Studies on the Genesis and Proton Conductivity of Imidazole-Based Linear and Open-Framework Zinc Phosphites

Three new zinc phosphites, [HIm]₂[Zn₃(HPO₃)₄] (1), [Zn₂(HPO₃)₂Im₂] (2), and [Zn(HPO₃)Im] (3) (Im = imidazole), have been synthesized from the hydro/solvothermal reaction of zinc acetate, dimethyl phosphite, and imidazole by varying the temperature and solvent of the reaction medium. The structure of 1 is built from vertex-sharing of four HPO₃-capped Zn₃P₃ units and adopts an open framework with 12-ring channels stabilized by HIm cations via N-H···O hydrogen bonds. For 2, the inorganic skeleton is comprised of alternating ZnO₄ and HPO₃ tetrahedra, while the coordinatively associated ZnN₂O₂ fragments occupy the 12-ring hexagonal channels. Compound 3 adopts a ladder-type one-dimensional structure and exhibits N-H···O hydrogen-bonding interactions to afford a supramolecular assembly. A plausible rationale on the genesis of 1-3 has been put forth by reacting the preformed inorganic zinc phosphites Zn{OP(O)(OMe)H}₂ or [Zn₂(HPO₃)₂(H₂O)₄]·H₂O with imidazole as the structure-directing ligand. Alternating-current impedance measurements reveal that 1 and 3 exhibit proton conductivities on the order of 10^-3-10^-4 S cm^-1 between 25 and 100 °C under 35 and 77% relative humidity in repeated impedance cycles (E_a = 0.22-0.35 eV). On the contrary, the conduction property is completely impaired in 2 under similar conditions.

Pillared-layered indium phosphites templated by amino acids: isoreticular structures, water stability, and fluorescence

Two crystalline open-framework indium phosphites (denoted SCU-31 and SCU-32) were prepared using amino acids as structure-directing agents. They have isoreticular pillared-layered structures built up from 6 × 1 and 4 = 1 clusters. Notably, the two compounds show excellent water stability and exhibit blue fluorescence under UV light irradiation at room temperature. The proton-conducting behaviour of SCU-31 was also investigated.

The Different Effects of Organic Amines on Synthetic Metal Phosphites/Phosphates

Four metal phosphites/phosphates crystal materials C₈N₄H₃₄Al₂P₄O₁₈ (1), C₃N₂H₁₇GaP₂O₈ (2), H₅In₂P₃O₁₀ (3), and H₉In₂P₃O₁₃ (4) have been solvothermally synthesized by organic amines in the presence of mixed solvents. Structural analyses indicate that compound 1 and 2 show one-dimensional (1D) chain structures; compound 3 and 4 are three-dimensional (3D) inorganic open-framework indium phosphites. Organic amines show different mechanisms in the four compounds. The 2,2′-bipyridine organic amine acts as a template source and it breaks down small molecules, which enter into the structure of compound 1. For compound 2, 1,2-propanediamine has a role as protonated template and it forms a hydrogen bond with the inorganic skeleton structure. As for compound 3 and 4 without the organic template, the benzylamine and 2,2′-bipyridine mainly serve as structure-directing agent. Especially, compound 3 has an odd seven-ring channel, and compound 4 contains 3D intersecting six-ring, eight-ring, and 10-ring channels. X-ray diffraction (XRD), scanning electron microscopy (SEM), CHN, inductive coupled plasma (ICP), Infrared (IR), and thermal gravimetric (TG) analyze the four compounds.

Ionothermal synthesis of crystalline metal phosphites using multifunctional protic ionic liquids

A mixed-valence iron phosphite was prepared under ionothermal conditions using a protic ionic liquid as a solvent, a structure-directing agent, a phosphorus source, and a reducing agent.

Coordinate bond- and hydrogen bond-assisted electron transfer strategy towards the generation of photochromic metal phosphites

The introduction of conjugated dipyridine-derivative units into metal phosphite system produces two hybrid zincophosphites driven by the coordinate bond- and hydrogen bond-assisted electron transfer.

