Person: Cabrera González, Justo Enrique
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First Name
Justo Enrique
Last Name
Cabrera González
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Orgánica
Area
Identifiers
17 results
Search Results
Now showing 1 - 10 of 17
Item Synthesis and self-assembly of a carboranecontaining ABC triblock terpolymer: morphology control on a dual-stimuli responsive system(Polymer Chemistry, 2019) Fernáncez Alvarez, Roberto; Hlavatovicová, Eva; Rodzén, Krzysztof; Strachota, Adam; Kereïche, Sami; Matejicek, Pavel; Cabrera González, Justo Enrique; Núñez, Rosario; Uchman, MariuszAmphiphilic triblock terpolymers have attractive applications in the preparation of nanoparticles with controlled morphology. An additional level of morphology control can be provided by reactive blocks, whose interactions with the solvent vary under different stimuli. In this work, we synthesized a triblock terpolymer (poly(acrylic acid)-b-poly(4-hydroxystyrene)-b-poly{1-[4-(1-methyl-1,2-dicarba-closo-dodecaborane-2-yl methyl)-phenyl]ethylene}) (PAA-b-PHS-b-PSC) containing carboranes as pendant groups by reversible addition fragmentation chain transfer (RAFT) polymerization and subsequently studied its behavior in aqueous solution. Once the nanoparticles were formed, the solubility of the second and third blocks was changed via pH and CsF reactions, respectively. The resulting micelles work as an ON/OFF system, using changes in fluorescence intensity at different pH values.Item Highly Dispersible and Stable Anionic Boron Cluster-Graphene Oxide Nanohybrids(Chemistry - A European Journal, 2016) Cabrera González, Justo EnriqueAn efficient process to produce boron cluster-graphene oxide nanohybrids that are highly dispersible in water and organic solvents is established for the first time. Dispersions of these nanohybrid materials in water were extraordinarily stable after one month. Characterization of hybrids after grafting of appropriate cobaltabisdicarbollide and closo-dodecaborate derivatives onto the surface of graphene oxide (GO) was done by FT-IR, XPS, and UV/Vis. Thermogravimetric analysis (TGA) clearly shows a higher thermal stability for the modified-GO nanohybrids compared to the parent GO. Of particular note, elemental mapping by energy-filtered transmission electron microscopy (EFTEM) reveals that a uniform decoration of the graphene oxide surface with the boron clusters is achieved under the reported conditions. Therefore, the resulting nanohybrid systems show exceptional physico-chemical and thermal properties, paving the way for an enhanced processability and further expanding the range of application for graphene-based materials.Item Redox-active metallacarborane-decorated octasilsesquioxanes. Electrochemical and thermal properties(Inorganic Chemistry, 2016) Cabrera González, Justo Enrique; Sanchez-Arderiu, Víctor; Viñas, Clara; Parella, Teodor; Teixidor, Francesc; Nuñez, RosarioPolyanionic and electroactive hybrids based on octasilsesquioxanes bearing metallacarborane units are developed. They show remarkable solubility in organic solvents and outstanding thermal stability. The metallacarboranes act as independent units simultaneously undergoing the reversible redox process.Item Tetrakis{[(p-dodecacarboranyl)methyl]stilbenyl}ethylene:A Luminescent Tetraphenylethylene (TPE) Core System(European Journal of Inorganic Chemistry, 2017) Cabrera González, Justo EnriqueThe synthesis and spectroscopic characterization of the first set of tetrakis{[(p-dodecacarboranyl)methyl]stilbenyl}ethylenes (TDSE), substituted either with a methyl or a phenyl group in the 2-position (Ccluster) of the ortho-carborane, are described. The complex absorption properties are elucidated by TD-DFT calculations, stressing the importance of through-bond conjugation. Enhanced conjugation and restriction of the conformational space are identified as the main factors for boosted luminescence properties in solution, compared with the tetraphenylethylene (TPE) core, effectively reducing internal conversion (IC). IC is further reduced when aggregate suspensions of our compounds are formed in water, providing highly luminescent materials of quasi-isolated (very weakly interacting) emitters.Item Ru(II) and Ir(III) phenanthroline-based photosensitisers bearing o-carborane: PDT agents with boron carriers for potential BNCT(Biomaterials Science, 2021) Conway-Kenny, Robert ; Ferrer-Ugalde, Albert ; Careta, Oriol ; Cui, Xiaoneng ; Zhao, Jianzhang; Nogués, Carme ; Núñez, Rosario ; Cabrera González, Justo Enrique; Draper, Sylvia M.Four novel transition metal-carborane photosensitisers were prepared by Sonogashira cross-coupling of 1-(4-ethynylbenzyl)-2-methyl-o-carborane (A-CB) with halogenated Ru(II)- or Ir(III)-phenanthroline complexes. The resulting boron-rich complexes with one (RuCB and IrCB) or two carborane cages (RuCB2 and IrCB2) were spectroscopically characterised, and their photophysical properties