Luminescent Functional Metal–Organic Frameworks

Synthesis of metal-organic frameworks (MOFs): routes to various MOF topologies, morphologies, and composites.

Metal–organic frameworks (MOFs) or porous coordination polymers (PCPs) are open, crystalline supramolecular coordination architectures with porous facets. These chemically tailorable framework materials are the subject of intense and expansive research, and are particularly relevant in the fields of sensory materials and device engineering. As the subfield of MOF-based sensing has developed, many diverse chemical functionalities have been carefully and rationally implanted into the coordination nanospace of MOF materials. MOFs with widely varied fluorometric sensing properties have been developed using the design principles of crystal engineering and structure–property correlations, resulting in a large and rapidly growing body of literature. This work has led to advancements in a number of crucial sensing domains, including biomolecules, environmental toxins, explosives, ionic species, and many others. Furthermore, new classes of MOF sensory materials utilizing advanced signal transduction by devices based on MOF photonic crystals and thin films have been developed. This comprehensive review summarizes the topical developments in the field of luminescent MOF and MOF-based photonic crystals/thin film sensory materials.

Metal-organic frameworks: functional luminescent and photonic materials for sensing applications.

A metal organic framework (MOF) represents a new class of hybrid material built from metal ions with well-defined coordination geometry and organic bridging ligands Over the past few years, MOFs have attracted a great deal of attention due to their intriguing framework architecture, topology, and optical properties MOFs have provided promising perspectives in various research fields, such as catalysis, energy storage, drug-delivery systems, non-linear optics, and gas storage Recently, the application of MOFs was further extended to cover new, interesting fields of sensing toward various target components, including small molecules, solvents, pesticides, explosives, and biological markers In this review, we focus on recent progress achieved in MOF research with respect to general sensing principles and analytical performance This review also discusses future industrial applications in sensing that are of immense research interest

Metal organic frameworks for sensing applications

A 3D metal–organic framework, [NH2(CH3)2]2[Cd17(L)12(μ3-H2O)4(DMF)2(H2O)2]·solvent (1), has been constructed with a π-electron rich aromatic ligand 2,4,6-tris[1-(3-carboxylphenoxy)ylmethyl]mesitylene (H3L) and d10 configuration metal ion Cd2+ under solvothermal conditions. The crystal structure reveals that complex 1 consists of hexanuclear and trinuclear cadmium building units, which are further bridged by the multicarboxylate ligands to give a (3, 6, 12)-connected topological net. This complex exhibits strong ligand originated photoluminescence emission, which is selectively sensitive to electron-deficient nitroaromatic explosives (nitrobenzene, 4-nitrotoluene, 1,4-dinitrobenzene, 1,3-dinitrobenzene and 2,4-dinitrotoluene). This property makes complex 1 a potential fluorescence sensor for these chemicals.

A luminescent metal–organic framework demonstrating ideal detection ability for nitroaromatic explosives

A new microporous europium-containing metal–organic framework [Eu2(μ2-pzdc)(μ4-pzdc)(μ2-ox)(H2O)4]·8H2O (1) (H2pzdc = 2,5-pyrazinedicarboxylic acid, H2ox = oxalic acid) has been hydrothermally synthesized via an unprecedented in situ formation of 2,5-pyrazinedicarboxylate (pzdc) and oxalate (ox) ligands. Structure 1 was characterized by both single-crystal and powder X-ray diffraction analysis. It can be described as a 4-connected binodal Moganite network with the Schlafli symbol of (4·64·8)2(42·62·82), which exhibits a reversible and highly selective sensing function with respect to acetone.

In situ 2,5-pyrazinedicarboxylate and oxalate ligands synthesis leading to a microporous europium–organic framework capable of selective sensing of small molecules

Two new 4d–4f heterometallic coordination polymers [AgLn(pydc)2(H2O)3] · x(H2O) [Ln = Eu, x = 1.25 (1); Ln = Tb, x = 1.25 (2); pydc = 2,6-pyridinedicarboxylate] have been synthesized and characterized by elemental analysis, IR spectroscopy, and single crystal X-ray diffraction. Both structures display the same unusual 1-D heterometallic coordination polymer based on Ln building blocks and Ag ions. Thermal stabilities and luminescent properties of 1 and 2 are presented.

1-D Ln–Ag (Ln = Eu; Tb) heterometallic coordination polymers with pyridine-2,6-dicarboxylate as the single ligand: Synthesis, crystal structures, and luminescence

Wei-Xia Wang

Papers

In situ 2,5-pyrazinedicarboxylate and oxalate ligands synthesis leading to a microporous europium–organic framework capable of selective sensing of small molecules

1-D Ln–Ag (Ln = Eu; Tb) heterometallic coordination polymers with pyridine-2,6-dicarboxylate as the single ligand: Synthesis, crystal structures, and luminescence