23 - Química

Permanent URI for this collection


Recent Submissions

Now showing 1 - 20 of 1470
  • Item
    Molecular self-assembly in a family of oxo-bridged dinuclear ruthenium(IV) systems
    (American Chemical Society (ACS), 2020) Orts Arroyo, Marta; Castro Bleda, Isabel; Lloret Pastor, Francisco; Martínez-Lillo, José
    A series of six novel RuIV compounds of formula (H2bpy)2[{RuCl5}2(μ-O)] (1), (PPh4)2[{RuCl4(H2O)}2(μ-O)]·4H2O (2), (PPh4)2[{RuCl4(MeCN)}2(μ-O)] (3), (PPh4)2[{RuCl4(dmf)}2(μ-O)] (4), (PPh4)2[{RuCl4(py)}2(μ-O)] (5), and [{RuCl3(bpym)}2(μ-O)]·6H2O (6) [H2bpy2+ = 4,4′-bipyridine-1,1′-diium cation; PPh4+ = tetraphenylphosphonium cation; dmf = N,N′-dimethylformamide; py = pyridine; bpym = 2,2′-bipyrimidine] have been prepared and spectroscopically, electrochemically, and magnetically characterized. Compounds 1, 2, 5, and 6 crystallize in the triclinic system with space group P1̅, whereas 3 and 4 crystallize in the monoclinic system with space group P21/c. While 1−5 are salts based on anionic dinuclear RuIV species, 6 is a neutral diruthenium(IV) complex. The Ru−O−Ru core is present in 1−6 [with values of the Ru−Ooxo bond length covering the range of 1.774(1)−1.816(1) Å and the values of the Ru−O−Ru angle (θ) varying in the range of 164.3−180.0°]. In their crystal lattice, intermolecular Ru(IV)−Cl···Cl−Ru(IV) halogen bonds (1 and 6), Cl···π (1 and 3−6), and π···π (5 and 6) type interactions as well as hydrogen bonds (1, 2, and 6) are present. These intermolecular interactions generate novel supramolecular structures based on the self-assembly of (μ-oxo)diruthenium(IV) complexes. Magnetic susceptibility measurements performed on microcrystalline samples of 1−6 confirmed the diamagnetic nature for the six compounds, which are strongly antiferromagnetically coupled. The study of the electrochemical properties of 2−6 through cyclic voltammetry (CV) in dmf allowed us to evaluate the effect of the ligand nature on the rich redox features along this series of (μ-oxo)diruthenium(IV) complexes
  • Item
    Pressure induced enhancement of the magnetic ordering temperature in rhenium(IV) monomers
    (Springer Science and Business Media LLC, 2016) Woodall, Christopher H.; Martínez-Lillo, José; Prescimone, Alessandro; Brechin, Euan K.; Cano Boquera, Joan; Faus, Juan
    Materials that demonstrate long-range magnetic order are synonymous with information storage and the electronics industry, with the phenomenon commonly associated with metals, metal alloys or metal oxides and sulfides. A lesser known family of magnetically ordered complexes are the monometallic compounds of highly anisotropic d-block transition metals; the 'transformation' from isolated zero-dimensional molecule to ordered, spin-canted, three-dimensional lattice being the result of through-space interactions arising from the combination of large magnetic anisotropy and spin-delocalization from metal to ligand which induces important intermolecular contacts. Here we report the effect of pressure on two such mononuclear rhenium(IV) compounds that exhibit long-range magnetic order under ambient conditions via a spin canting mechanism, with Tc controlled by the strength of the intermolecular interactions. As these are determined by intermolecular distance, 'squeezing' the molecules closer together generates remarkable enhancements in ordering temperatures, with a linear dependence of Tc with pressure.
  • Item
    Synthesis of α,α-diaryl-α-amino acid precursors by reaction of isocyanoacetate esters with o-quinone Diimides
    (American Chemical Society (ACS), 2023) Laviós, Adrián; Martínez-Pardo, Pablo; Sanz-Marco, Amparo; Vila, Carlos; Pedro, José R.; Blay, Gonzalo
    A novel procedure for the synthesis of α,α-diaryl-α-amino acid derivatives has been developed. Silver oxide catalyzes the conjugate addition of α-aryl isocyanoacetates to o-quinone diimide, affording the corresponding α,α-diarylisocyano esters in excellent yields and regioselectivities in short reaction times. Acid hydrolysis of the isocyano group provides the corresponding amino acids bearing a diarylated tetrasubstituted carbon atom. The reaction is also amenable to the synthesis of α-alkyl-α-arylisocyano esters, while the reaction with 3-hydroxy o-quinone diimides provides 4H-benzo[e][1,3]oxazines via a conjugate addition/cyclization process.