investigated. RuCB displayed the most attractive photophysical properties in solution (λem 635 nm, τT 2.53 μs, and φp 20.4%). Nanosecond time-resolved transient absorption studies were used to explore the 3MLCT nature of the triplet excited states, and the highest singlet oxygen quantum yields (ΦΔ) were obtained for the mono-carborane-phenanthroline complexes (RuCB: 52% and IrCB: 25%). None of the complexes produce dark toxicity in SKBR-3 cells after incubation under photodynamic therapy (PDT) conditions. Remarkably, mono-carboranes RuCB and IrCB were the best internalised by the SKBR-3 cells, demonstrating the first examples of tris-bidentate transition metal-carborane complexes acting as triplet photosensitisers for PDT with a high photoactivity; RuCB or IrCB killed ∼50% of SKBR-3 cells at 10 μM after irradiation. Therefore, the high-boron content and the photoactive properties of these photosensitisers make them potential candidates as dual anti-cancer agents for PDT and Boron Neutron Capture Therapy (BNCT).Item High-Boron-Content Porphyrin-Cored Aryl Ether Dendrimers: Controlled Synthesis, Characterization, and Photophysical Properties(Inorganic Chemistry, 2015) Cabrera González, Justo Enrique; Xochitiotzi-Flores, Elba; Viñas, Clara; Teixidor, Francesc; García-Ortega, Héctor; Farfán, Noberto; Santillan, Rosa; Parella, Teodor; Núñez, RosarioThe synthesis and characterization of a set of poly(aryl ether) dendrimers with tetraphenylporphyrin as the core and 4, 8, 16, or 32 closo-carborane clusters are described. A regioselective hydrosilylation reaction on the allyl-terminated functions with carboranylsilanes in the presence of Karstedt's catalyst leads to different generations of boron-enriched dendrimers. This versatile approach allows the incorporation of a large number of boron atoms in the dendrimers' periphery. Translational diffusion coefficients (D) determined by DOSY NMR experiments permit estimation of the hydrodynamic radius (RH) and molecular size for each dendrimer. Furthermore, a notable correlation between D and the molecular weight (MW) is found and can be used to predict their overall size and folding properties. The UV vis and emission behavior are not largely affected by the functionalization, therefore implying that the presence of carboranes does not alter their photoluminescence properties.Item Organotin dyes bearing anionic boron clusters as cell-staining fluorescent probes(Chemistry – A European Journal, 2018) Cabrera González, Justo EnriqueWithin the cell nucleus, in the nucleoli, ribosomal RNAs are synthesized and participate in several biological processes. To better understand nucleoli-related processes, their visualization is often required, for which specific markers are needed. Herein, we report the design of novel fluorescent organotin compounds derived from 4-hydroxy-N′-((2-hydroxynaphthalen-1-yl)methylene)benzohydrazide and their cytoplasm and nucleoli staining of B16F10 cells in vitro. Tin compounds bearing an aliphatic carbon chain (-C12H25) and an electron-donating group (-OH) were prepared, and the latter could be derivatized to bear the boron cluster anions [B12H12]2− and [3,3′-Co(1,2-C2B9H11)2]− (COSAN). All of the conjugates have been fully characterized and their luminescence properties have been assessed. In general, they show good quantum yields in solution (24–49 %), those for the COSAN derivatives being lower. Remarkably, the linking of [B12H12]2− and COSAN to the complexes made them more soluble, without being detrimental to their luminescence properties. Living B16F10 cells were treated with all of the compounds to determine their fluorescence staining properties; the compounds bearing the aliphatic chain showed a reduced staining capacity due to the formation of aggregates. Notably, the complexes bearing different boron clusters showed different staining effects; those bearing [B12H12]2− showed extraordinary staining of the nucleoli and cytoplasm, whereas those bearing COSAN were only detected in the cytoplasm. The remarkable fluorescence staining properties shown by these organotin compounds make them excellent candidates for fluorescence bioimaging in vitro.Item Reversible Optical Data Storage via Two-Photon Micropatterning of o‑Carboranes-Embedded Switchable Materials(Chemistry of Materials, 2023) Abdallah, Stephania; Mhanna, Rana; Cabrera González, Justo Enrique; Núñez, Rosario; Khitous, Amine ; Morlet-Savary, Fabrice ; Soppera, Olivier ; Versace, Davy-Louis ; Malval, Jean-PierreTwo-photon polymerization (2PP) constitutes a powerful light-triggered 3D stereolithography, allowing the fabrication of micro- or nanostructures with spatially encoded functionalities. In the present report, we take advantage of this programmable property in order to develop a photoresist authorizing the direct 2PP-lithography of luminescent switchable μ-structures. In this single step processing method, we highlight the pivotal role of a quadrupolar o-caborane