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

Ever since the discovery and development of polyoxometalates (POMs), it has been known that they can exist in electron-rich reduced forms of different archetypes, structural flexibilities and functionalities. There are now reliable synthetic strategies for electron-rich POMs — materials that have unique and potentially useful catalytic, electronic and magnetic properties. This Review covers the synthesis and applications of these reduced species, and also highlights their differences and advantages relative to fully oxidized POMs. More than 200 reduced POM structures are described in this Review, with emphasis placed on how reduction influences POM structure, function and properties. The metals in polyoxometalates need not be in their highest oxidation states. Indeed, polyoxometalates can exist in reduced forms, and several different metals can be incorporated into various structural archetypes. This Review describes the synthesis and characterization of these complexes, along with their topical catalytic, electronic and biological properties.

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Synthesis, structures and applications of electron-rich polyoxometalates

While the d0 transition-metal POMs of Group V (V5+, Nb5+, Ta5+) and Group VI (Mo6+, W6+) have been known for more than a century, the actinyl peroxide POMs, specifically those built of uranyl triperoxide or uranyl dihydroxidediperoxide polyhedra, were only realized within the last decade. While virtually every metal on the Periodic Table can form discrete clusters of some type, the actinyls are the only—in addition to the transition-metal POMs– whose chemistry is dictated by the prevalence of the ‘yl’ oxygen ligand. Thus this emerging structural, solution, and computational chemistry of actinide POMs warrants comparison to the mature chemistry of transition-metal POMs. This assessment between the transition-metal POMs and actinyl POMs (uranyl peroxide POMs, specifically) has provided much insight to the similarities and differences between these two chemistries. We further break down the comparison between the alkaline POMs of Nb and Ta; and the acidic POMs of V, Mo and W. This more indepth literature review and discussion reveals that while an initial evaluation suggests the actinyl POMs are more akin to the alkaline transition-metal POMs, they actually share characteristics unique to the acidic POMs as well. This tutorial review is meant to provide fodder for deriving new POM chemistries of both the familiar transition-metals and the emerging actinides, as well as fostering communication and collaboration between the two scientific communities.

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A comprehensive comparison of transition-metal and actinyl polyoxometalates

Polyoxometalates (POMs) are a remarkable class of inorganic compounds with enormous structural and compositional diversity and potential applications in various fields, such as catalysis, analytical chemistry, magnetism, nanotechnology, and medicine. In particular lacunary heteropolytungstates of the Keggin and Wells–Dawson type are useful inorganic, diamagnetic ligands allowing for encapsulation of various multinuclear metal-oxo assemblies. Examples of such kinds of structurally, catalytically, and magnetically interesting POMs are the manganese-containing derivative {Mn14W36}, [2a] the iron-containing derivatives {Fe9W12}, [3a] {Fe13W36}, [3b,c] {Fe16W48}, [3d] {Fe28W48}, [3e] the nickel-containing derivatives {Ni9W27}, [4a] {Ni8/Ni9W18}, [4b] {Ni12W35}, [4c] and {Ni20W34}, [4d] and the copper-containing derivatives {Cu14W36} [5a] and {Cu20W48X} (X=Cl, Br, I). [5b,c] Some transition-metal-containing polyoxomolybdates are also known, such as {Fe30Mo72}, [6a] {V30Mo72}, [6b] as well as {Co16Mo16} (two types of structures containing 16 cobalt centers, in the form of four tetramers). The class of cobalt-containing POMs was pioneered by Baker and Pope. Meanwhile a large number of POMbased Co complexes with nuclearities ranging from 2 to 16 has been reported. Our group has reported a nona-cobaltcontaining polyanion capped by six antenna-like Co ions in the solid state, as well as several polytungstates containing smaller numbers of cobalt ions. Very recently it was shown that [Co4(H2O)2(PW9O34)2] 10 [9a] is a hydrolytically and oxidatively stable homogeneous water-oxidation catalyst. During the past decade many high-nuclearity transitionmetal-based coordination complexes with interesting electronic and magnetic properties have been prepared. Some cobalt derivatives with nuclearities ranging from 2 to 32 are also known. It is a challenge to encapsulate high-nuclearity magnetic cores in diamagnetic POM shells, in particular by using conventional, soft synthesis methods. We have now succeeded in preparing the tetrameric 36-tungsto-8-phosphate [{Co4(OH)3PO4}4(PW9O34)4] 28 (1), containing 16 cobalt(II) centers (Figure 1).

Hexadecacobalt(II)-containing polyoxometalate-based single-molecule magnet.

