Diseño, síntesis y caracterización de sistemas híbridos. aplicaciones médicas y medioambientales.

El desarrollo que ha experimentado la Química Supramolecular en el campo del reconocimiento ha permitido a los investigadores, dar un paso adelante en el diseño y la síntesis de arquitecturas supramoleculares bien definidas, con un tamaño nanométrico a partir de la autoorganización de los receptores. En este sentido, el descubrimiento de nuevos materiales, procesos y el desarrollo de nuevas técnicas experimentales ha permitido el desarrollo de nuevos nanosistemas con aplicaciones muy innovativas en comparación con las especies por separado. Entre los posibles materiales que se pueden emplear, las nanopartículas presentan un gran interés debido a sus propiedades ópticas, magnéticas, electrónicas, etc., derivadas de su composición química y de sus dimensiones nanométricas. El efecto sinérgico logrado por la organización de las moléculas orgánicas en la superficie de las nanopartículas es el punto clave para la obtención de una mayor sensibilidad y selectividad del proceso de reconocimiento molecular. A lo largo de esta tesis se ha pretendido mostrar la importancia que tienen las interacciones supramoleculares en el reconocimiento de sustratos de diferente naturaleza. Además, y avanzando en el diseño de estructuras cada vez más organizadas y eficaces, se ha introducido el empleo de materiales nanoestructurados para la síntesis de nanosensores con aplicaciones muy diversas. Con el fin de contribuir al desarrollo de este campo se han aplicado los conocimientos adquiridos en la síntesis de nanopartículas oxídicas de bohemita y de bohemita-sílice con estructura núcleo-envoltura para obtener diferentes materiales híbridos, capaces de reconocer sustratos catiónicos y aniónicos en disolución acuosa mediante el uso de interacciones no covalentes. Para el diseño de los receptores híbridos se han empleado ligandos poliamínicos por las ventajas que presentan como su bajo coste, son fáciles de modificar mediante rutas sintéticas, presentan una gran versatilidad a la hora de interaccionar con los sustratos en función del pH del medio, los grupos amino son buenos átomos dadores para coordinar metales de transición o con sustratos aniónicos. Además, se ha empleado la luminiscencia como herramienta de señalización de los procesos de reconocimiento, debido al gran número de ventajas que se han expuesto anteriormente.The knowledge developed in the field of Supramolecular Chemistry about molecular recognition has allowed the researchers to go a step forward in the design and generation of well-defined, functional molecular and supramolecular architectures of nanometric size through self-organization of the receptors. In this sense, the advances in nanotechnology have provided a variety of nanostructured materials with highly controlled and exceptional properties. The discovery of novel materials, processes, and phenomena at the nanoscale and the development of new experimental and theoretical techniques for research provide fresh opportunities for the development of innovative nanosystems and nanostructured materials. The properties of materials at the nanoscale can be very different from those at a larger scale. Among these materials, nanoparticles exhibit an intense interest because of their unique optical, electronic, magnetic, catalytic, and other physical properties arising from the chemical composition of the material and the nanometer dimensions. The synergistic effect achieved by the organization and the structural rigidity of hosts on the solid surface is the key element for enhanced recognition of a guest, often resulting in an improved selectivity and sensitivity compared with the free, molecular hosts. The introduction of surface functionalities plays a decisive role in the development of such systems and has an important impact on the application of these hybrid materials in areas ranging from sensing to biotechnology and catalysis Throughout this thesis, we have tried to show the importance of supramolecular interactions in the recognition of substrates of different nature. Furthermore, progress in the design of increasingly organized and efficient structures, has introduced the use of nanostructured materials for the synthesis of nanosensors with very different applications. In order to contribute to the development of this field we have applied the knowledge acquired in the synthesis of boehmite oxidic nanoparticles and boehmite - silica core-shell nanoparticles for different hybrid materials, able to recognize cationic and anionic substrates in aqueous solution by using non-covalent interactions. For the design of hybrid receptors we have been employed polyamine ligands for the advantages offered as their low cost, are easily modified by synthetic routes, show great versatility to interact with the substrates depending on the pH of the medium, the amino groups are good donor atoms coordinating transition metals or anionic substrates. In addition, luminescence was used as a tool signaling recognition processes due to the large number of advantages set forth above

Assembly of Polyiodide Networks with Cu(II) Complexes of Pyridinol-Based Tetraaza Macrocycles

