Luminescent metal-organic frameworks for nitro explosives detection

Metal-organic frameworks （MOFs） have been emerging as important multifunctional hybrid materials, not only due to the diversify framework architectures, but also contribute to the rich interactions among metals, ligands and guests. Nitro explosives have important influences tbr environmental protection and national homeland security, in this review, a brief description of luminescent MOFs is presented, accompanied by a short comment on the four types of metal-based luminescent MOFs as sensing materials for nitro explosives detection. Then the trends and challenges of luminescent MOFs as sensing materials ibr nitro explosives are also prospected.

A Fluorescent Zirconium-Based Metal-Organic Framework for Selective Detection of Nitro Explosives and Metal Ions

In this work, a new porous Zrobased metal-organic framework （MOF） with a large Brunner-Emmet-Teller （BET） surface area was prepared by the solvothermal method using 4,4＇-（naphthalene-1,4-diyl）dibenzoic acid （NDDA） as the organic ligand, and the luminescent detection performance was studied systematically. The experiments comb- ing with computations indicate that the as-synthesized material can sensitively and selectively detect nitro explo- sives and metal ions, especially for 2,4,6-trinitrophenol （TNP） and Fe3＋, due to the possible electron transfer from inorganic moieties to organic moieties with naphthalene part. Interestingly, owing to its high porosity and large sur- face area, this Zr-MOF showed quick luminescent response time （in 1 min） for TNP and Fe3＋. The results obtained may provide useful information for the design of MOFs with the large permanent porosity in sensing applications for large molecules in the future.

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

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.