Molybdophosphonate Clusters as Building Blocks in the Oxomolybdate-Organodiphosphonate/Cobalt(II)−Organoimine System: Structural Influences of Secondary Metal Coordination Preferences and Diphosphonate Tether Lengths

An Organodiphosphate-Containing Polyoxoniobate Ring and Its Assembly into a Three-Dimensional Framework through Hydrogen Bonding

In this work, a novel organodiphosphate-containing inorganic-organic hybrid polyoxoniobate (PONb) ring {(PO3CH2CH2PO3H)4Nb8O16}4- (Nb8P8) has been achieved by a one-pot hydrothermal method. The ring is constructed from a tetragonal {Nb8O36} motif and four {PO3CH2CH2PO3H} ligands. Interestingly, Nb8P8 can be joined together via K-H2O clusters {K2(H2O)4(OH)2} to form one-dimensional chains {[K2(H2O)4(OH)2]Nb8P8}n and further linked by {Cu(en)2}2+ (en = ethylenediamine) complexes, resulting in a three-dimensional supramolecular framework {[Cu(en)2]2[K2(H2O)4(OH)2]Nb8P8}·3en·H2O (1). 1 exhibits good chemical and thermal stability and has a high water vapor adsorption capacity of ≤224 cm3 g-1 (22.71 mol·mol-1) at 298 K, outperforming most of the known polyoxometalate-based materials. Impedance measurements prove that 1 can transfer protons with moderate conductivity. This study not only contributes to the structural diversity of organodiphosphate-containing PONbs and PONb rings but also provides a reference for the development of PONb-based materials with unique performance.

A Macrocyclic Polyoxomolybdate with Phosphate and Phosphonate Linkers: Synthesis, Structure, and Proton Conductivity

A coordination macrocycle composed of eight identical [PMo8O27]- ({PMo8}) clusters connected by both organic tetraphosphonates and inorganic phosphates, (C3N2H5)29(NH4)6H12[(PMo8O27)8(C10P4O12N2H20)4(PO4)4Cs(Mo4O10(H2O)4)] (C3N2H5+ = imidazolium), is presented here. The primary building block, {PMo8}, is a tetravacant Keggin-type phosphomolybdate that has never been observed before. The compound shows a high proton conductivity of 9.70 × 10-3 S cm-1 at 373 K and 98% relative humidity. Control experiments on an imidazolium-free sample demonstrate the critical role of the imidazolium counterions as mobile proton carriers. The contribution of imidazolium necessitates a high activation energy (Ea = 0.502 eV) for proton conduction via the vehicle mechanism.

2D Windmill-like Ln-Containing Organophosphonate-Based Polyoxomolybdates: Synthesis, Characterization, Fluorescence, and Magnetism

By integration of {Ln(H₂O)₆}³⁺ into organophosphonate-based polyoxometalates, three Ln-containing organophosphonate-functionalized polyoxomolybdates Na_1.5H_1.5[{Ln(H₂O)₆}₂{(Mo₃O₈)(O₃PC(C₃H₆NH₃)OPO₃)}₄]·(CH₃CO₂)·43H₂O (Ln = Eu (1), Tb (2), and Dy (3)) are successfully prepared and systematically characterized. The X-ray crystallography analyses display complexes 1-3 crystallize in the C2/c space group of the monoclinic system and compose several distinctive tetramer windmill-like compounds that further assemble into two-dimensional (2D) frameworks associated with the {Ln(H₂O)₆}³⁺ core. The fluorescence spectra of 1-3 show red, green, and chartreuse emissions, respectively, originating in the typical f-f transitions of Ln³⁺ ions. More interestingly, complex 3 shows the field-induced single-molecule magnet (SMM) properties, resulting from the fact that [(Mo₃O₈)₄{O₃PC(C₃H₆NH₃)OPO₃}₄]^8- offers excellent magnetic isolation for Dy³⁺ ions by the nearest Dy1···Dy2 distance of 11.207 Å. The study demonstrates that the incorporation of {Ln(H₂O)₆}³⁺ into organophosphonate-based polyoxomolybdates is an effective synthetic strategy in implementing late-model opto-magnetic materials.

36-Nuclearity Organophosphonate-Functionalized Polyoxomolybdates: Synthesis, Characterization and Selective Catalytic Oxidation of Sulfides

The crown-shaped 36-molybdate cluster organophosphonate-functionalized polyoxomolybdates with the highest nuclearity in organophosphonate-based polyoxometalate chemistry, (NH₄ )₁₉ Na₇ H₁₀ [Cu(H₂ O)TeMo₆ O₂₁ {N(CH₂ PO₃ )₃ }]₆ ⋅31 H₂ O, has been reported for the first time. The synthesized 36-molybdate cluster was characterized by routine techniques and tested as a heterogeneous catalyst for selective oxidation of sulfides with impressive catalytic and selective performances after heat treatment. High efficiency (TON=15333) was achieved in the selective oxidation of sulfides to sulfoxides, caused by the synergic effect between copper and polyoxomolybdates and the generation of the cuprous species during the heat treatment.

