Syntheses, structures and photophysical properties of series of Ln coordination polymers (Ln=Yb, Ho, Er)

Three coordination polymers [Ln(NH2-C6H4-COO)(2)DMF(HCOO)(H2O)](n) (Ln=Yb 1,Ho 2, Er 3) were synthesized by the hydrothermal method and characterized by single-crystal X-ray diffraction, IR pectra, UV-Vis-NIR absorption spectra and the emission spectra (UV-Vis fluorescence and NIR emission spectra). Complexes 1 similar to 3 are isomorphous and crystallized in the monoclinic crystal system and No.14 space group. The structural analysis shows that the three complexes are 1D chain polymers. In their crystals, there are many hydrogen bands, through which 1D chain polymers are further extended to 3D network structures. In comparison with UV-Vis-NIR absorption spectra and the NIR emission spectra of complexes, we make reasonable explanation and assignment to the shift and splitting of emission bands in the NIR region. CCDC: 722575, 1; 722573, 2; 722574, 3.