Person: García Fresnadillo, David
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First Name
David
Last Name
García Fresnadillo
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Orgánica
Area
Química Orgánica
Identifiers
4 results
Search Results
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Item 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, NazarioSuitably 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.Item Photochemical Oxidation of Thioketones by Singlet Molecular Oxygen Revisited: Insights into Photoproducts, Kinetics, and Reaction Mechanism(Journal of organic chemistry, 2015) Sánchez Arroyo, Antonio José; Pardo Botero, Zulay D.; Moreno Jiménez, Florencio; Herrera Fernández, Antonio; Martín, Nazario; García Fresnadillo, DavidPhotosensitized oxidation of trimethyl[2.2.1]-bicycloheptane thioketones by 1 O2 can yield more photoproducts than exclusively ketones and sulfines. Moreover, the ketone/sulfine ratio can be reversed when protic conditions and high thioketone concentrations are used, conversely to earlier results reporting ketones as the main photoproducts. A new mechanistic proposal for sulfine formation is suggested following intermolecular oxygen transfer from a peroxythiocarbonyl intermediate to a second thioketone molecule. Reaction quantum yields (10−5−10−2) depend on the reaction conditions and time. Sulfine production reaches a maximum at short irradiation times, whereas decomposition to the corresponding ketone is observed at long reaction times. When the thioketone substrate has a hydrogen atom at the α position a peroxyvinylsulfenic acid intermediate can be formed by proton transfer. Reaction of this intermediate with another thioketone molecule can yield more sulfine and its tautomeric vinylsulfenic acid, which dimerizes in situ to the thiosulfinate. The hydroperoxyl group of the peroxyvinylsulfenic acid can also rearrange to the α position, and by reaction with the starting thioketone, α-hydroxy thioketone and additional sulfine can be formed, while dehydration yields the α-oxo thioketone. In situ [2 + 2] and [4 + 2] self-cycloaddition of the α-oxo thioketone yields significant amounts of the corresponding adducts at prolonged irradiation times.Item Rhodanine-based dyes absorbing in the entire visible spectrum(Organic chemistry frontiers, 2017) Sandoval Torrientes, Rafael; Calbo, Joaquín; García Fresnadillo, David; Santos, José; Ortí, Enrique; Martín, NazarioA series of new broad-absorbing dyes based on rhodanine derivatives conjugated with triarylamines using Q5 a fluorene backbone was synthesized. Spectroscopic and electrochemical characterizations, along with theoretical calculations at the B3LYP/cc-pVDZ level, revealed interesting properties of the dyes, which make the dyes efficiently absorb in the entire visible spectrum.Item Exploring BODIPY Derivatives as Singlet Oxygen Photosensitizers for PDT(Photochemistry and Photobiology, 2020) Prieto Moreno, Ruth; Prieto Castañeda, Alejandro; Sola Llano, Rebeca; Rodríguez Agarrabeitia, Antonia; García Fresnadillo, David; López Arbeloa, Íñigo María; Villanueva Oroquieta, Ángeles; Ortíz García, María Josefa; Moya Cerero, Santiago de la; Martínez Martínez, VirginiaThis minireview is devoted to honoring the memory of Dr. Thomas Dougherty, a pioneer of modern photodynamic therapy (PDT). It compiles the most important inputs made by our research group since 2012 in the development of new photosensitizers based on BODIPY chromophore which, thanks to the rich BODIPY chemistry, allows a finely tuned design of the photophysical properties of this family of dyes to serve as efficient photosensitizers for the generation of singlet oxygen. These two factors, photophysical tuning and workable chemistry, have turned BODIPY chromophore as one of the most promising dyes for the development of improved photosensitizers for PDT. In this line, this minireview is mainly related to the establishment of chemical methods and structural designs for enabling efficient singlet oxygen generation in BODIPYs. The approaches include the incorporation of heavy atoms, such as halogens (iodine or bromine) in different number and positions on the BODIPY scaffold, and also transition metal atoms, by their complexation with Ir(III) center, for instance. On the other hand, low‐toxicity approaches, without involving heavy metals, have been developed by preparing several orthogonal BODIPY dimers with different substitution patterns. The advantages and drawbacks of all these diverse molecular designs based on BODIPY structural framework are described.