Synthesis, structures, luminescence and terahertz time-domain spectroscopy of seven lanthanide complexes with tetrakis(O-isopropyl)methylenediphosphonate and 1,10-phenanthroline

Seven lanthanide–organic frameworks [(CeCl2L(phen))2(μ-Cl)2]·CH3CN (1) (L = tetrakis(O-isopropyl)methylenediphosphonate, phen = 1,10-phenanthroline) and [LnCl(H2O)3L(phen)]·nCH3CN (n = 0 for 2, n = 2 for 3, n = 1.5 for 4, n = 0 for 5, n = 1.5 for 6, n = 1.5 for 7) (Ln = Dy, Ho, Er, Tm, Yb, Lu for 2–7, respectively) have been synthesized by the reaction of lanthanide chlorides, the ligand L and phen in acetonitrile at room temperature. These title complexes were characterized by IR, elemental analyses, single-crystal X-ray diffraction analysis, luminescence, thermal analysis, 1H NMR and 31P NMR spectroscopy. The complex [(CeCl2Lphen)2(μ-Cl)2]·CH3CN (1) is a dinuclear compound and displays a two-dimensional mesh 63 topology formed by π–π interactions. Complexes 2–7 can be simplified as having a two-dimensional mesh 4.82 topology formed by hydrogen bonds (C–H⋯Cl and O–H⋯Cl). These interesting structures are rarely found. We found a fluorescence quenching phenomenon which may be due to the presence of crystalline water molecules and solvent. Their terahertz (THz) time-domain spectroscopy was also studied.