Two kinds of 2,4-dichlorobenzoate-based lanthanide coordination polymers tuned by 4,4′-bipyridine: Syntheses, structures, photoluminescence, and magnetism

Ln(NO3)(3)center dot nH(2)O reacted with 2,4-dichlorobenzoic acid (2,4-HDCB) and NaOH under solvothermal conditions of water and ethanol to yield four lanthanide-organic coordination polymers (CPs) [Eu(2,4-DCB)(3)(CH3CH2OH)(2)] (1) and [Ln(2,4-DCB)(3)(H2O)] [Ln = Gd (2), Tb (3), Dy (4)]. The second ligand 4,4'-bipyridine (4,4'-bpy) was introduced into the above reaction systems to provide four new lanthanide-organic CPs [Ln(2)(2,4-DCB)(6)(4,4'-bpy)(H2O)(2)] [Ln = Eu (5), Gd (6), Tb (7), Dy (8)]. Single-crystal and powder X-ray diffraction analyses reveal that CPs 1 and 2 possess similar one-dimensional (1D) structures, and CPs 2-4 and 5-8 are isostructural, respectively. In 1-4, the 2,4-DCB anions bridge the Ln(III) ions to form a 1D chain. In 5-8, six 2,4-DCB anions link two Ln(III) ions into a binuclear Ln(2)(2,4-DCB)(6) unit, and the Ln(2)(2,4-DCB)(6) units are further connected by the 4,4'-bpy co-ligands to generate a 1D chain. The photoluminescent and magnetic properties of 1-8 were investigated.