Near-infrared luminescence and magnetism of several lanthanide polymers by biphenyl carboxylic acid ligand

Abstract

Several new non-centrosymmetric coordination polymers incorporating a conjugated ligand of biphenyl-2,3,3′,5′-tetracarboxylic acid (H4bptc), namely, {[Tm(μ6-bptc) (H2O)2]·H2O}n (1-Tm), {[Nd(μ6-bptc) (H2O)3]}n (2-Nd), {[Pr(μ6-bptc) (H2O)2]·H2O }n (3-Pr), and {[Ho(μ6-bptc) (H2O)2]·H2O}n (4-Ho) have been successfully synthesized by hydrothermal method and characterized by elemental analysis, IR, TG and PXRD studies, and their structures were determined by X-ray diffractometer. The solid NIR- fluorescence properties and variable temperature susceptibility were also discussed in detail. All the four compounds showed very obvious luminescence emission in the near infrared region and their lifetime are sizable. The variable-temperature magnetic susceptibility of these four lanthanide complexes are different and the reasons are also given by literature analysis.