Hydrothermal syntheses and crystal structures of four novel lanthanide(III) complexes based on two mixed N,O-donor ligands

Synthesis, structures and properties of six lanthanide complexes based on a 2-(2-carboxyphenyl)imidazo(4,5-f)-(1,10)phenanthroline ligand

Six lanthanide complexes [Tb(2-NCP)₂(NO₃)]_n (1), [Eu(2-NCP)₂(3-PYC)]_n (2), [Sm(2-NCP)₂(3-PYC)]_n (3), [Eu(2-NCP)(SA)]_n (4), [Tb(2-NCP)(SA)]_n (5) and [Tb(2-NCP)(AA)]_n (6) (2-HNCP = 2-(2-carboxyphenyl)imidazo(4,5-f)-(1,10)phenanthroline, 3-HPYC = pyridine-3-carboxylic acid, H₂SA = succinic acid, H₂AA = adipic acid) have been synthesized by hydrothermal route, and the crystal structures were analyzed through elemental analysis, infrared spectroscopy, single crystal X-ray diffraction. Complexes 1 and 6 present two-dimensional (2D) layers, which are further connected to three-dimensional (3D) supramolecular architectures through C–H⋯π interactions. Complexes 2 and 3 exhibit infinite one-dimensional chains. Finally, the neighboring chains are packed by C–H⋯π interactions, giving rise to 3D supramolecular network. Complexes 4 and 5 display 2D layers, which are further extend to 3D supramolecular structures via C–H⋯O intermolecular hydrogen bonding. Six complexes possess good thermal stabilities, characteristic photoluminescence properties, and photocatalytic activities for the degradation of organic dyes under visible light irradiation. In addition, the complex 6 exhibits significantly enhanced photocatalytic activity for methylene blue, and the degradation rate could reach 81.2% in 370 min. Meanwhile trapping experiments indicated that the hole, ·O₂⁻ and ·OH are the main activated species. Furthermore, by comparing the photoluminescent and photocatalytic mutation results of same metal complexes induced by interconversion of coligands, we confirm that the properties mutation induced by coligands is much obvious and controllable.

Six lanthanide complexes based on 2-HNCP possess good thermal stabilities, characteristic photoluminescence properties, and photocatalytic activities for organic dyes degradation under visible light irradiation.

Lanthanide(III) complex metal-organic frameworks with a phenanthroline-carboxylate derivate and 2,5-thiophenedicarboxylate coligand: hydrothermal synthesis, crystal structure, and high thermostability

Based on 2-(4-carboxyphenyl)imidazo[4,5-f]-1,10-phenanthroline (HNCP) and 2,5-thiophenedicarboxylate (TDC2−) ligands, three new lanthanide-containing (Sm, Nd, and Pr) compounds, [Sm(NCP)(TDC)] n (1), [Nd(NCP)(TDC)] n ·2n(H2O)0.5 (2), and [Pr(NCP)(TDC)] n ·n(H2O)0.5 (3), have been synthesized using the hydrothermal method and structurally characterized using single-crystal X-ray diffraction. Structural analyses have revealed that compounds 1–3 are 3D isostructural metal-organic frameworks in which the [Ln2(COO)4] dimers can be regarded as 6-connecting nodes, and the TDC2− and NCP− ligands are simplified as connectors to achieve the double interspersed 3D networks with the point symbol {412·63}. Thermogravimetric analysis has illustrated that the rigid architecture contributes to superior thermal stability with a thermal decomposition temperature of more than 400°C for the resulting metal-organic frameworks.