Luminescent Functional Metal–Organic Frameworks

Recent startling interest for lanthanide luminescence is stimulated by the continuously expanding need for luminescent materials meeting the stringent requirements of telecommunication, lighting, electroluminescent devices, (bio-)analytical sensors and bio-imaging set-ups. This critical review describes the latest developments in (i) the sensitization of near-infrared luminescence, (ii) “soft” luminescent materials (liquid crystals, ionic liquids, ionogels), (iii) electroluminescent materials for organic light emitting diodes, with emphasis on white light generation, and (iv) applications in luminescent bio-sensing and bio-imaging based on time-resolved detection and multiphoton excitation (500 references).

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Lanthanide luminescence for functional materials and bio-sciences

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Metal–Organic Frameworks and Self-Assembled Supramolecular Coordination Complexes: Comparing and Contrasting the Design, Synthesis, and Functionality of Metal–Organic Materials

Metal–organic frameworks based on trivalent lanthanides (LnMOFs) are a very promising class of materials for addressing the challenges in engineering of luminescent centres. Lanthanide-bearing phosphors find numerous applications in lighting, optical communications, photonics and biomedical devices. In this critical review we discuss the potential of LnMOFs as multifunctional systems, which combine light emission with properties such as microporosity, magnetism, chirality, molecule and ion sensing, catalysis and activity as multimodal imaging contrast agents. We argue that these materials present a unique chance of observing synergy between several of these properties, such as the coupling between photoluminescence and magnetism. Moreover, an integrated approach towards the design of efficient, stable, cheap, environmentally-friendly and multifunctional luminescent LnMOFs is still missing. Although research into LnMOFs is at its early stage and much basic knowledge is still needed, the field is ripe for new ideas, which will enable sensor devices and photonic prototypes to become a commercial reality (81 references).

Luminescent multifunctional lanthanides-based metal–organic frameworks

This review (over 380 references) summarizes metal–organic frameworks (MOFs), Materials Institute Lavoisier (MILs), iso-reticular metal–organic frameworks (IR-MOFs), porous coordination networks (PCNs), zeolitic metal–organic frameworks (ZMOFs) and porous coordination polymers (PCPs) with selected examples of their structures, concepts for linkers, syntheses, post-synthesis modifications, metal nanoparticle formations in MOFs, porosity and zeolitic behavior for applications in gas storage for hydrogen, carbon dioxide, methane and applications in conductivity, luminescence and catalysis.

MOFs, MILs and more: concepts, properties and applications for porous coordination networks (PCNs)

Three porous, 3-D coordination polymers [Pr4(NDC)6(H2O)6]·2H2O (1), [Eu4(NDC)6(H2O)5]·3H2O (2) and [Yb2(NDC)3(H2O)]·H2O (3) based on lanthanide 2,6-naphthalenedicarboxylates (NDC) were synthesized by hydrothermal reactions of lanthanide chlorides with NDC and their properties were investigated. Polymers 1, 2 and 3 differ in the coordination environment of the LnIII ions. Their 3-D networks are reminiscent of the shape of a compressed honeycomb, showing 1-D open channels. The guest water molecules and coordinating water molecules are enclathrated in the channels. The photophysical properties of the Eu3+ complex were investigated by high-resolution luminescence spectroscopy. The results indicate that there are four EuIII ion sites in complex 2, which is in accordance with the results of the single-crystal X-ray diffraction studies. Thermogravimetric and variable-temperature powder X-ray diffraction analyses show that the porous frameworks of this series of complexes are relatively stable. The framework remained even when the guest molecules were lost and did not collapse until the temperature reached 430 °C. The magnetic properties of 2 were also investigated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

New porous lanthanide-organic frameworks: Synthesis, characterization, and properties of lanthanide 2,6-naphthalenedicarboxylates