Two- and three-dimensional hybrid zinc phosphites: syntheses, structures and photoluminescence properties

Two zinc-phosphites modified by a rigid amine 3,5-bis(imidazole-1-yl)pyridine (BIP), [Zn2(HPO3)2(BIP)]·H2O (1) and [Zn3(HPO3)3(BIP)(H2O)]·H2O (2), were solvothermally prepared. Compound 1 possesses a zincophosphite layer decorated by BIP moieties via coordinating to intralayer Zn(ii) ions. Compound 2 features a 3D frame with a pillar-layer structure, in which the organic BIP pillars the inorganic zincophosphite layer via coordinating to interlayer Zn(ii) ions. The structural diversity from a 2D layer to a 3D frame was mainly attributable to the different bridging modes of BIP in the process of assembly. Their temperature-dependent photoluminescence properties have also been studied.

An Ultrastable Heterobimetallic Uranium(IV)/Vanadium(III) Solid Compound Protected by a Redox-Active Phosphite Ligand: Crystal Structure, Oxidative Dissolution, and First-Principles Simulation

The first heterobimetallic uranium(IV)/vanadium(III) phosphite compound, Na₂UV₂(HPO₃)₆ (denoted as UVP), was synthesized via an in situ redox-active hydrothermal reaction. It exhibits superior hydrolytic and antioxidant stability compared to the majority of structures containing low-valent uranium or vanadium, further elucidated by first-principles simulations, and therefore shows potential applications in nuclear waste management.

Bipyridine-triggered modulation of structure and properties of zinc-diphosphonates: coordination role vs. template rule

Two layered zinc-diphosphonates driven by 4,4′-bipy are prepared and their structural diversities are caused by the distinct roles of 4,4′-bipy in the process of assembly. The luminescence and proton conduction are studied.

K2MnII2(H2O)2C2O4(HPO3)2: a new 2D manganese(ii) oxalatophosphite with double-layered honeycomb sheets stabilized by potassium ions

A novel 2D manganese(ii) phosphite containing oxalate bridges with double layered honeycomb sheets encouraged us to propose a new structural classification for metal oxalatophosphites with anionic frameworks.

An open-framework manganese(ii) phosphite and its composite membranes with polyvinylidene fluoride exhibiting intrinsic water-assisted proton conductance

An open-framework manganese(ii) phosphite shows intrinsic water-assisted proton conductance; homogenous composite membranes have been fabricated, and the water-assisted proton conductivities have been studied.

The first lead cobalt phosphite, PbCo2(HPO3)3

The first lead cobalt phosphite PbCo₂(HPO₃)₃ reveals weak antiferromagnetic interactions between Co ions inside the Co₂O₉ dimers combined through HPO₃ pseudo-tetrahedra into alternating 2D blocks of the non-centrosymmetric crystal structure of the title compound.

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.

Ax(H3O)2−xMn5(HPO3)6 (A = Li, Na, K and NH4): open-framework manganese(ii) phosphites templated by mixed cationic species

Four new manganese(ii) phosphites templated by alkali metal ions (Li⁺, Na⁺ and K⁺) and ammonium cations were achieved under mild hydrothermal conditions.

An open-framework beryllium phosphite with extra-large 18-ring channels

We report herein a 3D interrupted beryllium phosphite open-framework with a low density (1.594 g cm⁻³), which is the first case of a beryllium phosphite framework containing extra-large 18-ring channels.

