Estudo do controle da dimensionalidade de nanomagnetos moleculares via química supramolecular

Abstract

This work concerns the syntheses and study of magnetic properties of molecular systems which the dimensionality was controlled, and furthermore, presents the study of interactions between molecular systems and carbon nanotubes. lnitially were described thesyntheses and characterization of the capping ligand tris(2-pyridylmethyl)amine (tpa) and the bridging ligands: saol-l-, Me-saol-í-, Et-saofl-, Ph-saolI-, (sao = salicylaldoxime); orthophenilenebis(oxamato) (opba); and 4,5-dinitro-l ,2-phenilenebis( oxamato) (opba-dN), and its precursors 1,2-bis(p-tosylamine )benzene, 1,2-dinitro-4,5-bis(p-tosylamine )benzene and 1,2- dinitro-4,5-diaminobenzene. Also, the procedures to prepare the molecular magnets precursors (BU4N)2[Cu(opba)] and (Bli4N)2[Cu(opba-dN)] were described. These compoundsinitially obtained were used to prepare di-, tri- and polynuclear systems;: with homo- and heterometalic centres. The dinuclear systems [Mn20(sao)(tpah](Cl04h, [Mn20(Etsao)(tpa)2](Cl04)2 and [Mn-Ofl'h-sao )(tpa)2](Cl04)2 showed antiferromagnetic interactionsbetween the metal ions. Unlike the other dinuclear systems, the compound [Mn20(Mesao)(tpa)2](CI04)2 showed ferromagnetic interactions. For these dinuclear compounds it was the tpa ligand the responsible for dimensionality control. ln addition it was presented the synthesis and characterization of a trinuclear system, with formula (BU4N)2[CU{Cu(opbadN) h](DMSO)4 and free coordination sites on both sides, which could be used as a building block on the preparation of other molecular systems. Other compounds showing differentdimensionalities was also obtained: the pentanuclear systems [Co{Co(tpa)Cu(opba)}zCh] and [Mn{Mn(tpa)Cu(opba)hCb], and the heptanuclear system [Co{Co(tpa)Cu(opba)h(Cl04)2]. ln another step of this work, systems containing carbon nanotubes and copper and manganese ions were prepared. For the system SWNTs-(Bli4N)2[Cu(opba)] (SWNT = single walled carbon nanotube) were investigated for the first time the electronic interactions betweenSWNT and a oxamato based compound. For the other systems, scanning electron microscopy was carried out. The images indicated some rounded shape aggregation, tangled on the SWNT bundles, which was identified as metallic complexes formed on the carbon nanotubes surface.