Synthesis, crystal structures and magnetic properties of two heterometallic {Ln8Cr4} (Ln = Gd3+ and Tb3+) complexes with one-dimensional wave chain structure

Two isomorphic heterometallic 3d–4f cluster-based materials, formulated [Gd8Cr4(IN)18(μ3-O)2(μ3-OH)6(μ4-O)4(H2O)10]·13H2O (1) and [Tb8Cr4(IN)18(μ3-O)2(μ3-OH)6(μ4-O)4(H2O)10]·13H2O (2) (abbreviation: {Ln8Cr4}: Ln = Gd3+ (1); Tb3+ (2); HIN = isonicotinic acid), were achieved by hydro-/solvothermal method through using the ligand HIN. X-ray diffraction analysis illustrates eight lanthanide ions (Ln = Gd3+, Tb3+) and four transition-metal ions (Cr3+) of {Ln8Cr4} were constructed from two classical “drum-like” {Ln4Cr2} structures associated by organic ligands HIN, displaying a one-dimensional wave chain structure, which is rare. The magnetic properties of {Gd8Cr4} were inspected and showed the existence of antiferromagnetic coupling interactions between contiguous metal ions. On top of this, the magnetic entropy change of ΔSm can attain 23.40 J kg−1 K−1 (44.90 mJ cm−3 K−1) at about 3 K and ΔH = 7 T. Besides, fluorescence measurements of {Tb8Cr4} display typical characteristic Tb-based luminescence.