An investigation into the dependence of coordination polymer architectures on organic-acid ligands is reported on the basis of the reaction of Pb(NO3)2 and eight structurally related organic-acid ligands in the presence or absence of N-donor chelating ligands. Eight novel lead(II)−organic architectures, [Pb(adip)(dpdp)]2 1, [Pb(glu)(dpdp)] 2, [Pb(suc)(dpdp)] 3, [Pb(fum)(dpdp)]·H2O 4, [Pb2(oba)(dpdp)2]·2(dpdp)·2(NO3)·2H2O 5, [Pb2(1,4-bdc)2(dpdp)2]·H2O 6, [Pb(dpdc)(dpdp)] 7, and [Pb(1,3-bdc)(dpdp)]·H2O 8, where dpdp = dipyrido[3,2-a:2‘,3‘-c]-phenazine, H2adip = adipic acid, H2glu = glutaric acid, H2suc = succinic acid, H2fum = fumaric acid, H2oba = 4,4‘-oxybis(benzoic acid), 1,4-H2bdc = benzene-1,4-dicarboxylic acid, H2dpdc = 2,2‘-diphenyldicarboxylic acid, and 1,3-H2bdc = benzene-1,3-dicarboxylic acid, were successfully synthesized under hydrothermal conditions through varying the organic-acid linkers and structurally characterized by X-ray crystallography. Compounds 1−8 crystallize in the presence of orga...

Organic-Acid Effect on the Structures of a Series of Lead(II) Complexes

Five new polyoxometalate compounds built on lacunary Wells−Dawson anions and trivalent lanthanide cations, KNa3[Nd2(H2O)10(α2-P2W17O61)]·11H2O (1), (H3O)[Nd3(H2O)17(α2-P2W17O61)]·6.75H2O (2), (H2bpy)2[Nd2(H2O)9 (α2-P2W17O61)]·4.5H2O (3), (H2bpy)2[La2(H2O)9(α2-P2W17O61)]·4.5H2O (4), and (H2bpy)2[Eu2(H2O)9(α2-P2W17O61)]·5H2O (5), have been synthesized and characterized by elemental analysis, IR, TG, and single-crystal X-ray diffraction. Compound 1 shows a bisupporting polyoxometalate cluster structure where two {Nd(H2O)7}3+ fragments are supported on the polyoxometalate dimer [{Nd(H2O)3(α2-P2W17O61)}2]14-; this represents the first bisupporting polyoxometalate compound based on a polyoxometalate dimer. Compound 2 displays a 1D chain structure built up of bisupporting polyoxoanions [{Nd(H2O)7}2{Nd(H2O)3(α2-P2W17O61)}2]8- and Nd3+ ions. Compounds 3−5 are isostructural and show a 2D structure constructed of 1D polyoxometalate chains of [Ln(H2O)2(α2-P2W17O61)]n7n- linked by Ln3+ ions. Compounds 2−5 represent th...

New polyoxometalate compounds built up of lacunary Wells-Dawson anions and trivalent lanthanide cations.

To determine the influence of metal ions on the formation of metal−organic frameworks, five new coordination polymers, [Pb6(dpa)4O2]n (1), [Ag2(dpa)]n (2), [Nd2(dpa)3(H2O)2]n (3), [Zn(dpa)(H2O)]n (4), and [Cd2(dpa)2(phen)2(H2O)2]n (5), have been hydrothermally synthesized from 1,1‘-biphenyl-2,2‘-dicarboxylate acid (dpa). Complex 1 is a one-dimensional chain structure constructed from a new building unit, Pb6O18, which is connected by four different dpa molecules. Complex 3 is also a one-dimensional chain structure but is composed of a different building unit bridged by three dpa molecules. This complex is further extended into a two-dimensional supramolecular framework. Like complex 3, complex 4 is a two-dimensional supramolecular framework, which is connected by one-dimensional chains through π−π interactions and hydrogen bonding interactions. Complex 5 is a three-dimensional metal−organic supramolecular coordination polymer that possesses rectangular cavities. Different from the above four complexes, co...

Xinxin Xu

Papers

New polyoxometalate compounds built up of lacunary Wells-Dawson anions and trivalent lanthanide cations.

Metal-Controlled Assembly of Coordination Polymers with the Flexible Ligand 1,1‘-Biphenyl-2,2‘-dicarboxylate Acid

A new family of polyoxometalate compounds built up of Preyssler anions and trivalent lanthanide cations

Different aliphatic dicarboxylates affected assemble of new coordination polymers constructed from flexible-rigid mixed ligands

New photoluminescence coordination polymers constructed from different ligands, which are generated from maleic acid at hydrothermal conditions