Síntesis de nuevos materiales magnéticos multifuncionales con ligandos aromáticos polioxamato

The main goal of this Ph.D thesis concerns the synthesis of multifunctional magnetic coordination polymers with oxamato ligands, which is one of the most challenging topics for chemists and physicists working together in the multidisciplinary field of materials chemistry. In order to do so, we have taken advantage of the new developments of metallosupramolecular chemistry, in particular the molecular-programmed self-assembly methods that exploit the coordination preferences of metal ions and specifically tailored ligands. In this sense, the judicious choice of the appropriate oxamato-based metal building block (substitution pattern and steric requirements of the bridging ligand, as well as the electronic configuration and magnetic anisotropy of the metal ion) allowed us to control the different structural topologies as well as the interesting and predictable magnetic properties in the final compounds. Interestingly, most of the synthesized coordination polymers are anionic. Thus, we can, tentatively, insert an additional physical property (to the magnetic ones) by using the appropriate countercation. The results obtained along this Ph.D thesis are divided in three different chapters according to the dimensionality of the coordination polymer. Furthermore, each chapter is subdivided in two parts (A and B) depending on the properties exhibited by the compounds (Chapter I) and the nature of the precursor used to synthesized the coordination polymers (Chapters II and III). Chapter I has been divided in two parts in accordance with the properties of the one-dimensional compounds. Thus, in the first part we present the synthesis of a new family of neutral oxamato-bridged heterobimetallic chains MIICuII (M = Mn and Co) prepared by treating the corresponding anionic oxamatocopper(II) complexes with 3d cations using DMF or DMSO as solvents. Interestingly, this family of heterobimetallic chains provides several examples of Single Chain Magnets (SCMs), where the nature of the corresponding transition metal as well as the substitution pattern of the bridging ligand on the SCM behaviour were studied. In the second part of this chapter we prepared a new series of neutral oxamato-bridged heterobimetallic chiral chains MIICuII (M = Mn and Co), where only the enantiopure CoIICuII chains showed slow magnetic relaxation at low temperatures, which is characteristic of SCMs. Furthermore, solid circular dichroism (CD) spectra of the bimetallic chain compounds were recorded in order to establish their chiral and enantiomeric nature. As each couple of enantiomeric chains are non superimposable mirror images, they exhibit maximum positive and negative Cotton effects, constituting the first examples of enantiopure SCMs. In the second chapter, we present several two- (2D) and three-dimensional (3D) coordination polymers exhibiting different architectures and magnetic properties, that can somehow be controlled by means of the appropriate choice of the precursor and the metal ion used to build them. Furthermore, we present for the first time in oxamato-based compounds the porous properties of some of them. At this respect, in the first part of this chapter we explain the influence of the metal ions and the monooxamatocopper(II) complexes on the topology and the magnetic properties of the synthesized coordination polymers. In the second part we describe a family of heterobimetallic MIICuII (M = Mn and Co) bidimensional coordination polymers obtained by reaction of the corresponding dinuclear bis-oxamatocopper(II) complexes with the metal ions. Additionally, in this family we studied the influence of the substitution pattern of the bridging ligand on the magnetic properties. The last chapter is devoted to the introduction of multifunctionality in oxamato-based systems. It has been divided again in two parts in accordance with the nature of the precursor used to synthesize the multifunctional coordination polymer. Anyway both parts have a common background consisting on the use of the complex as ligand strategy in order to build the anionic inorganic network, the other physical property being brought by the organic countercation. At this respect, in the first part we focus on the use the monooxamatocopper(II) precursor complexes with different functional countercations, which added the new property, toward manganese(II) ions to obtain the corresponding bi- and tridimensional compounds that encapsulate the non-innocent counteractions. Similarly, in the second part we describe the synthesis of the same kind of multifunctional 2D and 3D polymers by using dinuclear oxamato-copper(II) precursors instead of the mononuclear ones. For example, herein we report the first oxamato-based examples of: (i) chiral magnets, (ii) luminescent magnets, (iii) porous magnets showing sorption properties and (iv) a porous magnet showing a solvatomagnetic switching