initiator comprising a 9, 10-disubstituted anthracene core capable of chemically entrap oxygen-inhibiting species during the free radical two-photon initiation step. Such an O2 sequestration approach not only enhances the two-photon initiation performance of the polymerization, but also generates a non-luminescent endoperoxide by-product embedded in the polymerized macrostructure. Interestingly, simple heating of the final materials promotes endoperoxide thermolysis, resulting in the recovery of the luminescent o-carborane dye. This original luminescence turn OFF/ON property exhibits excellent fatigue resistance through a large number of alternated thermal and light stimuli cycles. The potential of this direct laser writing strategy for reversible data storage applications is finally demonstrated by the two-photon patterning of a series of matricially organized μ-structures used as rewritable binary optical memories which can be easily encoded on demand.Item Photoluminescence in Carborane–Stilbene Triads: A Structural, Spectroscopic, and Computational Study(Chemistry - a European journal, 2016) Cabrera González, Justo Enrique; Viñas, Clara; Haukka, Matti; Bhattacharyya, Santanu; Gierschner, Johannes; Núñez, RosarioA set of triads in which o- and m-carborane clusters are bonded to two stilbene units through Ccluster−CH2 bonds was synthesized, and their structures were confirmed by X-ray diffraction. A study on the influence of the o- and m- isomers on the absorption and photoluminescence properties of the stilbene units in solution revealed no charge-transfer contributions in the lowest excited state, as confirmed by (TD)DFT calculations. The presence of one or two B−I groups in m-carborane derivatives does not affect the emission properties of the stilbenes in solution, probably due to the rather large distance between the iodo substituents and the fluorophore. Nevertheless, a significant redshift of the photoluminescence (PL) emission maximum in the solid state (thin films and powder samples) compared to solution was observed; this can be traced back to PL sensitization, most probably due to more densely packed stilbene moieties. Remarkably, the PL absolute quantum yields of powder samples are significantly higher than those in solution, and this was attributed to the restricted environment and the aforementioned sensitization. Thus, the bonding of the carborane clusters to two stilbene units preserves their PL behavior in solution, but produces significant changes in the solid state. Furthermore, iodinated species can be considered to be promising precursors for theranostic agents in which both imaging and therapeutic functions could possibly be combined.- Project number: 134
Item Nueva metodología de aprendizaje basado en investigación en el Laboratorio de Química Orgánica II (Grado en Química, Doble Grado en Química y Bioquímica)(2022) Illescas Martínez, Beatriz; Martínez Ruiz, María Paloma; Rodríguez Yunta, María Josefa; Gómez Aspe, Rafael; Lora Maroto, Beatriz; Martínez del Campo, Teresa; Descalzo López, Ana Belén; Santos Barahona, Jose Manuel; Cembellín Santos, Sara; Cabrera González, Justo Enrique; Patino Alonso, Jennifer; Serrano Buitrago, Sergio; Villalonga Chico, Anabel; Mayol Hornero, Beatriz; Hernández-Cornejo Pérez, JavierEste proyecto tiene como objetivo llevar a cabo un cambio conceptual del Laboratorio de Química Orgánica II, introduciendo métodos del aprendizaje mediante indagación guiada (“inquiry-guided learning”). Se ha desarrollado un aprendizaje centrado en el estudiante, que requiere que los alumnos realicen sus propias hipótesis, planifiquen su experimento, reflexionen y tomen decisiones durante el desarrollo de cada sesión. Se han utilizado como estrategias principales: 1) Diseño de una práctica piloto basada en los conceptos del aprendizaje mediante indagación guiada. Dicha práctica es diferente para cada alumno, lo que ha supuesto contar con una reserva de 12-15 prácticas diferentes previamente ensayadas. 2) Diseño y elaboración del material de laboratorio necesario para transformar las prácticas ya existentes en formato expositivo en experimentos basados en indagación, planteando preguntas que los alumnos deben responder a lo largo del experimento, sin proporcionarles previamente los resultados esperados, sino promoviendo un aprendizaje activo que integra los nuevos conceptos inferidos a partir de un verdadero proceso de experimentación e investigación. 3) Promover la discusión científica de los resultados introduciendo al final de la sesión una puesta en común con un alto componente de evaluación entre iguales (“peer-assessment”). 4) Con el fin de tutorizar el papel del profesor en este modelo de aprendizaje, se ha desarrollado una guía de ayuda al profesor. 5) Por último, se han realizado encuestas de evaluación para recibir la retroalimentación necesaria de los profesores y alumnos que se han enfrentado a esta nueva metodología en nuestro Departamento.