  • Item
    Molecular Rearrangement of an Aza-Scorpiand Macrocycle Induced by pH: A Computational Study
    (MDPI, 2016) Julián-Ortiz, Jesús Vicente de; Verdejo, Begoña; Polo, Víctor; Besalú, Emili; García-España, Enrique
    Molecular Rearrangement of an Aza-Scorpiand Macrocycle Induced by pH: A Computational Study
  • Item
    Cellulose nanocrystals from forest residues en reinforcing agentes for composites: A study from macro- nano-dimensiones
    (2016) Moriana, Rosana; Vilaplana, Francisco; Ek, Monica
    This study investigates for the first time the feasibility of extracting cellulose nanocrystals (CNCs) fromsoftwood forestry logging residues (woody chips, branches and pine needles), with an obtained gravimet-ric yield of over 13%. Compared with the other residues, woody chips rendered a higher yield of bleachedcellulosic fibers with higher hemicellulose, pectin and lignin content, longer diameter, and lower crys-tallinity and thermal stability. The isolation of CNCs from these bleached cellulosic fibers was verifiedby the removal of most of their amorphous components, the increase in the crystallinity index, and thenano-dimensions of the individual crystals. The differences in the physico-chemical properties of thefibers extracted from the three logging residues resulted in CNCs with specific physico-chemical prop-erties. The potential of using the resulting CNCs as reinforcements in nanocomposites was discussed interms of aspect ratio, crystallinity and thermal stability.
  • Item
    Nanosafety Analysis of Graphene-Based Polyester Resin Composites on a Life Cycle Perspective
    (2022) Aznar Mollá, F. ; Heredia Alvaro, J.A.; Andreu-Sánchez, O.; Fito-López, C.; Colmenar González, I.
    The use, production, and disposal of engineering nanomaterials (ENMs), including graphene-related materials (GRMs), raise concerns and questions about possible adverse effects on human health and the environment, considering the lack of harmonized toxicological data on ENMs and the ability of these materials to be released into the air, soil, or water during common industrial processes and/or accidental events. Within this context, the potential release of graphene particles, their agglomerates, and aggregates (NOAA) as a result of sanding of a battery of graphenebased polyester resin composite samples intended to be used in a building was examined. The analyzed samples were exposed to different weathering conditions to evaluate the influence of the weathering process on the morphology and size distribution of the particles released. Sanding studies were conducted in a tailored designed sanding bench connected to time and size resolving measurement devices. Particle size distributions and particle number concentration were assessed using an optical particle counter (OPC) and a condensation particle counter (CPC), respectively, during the sanding operation. A scanning electron microscope/energy dispersive X-ray (SEM/EDX) analysis was performed to adequately characterize the morphology, size, and chemical composition of the released particles. A toxicity screening study of pristine and graphene-based nanocomposites released using the aquatic macroinvertebrate Daphnia magna and relevant human cell lines was conducted to support risk assessment and decision making. The results show a significant release of nanoscale materials during machining operations, including differences attributed to the % of graphene and weathering conditions. The cell line tests demonstrated a higher effect in the human colon carcinoma cell line Caco2 than in the human fibroblasts (A549 cell line), which means that composites released to the environment could have an impact on human health and biota.
  • Item
    Heteroatom effect on star-shaped hole-transporting materials for perovskite solar cells
    (2018) García-Benito, I.; Zimmermann, I.; Urieta-Mora, J.; Aragó, J.; Calbo, J.; Perles,J.; Serrano, A.; Molina-Ontoria, A.; Ortí, E.; Martín, N.; Nazeeruddin, M. K.
