Influence of ligand substitution and the solvent effect on the structures and magnetic properties of dinuclear Dy supramolecular architectures constructed with the bis-β-diketonate-Dy building block as a metalloligand.

Based on the bis-β-diketonate-Dy metalloligand [Dy(pbth)]·2EtN (1, pbth = (3z,3'z)-4,4'-(1,3-phenylene)bis(1,1,1-trifluoro-4-hydroxybut-3-en-2-one)), six dinuclear complexes with eight-coordinated geometries were synthesized solvothermally through different capping N-donor coligands or solvent systems. These complexes are namely [Dy(pbth)(Phen)]·2CHOH (2), [Dy(pbth)(BPhen)]·2CHOH (3), [Dy(pbth)(Dppz)]·2CHOH (4), [Dy(pbth)(Dppz)]·2CHOH (4a), [Dy(pbth)(4-Dmbp)]·CHOH·CHOH (5) and [Dy(pbth)(5-Dmbp)]·CHOH (6) (Phen = 1,10-phenanthroline, BPhen = 4,7-diphenyl-1,10-phenanthroline, dppz = dipyrido [3,2-:2',3'-] phenazine, 4-Dmbp = 4,4'-dimethyl-2,2'-bipyridyl, 5-Dmbp = 5,5'-dimethyl-2,2'-bipyridyl), respectively. In the synthetic processes of 2-6, one of four bis-β-diketonate ligands in the metalloligand is replaced by two capping N-donor coligands. The coordination geometries, metal distances and M-L-M torsion angles of the synthesized complexes are perceptibly fine-tuned by the modification of the capping N-donor coligands or the latticed solvent molecules. Systematic magnetic investigations indicate the different magnetic relaxation dynamics of 1-6. Complex 1 displays no characteristics of single-molecule magnets (SMMs), while complexes 2-6 exhibit SMM behaviours in the absence of a static magnetic field. Complexes 2 and 3 possess effective energy barriers () of 110.18 (2) K and 133.21 (4) K, respectively. Theoretical analysis based on calculation provides some interpretations of experimental observation.