A series of heterobimetallic Ni(II)–Ln(III) (Ln = La, Ce, Pr and Nd) coordination polymers derived from 3-EtOsalamo and dicarboxylates: syntheses, crystal structures and fluorescence properties

Abstract

Four coordination polymers ∞2 [Ni(DMF)(L)Ln(bdc)1.5] (Ln = La (1) and Nd (4)) and ∞2 [Ni2(DMF)2(L)2Ln2(bdc)3]·CH3OH (Ln = Ce (2) and Pr (3)) were derived from a symmetrical salamo-based ligand (H2L) with Ni(OAc)2·4H2O, Ln(NO3)3·6H2O (Ln = La, Ce, Pr and Nd), and H2bdc (terephthalic acid). Coordination polymers 1–4 were synthesized and characterized by elemental analyses, X-ray single crystal diffraction, infrared spectroscopy and ultraviolet–visible absorption spectroscopy. Coordination polymers 1–4 have similar structures exhibiting two-dimensional coordination polymers with brick wall in which [Ni(DMF)(L)Ln] units were linked by exodentate (bdc)2− linker. In each unit, Ni(II) atoms adopted a slightly distorted octahedral geometry, the Ln(III) atoms were nine-coordinated, and the coordination polyhedron was a distorted tricapped trigonal prism. The crystal structure and supramolecular features were discussed in detail. At the same time, the fluorescent properties of coordination polymers 1–4 were also investigated.