Browsing by Author "Fuentealba, Denis"

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    New Benzotriazole and Benzodithiophene-Based Conjugated Terpolymer Bearing a Fluorescein Derivative as Side-Group: In-Ternal Forster Resonance Energy Transfer to Improve Organic Solar Cells
    (MDPI, 2022) Jessop, Ignacio A.; Cutipa, Josefa; Perez, Yasmin; Saldias, Cesar; Fuentealba, Denis; Tundidor-Camba, Alain; Terraza, Claudio A.; Camarada, Maria B.; Angel, Felipe A.
    A new benzodithiophene and benzotriazole-based terpolymer bearing a fluorescein derivative as a side group was synthesized and studied for organic solar cell (OSC) applications. This side group was covalently bounded to the backbone through an n-hexyl chain to induce the intramolecular Forster Resonance Energy Transfer (FRET) process and thus improve the photovoltaic performance of the polymeric material. The polymer exhibited good solubility in common organic chlorinated solvents as well as thermal stability (TDT10% > 360 degrees C). Photophysical measurements demonstrated the occurrence of the FRET phenomenon between the lateral group and the terpolymer. The terpolymer exhibited an absorption band centered at 501 nm, an optical bandgap of 2.02 eV, and HOMO and LUMO energy levels of -5.30 eV and -3.28 eV, respectively. A preliminary study on terpolymer-based OSC devices showed a low power-conversion efficiency (PCE) but a higher performance than devices based on an analogous polymer without the fluorescein derivative. These results mean that the design presented here is a promising strategy to improve the performance of polymers used in OSCs.
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    Removal of chlorpyrifos from water using biosorbents derived from cassava peel, crambe meal, and pinus bark
    (2022) Schwantes, Daniel; Goncalves Jr, Affonso Celso; Fuentealba, Denis; Carneiro, Maria Fernanda Hornos; Tarley, Cesar Ricardo Teixeira; Prete, Maiyara Carolyne
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    Supramolecular complex of tetracationic porphyrin with acyclic cucurbituril-like container induces quantitative singlet oxygen generation. Phototoxicity studies in vitro in MCF-7 human breast cancer cells
    (2024) Day, Skarlett; Pérez, Benjamín; Guerra Díaz, Daniel; Mariño-Ocampo, Nory; Zúñiga-Núñez, Daniel; Faúndez, Mario A.; Soto-Arriaza, Marco; Pizarro, Nancy; Heyne, Belinda; Fuentealba, Denis
    Singlet oxygen generation by porphyrin-based photosensitizers is one of the main strategies used in the photodynamic therapy of cancerous lesions. In this work, we report that the complexation of tetracationic 5,10,15,20-tetrakis(N-methylpiridinium-4-yl)porphyrin (TMPyP) with an acyclic cucurbituril-like container denominated M2C4 achieves quantitative generation of singlet oxygen. The complexation was studied by isothermal titration calorimetry, revealing a highly favored binding event controlled by enthalpic contributions, a stoichiometry of 1:1 and a high binding constant (K = (1.7 ± 0.2) × 107 M−1). Photophysical studies of the complex showed bathochromic shifts in the absorption bands, increased fluorescence emission quantum yield and lengthened fluorescence lifetime. Nonetheless, fluorescence emission was minor, being intersystem crossing with the consequent generation of singlet oxygen the main deactivation pathway for the excited state. All these properties were compared with the previously reported TMPyP and cucurbit[7]uril (CB[7]) complex, which showed a superiority of the acyclic complex in terms of quantum efficiencies. Phototoxicity studies in a breast cancer cell line (MCF-7) cultured in vitro, showed that the TMPyP@M2C4 complex is unable to enter the cells even after a 24 h incubation period. However, this issue could be circumvented by encapsulating the complex into liposomes which delivered the complex to the cells efficiently. Overall, this strategy showed good potential for a highly efficient photodynamic treatment using the TMPyP@M2C4 complex in liposomal formulations.