    Three new star-shaped hole-transporting materials (HTMs) incorporating benzotripyrrole, benzotrifuran, and benzotriselenophene central cores endowed with three-armed triphenylamine moieties (BTP-1, BTF-1, and BTSe-1, respectively) are designed, synthesized, and implemented in perovskite solar cells (PSCs). The impact that the heteroatom-containing central scaffold has on the electrochemical and photophysical properties, as well as on the photovoltaic performance, is systematically investigated and compared with their sulfur-rich analogue (BTT-3). The new HTMs exhibit suitable highest-occupied molecular orbitals (HOMO) levels regarding the valence band of the perovskite, which ensure efficient hole extraction at the perovskite/HTM interface. The molecular structures of BTF-1, BTT-3, and BTSe-1 are fully elucidated by single-crystal X-ray crystallography as toluene solvates. The optimized (FAPbI3)0.85(MAPbBr3)0.15- based perovskite solar cells employing the tailor-made, chalcogenide-based HTMs exhibit remarkable power conversion efficiencies up to 18.5%, which are comparable to the devices based on the benchmark spiro-OMeTAD. PSCs with BTP-1 exhibit a more limited power conversion efficiency of 15.5%, with noticeable hysteresis. This systematic study indicates that chalcogenide-based derivatives are promising HTM candidates to compete efficiently with spiro-OMeTAD.
  • Item
    P-recovery in a pilot-scale struvite crystallisation reactor for source separated urine systems using seawater and magnesium chloride as magnesium sources
    (2019) Aguado, D. ; Barat, R. ; Bouzas, A.; Seco, A. ; Ferrer, J.
    Practical recovery of a non-renewable nutrient, such as phosphorus (P), is essential to support modern agriculture in the near future. The high P content of urine, makes it an attractive source for practicing the recovery of this crucial nutrient. This paper presents the experimental results at pilot-plant scale of struvite crystallization from a source-separated urine stream using two different magnesium sources, namely magnesium chloride and seawater. The latter was chosen as sustainable option to perform P-recovery in coastal areas. Real seawater was used to assess in a more realistic way its efficiency to precipitate P as struvite, since its composition (with noticeable concentration of ions such as Ca2+, SO4 2-, Na+,¿) could lead to the formation of impurities and other precipitates. 0.99 grams of struvite were obtained per litre of urine irrespective of the operational conditions tested. In all tested conditions, precipitation efficiencies exceeded 90% and recovery efficiencies were higher than 87%, with an average struvite crystal size higher than 110 μm (and up to 320 μm, depending on the experimental conditions) in the harvested struvite samples. Almost pure struvite was obtained when MgCl2 was used as precipitant, while amorphous calcium phosphate and other impurities appeared in the precipitates using seawater as magnesium source. However, the lower settling velocity of the amorphous precipitates in comparison with the struvite precipitates suggest that their separation at industrial scale could be relatively straightforward.
  • Item
    Implementation of a global P-recovery system in urban wastewater treatment plants
    (2019) Bouzas,A.; Martí, N. ; Grau, S.; Barat, R.; Mangin, D.; Pastor, L.
    Current wastewater treatment plants (WWTPs) paradigm is moving towards the so-called water resource recovery facilities in which sewage is considered a source of valuable resources. In particular, urban WWTPs are crucial systems to enhance phosphorus (P) recycling. This paper evaluates the implementation of a P-recovery system in Calahorra WWTP combining the operation of a new sludge line configuration coupled to a struvite crystallisation reactor at demonstration-scale. This new configuration consisted in the elutriation in the gravity thickener of the mixed sludge contained in the mixing chamber in order to reduce the phosphate load to the anaerobic digestion. The results indicated that the P available in the primary sludge overflow was nearly five times more than the obtained for the conventional configuration (1.88 vs. 0.39 gP/kg sludge treated), and the uncontrolled P precipitation inside the anaerobic digester was reduced by 43%. Regarding the total P entering the WWTP, 19% of the total P could be recovered with the new configuration proposed in comparison with 9% in the previous conventional configuration. The average recovery efficiency in the crystallisation plant was 86.9 ± 0.4%, yielding a struvite recovery of 8.0 ± 0.6 kg/d (0.67 ± 0.04 kg/m3 fed to the crystalliser). The potential struvite production with the new configuration would be around 41 kg/d (15 t/y) crystallising the thickener supernatant which could be increased up to around 103 kg/d (38 t/y) treating all the Penriched streams (thickener supernatant and centrate streams). The paper demonstrates that WWTPs can contribute to reduce P scarcity, resulting in environmental and economic benefits.
  • Item
    Co-digestion of harvested microalgae and primary sludge in a mesophilic anaerobic membrane bioreactor (AnMBR): Methane potential and microbial diversity.
