A Metal-Based Receptor for Selective Coordination and Fluorescent Sensing of Chloride

A scorpionate Zn2+ complex, constituted by a macrocyclic pyridinophane core attached to a pendant arm containing a fluorescent pyridyl-oxadiazole-phenyl unit (PyPD), has been shown to selectively recognize chloride anions, giving rise to changes in fluorescence emission that are clearly visible under a 365 nm UV lamp. This recognition event has been studied by means of absorption, fluorescence, and NMR spectroscopy, and it involves the intramolecular displacement of the PyPD unit by chloride anions. Moreover, since the chromophore is not removed from the system after the recognition event, the fluorescence can readily be restored by elimination of the bound chloride anion

Diseño y análisis de productos y espacios con técnicas de prototipado virtual interactivo

[ES] El trabajo muestra cómo el empleo de técnicas de visualización inmersiva influyen en el proceso creativo, mejorando las ideas proyectadas y facilitando un análisis de los productos y espacios ideados. Se plasma el proceso innovador de la asignatura “Visualizaciones avanzadas. Realidad virtual aplicada al diseño de productos” impartida en el Máster Universitario de Ingeniería del Diseño, de la ETSID-UPV, en donde el alumnado idea, diseña y experimenta con modelos tridimensionales, visualizados en soportes bidimensionales y maquetas y prototipos virtuales inmersivos. Se muestra el trabajo desde la motivación, la sorpresa, la aproximación a la realidad más tangible y un conjunto de acciones derivadas de esa aproximación que posibilita al estudiante ver su proyecto hecho realidad. La evolución de la tecnología y su implementación en la universidad permite, a su vez, implementar la docencia con herramientas que ya están al alcance del alumnado, convirtiendo la experiencia docente en la máxima aproximación a la realidad laboral que en breve les espera.[EN] This work shows how the use of immersive visualization techniques can influence the creative process, improving the projected ideas and making the analysis of the products and spaces designed easier. The innovative process of the course "Advanced Visualizations. Virtual reality applied to the design of products" taught in the Master's Degree in Design Engineering, ETSID-UPV, where the students think, design and experiment with three-dimensional models visualized on two-dimensional media, models and immersive virtual prototypes. The work is shown from the motivation, the surprise and the approach to the most tangible reality and a set of actions derived from that approach that allows the student to see his project come real. The evolution of technology and its implementation at the university allows, to improve teaching with tools that are already available to students, making the teaching experience the maximum approach to the career that will soon come to them.Saiz Mauleón, B.; Ivorra Martínez, E.; Verdejo Gimeno, P.; Cisneros Vivó, JJ. (2021). Diseño y análisis de productos y espacios con técnicas de prototipado virtual interactivo. En IN-RED 2020: VI Congreso de Innovación Educativa y Docencia en Red. Editorial Universitat Politècnica de València. 388-401. https://doi.org/10.4995/INRED2020.2020.11953OCS38840

A tetraazahydroxypyridinone derivative as inhibitor of apple juice enzymatic browning and oxidation

[EN] Enzymatic browning in fruits and vegetables can produce undesirable colour changes and adversely affect the taste, flavour, and nutritional value. This fact poses a challenge to the food industry to apply appropriate inhibitors to control enzymatic browning to maintain food quality. Accordingly, this study aims to evaluate the effect of small mazamacrocyclic compounds modified with a hydroxypyridinone similar to kojic acid on enzymatic browning, total polyphenols and antioxidant activity in apple juice. The results showed how these compounds interact with the tyrosinase enzyme in a complex interaction inhibiting its activity. The hydroxypyridinone attached to the macrocycle (I1) was crucial to induce the greatest inhibition, being the most powerful inhibitor. The kinetic studies of I1 reveal mixed-type inhibition over tyrosinase with an IC50 of 0.30 mM, which was much higher than the calculated IC50 for I2 and I3. Furthermore, I1 at a concentration of 2.25 mM, significantly reduced the enzymatic browning in fresh apple juice by more than 50% after 1 h under stirring. Also, it completely stops the decrease in the total phenolic content and delays loss of antioxidant capacity during the first 30 min.Grant RTI2018-100910-B-C44 funded by MCIN/AEI/10.13039/501100011033 and by "ERDF A way of making Europe" and the Spanish Ministerio de Economia y Competitividad (Projects CTQ2016-78499C6-1-R, CTQ2017-90852-REDC, RED2018-102331-T, PID 2019110751RB-I00 and Unidad de Excelencia CEX2019-000919-M).Muñoz-Pina, S.; Duch-Calabuig, A.; Ros-Lis, JV.; Verdejo, B.; García-España, E.; Argüelles Foix, AL.; Andrés Grau, AM. (2022). A tetraazahydroxypyridinone derivative as inhibitor of apple juice enzymatic browning and oxidation. LWT - Food Science and Technology. 154:1-7. https://doi.org/10.1016/j.lwt.2021.1127781715

Ditopic Aza-Scorpiand Ligands Interact Selectively with ds-RNA and Modulate the Interaction upon Formation of Zn2+ Complexes

