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
6 results
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Now showing 1 - 6 of 6
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 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 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.Item Blue Emitting Star-Shaped and Octasilsesquioxane-Based Polyanions Bearing Boron Clusters. Photophysical and Thermal Properties(Molecules, 2020) Cabrera González, Justo Enrique; Chaari, Mahdi; Teixidor, Francesc; Viñas, Clara; Núñez, RosarioHigh boron content systems were prepared by the peripheral functionalisation of 1,3,5-triphenylbenzene (TPB) and octavinylsilsesquioxane (OVS) with two different anionic boron clusters: closo-dodecaborate (B12) and cobaltabisdicarbollide (COSAN). TPB was successfully decorated with three cluster units by an oxonium ring-opening reaction, while OVS was bonded to eight clusters by catalysed metathesis cross-coupling. The resulting compounds were spectroscopically characterised, and their solution-state photophysical properties analysed. For TPB, the presence of COSAN dramatically quenches the fluorescence emission (λem = 369 nm; ΦF = 0.8%), while B12-substituted TPB shows an appreciable emission efficiency (λem = 394 nm; ΦF = 12.8%). For octasilsesquioxanes, the presence of either COSAN or B12 seems to be responsible for ∼80 nm bathochromic shift with respect to the core emission, but both cases show low emission fluorescence (ΦF = 1.4–1.8%). In addition, a remarkable improvement of the thermal stability of OVS was observed after its functionalisation with these boron clusters.