Syntheses, structures and near-infrared luminescent properties of a series of Ln(III) coordination polymers

Using aromatic carboxylic acids as main ligands, four Ln(III) coordination polymers, [Er(CH3C6H4COO)(2)(Ac)(H2O)](n) (1), [Yb(beta-C10H7COO)(2)(Ac)(H2O)](n) (2), [Nd(C9H7O2)(3)](n) (3) and [Ho(C9H7O2)(3)](n) (4) (CH3C6H4COO = p-toluylate, Ac = acetate, beta-C10H7COO = beta-naphthoyloxy, C9H7O2 = cinnamate), were synthesized by hydrothermal method and their structures were studied by single-crystal X-ray diffraction. Polymers 1 and 2 possess 2D layer structures, and polymers 3 and 4 possess 1D chain structures. At room temperature in the solid state, the IR. UV-Vis-NIR spectra and the emission spectra in the visible and near-infrared (NIR) regions of the four polymers were determined. In the NIR region, polymers 1-4 show characteristic emission bands of the corresponding Ln(III) ions which exhibit shift, splitting or broadness in comparison with their theoretical emission bands. This can be confirmed by their UV-Vis-NIR spectra and discussed emphatically. (C) 2012 Elsevier B.V. All rights reserved.