Artikuluak-IMaCris / MaKrisI ikerketa taldea;;Artículos-Grupo de investigación IMaCris / MaKrisI
http://hdl.handle.net/10810/15683
2024-03-29T10:43:39ZEncapsulation of β-alanine model amino-acid in zirconium(IV) metal organic frameworks: Defect engineering to improve host guest interactions
http://hdl.handle.net/10810/38426
Encapsulation of β-alanine model amino-acid in zirconium(IV) metal organic frameworks: Defect engineering to improve host guest interactions
Rodríguez Muguruza, Asier; Fernández de Luis, Roberto; Iglesias, Naroa; Bazán Blau, Begoña del Pilar; Urtiaga Greaves, Miren Karmele; Serrano Larrea, Edurne; Fidalgo Marijuan, Arkaitz; Barandika Argoitia, Miren Gotzone
Metal-Organic Frameworks (MOFs) are porous coordination networks assembled through
metal complexes with organic linkers. Due to their chemical versatility, these materials are
being investigated for various applications including gas storage and separation,
biomedicine and catalysis. The aim of this work is the encapsulation of the model β-alanine
amino-acid in the nanostructured zirconium-based MOF (UiO-66) which contains the ligand
H2BDC (1,4-benzenedicaboxylic acid). Additionally, ligand functionalization (by using
H2doBDC (2,5-dihydroxy-1,4-benzenedicarboxylic acid) and defect engineering have been carried out to produce UiO-66 derivatives, in order to modify the host-guest interactions,
and hence study their influence on the β-alanine loading capacity and release kinetics. The
as-obtained materials have been characterized by X-ray diffraction (XRD), X-ray thermo
diffraction (TDX), infrared (IR) spectroscopy, thermogravimetric analysis-differential
scanning calorimetry (TG-DSC) and elemental analysis (EA). Morphology of nanoscale MOFs
has been explored by transition electron microscopy (TEM). Adsorption isotherms have
been constructed, and the concentration of β-alanine in the post-adsorption solution
(supernatant) has been quantified by high performance liquid chromatography coupled
with mass spectroscopy (HPLC-MS) and EA. Adsorption capacity values indicate that the
presence of hydroxyl groups at the organic linker H2doBDC enhances the host-guess affinity
between the framework and the adsorbate β-alanine. The influence of defect engineering,
on the adsorption however, is not that obvious. On the other hand, desorption experiments
show similar behaviour for H2doBDC-based derivatives. An adsortion mechanism has been
proposed consisting of a combination of host-guest interaction at low concentrations, and
covalent anchoring/ligand displacement by β-alanine at the inorganic clusters.
2020-04-01T00:00:00ZStructural Transformations in the Thermal Dehydration of [Cu2(bpa)(btec)(H2O)4]n Coordination Polymer
http://hdl.handle.net/10810/32847
Structural Transformations in the Thermal Dehydration of [Cu2(bpa)(btec)(H2O)4]n Coordination Polymer
Bravo García, Laura; Serrano Larrea, Edurne; Artetxe Arretxe, Beñat; Lezama Diago, Luis María; Gutiérrez Zorrilla López, Juan Manuel; Arriortua Marcaida, María Isabel
Reactions between pyridinic ligands such as 1,2-bis(4-pyridyl)ethane (bpa) and transition metal cations are a very widespread technique to produce extended coordination polymers such as Metal-Organic Frameworks. In combination with a second ligand these systems could present different topologies and behaviors. In this context, the use of 1,2,4,5-benzenetetracarboxylic acid (H4btec) gave us a novel 2D compound, [Cu2(bpa)(btec)(H2O)4]n (1), which was prepared by microwave-assisted synthesis and structurally characterized by means of single crystal X-ray diffraction. Its thermal behavior was analyzed through thermogravimetric analysis and variable temperature powder X-ray diffraction, concluding that thermal stability is influenced by the coordination water molecules, allowing two sequential thermochromic phase transformations to take place. These transformations were monitored by electronic paramagnetic resonance spectroscopy and magnetic susceptibility measurements. In addition, the crystal structure of the anhydrous compound [Cu2(bpa)(btec)]n (1.ah) was determined. Finally, a topological study was carried out for the bpa ligand considering all the structures deposited in the Cambridge Structural Databased. More than 1000 structures were analyzed and classified into 17 different topologies, according to the role of the ligand.