Polyiodide networks are currently of great practical interest for the preparation of new electronic materials. The participation of metals in the formation of these networks is believed to improve their mechanical performance and thermal stability. Here we report the results on the construction of polyiodide networks obtained using Cu(II) complexes of a series of pyridinol-based tetraazacyclophanes as countercations. The assembly of these crystalline polyiodides takes place from aqueous solutions on the basis of similar structural elements, the [CuL]2+ and [Cu(H-1L)]+ (L = L2, L2-Me, L2-Me3) complex cations, so that the peculiarities induced by the increase of N-methylation of ligands, the structural variable of ligands, can be highlighted. First, solution equilibria involving ligands and complexes were analyzed (potentiometry, NMR, UV-vis, ITC). Then, the appropriate conditions could be selected to prepare polyiodides based on the above complex cations. Single-crystal XRD analysis showed that the coordination of pyridinol units to two metal ions is a prime feature of these ligands, leading to polymeric coordination chains of general formula {[Cu(H-1L)]}nn+ (L = L2-Me, L2-Me3). In the presence of the I-/I2 couple, the polymerization tendency stops with the formation of [(CuL)(CuH-1L)]3+ (L = L2-Me, L2-Me3) dimers which are surrounded by polyiodide networks. Moreover, coordination of the pyridinol group to two metal ions transforms the surface charge of the ring from negative to markedly positive, generating a suitable environment for the assembly of polyiodide anions, while N-methylation shifts the directional control of the assembly from H-bonds to I···I interactions. In fact, an extended concatenation of iodine atoms occurs around the complex dimeric cations, the supramolecular I···I interactions become shorter and shorter, fading into stronger forces dominated by the orbital overlap, which is promising for effective electronic materials

Correlation between the molecular structure and the kinetics of decomposition of azamacrocyclic copper(II) complexes

The formation of copper(II) complexes with symmetrical dinucleating macrocyclic ligands containing two either monomethylated (L1) or trimethylated (L2) diethylenetriamine (Medien or Me3dien) subunits linked by pyridine spacers has been studied by potentiometry. Potentiometric studies show that L1 has larger basicity than L2 as well as higher stability of its mono- and binuclear complexes. The crystal structures of L1·6HCl (1), [Cu2(L1)Cl2](CF3SO3)2 (2), [Cu2(L1)(OH)](ClO4)3·3H2O (3) and [Cu(L1)](ClO4)2 (4) show that L1 adopts different coordination modes when bound to copper(II). Whereas in 2, each copper(II) is bound to one Medien subunit and to one pyridine group, in 3 each metal center is coordinated to one 2,6-di(aminomethyl) pyridine moiety (damp) and to one aminomethyl group. The mononuclear complex 4 shows pseudo-octahedral coordination with two weakly coordinated axial nitrogens. Kinetic studies indicate that complex decomposition is strongly dependent on the coordination mode of L1. Upon addition of an acid excess, all the species except [Cu2(L1)]4+ convert very rapidly to an intermediate that decomposes more slowly to copper(II) and a protonated ligand. In contrast, [Cu2(L1)]4+ decomposes directly without the formation of any detectable intermediate. These results can be rationalized by considering that the crystal structures are maintained in solution and that the weakest Cu–N bonds are broken first, thus indicating that kinetic measurements on complex decomposition can be used to provide information about structural reorganizations in the complexes. In any case, complete decomposition of the L1 complexes takes place in a maximum of two kinetically resolvable steps. However, minor changes in the structure of the complexes can lead to drastic changes in the kinetics of decomposition and the L2 complexes decompose with polyphasic kinetics in which up to four different steps associated with the successive breaking of the different Cu–N bonds can be resolved

Enhancement of SOD activity in boehmite supported nanoreceptors

The binuclear Cu2+ complex of a pyridinophane polyamine ligand ranking amongst the fastest SOD mimetics so far reported displays a remarkable SOD activity enhancement when grafted to the surface of boehmite (γ-AlO(OH)) nanoparticles (BNPs)

Inhibitory Effect of Azamacrocyclic Ligands on Polyphenol Oxidase in Model and Food Systems

