Synthesis, crystal structures and magnetic properties of two heterometallic {Ln(8)Cr(4)} (Ln = Gd(3+) and Tb(3+)) complexes with one-dimensional wave chain structure

Two isomorphic heterometallic 3d–4f cluster-based materials, formulated [Gd(8)Cr(4)(IN)(18)(μ(3)-O)(2)(μ(3)-OH)(6)(μ(4)-O)(4)(H(2)O)(10)]·13H(2)O (1) and [Tb(8)Cr(4)(IN)(18)(μ(3)-O)(2)(μ(3)-OH)(6)(μ(4)-O)(4)(H(2)O)(10)]·13H(2)O (2) (abbreviation: {Ln(8)Cr(4)}: Ln = Gd(3+) (1); Tb(3+) (2); HIN = isonicotinic acid), were achieved by hydro-/solvothermal method through using the ligand HIN. X-ray diffraction analysis illustrates eight lanthanide ions (Ln = Gd(3+), Tb(3+)) and four transition-metal ions (Cr(3+)) of {Ln(8)Cr(4)} were constructed from two classical “drum-like” {Ln(4)Cr(2)} structures associated by organic ligands HIN, displaying a one-dimensional wave chain structure, which is rare. The magnetic properties of {Gd(8)Cr(4)} were inspected and showed the existence of antiferromagnetic coupling interactions between contiguous metal ions. On top of this, the magnetic entropy change of ΔS(m) 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 {Tb(8)Cr(4)} display typical characteristic Tb-based luminescence.