    (2020) Serna-García, R.; Zamorano-López, N.; Seco, A.; Bouzas, A.
    Anaerobic co-digestion of primary sludge and raw microalgae (Scenedesmus and Chlorella) was performed in a lab-scale semi-continuous anaerobic membrane bioreactor to assess the biological performance and identify the microbial community involved in the co-digestion process. The reactor was operated at 35 °C for 440 days, working at a solids retention time of 100 days. The system achieved 73% biodegradability and showed high stability in terms of pH and volatile fatty acids. An enriched microbial community was observed. Of the several phyla, Chloroflexi and Proteobacteria were the most abundant. Cellulose-degraders phyla (Bacteroidetes, Chloroflexi and Thermotogae) were detected. Syntrophic microorganisms played an important role in intermediate degradation, enhancing methane production, mainly carried out by Methanosaeta. A nutrient-rich effluent (400 mg NH4-N·L−1 and 29 mg PO4-P·L−1) and digestate (860 mg N·L−1 and 151 mg P·L−1) were obtained. The bio-nutrients released from anaerobic co-digestion could be reused for microalgae cultivation or agricultural applications.
  • Item
    Maximising resource recovery from wastewater grown microalgae and primary sludge in an anaerobic membrane co-digestion pilot plant coupled to a composting process
    (2021) Serna-García, R.; Ruiz-Barriga,P.; Noriega-Hevia, G.; Serralta, J.; Pachés, M.; Bouzas, A.
    A pilot-scale microalgae (Chlorella spp.) and primary sludge anaerobic co-digestion (ACoD) plant was run for one year in an anaerobic membrane bioreactor (AnMBR) at 35 °C, 70 d solids retention time and 30 d hydraulic retention time, showing high stability in terms of pH and VFA concentration. The plant achieved a high degree of microalgae and primary sludge substrate degradation, resulting in a methane yield of 370 mLCH4·gVSinf−1. Nutrient-rich effluent streams (685 mgN·L−1 and 145 mgP·L−1 in digestate and 395 mgNH4-N·L−1 and 37 mgPO4-P·L−1 in permeate) were obtained, allowing posterior nutrient recovery. Ammonium was recovered from the permeate as ammonia sulphate through a hydrophobic polypropylene hollow fibre membrane contactor, achieving 99% nitrogen recovery efficiency. However, phosphorus recovery through processes such as struvite precipitation was not applied since only 26% of the phosphate was available in the effluent. Composting process of the digestate coming from the ACoD pilot plant was assessed on laboratory-scale Dewar reactors, as was the conventional sludge compost from an industrial WWTP digestion process, obtaining similar values from both. Sanitised (free of Escherichia coli and Salmonella spp.) and stable compost (respirometric index at 37 °C below 0.5 mgO2·g organic matter−1·h−1) was obtained from both sludges.
  • Item
    Amine-bridged periodic mesoporous organosilica adsorbents for CO2 capture
    (2023) Erans, María; Arencibia, Amaya; Sanz-Pérez, Eloy S.; Sanz, Raúl
    Novel periodic mesoporous organosilica (PMOs) were synthesized using different commercial non-aminated and aminated bisilanes in order to incorporate aminated sites within the silica walls. Three different commercial bisilanes were employed: i)without amine groups, ii)with one amine group, and iii)with two amine groups. Moreover, materials were prepared with different molar ratios of non-aminated and aminated bisilanes. P123 was used as structure directing agent for the mesoporosity. The amino functional groups of the PMOs so prepared were incorporated within the silica walls of the obtained solid particles. Moreover, for comparative purposes, BEBA-0, that is a non-aminated PMO, was functionalized via grafting with N1-(3-trimethoxysilylpropyl)diethylenetriamine (DT) and impregnation with polyethyleneimine (PEI) to produce amino functionalized materials. All these materials were tested for CO2 capture through CO2 adsorption/desorption isotherms and TGA studies. It was observed that increasing the concentration of amine containing bisilane increased the CO2 capture capacity significantly from 21.4 mg/g to 47.3 mg/g. The PMO synthesized with the bisilane containing two amine groups had higher CO2 uptake than the one containing one amine group from 47.3 to 62.6 mg/g due to the presence of more functional groups in the final material (6.0 versus 9.4% wt N, respectively). The cyclic capacity of the adsorbents via a series of adsorption/desorption tests has also been determined, the results showing the low reactivity decay (less than 3%) of the novel PMOs and materials prepared by grafting during the first 10 cycles, when compared with the 13% of PEI-impregnated material.
