Browsing by Author "Pizarro, Nancy"

Now showing 1 - 6 of 6
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    Experimental and Theoretical Studies of the ancillary ligand (E)-2-((3-amino- pyridin-4-ylimino)-methyl)-4,6-di-tert-butylphenol in Rhenium(I) core
    (2015) Carreno, Alexander; Gacitua, Manuel; Schott Verdugo, Eduardo Enrique; Zarate, Ximena; Manriquez, Juan Manuel; Preite, Marcelo Daniel; Ladeira, Sonia; Castel, Annie; Pizarro, Nancy; Vega, Andres; Chavez, Ivonne; Arratia-Perez, Ramiro
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    Fatty Acid Conjugates of Toluidine Blue O as Amphiphilic Photosensitizers: Synthesis, Solubility, Photophysics and Photochemical Properties(dagger)
    (2021) Robinson Duggon, José Luis; Pizarro, Nancy; Gunthe, Germán; Zúñiga Núñez, Daniel; Edwards M., Ana María; Greer, Alexander; Fuentealba Patiño, Denis Alberto
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    Fluorescence properties of aurone derivatives: an experimental and theoretical study with some preliminary biological applications
    (2017) Espinosa Bustos, Christian Marcelo; Cortes Arriagada, Diego; Soto Arriaza, Marco; Robinson Duggon, José Luis; Pizarro, Nancy; Cabrera Caballero, Alan Raúl; Fuentealba Patiño, Denis Alberto; Salas Sánchez, Cristián Osvaldo
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    New Light-Green Thermally Activated Delayed Fluorescence Polymer Based on Dimethylacridine-Triphenyltriazine Light-Emitting Unit and Tetraphenylsilane Moiety as Non-Conjugated Backbone
    (MDPI, 2023) Hauyon Sepúlveda, Rene Alejandro; Sobarzo Aucal, Patricio Antonio; Medina Martínez, Jean André; Garcia, Luis; Tundidor Camba, Alain; Terraza Inostroza, Claudio Alberto; Fuentealba Patino, Denis Alberto; Pizarro, Nancy; Ortega Alfaro, María C.; Ugalde Saldívar, Víctor M.; Jessop Rivera, Ignacio Andrés; González Henríquez, Carmen
    In the search for solution-processable TADF materials as a light emitting layer for OLED devices, polymers have attracted considerable attention due to their better thermal and morphological properties in the film state with respect to small molecules. In this work, a new polymer (p-TPS-DMAC-TRZ) with thermally activated delayed fluorescence (TADF) light-emitting characteristics was prepared from a conjugation-break unit (TPS) and a well-known TADF core (DAMC-TRZ). This material was designed to preserve the photophysical properties of DAMC-TRZ, while improving other properties, such as thermal stability, promoted by its polymerization with a TPS core. Along with excellent solubility in common organic solvents such as toluene, chloroform and THF, the polymer (Mn = 9500; Mw = 15200) showed high thermal stability (TDT5% = 481 °C), and a Tg value of 265 °C, parameters higher than the reference small molecule DMAC-TRZ (TDT5% = 305 °C; Tg = 91 °C). The photoluminescence maximum of the polymer was centered at 508 nm in the solid state, showing a low redshift compared to DMAC-TRZ (500 nm), while also showing a redshift in solution with solvents of increasing polarity. Time-resolved photoluminescence of p-TPS-DMAC-TRZ at 298 K, showed considerable delayed emission in solid state, with two relatively long lifetimes, 0.290 s (0.14) and 2.06 s (0.50), and a short lifetime of 23.6 ns, while at 77 K, the delayed emission was considerably quenched, and two lifetimes in total were observed, 24.6 ns (0.80) and 180 ns (0.20), which was expected from the slower RISC process at lower temperatures, decreasing the efficiency of the delayed emission and demonstrating that p-TPS-DMAC-TRZ has a TADF emission. This is in agreement with room temperature TRPL measurements in solution, where a decrease in both lifetime and delayed contribution to total photoluminescence was observed when oxygen was present. The PLQY of the mCP blend films with 1% p-TPS-DMAC-DMAC-TRZ as a dopant was determined to be equal to 0.62, while in the pure film, it was equal to 0.29, which is lower than that observed for DMAC-TRZ (0.81). Cyclic voltammetry experiments showed similarities between p-TPS-DMAC-TRZ and DAMC-TRZ with HOMO and LUMO energies of ?5.14 eV and ?2.76 eV, respectively, establishing an electrochemical bandgap value of 2.38 eV. The thin film morphology of p-TPS-DMAC-TRZ and DMAC-TRZ was compared by AFM and FE-SEM, and the results showed that p-TPS-DMAC-TRZ has a smoother surface with fewer defects, such as aggregations. These results show that the design strategy succeeded in improving the thermal and morphological properties in the polymeric material compared to the reference small molecule, while the photophysical properties were mostly maintained, except for the PLQY determined in the pure films. Still, these results show that p-TPS-DMAC-TRZ is a good candidate for use as a light-emitting layer in OLED devices, especially when used as a host-guest mixture in suitable materials such as mCP.
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    Photophysics and photochemistry of naphthoxazinone derivatives
    (2008) Nonell, Santi; Ferreras, Lourdes R.; Cañete Molina, Álvaro; Lemp, Else; Günther, German; Pizarro, Nancy; Zanocco, Antonio L.
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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.