The development in the field of coordination polymers or metal-organic coordination networks, MOCNs (metal-organic frameworks, MOFs) is assessed in terms of property investigations in the areas of catalysis, chirality, conductivity, luminescence, magnetism, spin-transition (spin-crossover), non-linear optics (NLO) and porosity or zeolitic behavior upon which potential applications could be based.

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Engineering coordination polymers towards applications

Sasidharan Swarnalatha Lucky,†,§ Khee Chee Soo,‡ and Yong Zhang*,†,§,∥ †NUS Graduate School for Integrative Sciences & Engineering (NGS), National University of Singapore, Singapore, Singapore 117456 ‡Division of Medical Sciences, National Cancer Centre Singapore, Singapore, Singapore 169610 Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore, Singapore 117576 College of Chemistry and Life Sciences, Zhejiang Normal University, Zhejiang, P. R. China 321004

Nanoparticles in photodynamic therapy.

This critical review presents a comprehensive study of transition-metal carboxylate clusters which may serve as secondary building units (SBUs) towards construction and synthesis of metal–organic frameworks (MOFs). We describe the geometries of 131 SBUs, their connectivity and composition. This contribution presents a comprehensive list of the wide variety of transition-metal carboxylate clusters which may serve as secondary building units (SBUs) in the construction and synthesis of metal–organic frameworks. The SBUs discussed here were obtained from a search of molecules and extended structures archived in the Cambridge Structure Database (CSD, version 5.28, January 2007) which included only crystals containing metal carboxylate linkages (241 references).

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Secondary building units, nets and bonding in the chemistry of 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)

2.4.2. Interpenetrated Ladders 711 2.4.3. Unusual Motifs of Ladders 713 2.4.4. Properties of Ladderlike Chains 713 2.5. Rotaxane Polymers 714 2.5.1. 1D Polyrotaxanes 714 2.5.2. 2D Polyrotaxanes 715 2.5.3. 3D Polyrotaxanes 716 2.5.4. Hydrogen-Bonded Polyrotaxanes 716 2.6. Ribbon/Tape Polymers 717 2.7. Metal Cluster As Building Blocks for 1D CP 718 2.7.1. Metal Carboxylate Clusters 718 2.7.2. Metal Halide Clusters 719 2.7.3. Metal Chalcogenide Clusters 720 2.7.4. Polyoxometalate Clusters 721 2.7.5. Single Molecular Magnets as Building Blocks 722

One-Dimensional Coordination Polymers: Complexity and Diversity in Structures, Properties, and Applications

The visible green and red upconversion emissions in Er3+/Yb3+ doped β-NaGdF4 nanoparticles were enhanced by tridoping with Fe3+ ions (0–40 mol%). XRD, XPS, ICP-AES and EDS data demonstrated successful incorporation of Fe3+ ions in NaGdF4:Yb3+/Er3+ nanoparticles. The effect of Fe3+ tridoping on the upconversion luminescence in NaGdF4:Yb3+/Er3+ NPs was investigated in detail. The green and red emission intensities were enhanced by 34 and 30 times, respectively. The maximum emission was observed in a sample containing 30 mol% Fe3+ ions. A possible mechanism for the enhanced upconversion emission is proposed. In addition, a layer of silica was coated onto the surface of UCNPs to improve the biocompatibility. Folic acid was covalently linked to the silica coated UCNPs to form UCNP@SiO2–FA nanoprobes, which have been successfully applied to the fluorescent imaging HeLa cells.

Enhanced upconversion luminescence in NaGdF4:Yb,Er nanocrystals by Fe3+ doping and their application in bioimaging

A simple and efficient coating method of silver nanowires with uniform shells of TiO2 has been established using 2-mercaptoethanol monolayers. The thickness of the titania coating layer can be controlled by changing the concentration of the precursor solution. In situ TEM thermal annealing studies showed that the silver nanowire core remains intact until temperatures of 750 °C, which is significantly higher than the melting temperature of the bare silver nanowires. After this temperature, the Ag nanowires were melted and subsequently vaporized, leaving TiO2 nanotubes. The effects derived from the growth of titania shells on the optical properties of silver nanowires have been investigated as a function of the shell thickness. The surface plasmon resonance mode of these nanowires undergoes a gradual red shift and decreases in intensity upon systematic build-up of the dielectric cover.

Effects of TiO2 shells on optical and thermal properties of silver nanowires

Low-field magnetic studies on [Mn(4,4‘-bipyridine)(N3)2]n reveal a spontaneous magnetization below ordering temperatures of 42.5 K, due to a transition to a weak ferromagnetic ground state.

Weak ferromagnetism in a three-dimensional manganese(II) azido complex, [Mn(4,4'-bipy)(N3)2]n (bipy = bipyridine).

The electronic and optoelectronic properties of tin selenide nanostructures are of great interest for application in energy conversion and storage devices Despite the great progress achieved in nanoparticle synthesis, controlling the crystal phase in tin selenide nanostructures remains a challenge In this article, we present a simple solvothermal approach for the phase controlled synthesis of SnSe and SnSe2 hierarchical nanostructures (HNs) for the first time SnSe HNs have been prepared by reacting SnCl4 and SeO2 under solvothermal conditions using oleylamine as solvent By adding a calculated amount of 1-dodecanethiol (1-DDT) to the reaction mixture the crystal phase can be tuned from SnSe to SnSe2 The obtained HNs were composed of single crystalline thin nanosheets with thickness in the range of 7–12 nm A possible mechanism has been proposed for the phase controlled synthesis of tin selenides The obtained SnSe and SnSe2 HNs showed good electrocatalytic activity in the redox reaction of the I−/I3− shuttle Dye sensitized solar cells (DSSC) employing SnSe and SnSe2 HNs as counter electrodes showed photovoltaic performances similar to the device made with a conventional platinum (Pt) counter electrode

Phase controlled synthesis of SnSe and SnSe2 hierarchical nanostructures made of single crystalline ultrathin nanosheets

Currently, one of the major factors limiting the efficiency of solar cells is the spectral mismatch between the energy distribution of photons in the incident solar spectrum and the bandgap of a semiconductor material. To reduce spectral mismatch losses, wavelength conversion of sunlight is regarded as an effective route. Both upconversion and downconversion materials are currently being explored as spectral converters for solar cells. In an upconversion process, photons with energy lower than the band gap of the solar cell are converted to higher energy photons that can be absorbed by the semiconductor. This review focuses on the various synthetic approaches to upconversion nanocrystals and methods to improve upconversion luminescence, as well as it gives an overview of the recent developments in the photovoltaic applications of upconversion nanomaterials.

Jinkwon Kim

Papers

Enhanced upconversion luminescence in NaGdF4:Yb,Er nanocrystals by Fe3+ doping and their application in bioimaging

Effects of TiO2 shells on optical and thermal properties of silver nanowires

Weak ferromagnetism in a three-dimensional manganese(II) azido complex, [Mn(4,4'-bipy)(N3)2]n (bipy = bipyridine).

Phase controlled synthesis of SnSe and SnSe2 hierarchical nanostructures made of single crystalline ultrathin nanosheets

Upconversion nanophosphors for solar cell applications