Ligand ratio/solvent-influenced syntheses, crystal structures, and magnetic properties of polydentate Schiff base ligand-Dy(iii) compounds with β-diketonate ligands as co-ligands

Abstract

Tuning the synthesis conditions and further regulating the magnetic dynamics of single-molecule magnets (SMMs) are crucial challenges for chemists. Some feasible approaches have been developed to understand magneto-structural correlations and regulate relaxation behaviors via rational design. Based on the solvent-induced effect or ligand ratio regulation, three new dysprosium(III) coordination compounds, [Dy(L)(Dppd)]·solvent (1), [Dy(L)(Dppd)] (2) and [Dy(L)(Dppd)₂]·solvent (3) (H₂L = N,N′-bis(2-hydroxy-5-methyl-3-formylbenzyl)-N,N′-bis-(pyridin-2-ylmethyl)ethylenediamine, Dppd = dibenzoylmethane) have been successfully prepared. Compounds 1 and 2 are mononuclear structures. 3 is a dinuclear core in which the metal centers are bridged by two phenol-O atoms of one L²⁻ ligand. Dy(III) cations in compounds 1–3 present acta-coordination geometries. More interestingly, compounds 1 and 2 can be mutually transformed through the reversible single-crystal-to-single-crystal (SCSC) transformation under different solvent environments. The crystals of 1 and 2 underwent a dissolution–precipitation process and changed into 3, respectively. The distinct structures and magnetic properties were determined through combined structural, experimental and theoretical investigations.