Syntheses and properties of two types of linear tetranuclear heterometallic clusters with identical formulas but different structures

Abstract

Eight 3d-4f heterometallic complexes, Ln2Ni2(3,4-DCB)10(phen)2 [Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6), Er (7) and Yb (8)], were successfully prepared through the self-assembly reactions of Ln(NO3)3·nH2O, NiCl2·6H2O, 3,4-dichlorobenzoic acid (3,4-HDCB), NaOH and 1,10-phenanthroline (phen) under solvothermal conditions. These eight complexes were characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). Complexes 1–8 have identical formulas, but different molecular structures. Complexes 1–6 and 7–8 are isostructural. In 1–8, the 3,4-DCB anions link the Ni(II) and Ln(III) ions by different coordination modes to form two types of linear tetranuclear heterometallic clusters. Adjacent tetranuclear clusters are connected by π–π interactions between 3,4-DCB and phen into a one-dimensional (1D) supramolecular chain. The photoluminescent properties of 3 and the magnetic properties of 1–2 and 4–8 were investigated.