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

Lanthanide NIR luminescence for telecommunications, bioanalyses and solar energy conversion

Metal organic framework g-C 3 N 4 /MIL-53(Fe) heterojunctions with enhanced photocatalytic activity for Cr(VI) reduction under visible light

Among the recent developments in metal-organic frameworks (MOFs), porous layered coordination polymers (CPs) have garnered attention due to their modular nature and tunable structures. These factors enable a number of properties and applications, including gas and guest sorption, storage and separation of gases and small molecules, catalysis, luminescence, sensing, magnetism, and energy storage and conversion. Among MOFs, two-dimensional (2D) compounds are also known as 2D CPs or 2D MOFs. Since the discovery of graphene in 2004, 2D materials have also been widely studied. Several 2D MOFs are suitable for exfoliation as ultrathin nanosheets similar to graphene and other 2D materials, making these layered structures useful and unique for various technological applications. Furthermore, these layered structures have fascinating topological networks and entanglements. This review provides an overview of different aspects of 2D MOF layered architectures such as topology, interpenetration, structural transformations, properties, and applications.

Two-Dimensional Metal-Organic Framework Materials: Synthesis, Structures, Properties and Applications.

Four novel hetero-tetranuclear d–f coordination complexes, [Ln2Cd2(p-toluylate)10(phen)2] (Nd, 1; Pr, 2; Sm, 3) and [Ho2Cd2(p-chloro-benzoate)10(phen)2](4) (phen = 1, 10-phenanthroline), are synthesized by the hydrothermal method, and their structures are studied by single-crystal X-ray diffraction. Structures 1–3 are isomorphous and structure 4 has a similar molecular structure. In the near-infrared (NIR) region or in the visible region, complexes 1–4 show the characteristic emission bands of Ln(III) ions, which are attributed to the sensitization from the ligands and d-block (cadmium–ligand section) to f-block (lanthanide–ligand section). Moreover, in the Cd–Ln complexes, the Cd⋯Ln separation is very close, so the d-orbital of the Cd(II) ion and the f-orbital of the Ln(III) ion may influence each other, which probably cause the intra-levels to be adjusted. This can have a significant effect on the emission bands in the NIR region, hence the corresponding emission bands of complexes 1, 2 and 4 exhibit shift or splitting compared with isolated Ln(III) ions. At the same time in the UV-Vis-NIR absorption spectra of the complexes, the corresponding absorption bands also show shift or splitting. The shift or splitting of bands in the NIR emission spectra and in the absorption spectra can evidence each other.

Syntheses, structures and photophysical properties of tetranuclear Cd–Ln coordination complexes

Three novel NiII coordination polymers [Ni2(HCOO)4(H2O)4]n (1), [Na2Ni(btec)(H2O)8]n (2; H4btec = 1,2,4,5-benzenetetracarboxylic acid) and [{Ni(pdc)(H2O)2}·H2O]n (3; H2pdc = pyridine-2,5-dicarboxylic acid) have been hydrothermally synthesized and their structures determined by single-crystal X-ray diffraction. The formate groups in complex 1 bridge the NiII ions to form a infinite 3D structure. Complex 2 also possesses a infinite 3D structure and the coordination environment of the NiII ion is a perfect octahedron. Complex 3 is a 2D infinite coordination polymer. The surface photovoltage spectra of complexes 1–3 indicate that they all show three positive surface photovoltage (SPV) responses in the range of 300–800 nm and all show p-type semiconductor characteristics. Although the intensities of the SPV responses are obviously different, this can mainly be attributed to the difference of their structures. The field-induced surface photovoltage spectra (FISPS) of complexes 1–3 confirm their p-type semiconductor characteristics. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Synthesis, Structure and Surface Photovoltage of a Series of NiII Coordination Polymers

Six novel heterodinuclear d–f coordination complexes [LnCd(C8H7O3)5(phen)(H2O)] (Ln = Sm 1, Eu 2, Tb 3, Nd 4, Ho 5, Er 6; C8H7O3 = 4-methoxybenzoato; phen = 1,10-phenanthroline) were synthesized by the hydrothermal method, and their structures were studied by single-crystal X-ray diffraction. The IR and UV/Vis/NIR absorption spectra and the luminescence spectra of the six complexes were determined at room temperature. They have the same molecular structure, and two neighboring molecules are connected by hydrogen bonds or by a Ln···O weak interaction to form dimer crystals. In the visible region, the emission spectra of complexes 1–3 show the intense characteristic bands of the corresponding LnIII ions, which are mainly attributed to the efficient energy transfer from the d block to the f block, that is, to the good sensitization of the d block. Moreover, in the Cd–Ln coordination complexes, the Cd···Ln separation is very small, and the 4d orbitals of the CdII ion may influence the 4f orbitals of the LnIII ion, which probably causes some of the f levels of the LnIII ion to be adjusted, and this effect can be observed in the shifts or splittings of the absorption bands in the UV/Vis/NIR spectra of the complexes. Especially in complexes 4–6, some energy levels of the LnIII ions have shifts or splittings, hence the corresponding emission bands exhibit shifts or splittings in the NIR region. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Jing Jin

Papers

Syntheses, structures and photophysical properties of tetranuclear Cd–Ln coordination complexes

Synthesis, Structure and Surface Photovoltage of a Series of NiII Coordination Polymers

Syntheses, Structures and Photophysical Properties of New Heterodinuclear Cd–Ln Coordination Complexes (Ln = Sm, Eu, Tb, Nd, Ho, Er)

Crystal structure and surface photovoltage of a series of Ni(II) coordination supramolecular polymer

Syntheses, structures and photophysical properties of a series of Zn-Ln coordination polymers (Ln = Nd, Pr, Sm, Eu, Tb, Dy)