Efficient dye degradation and THz spectra of {PMo12} based rare earth phosphine oxide complexes

Abstract

In today's world, water pollution is a serious problem. Dye adsorption and photocatalytic degradation are effective methods to deal with water pollution. The key to dealing with water pollution is to find suitable adsorbents and catalysts. We synthesized a series of rare earth complexes containing [PMo₁₂O₄₀]³⁻ and a PO ligand, [REL₄](PMo₁₂O₄₀)·nCH₃CN (RE = La for 1, Ce for 2, Pr for 3, Sm for 4, Eu for 5, Gd for 6, and Tb for 7; n_1,2,3,5,6 = 2 and n_4,7 = 0; L = tetraethyl ethylenediphosphonate), and [REL₃(H₂O)](PMo₁₂O₄₀)·CH₃CN (RE = Tm for 8, Yb for 9, and Y for 10). Complexes 1–7 are all eight-coordinated mononuclear structures centered on lanthanide ions, [PMo₁₂O₄₀]³⁻ anions and solvent molecules are not coordinated with metal ions, while complexes 8–10 are seven-coordinated mononuclear structures. These mononuclear structures eventually form complicated 3D supramolecular structures through hydrogen bond weak interactions. These complexes have good adsorption properties for rhodamine B (RhB) and can degrade methylene blue (MB) under UV irradiation. Furthermore, terahertz time-domain spectroscopy (THz-TDS) is used to characterize the structures of complexes and ligands, which will provide useful information for building bridges between THz spectra and the structures of complexes in coordination chemistry.