Dysprosium(iii) compounds assembled via a versatile ligand incorporating salicylic hydrazide and 8-hydroxyquinolin units: syntheses, structures and magnetic properties

Abstract

Assembly of dysprosium(III) salts with a multidentate ligand H₃L ((2-hydroxy)-N′-((8-hydroxyquinolin-2-yl)methylene)-benzohydrazide) affords a variety of products with different topological structures, namely [Dy(H₂L)(HL)]·CH₃OH (1), [Dy₂(HL)₂(C₆H₅COO)₂(CH₃OH)₂]·3CH₃OH (2), [Dy₂(HL)₂(NO₃)₂(DMF)₄]·4DMF (3), [Dy₄L₄(CH₃OH)₄]·2CH₃OH·4H₂O (4) and ([Dy₄(HL)₄(C₆H₅COO)₄(CH₃OH)(H₂O)]·2CH₃OH·CH₃CN·H₂O)_n (5). The versatile and flexible coordination modes of phenoxo groups from salicylic hydrazide prove to be a key factor in the assembly of corresponding structures depending upon the reaction conditions. It is noteworthy that ligands HL²⁻ act as a long-distance link and further connect the Dy₂ fragments into an infinite 1D chain due to the conformational flexibility resulting from the rotatable C–C bond in 5. Furthermore, the magnetic measurements were performed on all complexes. The dc magnetic susceptibility data evidence distinct magnetic coupling interactions in the dinuclear complexes 2 (antiferromagnetic) and 3 (ferromagnetic) despite their similar structures, and only complex 3 shows slow relaxation behavior of magnetization. Ab initio calculations and electrostatic potential analysis on complexes 2, 3, and three other complexes (6, 7, 8) incorporating different kinds of ligands reveal the important interrelationship of magnetic anisotropy, magnetic coupling interactions and SMM properties.