  • Item
    Reinforced room-temperature spin filtering in chiral paramagnetic metallopeptides
    (2020) Torres-Cavanillas, Ramón; Escorcia-Ariza, Garin; Brotons-Alcázar, Isaac; Sanchis-Gual, Roger; Chandra Mondal, Prakash; Rosaleny, Lorena E.; Giménez-Santamarina, Silvia; Sessolo, Michele; Galbiati, Marta; Tatay, Sergio; Gaita-Ariño, Alejandro; Forment-Aliaga, Alicia; Cardona-Serra, Salvador
    Chirality-induced spin selectivity (CISS), whereby helical molecules polarize the spin of electrical current, is an intriguing effect with potential applications in nanospintronics. In this nascent field, the study of the CISS effect using paramagnetic chiral molecules, which could introduce another degree of freedom in controlling the spin transport, remains so far unexplored. To address this challenge, herein, we propose the use of self-assembled monolayers (SAMs) of helical lanthanide-binding peptides. In order to elucidate the effect of the paramagnetic nuclei, monolayers of the peptide coordinating paramagnetic or diamagnetic ions are prepared. By means of spin-dependent electrochemistry, CISS effect is demonstrated by cyclic voltammetry and electrochemical impedance measurements for both samples. Additionally, an implementation of the standard liquid-metal drop electron transport setup has been carried out, demonstrating their suitability for solid-state devices. Remarkably, the inclusion of a paramagnetic center in the peptide increases the spin polarization as independently proved by different techniques. These findings permit the inclusion of magnetic biomolecules in the CISS field, paving the way to their implementation in a new generation of (bio)spintronic nanodevices.
  • Item
    Effects of BIS076 in a model of osteoarthritis induced by anterior cruciate ligament transection in ovariectomised rats
    (2015) Ferrándiz, M.L.; Terencio, M.C.; Carceller, M.C.; Ruhí, R.; Dalmau, P.; Vergés, J.; Montell, E.; Torrent, A.; Alcaraz, M.J.
    Background: Osteoarthritis (OA) is the most frequent articular disease and a leading cause of disability. There is a need for effective treatments able to slow the progression of disease. Some of the available treatments are dietary supplements providing natural components. Recent studies have shown that estrogen deficiency contributes to the pathophysiological events of OA progression. Methods: We have used the anterior cruciate ligament transection model of OA in ovariectomised rats to study the effects of BIS076, a new formulation of a natural porcine cartilage extract associated with hydroxyapatite (as a source of calcium) and vitamin D3. Cartilage degradation, proteoglycan depletion and synovitis were followed by histochemistry. Effects on bone microstructure were determined by μCT. The levels of biomarkers in serum and inflammatory mediators in knee homogenates were measured by luminex or ELISA. Results: Oral administration of BIS076 reduced articular cartilage damage and serum levels of cartilage degradation markers C-telopeptide of type II collagen and cartilage oligomeric matrix protein, as well as matrix metalloproteinase-3. The local inflammatory response was down-regulated by BIS076 with lower production of pro-inflammatory cytokines and prostaglandin E2 in joint tissues. In addition, BIS076 was effective on metaphyseal bone alterations as this formulation increased volumetric bone mineral density and improved bone micro-architecture. These effects were related to the modification of bone metabolism reflected by changes in bone biomarkers with reductions in the ratio receptor activator of nuclear factor κB ligand/osteoprotegerin and the levels of tartrate-resistant acid phosphatase-5b, suggesting an inhibitory activity of BIS076 on trabecular bone resorption. Conclusions: We have demonstrated the protective properties of a new formulation (BIS076) on joint lesion and bone alterations in an experimental model of OA in ovariectomised rats. This study supports the interest of BIS076 in OA treatments.
  • Item
    Extracellular vesicles do not mediate the anti-Inflammatory actions of mouse-derived adipose tissue mesenchymal stem cells secretome.
