Browsing by Autor "Alexis Tigreros"

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    Pyrazolo[1,5-<i>a</i>]pyrimidines-based fluorophores: a comprehensive theoretical-experimental study
    (Royal Society of Chemistry, 2020) Alexis Tigreros; Sandra‐L. Aranzazu; Néstor-F. Bravo; Jhon Zapata‐Rivera; Jaime Portilla
    Fluorescent molecules are crucial tools for studying the dynamics of intracellular processes, chemosensors, and the progress of organic materials. In this study, a family of pyrazolo[1,5-<i>a</i>]pyrimidines (PPs) 4a-g has been identified as strategic compounds for optical applications due to several key characteristics such as their simpler and greener synthetic methodology (RME: 40-53%) as compared to those of BODIPYS (RME: 1.31-17.9%), and their tunable photophysical properties (going from <i>ε</i> = 3320 M<sup>-1</sup> cm<sup>-1</sup> and <i>ϕ</i> <sub>F</sub> = 0.01 to <i>ε</i> = 20 593 M<sup>-1</sup> cm<sup>-1</sup> and <i>ϕ</i> <sub>F</sub> = 0.97), in which electron-donating groups (EDGs) at position 7 on the fused ring improve both the absorption and emission behaviors. The PPs bearing simple aryl groups such as 4a (4-Py), 4b (2,4-Cl<sub>2</sub>Ph), 4d (Ph) and 4e (4-MeOPh), allow good solid-state emission intensities (QY<sub>SS</sub> = 0.18 to 0.63) in these compounds and thus, solid-state emitters can be designed by proper structural selection. The properties and stability found in 4a-g are comparable to commercial probes such as coumarin-153, prodan and rhodamine 6G. Ultimately, the electronic structure analysis based on DFT and TD-DFT calculations revealed that EDGs at position 7 on the fused ring favor large absorption/emission intensities as a result of the ICT to/from this ring; however, these intensities remain low with electron-withdrawing groups (EWGs), which is in line with the experimental data and allows us to understand the optical properties of this fluorophore family.
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    Recent progress in chemosensors based on pyrazole derivatives
    (Royal Society of Chemistry, 2020) Alexis Tigreros; Jaime Portilla
    Colorimetric and fluorescent probes based on small organic molecules have become important tools in modern biology because they provide dynamic information concerning the localization and quantity of the molecules and ions of interest without the need for genetic engineering of the sample. In the past five years, these probes for ions and molecules have attracted great attention because of their biological, environmental and industrial significance combined with the simplicity and high sensitivity of absorption and fluorescence techniques. Moreover, pyrazole derivatives display a number of remarkable photophysical properties and wide synthetic versatility superior to those of other broadly used scaffolds. This review provides an overview of the recent (2016-2020) findings on chemosensors containing pyrazole derivatives (pyrazoles, pyrazolines and fused pyrazoles). The discussion focuses on the design and physicochemical properties of chemosensors in order to realize their full potential for practical applications in environmental and biological monitoring (sensing of metal ions, anions, explosives, and biomolecules). We also present our conclusions and outlook for the future.
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    Synthesis of Pyrrolo[2,3‐c]isoquinolines via the Cycloaddition of Benzyne with Arylideneaminopyrroles: Photophysical and Crystallographic Study
    (Centre National de la Recherche Scientifique, 2019) Juan‐Carlos Castillo; Alexis Tigreros; Yoann Coquerel; Jean Rodriguez; Mario A. Macías; Jaime Portilla