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 Δ S m can attain 23.40 J kg -1 K -1 (44.90 mJ cm -3 K -1 ) at about 3 K and Δ H = 7 T. Besides, fluorescence measurements of {Tb 8 Cr 4 } display typical characteristic Tb-based luminescence.