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

Layered double hydroxides (LDHs) are a class of ionic lamellar compounds made up of positively charged brucite-like layers with an interlayer region containing charge compensating anions and solvation molecules. Delamination of LDHs is an interesting route for producing positively charged thin platelets with a thickness of a few atomic layers, which can be used as nanocomposites for polymers or as building units for making new designed organic-inorganic or inorganic-inorganic nanomaterials. The synthesis of nanosized LDH platelets can be generally classified into two approaches, bottom-up and top-down. It requires modification of the LDH interlamellar environment and then selection of an appropriate solvent system. In DDS intercalated LDHs, the aliphatic tails of the DDS- anions exhibit a high degree of interdigitation in order to maximize guest-guest dispersive interactions. Bellezza reported that the LDH colloids can also been obtained by employing a reverse microemulsion approach.

Recent advances in the synthesis and application of layered double hydroxide (LDH) nanosheets.

The purpose of this critical review is to give a representative and comprehensive overview of the arising developments in the field of magnetic metal–organic frameworks, in particular those containing cobalt(II). We examine the diversity of magnetic exchange interactions between nearest-neighbour moment carriers, covering from dimers to oligomers and discuss their implications in infinite chains, layers and networks, having a variety of topologies. We progress to the different forms of short-range magnetic ordering, giving rise to single-molecule-magnets and single-chain-magnets, to long-range ordering of two- and three-dimensional networks (323 references).

Magnetic metal-organic frameworks.

Magnetism of lanthanides in molecular materials with transition-metal ions and organic radicals.

THE rational design of molecular compounds that exhibit spontaneous magnetic ordering might enable one to tailor magnetic properties for specific applications in magnetic memory devices1–4. In such materials synthesized previously5–17, however, the underlying weak magnetic interactions are incapable of maintaining ordering at ambient temperatures. One remarkable exception is a compound derived from vanadium and tetracyanoethylene18, but the material is amorphous and fragile, and consequently the molecular interactions responsible for its striking properties are not understood. Here we demonstrate another route to the synthesis of a room-temperature organometallic magnet, in which we combine a hexa-cyanometalate [M(CN)6]q− with a Lewis acid Lp+ If L and M are transition-metal ions, then the orbital interactions in the resulting compound can be described by well understood principles21–24, and it is therefore possible to choose the metals to tune the compound's magnetic properties–in particular, the magnetic ordering (Curie) temperature Tc (refs 21–26). We have synthesized a room-temperature magnetic material (TC = 315 K) that belongs to the Prussian blue family of compounds27 (where M is chromium and L is vanadium), demonstrating that transition-metal hexacyano complexes are promising components for the construction of molecule-based high-Tc magnets.

A room-temperature organometallic magnet based on Prussian blue

The reaction of K 3 [Cr(ox) 3 ].3H 2 O, a metal(II) salt, and tetra(n-butyl)ammonium bromide in the molar ratio of 1:1:1.5 in water at room temperature afforded a series of mixed-metal assemblies with the formula {NBu 4 [MCr(ox) 3 ]} x (M=Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ ).

Design of metal-complex magnets. Syntheses and magnetic properties of mixed-metal assemblies {NBu4[MCr(ox)3]}x (NBu4+ = tetra(n-butyl)ammonium ion; ox2- = oxalate ion; M = Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+)

The following oxalate-bridged heterodinuclear Cr(III)M(II) (M=Cu, Ni, Co, Fc, Mn) complexes have been synthesized: [Cr(salen)(ox)Cu(acpy)] (1) (salen= N,N'-ethylenebis(salicylideneaminate), ox 2- =oxalate ion, acpy =N-acctylacetonylidene-N-(2-pyridylethyl)aminate) and [Cr(salen)(ox)M(taca)] (BPh 4 ) (M=Ni (2), Co (3), Fe(4), Mn (5)) (taea=tris(2-aminoethyl)amine). The [Cr(salen)(ox)Cu(acpy)2DMF.MeOH (1') complex crystallines in the monoclinic system of the spacc group P2 1 /n with a=16.429(6) A, b=25.303(14) A, c=10.191(4) A, β=109.78(2) o , V=3986(3) A 3 , and Z=4

Oxalate-bridged dinuclear Cr(III)-M(II) (M = Cu, Ni, Co, Fe, Mn) complexes: Synthesis, structure, and magnetism

Hetero-metal assemblies, (NBu4=tetra(n-butyl)ammonium ion; ox=oxalate ion; M(II)=Ni(1), Fe(2), Mn(3), Zn(4)) have been synthesized by the use of [Fe(ox)3]3- as the building block. 1 and 2 are ferri...

Ferrimagnetic Mixed-Metal Assemblies {NBu4[MFe(ox)3]}x

Mixed-metal assemblies {NBu4[M(II)Fe(III)(ox)3]}3∞ (M = Ni (1), Fe (2), Mn, Zn) have been prepared and characterized, where NBu4+ = tetra(n-butyl)ammonium ion, ox2− = oxalate ion. Each assumes a three-dimensional network structure consisting of alternately arrayed Fe(III) and M(II) ions. The compounds 1 and 2 are shown to be ferrimagnet with a magnetic phase-transition temperature of 28 and 43 K, respectively.

Metal-Complex Ferrimagnets with the Formula {NBu4[M(II)Fe(III)(ox)3]}3∞ (NBu4+ = Tetra(n-butyl)ammonium Ion, ox2− = Oxalate Ion, M = Fe2+, Ni2+)

Ferromagnetic spin-coupling between Cu(II) and Gd(III) ions was observed in a binuclear Cu(II)–Gd(III) complex CuGd(fsaen)NO3·4H2O (H4fsaen = N,N′-bis(3-carboxysalicylidene)ethylenediamine). The magnetic behavior was well reproduced by the equation derived from H = −2JSCu·SGd (SCu = 1/2, SGd = 7/2) with g = 2.01 and J = +1.7 cm−1.

Hiroko Tamaki

Papers

Design of metal-complex magnets. Syntheses and magnetic properties of mixed-metal assemblies {NBu4[MCr(ox)3]}x (NBu4+ = tetra(n-butyl)ammonium ion; ox2- = oxalate ion; M = Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+)

Oxalate-bridged dinuclear Cr(III)-M(II) (M = Cu, Ni, Co, Fe, Mn) complexes: Synthesis, structure, and magnetism

Ferrimagnetic Mixed-Metal Assemblies {NBu4[MFe(ox)3]}x

Metal-Complex Ferrimagnets with the Formula {NBu4[M(II)Fe(III)(ox)3]}3∞ (NBu4+ = Tetra(n-butyl)ammonium Ion, ox2− = Oxalate Ion, M = Fe2+, Ni2+)

Ferromagnetic Spin-Coupling in a Binuclear Cu(II)–Gd(III) Complex