This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Journal of Agricultural and Food Chemistry, copyright © American Chemical Society after peer review. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acs.jafc.0c02407[EN] Enzymatic browning is one of the main problems faced by the food industry due to the enzyme polyphenol oxidase (PPO) provoking an undesirable color change in the presence of oxygen. Here, we report the evaluation of 10 different azamacrocyclic compounds with diverse morphologies as potential inhibitors against the activity of PPO, both in model and real systems. An initial screening of 10 ligands shows that all azamacrocyclic compounds inhibit to some extent the enzymatic browning, but the molecular structure plays a crucial role on the power of inhibition. Kinetic studies of the most active ligand (L2) reveal a S-parabolic I-parabolic noncompetitive inhibition mechanism and a remarkable inhibition at micromolar concentration (IC50 = 10 mu M). Furthermore, L2 action has been proven on apple juice to significantly reduce the enzymatic browning.Financial support by the Spanish Ministerio de Ciencia, Innovacion y Universidades (project RTI2018-100910-B-C44), Ministerio de Economia y Competitividad (projects CTQ2016-78499-C6-1-R, Unidad de Excelencia MDM 2015-0038 and CTQ2017-90852-REDC), and Generalitat Valenciana (Project PROMETEOII2015-002) is gratefully acknowledged.Muñoz-Pina, S.; Ros-Lis, JV.; Delgado-Pinar, E.; Martínez-Camarena, Á.; Verdejo, B.; García-España, E.; Argüelles Foix, AL.... (2020). Inhibitory Effect of Azamacrocyclic Ligands on Polyphenol Oxidase in Model and Food Systems. Journal of Agricultural and Food Chemistry. 68(30):7964-7973. https://doi.org/10.1021/acs.jafc.0c02407796479736830Simpson, B. K. (Ed.). (2012). 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Journal of the American Chemical Society, 140(11), 3916-3928. doi:10.1021/jacs.7b11400Martínez-Camarena, Á., Liberato, A., Delgado-Pinar, E., Algarra, A. G., Pitarch-Jarque, J., Llinares, J. M., … García-España, E. (2018). Coordination Chemistry of Cu2+ Complexes of Small N-Alkylated Tetra-azacyclophanes with SOD Activity. Inorganic Chemistry, 57(17), 10961-10973. doi:10.1021/acs.inorgchem.8b01492Algarra, A. G., Basallote, M. G., Belda, R., Blasco, S., Castillo, C. E., Llinares, J. M., … Verdejo, B. (2009). Synthesis, Protonation and CuIIComplexes of Two Novel Isomeric Pentaazacyclophane Ligands: Potentiometric, DFT, Kinetic and AMP Recognition Studies. European Journal of Inorganic Chemistry, 2009(1), 62-75. doi:10.1002/ejic.200800576Díaz, P., Basallote, M. G., Máñez, M. A., García-España, E., Gil, L., Latorre, J., … Luis, S. V. (2003). Thermodynamic and kinetic studies on the Cu2+ coordination chemistry of a novel binucleating pyridinophane ligandElectronic supplementary information (ESI) available: Table S1: observed rate constants for the acid-promoted decomposition of Cu2+ complexes with ligand L. Table S2: observed rate constants for the acid-promoted decomposition of Cu2+ complexes with macrocycle L1. Fig. S1: Variation of some selected 13C chemical shifts as a function of pH. See http://www.rsc.org/suppdata/dt/b2/b209013a/. Dalton Transactions, (6), 1186-1193. doi:10.1039/b209013aBasallote, M. G., Doménech, A., Ferrer, A., García-España, E., Llinares, J. M., Máñez, M. A., … Verdejo, B. (2006). Synthesis and Cu(II) coordination of two new hexaamines containing alternated propylenic and ethylenic chains: Kinetic studies on pH-driven metal ion slippage movements. 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One-pot preparation of surface modified boehmite nanoparticles with rare-earth cyclen complexes

We report on the one-pot synthetic procedure of cyclen derivatives bearing three acetate groups attached on boehmite nanoparticles, the complexing capabilities of these inorganic–organic hybrid materials with rare earth cations, and the behaviour as contrast agents or fluorescence probes.Delgado Pinar, Estefania, [email protected] ; Frias Martinez, Juan Carlos, [email protected] ; Albelda Gimeno, Maria Teresa, [email protected] ; Alarcon Navarro, Javier, [email protected] ; Garcia-España Monsonis, Enrique, [email protected]

Characterization of a Ferryl Flip in Electronically Tuned Nonheme Complexes. Consequences in Hydrogen Atom Transfer Reactivity

