Person:
Jiménez Aparicio, Reyes

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First Name
Reyes
Last Name
Jiménez Aparicio
URI
https://hdl.handle.net/20.500.14352/76314
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Inorgánica
Area
Química Inorgánica
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Author: Javier Torroba ×

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    Tuning of Adsorption and Magnetic Properties in a Series of Self-Templated Isostructural Ni(II) Metal−Organic Frameworks
    (Crystal Growth and Design, 2013) Cortijo Montes, Miguel; Herrero Domínguez, Santiago; Jiménez Aparicio, Reyes; Perles Hernáez, Josefina; Priego Bermejo, José Luis; Javier Torroba
    An isomorphous series of five metal–organic frameworks of formula [Ni4(O2CR)(OH)2(4-pyc)5] [4-pyc = 4-pyridinecarboxylate or isonicotinate; R = C6H5 (1), 4-OMe-C6H4 (2), 2,6-(OMe)2-C6H3 (3), 3,5-(OMe)2-C6H3 (4), 3,4,5-(OMe)3-C6H2 (5)] were obtained by solvothermal reactions. These compounds display a three-dimensional framework where the nickel atoms are coordinated to the hydroxyde anions and two different organic ligands: isonicotinate and phenylcarboxylate. Both hydroxyde (μ3-OH) and phenylcarboxylate (μ3-1κO,2κO,3κO′) ligands are coordinated to nickel atoms of the same secondary building unit (SBU). The SBU consists of four edge-sharing NiA6 octahedra (A = O, N). The isonicotinate ligands, however, act as linkers between SBUs displaying three different coordination modes: μ-1κN,2κO; μ3-1κN,2κO,3κO′; and μ4-1κN,2:3κ2O,4κO′. Nitrogen adsorption measurements were done to obtain textural parameters of these microporous networks. Micropore size distributions indicate cylindrical pores with diameters of approximately 0.80 nm. The values of Brunauer–Emmett–Teller surface areas (SBET) obtained are in the range of 382–488 m2/g, and the micropore volumes are between 0.13 cm3/g and 0.19 cm3/g. Both parameters are influenced by the substitution grade and position of the methoxy groups of the phenylcarboxylate ligand. The magnetic properties, which also depend on the arylcarboxylate ligands, vary from compound 1 (with only antiferromagnetic interactions) to compound 5, which shows a spin glass behavior (Tg = 15 K).
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    Hybrid Polyfunctional Systems Based on Nickel(II) Isonicotinate
    (European Journal of Inorganic Chemistry, 2013) Cortijo Montes, Miguel; Herrero Domínguez, Santiago; Jiménez Aparicio, Reyes; Perles Hernáez, Josefina; Priego Bermejo, José Luis; M. José Torralvo; Javier Torroba
    Several metal–organic frameworks of nickel(II) were obtained starting from the molecular complex 1, [Ni(OH2)4(4-pyc)2] (4-pyc = 4-pyridinecarboxylate or isonicotinate). By using different reaction conditions, two polymorphs of the anhydrous complex [Ni(4-pyc)2]n (2a and 2b) and the polynuclear compound [Ni5(OH2)3(4-pyc)10]n (3) were obtained in very high yield. All of the compounds were characterized by elemental analysis and spectroscopic data. The crystal structure determination of compounds 2b and 3 was also carried out. Structural and topological analysis of these new structural types and other related ones were performed. It was found that compounds 2a and 2b are a rare case of coordination framework isomers. Thermogravimetric studies indicate that compounds 2b and 3 lose the pore-allocated solvent molecules at moderate temperatures without any significant structural change, and at higher temperatures, compounds 1 and 3 are transformed into 2a. Textural parameters that characterize the microporous networks for 2b and 3 were obtained by nitrogen-adsorption measurements. For both samples, the micropore size distribution indicates cylindrical pores with diameters of 0.85 (2b) and 0.90 nm (3). The values of Brunauer–Emmett–Teller and Langmuir surface areas are 178 and 185 m2 g–1 for compound 2b, and 995 and 982 m2 g–1 for compound 3. Micropore volumes are 0.065 and 0.350 cm3 g–1 for 2b and 3, respectively. The magnetic properties of compounds 1, 2a, and 2b are consistent with the presence of zero-field splitting and a small antiferromagnetic coupling between the metal atoms. The magnetic properties of the pentanuclear compound 3 were analyzed by considering one monomer with zero-field splitting caused by axially distorted NiII octahedral compounds, and two dimeric fragments with magnetic interactions within each dimetallic unit.