria; Brasil; UFSM; Programa de Pós-Graduação em Química; Centro de Ciências Naturais e Exatas
• Palavras-chave em Português: Líquidos iônicos; Auto-organização; G-quadruplex; Estabilidade térmica; Ionic liquids; Self-organization; Thermal stability; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: http://repositorio.ufsm.br/handle/1/36845

This study reports the functionalization of imidazolium-based ionic liquids (ILs) (4- (bromoalkyl)-3-methylimidazol-1-ium bromide [Cn(MIM)Br][Br] with alkyl = butyl, hexyl, octyl, and decyl) with aromatic compounds (3-amino-5-methylpyrazole, clioquinol, 2,4-dibromophenol, benzimidazole derivative, quinoline derivative, eugenol, 1-naphthol, and N-methylaniline), aiming to develop ligands for G-quadruplexes (G4s) and evaluate their potential use as sensors in biological systems. The ILs were characterized using spectroscopic techniques, and their physicochemical, thermal, photophysical, and self-organization properties in aqueous solution were determined. The results demonstrated that the functionalization of the ILs enhanced the solubility of the aromatic compounds, making them more soluble in polar solvents (such as water). A similar trend was observed for thermal stability, where the functionalized ILs exhibited higher stability than the aromatic compounds. The functionalized ILs displayed densities higher than that of water (> 1.00 g cm⁻³ at 25 °C). ILs obtained via O-alkylation reactions were investigated for self-organization in aqueous solution using electrical conductivity, dynamic and static light scattering (DLS and SLS), and surface tension measurements. The ∆G°_agg values indicated that aggregation occurs spontaneously, and the increasing order of critical aggregation concentration (CAC) was established as: [DBFB(MIM)][Br] < [ClioB(MIM)][Br] = [NaftB(MIM)][Br] < [EugeB(MIM)][Br]. The hydrophobicity of the compounds was determined using contact angle (θ) data, the spreading coefficient (S), and the surface free energy (ΔG) of the ILs on PET surfaces. The results showed that [DBFB(MIM)][Br] was the most hydrophobic and exhibited the highest tendency to form aggregates in water (lowest CAC), while [EugeB(MIM)][Br] displayed the lowest hydrophobicity and the lowest tendency to aggregate in solution. Photophysical studies revealed that the functionalized ILs exhibit solvent-modulated fluorescence, with significant fluorescence intensity and Stokes shifts in the range of 31–190 nm. Cell viability analyses indicated low cytotoxicity in healthy cells, making these compounds promising for biomedical applications. The results confirm the potential of the functionalized ILs for future applications in the detection and stabilization of G4s, and they may be further explored in the development of fluorescent biosensors and innovative therapeutic agents.