A Redox-Active Bridging Ligand to Promote Spin Delocalization, High-Spin Complexes, and Magnetic Multi-Switchability

A dinuclear Co^II complex, [Co₂ (tphz)(tpy)₂ ]ⁿ⁺ (n=4, 3 or 2; tphz: tetrapyridophenazine; tpy: terpyridine), has been assembled using the redox-active and strongly complexing tphz bridging ligand. The magnetic properties of this complex can be tuned from spin-crossover with T_1/2 ≈470 K for the pristine compound (n=4) to single-molecule magnet with an S_T =5/2 spin ground state when once reduced (n=3) to finally a diamagnetic species when twice reduced (n=2). The two successive and reversible reductions are concomitant with an increase of the spin delocalization within the complex, promoting remarkably large magnetic exchange couplings and high-spin species even at room temperature.

Syntheses and characterization of phosphonates and diphosphonates of molybdenum, A4[(MoO3)5(O3PR)2]·xH2O, A2[Mo2O5(O3PR)2] and A2[Mo2O5(O3P-R-PO3)] (A = K, Rb, Cs, Tl, NH4)

Cs₄[(MoO₃)₅(O₃PPh)₂]·6H₂O and K_1.5(H₃O)_0.5[Mo₂O₅(O₃PPh)₂] are molecular and non-molecular phenylphosphonates of molybdenum that contain discrete [(MoO₃)₅(O₃PPh)₂]⁴⁻ and layered [Mo₂O₅(O₃PPh)₂]²⁻ anions respectively.

Controllable assembly, characterization and catalytic properties of a new Strandberg-type organophosphotungstate

A new Strandberg-type organophosphotungstate was assembled under hydrothermal conditions and displayed good fluorescence properties and catalytic activity.

Synthesis and structural characterization of a novel copper(II)/lead(II) heterometallic organic–inorganic hybrid

A new copper(II)/lead(II) complex [(terpy)3CuPb5Br12] (1) (terpy = 2,2′:6′,2″-terpyridine) has been synthesized and characterized by IR, elemental analysis, and single-crystal X-ray diffraction analysis. The copper(II) and lead(II) ions in the title complex are in distorted six- (Cu(II), Pb(II)) and eight-fold (Pb(II)) coordination environments, in which the donor atoms are provided by bromide anions and nitrogen atoms of the 2,2′:6′,2″-terpyridine ligands. Complex 1 contains [(terpy)4Pb9Br20]2– building blocks. These bromoplumbate(II) clusters are connected by (terpy)2Cu2Br4 units along the crystallographic b axis and by PbBr6 units along the a axis, thereby forming an extended sheet structure.

Grafting transition metal–organophosphonate fragments onto heteropolyoxomolybdate: activity in photocatalysis

Polyanion 1a can be seen as the structure decorated by three isolated {Ni(OOCCH₂NHCH₂PO₃)₂} based on the “Z-shaped” framework {Ni₃O₂(H₂O)₆(PMo₆O₂₄)₂(μ₃-O)₂(μ₂-O)₆}.

Synthesis, structures, luminescent and molecular recognition properties of three new alkaline earth metal carboxyphosphonates with a 3D supramolecular structure

Three new alkaline earth metal carboxyphosphonates with a 3D supramolecular structure, namely, Ca[(H₃L)(H₂O)] (1), Sr[(H₃L)(H₂O)₂] (2) and Ba₂[(H₃L)₂(H₂O)₄] (3) have been hydrothermally synthesized. The luminescent and molecular recognition properties of compounds 1–3 were investigated.

Two novel cadmium(ii) carboxyphosphonates with 3D framework structure: synthesis, crystal structures, luminescence and molecular recognition properties

Two novel cadmium(ii) carboxyphosphonates with 3D framework structure have been synthesized under hydrothermal conditions. The luminescence properties and molecular recognition properties of the compounds have been investigated.

Controlled assembly of hybrid architectures based on carboxylic acid ligands and [(O3PCH2PO3)Mo6O22]12−

Polyanion 2a with a reverse symmetrical “crown-type” structure is composed of two {(HO₃PCH₂PO₃)Mo₆O₁₈(CH₃CO₂)₂} subunits and a linking bridge.

Two novel oxovanadium–organophosphonate hybrids with a 3D supramolecular structure: synthesis, crystal structures, surface photovoltage and luminescent properties

Two novel oxovanadium–organophosphonates with a 3D supramolecular structure, [{M(1,10–phen)}(VO)(OH)(hedp)]·H₂O (M = Cu (1), Zn (2)), have been hydrothermally synthesized. The surface photovoltage and luminescent properties of the two compounds have been studied.