    (2021) Carceller, María Carmen; Guillén, María Isabel; Gil, María Luisa; Alcaraz, María José
    Adipose tissue represents an abundant source of mesenchymal stem cells (MSC) for therapeutic purposes. Previous studies have demonstrated the anti-inflammatory potential of adipose tissue-derived MSC (ASC). Extracellular vesicles (EV) present in the conditioned medium (CM) have been shown to mediate the cytoprotective effects of human ASC secretome. Nevertheless, the role of EV in the anti-inflammatory effects of mouse-derived ASC is not known. The current study has investigated the influence of mouse-derived ASC CM and its fractions on the response of mouse-derived peritoneal macrophages against lipopolysaccharide (LPS). CM and its soluble fraction reduced the release of pro-inflammatory cytokines, adenosine triphosphate and nitric oxide in stimulated cells. They also enhanced the migration of neutrophils or monocytes, in the absence or presence of LPS, respectively, which is likely related to the presence of chemokines, and reduced the phagocytic response. The anti-inflammatory effect of CM may be dependent on the regulation of toll-like receptor 4 expression and nuclear factor-κB activation. Our results demonstrate the anti-inflammatory effects of mouse-derived ASC secretome in mouse-derived peritoneal macrophages stimulated with LPS and show that they are not mediated by EV.
  • Item
    Thermal characterisation of photo-oxidized HDPE/Mater-Bi and LDPE/Mater-Bi blends buried in soil
    (2008) Moriana-Torró, Rosana; Contat-Rodrigo, Laura; Santonja-Blasco, Laura; Ribes-Greus, Amparo
    Blends of high and low density polyethylene with a commercial biodegradable material (Mater-Bi) were subjected to an accelerated soil burial test. A set of samples was previously photo-oxidized to evaluate the effects of UV-irradiation on the degradation in soil process of these blends. Thermogravimetric as well as calorimetric analysis were performed to study the biodegradation, photo-degradation and their synergetic effects. Differential scanning calorimetry was carried out to analyze the morphological changes as a consequence of the photo-oxidation process. UV-irradiation slightly modifies the crystalline content of HDPE/Mater-Bi blends, increasing the heterogeneity of this blend. Criado master curves were plotted to analyses the degradation kinetic model. Broido and Coats-Redfern methods have been used for calculating the Ea of the thermal decomposition mechanisms. Thermogravimetric results reveal that noncomplexed starch is more affected by biodegradation than the polyethylene matrix and the starch/ EVOH complexes chains from Mater-Bi. However, the effects of both photo-oxidation and biodegradation processes on the thermal decomposition of Mater-Bi is influenced by the polymeric matrix used. Previous photo-oxidation finds to slow down the degradative effects caused by the soil burial test on the HDPE/Mater-Bi blends.
  • Item
    Assessing the influence of cotton fibers on the degradation in soil of a thermoplastic starch-based biopolymer
    (2010) Moriana, Rosana; Karlsson, Sigbritt; Ribes-Greus, Amparo
    Biocomposites consisting of cotton fibers and a commercial starch-based thermoplastic were subjected to accelerated soil burial test. Fourier transform infrared (FTIR) spectrometry analysis was carried out to provide chemical-structural information of the polymeric matrix and its reinforced biocomposites. The effects that take place as a consequence of the degradation in soil of both materials were studied by FTIR-ATR, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). When the polymeric matrix and the reinforced biocomposite are submitted to soil burial test, the infrared studies display a decrease in the CO band associated to the ester group of the synthetic component as a consequence of its degradation. The crystalline index of both materials decreased as a function of the degradation process, where the crystalline structure of the reinforced biocomposite was the most affected. In accordance, the degraded reinforced biocomposite micrographs displayed a more damaged morphology and fracture surface than the degraded polymeric matrix micrographs. On the other hand, the same thermal decomposition regions were assessed for both materials, regardless of the degradation time. Kissinger, Criado, and Coats-Redfern methods were applied to analyze the thermogravimetric results. The kinetic triplet of each thermal decomposition process was determined for monitoring the degradation test. The thermal study confirms that starch was the most biodegradable polymeric matrix component in soil. However, the presence of cotton fiber modified the degradation rate of both matrix components; the degradability in soil of the synthetic component was slightly enhanced, whereas the biodegradation rate of the starch slowed down as a function of the soil exposure time
