Lanthanide-organic frameworks based on terphenyl-tetracarboxylate ligands： syntheses, structures, optical properties and selective sensing of nitro explosives

• Published in: Science China. Chemistry 2017-08, Vol.60 (8), p.1130-1135
• Main Authors: Zhou, Xinhui, Zhu, Yali, Li, Liang, Yang, Tao, Wang, Jin, Huang, Wei
• Format: Article
• Language: English
• Subjects: Aromatic compounds; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Emission spectra; Fluorescence; Gadolinium; Ligands; Metal-organic frameworks; Nitro compounds; Nodes; Optical properties; Oxygen atoms; Quenching; Samarium
• ISSN: 1674-7291; 1869-1870
• DOI: 10.1007/s11426-016-9006-x

Three isostructural three-dimensional （3D） lanthanide-based metal-organic frameworks [Ln2L（H2L）（NMP）2]＇H20 （Ln=Sm（l）, Eu （2）, Gd （3）; H4L= 1,1 ＇：4＇, 1 ＂-terphenyl-2＇,4,4＂,5＇-tetracarboxylic acid; NMP=N-methyl-2-pyrrolidone） have been synthesized and structurally characterized. In 1-3, two Ln3＋ ions are doubly-bridged by two oxygen atoms of two carboxylate groups to form the dinuclear Lnz（Oco ）a unit. Each Ln2（Ocoo ）2 unit links with four H2L2 ligands and four L4- ligands to lead to the 3D framework, which can be rationalized as a new trinodal 4,4,8-connected （44.62）（45.6）（412.616） topological network by considering the dinuclear Ln2（Ocoo ）2 units as 8-connected nodes and L4-/H2L2- ligands as planar 4-connected nodes, respectively. 1 and 3 exhibit blue emission originated from the ligand with the emission maximum at 384 nm, while 2 shows intense characteristic red emission of Eu3＋ ions and weak ligand-centered emission. Moreover, 2 has fluorescent quenching response towards the aromatic nitro compounds, especially for the 3,4-dinitrotoluene （3,4-DNT） with the linear Stern-Volmer relationship in the concentration range of 0-1 mM and the quenching constant （Ksv） of 2.084-103 M 1.