Crystal Structures, Terahertz Spectra and Dye Adsorption Performance of Three Lanthanide-bisphosphonate Complexes Containing Keggin Polyoxometalates

Three lanthanide complexes [LnL_(3)(H_(2)O)]PMo_(12)O_(40)·CH_(3)CN(Ln = Dy^(3+) for 1, Ln = Ho^(3+) for 2, Ln = Lu^(3+) for 3, L = tetraethyl ethylenediphosphonate) have been synthesized, and characterized by single-crystal X-ray diffraction, elemental analysis, IR, PXRD, thermogravimetric analysis and terahertz time-domain spectroscopy(THz-TDS). Structural analysis results show that they have the same coordination mode and similar steric structures. Complexes 1~3 all crystallize in the monoclinic crystal system with space group P2_(1/c). The centered Ln(Ⅲ) obtained a seven-coordinated mononuclear structure by linking with three tetraethyl ethylenediphosphonates and one water molecule, resulting in a three-dimensional supramolecular structure through hydrogen bonding. The three complexes have good adsorption properties for rhodamine B(RhB) in powder state. Moreover, terahertz time-domain spectroscopy(THz-TDS) was applied to represent the structures of complexes and ligands, which will provide useful information for establishing bridge between THz and complex structure in coordination chemistry.