2019-05-13T00:00:00ZCombustion synthesis and characterization of Ln1−xMxCr0.9Ni0.1O3 (Ln = La and/or Nd; M = Sr and/or Ca; x ≤ 0.25) perovskites for SOFCs anodes
http://hdl.handle.net/10810/28819
Combustion synthesis and characterization of Ln1−xMxCr0.9Ni0.1O3 (Ln = La and/or Nd; M = Sr and/or Ca; x ≤ 0.25) perovskites for SOFCs anodes
Ortega-San-Martín, Luis; Morán Ruiz, Aroa; Wain Martin, Aritza; Vidal García, Karmele; Larrañaga Varga, Aitor; Laguna-Bercero, Miguel Angel; Arriortua Marcaida, María Isabel
A series of chromite perovskites with the general formula Ln1−xMxCr0.9Ni0.1O3 (Ln = La and/or Nd; M = Sr and/or Ca; x ≤ 0.25) has been prepared by three combustion synthesis routes using a different combustible substance each time: glycine, urea and sucrose. In order to isolate the effect of divalent dopant concentration from the A cation steric effects, the whole group has a fixed mean A cation radius, < rA> ≈ 1.22 Å, and cation size disorder, σ2(rA) ≈ 0.0001 Å2, but variable doping x. Their crystal structure, microstructure, electrical properties and expansion coefficients have been investigated on the basis of their possible use as anode materials for intermediate temperature solid oxide fuel cells (SOFC). Cell parameters, grain sizes, expansion coefficients and conductivities all are found to be dependent on x and the combustible substance used. The most interesting relationship is the negative dependence of the conductivity with x under H2 atmosphere: conductivity decreases with doping which is the opposite to the expected behavior for a p-type doped perovskites and has not been reported before.
2018-02-01T00:00:00ZCharacterization of Ln4Al2O9 (Ln=Y, Sm, Eu, Gd, Tb) rare-earth aluminates as new high-temperature barriers
http://hdl.handle.net/10810/28744
Characterization of Ln4Al2O9 (Ln=Y, Sm, Eu, Gd, Tb) rare-earth aluminates as new high-temperature barriers
Morán Ruiz, Aroa; Vidal García, Karmele; Larrañaga Varga, Aitor; Arriortua Marcaida, María Isabel
A family of cuspidine-type rare-earth (RE) aluminates with the general formula Ln4Al2O9 (Ln= Y, Sm, Eu, Gd, Tb) was prepared for potential use as thermal-barrier coating (TBC) materials with appropriate properties. Various trivalent lanthanides were applied to tailor the properties of the oxides for use as ceramic top coat (TC) materials intended for high-temperature applications. Following various heat treatments, the X-ray diffraction (XRD) results obtained demonstrated that Eu4Al2O9 (EuAM) possessed the greatest structural stability of all the samples at 1200 and 1300 °C. Moreover, Y4Al2O9 (YAM) had a long lifetime at 1000 °C, and was stable at 1100 °C. At 1200 °C, Sm4Al2O9 (SmAM) and Gd4Al2O9 (GdAM) were more stable than Tb4Al2O9 (TbAM). However, at 300–1000 °C, the TbAM exhibited the highest thermal expansion coefficient (TEC) of all the samples. At 600 °C, the thermal diffusivity values of the five compositions were favourable, and were lower than that of yttria-stabilised zirconia (YSZ) oxides.
2018-06-01T00:00:00Z