Syntheses, structures, thermal stabilities and luminescence of two new 3D zinc phosphonates

Optimizing the Proton Conductivity of Fe-Diphosphonates by Increasing the Relative Number of Protons and Carrier Densities

Proton conductive materials have attracted extensive interest in recent years due to their fascinating applications in sensors, batteries, and proton exchange membrane fuel cells. Herein, two Fe-diphosphonate chains (H₄-BAPEN)_0.5·[Fe^III(H-HEDP)(HEDP)_0.5(H₂O)] (1) and (H₄-TETA)₂·[Fe^III₂Fe^II(H-HEDP)₂(HEDP)₂(OH)₂]·2H₂O (2) (HEDP = 1-hydroxyethylidenediphosphonate, BAPEN = 1,2-bis(3-aminopropylamino)ethane, and TETA = triethylenetetramine) with different templating agents were prepared by hydrothermal reactions. The valence states of the Fe centers were demonstrated by ⁵⁷Fe Mössbauer spectra at 100 K, with a high-spin Fe^III state for 1 and mixed high-spin Fe^III/Fe^II states for 2. Their magnetic properties were determined, which featured strong antiferromagnetic couplings in the chain. Importantly, the proton conductivity of both compounds at 100% relative humidity was explored at different temperatures, with 2.79 × 10^-4 S cm^-1 at 80 °C for 1 and 7.55 × 10^-4 S cm^-1 at 45 °C for 2, respectively. This work provides an opportunity for improving proton conductive properties by increasing the relative number of protons and the carrier density using protonated flexible aliphatic amines.

Cadmium benzylphosphonates – the close relationship between structure and properties

Structure-properties relationship of new Cd-benzylphosphonates differing in their fluorine content.

N,N,N-Tris(diphenylphosphorylmethyl)amine

The structure ofN,N,N-tris(diphenylphosphorylmethyl)amine, C39H36NO3P3, at 103 K has monoclinic (P21/c) symmetry. Two molecules, each with pseudo-threefold rotation symmetry, crystallize in the asymmetric unit of the monoclinic unit cell. The compound acts as ligand for the stabilization of metal ions with flexible coordination enabling three- or fourfold coordination.

Two hybrid transition metal triphosphonates decorated with a tripodal imidazole ligand: synthesis, structures and properties

Two transition-metal triphosphonates with pillar-layered structures were synthesized and characterized. The luminescence, magnetic and proton conductive properties were investigated.

Three Zinc(II) Phosphonates: Syntheses, Structures and Sensing of Copper(II) Ions

Three zinc(II) phosphonocarboxylates, [Zn₃ (m-bpc)₂ (OH)]⋅(CH₃ )₂ NH₂ ⋅H₂ O (1), [Zn₂ (m-bpc)(m-Hbpc)(4,4'-bpy)]⋅(CH₃ )₂ NH₂ ⋅H₂ O (2) and [Zn₃ (m-bpc)₂ (4,4'-bpy)(CH₃ )₂ NH]⋅H₂ O (3) (m-H₃ bpc=3-phosphonobenzoic acid, 4,4'-bpy=4,4'-bipyridine), have been solvothermally synthesised to generate unique topologies, as characterised by single-crystal XRD. Compound 1 possesses a diamond topology, which has rarely been found among phosphonate-based metal-organic frameworks. Compound 2 shows a 2D layered structure with pendant m-Hbpc and 4, 4'-bpy ligands, in which the layers feature as a zeolite-like network. Compound 3 has a 3D sandwich pillared-layer framework with an interesting double-helix structure. Only 1 shows an adsorption capacity for CO₂ of 28.5 cm³  g^-1 at 273 K. Luminescence studies revealed that both 1 and 2 could be potential sensors to copper(II) ions.

Molecular and polymeric zinc(II) phosphonates: isolation of an octanuclear ellipsoidal ensemble

The reaction of zinc(II) perchlorate with trichloromethyl phosphonic acid at room temperature afforded, upon crystallization, a two-dimensional layered coordination polymer possessing a dinuclear repeat unit, [{Zn2(Cl3CPO3)2(H2O)3}·1.5H2O]n (1). Modification of the above reaction by involving a co-ligand afforded the tetranuclear complex, [{Zn4(η(1)-DMPzH)6(Cl3C-PO3)2}(μ-OH)2(ClO4)2] (2). The molecular structure of 2 reveals that the tetranuclear core is non-planar and consists of three contiguous inorganic rings which include one 8-membered Zn2P2O4 ring and two six-membered Zn2PO3 rings. Replacement of Zn(ClO4)2·6H2O with ZnCl2 under the same reaction conditions that afforded 2 allowed the formation of the dinuclear complex [{(ZnCl)2(η(2)-Pz)2(Cl3CPO3)}(Et3NH)2] (3). 3 possesses a bicyclic core containing a seven-membered Zn2N2O2P ring. In 3, the phosphoryl oxygen atom (P=O) is involved in a bifurcated hydrogen bonding interaction with the triethylammonium cation. The reaction of ZnCl2 and 2,3,5,6-(Me)4C6HCH2PO3H2 afforded the octanuclear complex [Zn8(Cl)6{2,3,5,6-(Me)4C6HCH2PO3}6(Et3N)2](Et3NH)2]·2n-hexane·3H2O (4). The core of 4 is ellipsoid-shaped with the end-end polar distance (C-C) being ~20 Å.

Di-, tri- and tetranuclear molecular vanadium phosphonates: a chloride encapsulated tetranuclear bowl

Synthesis and characterization of three dinuclear, two dinuclear and one tetranuclear vanadium phosphonates is being reported. These include a chloride encapsulated tetranuclear bowl-shaped complex.