Two oxoiron(IV) isomers (R2a and R2b) of general formula [FeIV(O)(RPyNMe3)(CH3CN)]2+ are obtained by reaction of their iron(II) precursor with NBu4IO4. The two isomers differ in the position of the oxo ligand, cis and trans to the pyridine donor. The mechanism of isomerization between R2a and R2b has been determined by kinetic and computational analyses uncovering an unprecedented path for interconversion of geometrical oxoiron(IV) isomers. The activity of the two oxoiron(IV) isomers in hydrogen atom transfer (HAT) reactions shows that R2a reacts one order of magnitude faster than R2b, which is explained by a repulsive noncovalent interaction between the ligand and the substrate in R2b. Interestingly, the electronic properties of the R substituent in the ligand pyridine ring do not have a significant effect on reaction rates. Overall, the intrinsic structural aspects of each isomer define their relative HAT reactivity, overcoming changes in electronic properties of the ligand.10 página

Characterization of a Ferryl Flip in Electronically Tuned Nonheme Complexes. Consequences in Hydrogen Atom Transfer Reactivity

Two oxoiron(IV) isomers (R2a and R2b) of general formula [FeIV(O)(RPyNMe3)(CH3CN)]2+ are obtained by reaction of their iron(II) precursor with NBu4IO4. The two isomers differ in the position of the oxo ligand, cis and trans to the pyridine donor. The mechanism of isomerization between R2a and R2b has been determined by kinetic and computational analyses uncovering an unprecedented path for interconversion of geometrical oxoiron(IV) isomers. The activity of the two oxoiron(IV) isomers in hydrogen atom transfer (HAT) reactions shows that R2a reacts one order of magnitude faster than R2b, which is explained by a repulsive noncovalent interaction between the ligand and the substrate in R2b. Interestingly, the electronic properties of the R substituent in the ligand pyridine ring do not have a significant effect on reaction rates. Overall, the intrinsic structural aspects of each isomer define their relative HAT reactivity, overcoming changes in electronic properties of the ligand

A water-soluble bithiophene with increased photoluminescence efficiency and metal recognition ability

A new water-soluble tri-tert-butyl-bithiophenesulfonamide (α2-tbS) was synthesized and a comprehensive spectroscopic and photophysical study was undertaken in organic solvents and water at different pH values. In contrast to the behaviour found for the parent (and un-substituted) α,α'-bithiophene (α2), in which radiationless decay processes are the main excited-state deactivation channels, the tert-butylsulfonamide derivative presents a significant fluorescence quantum yield (φF) (ca. one order of magnitude higher than that of α2). The high φF allowed further exploring α2-tbS as a selective fluorimetric sensor for metal ions. A strong selectivity towards Cu(ii) is observed at neutral pH values, whereas at pH = 9.5 a strong quenching upon the addition of Hg(ii) is observed. An additional high sensitivity of 0.64 ± 0.02 ppm towards Cu(ii) was observed, well below 1.25 ppm (∼20 μM), the maximum value allowed in drinking water by the EPA

Highly Selective Fluorescent Sensors: Polyethylenimine Derivatives of Triphenylamine and Coumarin for GTP and ATP Interaction via Fluorescence Lifetime Imaging Microscopy

Chemical derivatives of polyethylenimine (PEI) receptors with either triphenylamine (TPA) or 7-hydroxy-4-methyl-coumarin (Cou) form stable complexes with adenine and guanine nucleotides in water. The host-guest complex modulation is found to be based on noncovalent molecular interactions such as π-π stacking and hydrogen bonding, which are dependent on the aromatic moieties attached to the polyaminic (PEI) backbone. PEI-TPA acts as a chemosensor with a recognition driving force based on aggregation-induced emission (AIE), involving π-π interaction between the nucleic base and TPA. It detects GTP by a chelation enhancement quenching effect of fluorescence (CHEQ) with a measured logarithm stability constant, log β = 7.7. By varying the chemical characteristics of the fluorophore, as in the PEI-Cou system, the driving force for recognition changes from a π-π interaction to an electrostatic interaction. The coumarin derivative detects ATP with a log β value one order of magnitude higher than that for GTP, allowing for the selective recognition of the two nucleotides in a 100% aqueous solution. Furthermore, fluorescence lifetime imaging microscopy (FLIM) allows for a correlation between the selectivity of PEI-TPA toward nucleotides and the morphology of the structures formed upon ATP and GTP recognition. This study offers valuable insights into the design of receptors for the selective recognition of nucleotides in water