Síntese e estudo de magnetos de íons únicos de metais terras raras e ligantes do tipo oxamato

Abstract

This work describes the synthesis, structural, and magnetic characterization of rare-earth complexes with oxamate-type ligands of the first generation [N-phenyl(oxamate) acid (Hphox), N-2,4,6-trimethylphenyl(oxamate) (Htmpa)] and second generation [N,N'-2,2'- ethylenediphenylenebis(oxamate) (H2edpba)] with the aim of evaluating the potential of these compounds as candidates for spin qubit. The complexes were obtained using the tetrabutylammonium counter-ion (n-Bu₄N⁺) via a one-pot strategy, resulting in the calixarenetype compounds: (n-Bu4N)2[Ln(Hphox)4][Ln(Hphox)4(DMSO)]·DMSO·2H2O [Ln = Ho³⁺ (Hophox), Er³⁺ (Erphox), Yb³⁺ (Ybphox)]; and the inclusion complexes: nBu₄N[Ho(H₂O)(Htmpa)₄]‧3DMSO‧1.64H₂O (Hotmpa); nBu₄N[Er(H₂O)(Htmpa)₄]‧3DMSO‧1.5H₂O (Ertmpa); n-Bu₄N[Yb(Htmpa)₄]‧DMSO‧H₂O (Ybtmpa). Additionally, highly thermally stable compounds were synthesized, such as nBu₄N[Ln(edpba)₂], where Ln = Tb³⁺ (Tbedpba), Dy³⁺ (Dyedpba), Er³⁺ (Eredpba), and Yb³⁺ (Ybedpba). The crystalline structures of Erphox, Hotmpa, Ertmpa, Ybtmpa, Tbedpba, Dyedpba and Eredpba were determined via single-crystal X-ray diffraction. The structural equivalence of the remaining compounds was corroborated by comparing the diffraction patterns obtained from the crystalline structures of a representative compound within the respective series to the patterns from powder X-ray diffraction experiments. The Ho³⁺-based compounds did not exhibit slow relaxation of magnetization. Conversely, the others behaved as single-ion magnets (SIMs) induced by a magnetic field, except for Tbedpba and Dyedpba, which displayed the phenomenon in the absence of an external field. These results suggest that all of SIM evaluated compounds have potential as candidates for spin qudit.