resumo
We report herein the synthesis of three dinuclear Dy III helicates, [Dy III 2 (H 2 L R ) 3 ](NO 3 ) 3 & sdot; xH 2 O ( 1 -3, R = Me, Cl, Br), by reacting Dy(NO 3 ) 3 & sdot; 5H 2 O and three closely related Schiff bases derived from 3-Hydroxy-2-naphthohydrazide and three different 2,6-diformylphenols. Single crystal X-ray structural characterization revealed that all these complexes are isostructural and composed of complex cations of general formula [Dy III 2 (H 2 L R ) 3 ] 3+ , in which three monoanionic Schiff base ligands are wrapped around two Dy III centers, leading to triple-stranded helical structures. Notably, the configuration of monoanionic H 2 L R ligands imparts a coordination-induced chirality on individual complex cation, and the presence of equivalent amounts of enantiopure Lambda and Delta complex cations made the solid products as racemic mixtures, crystalizing in the centrosymmetrical space groups. Variabletemperature magnetic susceptibility measurements have been performed in the temperature range 2 - 300 K for a representative complex 2 , and AC susceptibility studies further disclose the slow relaxation of magnetization in 2 , characteristics for single-molecule magnets.
palavras-chave
X-RAY-STRUCTURE; LANTHANIDE COMPLEXES; RELAXATION; ANISOTROPY; MAGNETIZATION; BLOCKING; DESIGN
categoria
Chemistry
autores
Pramanik, K; Jana, NC; Sun, YC; Brandäo, P; Wang, XY; Saha, A; Panja, A
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) . 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) .