RT info:eu-repo/semantics/masterThesis
T1 New luminescent metal-organic frameworks
A1 Varela Núñez, Carla
K1 Nanociencia, Nanotecnología Molecular
AB The present master thesis entitled New Luminescent Metal-Organic Frameworksfocuses on the synthesis and characterization of several new metal–organic frameworks (MOFs), which are a kind of organic-inorganic hybridcompounds with one-, two-, or three-dimensional structural topologies consistingof inorganic metal ions/clusters and organic ligands. The relevance ofthe new MOFs synthesized dwells in the luminescence properties that theyexhibit.The construction of new MOFs has been rapidly developed in recentyears, not only due to their interesting molecular topologies and crystalpacking motifs but also due to their potential applications as functional materials.MOFs can be readily synthesized from the self-assembly of metalion nodes with organic ligands. Multi-carboxylic acids have been widelyused to synthesize high dimensional frameworks. In particular, 1,2,4,5-benzenetetracarboxylate is a versatile ligand that leads to numerous differentcoordination polymers with lanthanide ions.Among the wide variety of properties of interest that a given material canexhibit, luminescence is attracting an increasing attention due to its potentialapplication in optical devices for lighting equipment and optical storage, optical switching, and sensing. At this respect, luminescent metal–organicframeworks (LMOFs) are a quickly growing class of crystalline materials withgreat potential for use across a broad range of applications. The lanthanideelements, which possess partially filled 4f orbitals, can form coordinationpolymers that exhibit various coordination geometries even with the sameligand.An extensive work has been carried out using 1,2,4,5-benzenetetracarboxylicacid (H4bta) as ligand and 1,2-di(4-pyridyl)-ethylene (bpe), 1,2,4-triazole (tz), imidazole (im) and 4,4’-azobis(pyridine) (azpy) in order to performcation exchanges. Several lanthanide coordination polymers with goodluminescence properties have been synthesized by hydrothermal method, andan investigation on the formation of lanthanide coordination compoundsbased on the use of cation exchange has also been performed. The sevenLMOFs prepared are, specifically: [Ln(bta)][(CH2)2NH2] (Ln=Tb (1), Ln=Pr(2)), [Ln(bta)]2(bpe) (Ln= Tb (3), Ln=Pr (4)), [Tb(bta)](im) (5), [Tb(bta)]2(azpy) (6), and [Tb(bta)](tz) (7).Single-crystal X-ray diffraction reveals that complex 1 crystallizes in theto orthorhombic space group P212121, while complexes 2 and 3 in the triclinicspace group P-1. The Pr-complexes obtained are isostructural as deducedby means of single crystal and powder X-ray diffraction analysis, unlikeTb-complexes, which are found to possess different crystal structures. Luminescencemeasurements reveal that the Tb3+ compounds exhibit severalstrong characteristic emission bands for isolated Tb3+ ions in the visible regionwhen excited between 320 and 375 nm; similarly, the Pr3+ compoundsdisplay the characteristic emission bands for isolated Pr3+ ions.
YR 2018
FD 2018
LK http://riull.ull.es/xmlui/handle/915/11197
UL http://riull.ull.es/xmlui/handle/915/11197
LA es
DS Repositorio institucional de la Universidad de La Laguna
RD 26-dic-2024