Nucleic acids are essential biomolecules in living systems and represent one of the main targets of chemists, biophysics, biologists, and nanotechnologists. New small molecules are continuously developed to target the duplex (ds) structure of DNA and, most recently, RNA to be used as therapeutics and/or biological tools. Stimuli-triggered systems can promote and hamper the interaction to biomolecules through external stimuli such as light and metal coordination. In this work, we report on the interaction with ds-DNA and ds-RNA of two aza-macrocycles able to coordinate Zn2+ metal ions and form binuclear complexes. The interaction of the aza-macrocycles and the Zn2+ metal complexes with duplex DNA and RNA was studied using UV thermal and fluorescence indicator displacement assays in combination with theoretical studies. Both ligands show a high affinity for ds-DNA/RNA and selectivity for ds-RNA. The ability to interact with these duplexes is blocked upon Zn2+ coordination, which was confirmed by the low variation in the melting temperature and poor displacement of the fluorescent dye from the ds-DNA/RNA. Cell viability assays show a decrease in the cytotoxicity of the metal complexes in comparison with the free ligands, which can be associated with the observed binding to the nucleic acids

Hydrogen-ion driven molecular motions in Cu2+-complexes of a ditopic phenanthrolinophane ligand

One of the first kinetic evaluations of a metal ion interchange between the two coordination sites of a ditopic macrocycle is presented.Garcia-España Monsonis, Enrique, [email protected] ; Soriano Soto, Concepción, [email protected] ; Verdejo Viu, Begoña, [email protected]

Trapping a Highly Reactive Nonheme Iron Intermediate That Oxygenates Strong CH Bonds with Stereoretention

An unprecedentedly reactive iron species (2) has been generated by reaction of excess peracetic acid with a mononuclear iron complex [FeII(CF3SO3)2(PyNMe3)] (1) at cryogenic temperatures, and characterized spectroscopically. Compound 2 is kinetically competent for breaking strong C―H bonds of alkanes (BDE ≈ 100 kcal·mol−1) through a hydrogen-atom transfer mechanism, and the transformations proceed with stereoretention and regioselectively, responding to bond strength, as well as to steric and polar effects. Bimolecular reaction rates are at least an order of magnitude faster than those of the most reactive synthetic high-valent nonheme oxoiron species described to date. EPR studies in tandem with kinetic analysis show that the 490 nm chromophore of 2 is associated with two S = 1/2 species in rapid equilibrium. The minor component 2a (∼5% iron) has g-values at 2.20, 2.19, and 1.99 characteristic of a low-spin iron(III) center, and it is assigned as [FeIII(OOAc)(PyNMe3)]2+, also by comparison with the EPR parameters of the structurally characterized hydroxamate analogue [FeIII(tBuCON(H)O)(PyNMe3)]2+ (4). The major component 2b (∼40% iron, g-values = 2.07, 2.01, 1.95) has unusual EPR parameters, and it is proposed to be [FeV(O)(OAc)(PyNMe3)]2+, where the O―O bond in 2a has been broken. Consistent with this assignment, 2b undergoes exchange of its acetate ligand with CD3CO2D and very rapidly reacts with olefins to produce the corresponding cis-1,2-hydroxoacetate product. Therefore, this work constitutes the first example where a synthetic nonheme iron species responsible for stereospecific and site selective C―H hydroxylation is spectroscopically trapped, and its catalytic reactivity against C―H bonds can be directly interrogated by kinetic methods. The accumulated evidence indicates that 2 consists mainly of an extraordinarily reactive [FeV(O)(OAc)(PyNMe3)]2+ (2b) species capable of hydroxylating unactivated alkyl C―H bonds with stereoretention in a rapid and site-selective manner, and that exists in fast equilibrium with its [FeIII(OOAc)(PyNMe3)]2+ precursor

Binuclear Cu2+ complex mediated discrimination between L-glutamate and L-aspartate in water

L-Glutamate and L-aspartate selectivity is achieved by the action of two Cu2+ metal ions rightly disposed in a cyclophanetype macrocyclic framework; electrochemical sensing of glutamate has been achieved by adsorption of the copper complexes on graphite electrodes.Verdejo Viu, Begoña, [email protected] ; Domenech Carbo, Antonio, [email protected] ; Jimenez Garcia, Hermas Rafael, [email protected] ; Soriano Soto, Concepción, [email protected] ; Garcia-España Monsonis, Enrique, [email protected]

Transition Metals Meet Scorpiand-like Ligands

Scorpiand-like ligands combine the preorganization of the donor atoms of macrocycles and the degrees of freedom of the linear ligands. We prepared the complexes of several of these ligands with transition metal ions and made a crystallographic and water solution speciation studies. The analysis of the resulting crystal structures show that the ligands have the ability to accommodate several metal ions and that the coordination geometry is mostly determined by the ligand. Ligand 6-[3,7-diazaheptyl]-3,6,9–triaza-1-(2,6)-pyridinacyclodecaphane (L3) is an hexadentate ligand that affords a family of isostructural crystals with Cu(II), Mn(II), Ni(II) and Zn(II). The attempts to obtain Co(II) crystals afforded the Co(III) structures instead. Ligand 6-[4-(2-pyridyl)-3-azabutyl]-3,6,9-triaza-1(2,6)-pyridinacyclodecaphane (L2) is very similar to L3 and yields structures similar to it, but its behavior in solution is very different due to the different interaction with protons. Ligand 6-(2-aminoethyl)-3,6,9–triaza-1-(2,6)-pyridinacyclodecaphane (L1) is pentadentate and its complexes allow the metal to be more accessible from the solvent. A Zn(II) structure with L1 shows the species [ZnBrHL1]2+, which exists in a narrow pH range