Person:
Ramírez Barroso, Sergio

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First Name
Sergio
Last Name
Ramírez Barroso
URI
https://hdl.handle.net/20.500.14352/85588
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Orgánica
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2021 - 20233
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    An Ultra‐Long‐Lived Triplet Excited State in Water at Room Temperature: Insights on the Molecular Design of Tridecafullerenes
    (Angewandte Chemie International Edition, 2021) Ramos Soriano, Javier; Pérez Sánchez, Alfonso; Ramírez Barroso, Sergio; Illescas, Beatriz M.; Azmani, Khalid; Rodríguez Fortea, Antonio; Poblet, Josep M.; Hally, Cormac; Nonell, Santi; García Fresnadillo, David; Rojo, Javier; Martín León, Nazario
    Suitably engineered molecular systems exhibiting triplet excited states with very long lifetimes are important for high-end applications in nonlinear optics, photocatalysis, or biomedicine. We report the finding of an ultra-long-lived triplet state with a mean lifetime of 93 ms in an aqueous phase at room temperature, measured for a globular tridecafullerene with a highly compact glycodendrimeric structure. A series of three tridecafullerenes bearing different glycodendrons and spacers to the C60 units have been synthesized and characterized. UV/Vis spectra and DLS experiments confirm their aggregation in water. Steady-state and time-resolved fluorescence experiments suggest a different degree of inner solvation of the multifullerenes depending on their molecular design. Efficient quenching of the triplet states by O2 but not by waterborne azide anions has been observed. Molecular modelling reveals dissimilar access of the aqueous phase to the internal structure of the tridecafullerenes, differently shielded by the glycodendrimeric shell.
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    N‐type fullerene‐carbon dots: synthesis and electrochemical and photophysical properties
    (Chemistry-A European Journal, 2023) Andrés Ferrer‐Ruiz; Juan Manuel Moreno‐Naranjo; Rodríguez Pérez, Laura; Ramírez Barroso, Sergio; Martín León, Nazario; Herranz Astudillo, María Ángeles
    The covalent incorporation of C60 and C70 derivatives of the well-known n-type organic semiconductor PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) onto carbon dots (CD) is described. Morphological and structural characterization reveal combined features of both pristine starting materials (CD and PCBM). Electrochemical investigations evidenced the existence of additional reduction processes to that of CD or PCBM precursors, showing rich electron-acceptor capabilities, with multistep processes in an affordable and narrow electrochemical window (ca. 1.5 V). Electronic communication in the obtained nanoconjugated species were derived from steady-state absorption and emission spectroscopies, which showed bathochromically shifted absorptions and emissions well entering the red region. Finally, the lower fluorescence quantum yield of CD-PCBM nanoconjugates, compared with CD, and the fast decay of the observed emission of CD, support the existence of an electronic communication between both CD and PCBM units in the excited state.
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    Carbon dots: composition, structure and photophysics
    (2023) Ramírez Barroso, Sergio; Wannemacher, Reinhold; García Fresnadillo, David; Nazario Martín León, Nazario
    The main part of this thesis focuses on the production and characterisation of carbon nanodots. Regarding the production methods of the CNDs chosen in this work, CNDs produced by two clearly different bottom-up methods have been studied in detail. On the one hand, the solvothermal method has been used. This method consists of heating a liquid, in a closed container, above its boiling point, generating a pressure higher than atmospheric pressure, and thus inducing the condensation of CNDs. The obvious advantages of this synthetic method are: it is easy, cheap and environmentally friendly (provided that the solvent used in the solvothermal method is an environmentally friendly solvent, in our case we used water and ethanol). All these advantages provided a great opportunity to easily prepare and investigate CNDs, which, when prepared by this method, were found to have promising properties such as solubility in aqueous media, biocompatibility, photocatalytic activity in heterostructures with TiO2 and biocidal properties that can be employed to prepare biocidal polymer surfaces. The combination of the advantages proposed by the synthetic method and the promising properties of the products obtained have made this method the most common synthetic procedure for the production of CNDs...