Synthesis, structure and fluorescence of Er(III) complexes with benzoic acid and 4-chlorobenzoic acid

•The single crystal structure of the complexes has been analyzed.•The lanthanide-organic complexes are well thermally stable.•The IR emission of Er has been greatly sensitized by the ligand.

Two complexes with benzoic acid (BA) and 4-chlorobenzoic acid (CBA) as ligands and trivalent erbium ion as central ion, [Er2(BA)6(DMF)2(H2O)2], DMF = N, N-dimethylformamide, C3H7NO, (Er-BA) (1) and [Er2(CBA)6(DMF)2(H2O)2] (Er-CBA) (2), have been synthesized by hydrothermal method. The complexes were characterized by single-crystal X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectra, ultraviolet–visible (UV–Vis) absorption spectra, thermogravimetric analysis (TGA) and photoluminescence (PL). The XRD results indicate that each erbium ion is coordinated by eight oxygen atoms in a trigonal dodecahedron. The TGA results show that the complexes are well thermally stable. PL spectra illustrate that the ligand of BA can sensitize erbium ions effectively, hence the complexes show intense emission in near infrared region, which makes the complex as a potential emitting material for bio-labeling and fiber communication.

Graphical abstractThe erbium ion in the complex is bridged by eight oxygen atoms respectively in a trigonal dodecahedron. The complex has been greatly sensitized by the ligand and intense NIR emission of Er3+ is recorded.Figure optionsDownload full-size imageDownload as PowerPoint slide