resumo
In the last two decades, efforts have been devoted to obtaining insight into the magnetic interactions between Cu-II and Ln(III) utilizing experimental and theoretical means. Experimentally, it has been observed that the exchange coupling (J) in Cu-II-Ln(III) systems is often found to be ferromagnetic for >= 4f(7) metal ions. However, exchange interactions at sub-Kelvin temperatures between Cu-II and the anisotropic/isotropic Ln(III) ions are not often explored. In this report, we have synthesized a series of heterobimetallic [CuLn(HL)(mu-piv)(piv)(2)] complexes (Ln(III) = Gd (1), Tb (2), Dy (3) and Er (4)) from a new compartmental Schiff base ligand, N,N'-bis(3-methoxy-5-methylsalicylidene)-1,3-diamino-2-propanol (H3L). X-ray crystallographic analysis reveals that all four complexes are isostructural and isomorphous. Magnetic susceptibility measurements reveal a ferromagnetic coupling between the Cu-II ion and its respective Ln(III) ion for all the complexes, as often observed. Moreover, mu-SQUID studies, at sub-Kelvin temperatures, show S-shaped hysteresis loops indicating the presence of antiferromagnetic coupling in complexes 1-3. The antiferromagnetic interaction is explained by considering the shortest Cu & ctdot;Cu distance in the crystal structure. The nearly closed loops for 1-3 highlight their fast relaxation characteristics, while the opened loops for 4 might arise from intermolecular ordering. CASSCF calculations allow the quantitative assessment of the interactions, which are further supported by BS-DFT calculations.
palavras-chave
SINGLE-MOLECULE MAGNETS; BASIS-SETS; EXCHANGE INTERACTIONS; DY-III; COPPER(II)-GADOLINIUM(III) COMPLEXES; LANTHANIDE COMPLEXES; TB-III; GD-III; CU-II; CO-II
categoria
Chemistry
autores
Panja, A; Paul, S; Moreno-Pineda, E; Herchel, R; Jana, NC; Brandao, P; Novitchi, G; Wernsdorfer, W
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). E. M.-P. is thankful for the support from the Panamanian National System of Investigators (SNI, SENACYT). P. B. gratefully acknowledges the financial support for this work by the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 and LA/P/0006/2020, financed by national funds through the FCT/MCTES (PIDDAC). We acknowledge the DFG-CRC 1573 "4f for the future". W. W. acknowledges the A. v. Humboldt Foundation and the ERC grant MoQuOS No. 741276. R. H. acknowledges the financial support from the institutional sources of the Department of Inorganic Chemistry, Palack & yacute; University Olomouc, Czech Republic.