Estudio de nuevos sistemas supramoleculares basados en interacciones Au(I)-Pb(II) no soportadas stars

Abstract

The present work is devoted to the synthesis and study of the properties of new heterometallic lead(II) and gold(I) complexes containing polydentate nitrogen donor molecules and perhalophenyl groups, respectively, as ligands. Their characterization has been carried out through the usual techniques, in addition to through single crystal X-ray diffraction studies on a large number of cases. The crystal structures of these compounds have confirmed the presence of unsupported gold(I)·lead(II) interactions, very scarcely represented till the beginning of this work, in addition to aurophilic interactions in some cases. Theoretical studies on models based on the crystal structures have allowed us to analyze the relationship between the optical properties that these new derivatives present and their structures. This dissertation is divided in three chapters: The first chapter gathers the synthesis of heterometallic lead(II) and gold(I) compounds with different perhalophenyl groups (C6F5, 3,5-C6Cl2F3, C6Cl5, o-C6BrF4, o-C6F4I, p-C6BrF4 y p-C6F4I) bonded to the gold centers, as well as different donor nitrogen ligands (neocuproine, terpyridine and tetra-2-pyridinilpyrazine) coordinated to lead with the aim to analyze the possible influence of both types of ligands in the stoichiometry, structure and properties of the new derivatives synthesized, observing the formation of complexes of different nuclearity depending on the ligands employed, as well as the presence of different types of weak interactions as a function of the substituents in the aryl groups. Furthermore, a dependence of the optical properties, on which theoretical studies have been developed with the aim to understand their nature, on the ligands has been observed. In the second chapter, a couple of derivatives with pentafluorophenyl and terpyridine groups bonded to gold and lead, respectively, have been designed and subsequently employed as if they were puzzle pieces to the controlled preparation of a decanuclear Au6Pb4 complex in which the building blocks are joined together through unsupported metallophilic interactions. Besides, one of these compounds exhibits a vapochromic reversible behavior against vapors of different small organic molecules, thus being a posible candidate to be employed as a volatile organic compounds (VOCs) sensor. In this chapter, the results obtained from the X-ray diffraction study at different pressures (between 0 and 2.1 GPa) carried out on some of the new derivatives in order to analyze the effect of this external factor in their crystal structures, and therefore, in their optical properties, merits a special mention. As in the previous chapter, theoretical studies that allow us to understand the origin of the emissive properties that these new complexes display are included. The third and last chapter of this work is devoted to another type of supramolecular compounds, host-guest inclusion compounds. Thus, we were initially focused on the design and synthesis of trinuclear perhalophenyl gold(I) compounds with a tris(pyrazolyl)borate bridging ligand that can behave as organometallic host, studying the influence of the perhalophenyl groups bonded to gold in the size of the cavity of the host. Subsequently, these compounds were treated with a tris(pyrazolyl)borate lead complex likely to act as a guest, accommodating this compound within the host cavity, thus forming novel supramolecular host-guest complexes in which both parts are kept together thanks a series of weak interactions, among them standing out gold···lead contacts and non-conventional B-H·Pb hydrogen bonds. In addition, this chapter is completed with the theoretical study of the interactions present in this system to allow the encapsulation and accommodation of the guest molecule.