  • Item
    Ferromagnetic exchange interaction in a new Ir(IV)-Cu(II) chain based on the hexachloroiridate(IV) anion
    (2019) Sanchis-Perucho, A.; Martínez-Lillo, José
    The iridium(IV) complex (NBu4)2[IrCl6] (1) has been synthetised, characterised and used as a precursor to prepare the new chloro-bridged heterobimetallic IrIV-CuII chain of formula {IrCl5(μ-Cl)Cu(viim)4}n (2) [viim = 1-vinylimidazole]. The crystal structure and magnetic properties of 1 and 2 have been investigated. Both compounds crystallise in the monoclinic system with space group C2/c. Each Ir(IV) ion in both 1 and 2 is six-coordinate and bonded to six chloride ions in a regular octahedral geometry. In compound 2, the Cu(II) ion exhibits an axially elongated octahedron with four N atoms, from four monodentate viim ligands, that form the equatorial plane, and two chloride ions that occupy the axial positions. The way in which the anionic [IrCl6]2− units are arranged in the crystal packing of 1, well separated from each other by means of the bulky NBu4+ cations, avoids significant intermolecular Ir-Cl⋯Cl-Ir interactions. The crystal lattice of 2 shows adjacent Ir(IV)-Cu(II) chains that are connected through π⋯π stacking interactions, and are organized adopting perpendicular arrangements. The study of the magnetic properties of 1 and 2 through dc magnetic susceptibility measurements reveals that 1 shows magnetic behaviour typical of noninteracting mononuclear centres with S = 1/2, whereas 2 exhibits ferromagnetic exchange coupling between the Cu(II) and Ir(IV) metal ions linked through chloride ligands. In addition, ac magnetic susceptibility measurements show a field-induced slow relaxation of the magnetisation for 1, indicating single-ion magnet (SIM) behaviour for this mononuclear Ir(IV) system.
  • Item
    A Chiral, Photoluminescent, and Spin-Canted {CuIReIV2}n Branched Chain
    (2015) Martínez-Lillo, José; Armentano, D.; Fortea-Pérez, F. R.; Stiriba, S.-E.; De Munno, G.; Lloret, F.; Julve, M.; Faus, Juan
    A new heteroleptic 1D Cu(I)−Re(IV) coordination polymer of the formula {Cu(I)Re(IV)Cl4(μ-Cl)(μ-pyz)[Re(IV)Cl4(μ-bpym)]}n·nMeNO2 (1; pyz = pyrazine, bpym = 2,2′-bipyrimidine) has been prepared through the Cu(I)-mediated self-assembly of two different Re(IV) metalloligands, namely, [ReCl5(pyz)]− and [ReCl4(bpym)]. 1 consists of chiral branched chains with an overall rack-type architecture displaying photoemission and magnetic ordering. These results constitute a first step toward making new multifunctional magnetic materials based on mixed 3d−5d molecular systems.
  • Item
    Deciphering the Electroluminescence Behavior of Silver(I) Complexes in Light-Emitting Electrochemical Cells: Limitations and Solutions toward Highly Stable Devices
    (WILEY-VCH Verlag GmbH & Co, 2019-05-30) Fresta, Elisa; Carbonell-Vilar, José M.; Yu, Jianyin; Armentano, Donatella; Cano, Joan; Viciano-Chumillas, Marta; Costa, Rubén D.
    Ionic transition-metal complexes based on silver(I) metal core (Ag-iTMCs) represent an appealing alternative to other iTMCs in solid-state lighting owing to (i) their low cost and well-known synthesis, (ii) the tunable bandgap, and (iii) the highly efficient photoluminescence. However, their electrolumi nescence behavior is barely studied. Herein, the archetypal green-emitting Ag-iTMCs, namely [Ag(4,4′-dimethoxy-2,2′-bipyridine)(Xantphos)]X (X = BF4, PF6, and ClO4), are thoughtfully investigated, revealing their electrolumines cent features in light-emitting electrochemical cells (LECs). Despite optimizing device fabrication and operation, luminance of 40 cd m−2, efficacy of 0.2 cd A−1, and a very poor stability of 30 s are achieved. This outcome encourages the comprehensive study of the degradation mechanism combining electrochemical impedance spectroscopy, X-ray diffraction, and cyclic voltammetry techniques. These results point out the irreversible formation of silver nanoclusters under operation strongly limiting the device performance. As such, LECs are further optimized by (i) changing the counterions (PF6− and ClO4−) and (ii) decoupling electron injection and exciton formation using a double-layered architecture. The synergy of both approaches leads to a broad exciplex-like whitish electroluminescence emission (x/y CIE of 0.40/0.44 and color rendering index of 85) with an outstanding improved stability of ≈4 orders of magnitude (>80 h) without losing brightness (35 cd m−2)