Four novel coordination polymers of NiII and CoII with flexible ligands, namely [Ni(oba)(bpe)]n·nH2O (1), [Co(oba)(bpe)]n (2), [Ni2(oba)2(bpy)2(H2O)2]n·nbpy (3), and [Co(oba)(bpy)1/2]n (4) [H2oba = 4,4′-oxybis(benzoic acid), bpe = 1,2-bis(4-pyridyl)ethane, bpy = 4,4′-bipyridine] were synthesised by hydrothermal reactions and characterised by single-crystal X-ray diffraction, elemental analysis and IR spectroscopy. The NiII ions in complex 1 are linked by flexible oba and bpe ligands to form square-grid-like corrugated sheets. These sheets are interpenetrated with each other, resulting in the formation of a 3D porous network with lattice water molecules in the channels. The variable temperature X-ray diffraction analysis shows that the framework is stable up to 300 °C despite the complete removal of the lattice water molecules during the heat treatment. Complex 2 can be regarded as possessing a α-polonium-related topology. Triple interpenetration occurs to form a nonporous structure. In complex 3, the oba and bpy ligands link NiII ions into 1D train-like boxes. These boxes are entangled, with the aid of hydrogen bonds, leading to the formation of a 3D porous supramolecular architecture. Free bpy ligands reside in the channels. The CoII ions in complex 4 are linked by oba and bpy ligands to form a complicated 3D coordination polymer. The lattice water molecules in complex 1 and free bpy ligands in complex 3 can be regarded as templates that play an important role in the formation of the porous structures of complexes 1 and 3. The magnetic properties of complexes 1, 2, and 4 have also been investigated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Multiple Regulated Assembly, Crystal Structures and Magnetic Properties of Porous Coordination Polymers with Flexible Ligands

Six novel manganese(II) coordination polymers, namely [Mn(oba)(4,4′-bpy)]n·n(4,4′-bpy) (1), [Mn(oba)(phen)(H2O)]n (2), [Mn2(oba)2(2,2′-bpy)2(H2O)2]n·nH2oba (3), [Mn2(cca)2(4,4′-bpy)2]n·2n(4,4′-bpy) (4), [Mn(cca)(phen)]n (5) and [Mn(cca)(2,2′-bpy)]n·0.25nH2O (6) [H2oba = 4,4′-oxybis(benzoic acid); 4,4′-bpy = 4,4′-bipyridine; phen = 1,10-phenanthroline; 2,2′-bpy = 2,2′-bipyridine; H2cca = p-carboxycinnamic acid] have been synthesised under hydrothermal conditions. Complexes 1 and 4 possess 3D microporous metal-organic frameworks with free 4,4′-bpy ligands in the channels. The MnII ions in complex 2 are bridged into 1D infinite double-chain structures, and those in complex 3 are bridged into 1D zigzag chains. Hydrogen bonds cause the formation of 3D supramolecular networks for complexes 2 and 3. Complex 5 is a complicated 3D metal-organic framework, and the MnII ions in complex 6 are linked into 2D layers with cavities; interpenetration of these 2D layers results in the formation of a 3D supramolecular network. Magnetic susceptibility measurements indicate that complex 2 displays a weak ferromagnetic interaction between the MnII ions with the following parameters: J = 0.462(3) cm–1, g = 2.0387(6), zJ′ =–0.0062(3) cm–1 and R = 8.0 × 10–6. Complex 4 shows antiferromagnetic coupling between the MnII ions with J =–0.718(4) cm–1, g = 1.986(4) and R = 2.3 × 10–4. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Chang-Yan Sun

Papers

New porous lanthanide-organic frameworks: Synthesis, characterization, and properties of lanthanide 2,6-naphthalenedicarboxylates

Multiple Regulated Assembly, Crystal Structures and Magnetic Properties of Porous Coordination Polymers with Flexible Ligands

Hydrothermal Syntheses, Architectures and Magnetic Properties of Six Novel MnII Coordination Polymers with Mixed Ligands

Assembly and upconversion luminescence of lanthanide–organic frameworks with mixed acid ligands

Assembly and structures of five new Cu(II) complexes based on the V-shaped building block [Cu(dbsf)]