resumo
This report details the synthesis and characterization of heterobimetallic 3d-4f complexes, labeled as 1 and 2, utilizing a new Schiff base ligand derived from the condensation of 2-aminobenzyl alcohol with a methyl-substituted o-vanillin. A comprehensive structural analysis reveals that complex 1 comprises a CoIII-DyIII assembly, bridged by two alkoxide groups, in which the CoIII center adopts an octahedral geometry, and the DyIII ion is situated within a DyO9 coordination sphere. Under nearly identical reaction conditions, an intramolecular nucleophilic attack led to a subtle modification of approximately one-half of the ligand from H2L to HL ', resulting in the isolation of complex 2. This complex features a CoII-DyIII core, bridged by a pivalate ion along with phenoxide groups. To the best of our knowledge, this is a rare instance of dinuclear Co-Dy systems exhibiting variable oxidation states of the cobalt center within a similar ligand framework. Both complexes 1 and 2 exhibit field-induced slow relaxation of magnetization, and theoretical analysis revealed that in complex 1, the principal magnetic axis aligns with the shortest Dy-O bond, underscoring the charge polarization effect exerted by the diamagnetic CoIII ion in tuning the crystal field around the DyIII ion, thereby influencing its magnetic anisotropy. Conversely, in complex 2, the ferromagnetic interaction between the CoII and DyIII ions significantly reduces quantum tunneling of magnetization (QTM). Additionally, we employed quantum theory of atoms in molecules (QT-AIM) calculations to investigate the nature of the coordination bonds in these 3d-4f complexes, which provided insights into the crystal field strength around the LnIII ions and their subsequent magnetic anisotropy. This study broadens the exploration of Schiff base-derived 3d-4f complexes and their magnetic properties, highlighting the potential for further advancements in this field.
palavras-chave
BASIS-SETS; CO-II; LANTHANIDE COMPLEXES; SLOW RELAXATION; GROUND-STATE; DY-III; VALENCE; ION; ANISOTROPY; TB
categoria
Chemistry
autores
Panja, A; Jaglicic, Z; Herchel, R; Jana, NC; Brandao, P; Pramanik, K
nossos autores
Paula Cristina Ferreira da Silva Brandão
Investigador AuxiliarProjectos
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
agradecimentos
A. P. gratefully acknowledges the financial support of this work by the CSIR, New Delhi, India (Sanction no. 01/3118/23/EMR-II dated 08.07.23). Z. J. acknowledges the financial support of the Slovenian Research Agency (Grant No. P2-0348). R. H. acknowledges financial support from the Czech Science Foundation (GACR 23-07175S). P. B. gratefully acknowledges the financial support of this work by the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by National funds through the FCT/MCTES (PIDDAC).