K6[Fe8.27(HPO3)12]: a new mixed-valence iron phosphite

The title compound, hexapotassium octairon(II,III) dodecaphosphonate, exhibiting a two-dimensional structure, is a new mixed alkali/3d metal phosphite. It crystallizes in the space group R3m, with two crystallographically independent Fe atoms occupying sites of 3m (Fe1) and 3m (Fe2) symmetry. The Fe2 site is fully occupied, whereas the Fe1 site presents an occupancy factor of 0.757 (3). The three independent O atoms, one of which is disordered, are situated on a mirror and all other atoms are located on special positions with 3m symmetry. Layers of formula [Fe3(HPO3)4](2-) are observed in the structure, formed by linear Fe3O12 trimer units, which contain face-sharing FeO6 octahedra interconnected by (HPO3)(2-) phosphite oxoanions. The partial occupancy of the Fe1 site might be described by the formation of two [Fe(HPO3)2](-) layers derived from the [Fe3(HPO3)4](2-) layer when the Fe1 atom is absent. Fe(2+) is localized at the Fe1 and Fe2 sites of the [Fe3(HPO3)4](2-) sheets, whereas Fe(3+) is found at the Fe2 sites of the [Fe(HPO3)2](-) sheets, according to bond-valence calculations. The K(+) cations are located in the interlayer spaces, between the [Fe3(HPO3)4](2-) layers, and between the [Fe3(HPO3)4](2-) and [Fe(HPO3)2](-) layers.

Hybrid vanadates constructed from extended metal–organic arrays: crystal architectures and properties

Classification of inorganic–organic vanadates constructed from bridging ligands based on the metal–organic and inorganic substructures dimensionalities.

Fluorinated mixed valence Fe(ii)–Fe(iii) phosphites with channels templated by linear tetramine chains. Structural and magnetic implications of partial replacement of Fe(ii) by Co(ii)

Three novel 3D open-framework fluorinated mixed valence Fe(ii)–Fe(iii) phosphites with channels templated by protonated tetramine chains were synthesized.

Synthesis, characterization and selective de-esterification of diorganotinbis(O-methylphosphite)s

A one-pot reaction between di-n-butyl/diethyl/dimethyltin dichloride and dimethylphosphite (MeO)2P(O)H in a solvent free medium (120 °C, 18 h) proceeds smoothly to yield the corresponding diorganotinbis(O-methylphosphite)s, [R2Sn(OP(O)(OMe)H)2]n [R = n-Bu (1), Et (2), Me (3)]. The identity of 1-3 has been established by IR, multinuclear ((1)H, (13)C, (31)P, (119)Sn) NMR, powder X-ray diffraction (PXRD) and X-ray crystallography. The coordination framework in each case adopts a one-dimensional structural motif comprising an infinite array of eight-membered [Sn-O-P-O]2 cyclic rings, with the phosphite ligands acting in a bridging bidentate mode. The structures are extended to two- (for 1) and three-dimensional (for 2, 3) assemblies by virtue of C-H···O hydrogen bonding interactions. The stability and bulk properties of 1-3 have been investigated upon exposure to humid laboratory conditions using (1)H NMR, PXRD and SEM studies. The results conform to a unique chemical modification of 1-3 involving selective de-esterification of P-OMe bonds and the formation of corresponding diorganotinbis(phosphite)s, [R2Sn(OP(O)(OH)H)2]n (1a-3a), as insoluble solids. The results obtained from impedance studies (σ = 10(-4)-10(-6) S cm(-1); E(a) = 0.33-0.42 eV) reveal potential application of 1a-3a as proton conducting materials.

Thermal response, catalytic activity, and color change of the first hybrid vanadate containing Bpe guest molecules

Four isomorphic compounds with formula [{Co2(H2O)2(Bpe)2}(V4O12)]·4H2O·Bpe, CoBpe 1; [{CoNi(H2O)2(Bpe)2}(V4O12)]·4H2O·Bpe, CoNiBpe 2; [{Co0.6Ni1.4(H2O)2(Bpe)2}(V4O12)]·4H2O·Bpe, NiCoBpe 3; and [{Ni2(H2O)2(Bpe)2}(V4O12)]·4H2O·Bpe, NiBpe 4, have been obtained by hydrothermal synthesis. The crystal structures of CoBpe 1 and NiBpe 4 were determined by single-crystal X-ray diffraction (XRD). The Rietveld refinement of CoNiBpe 2 and NiCoBpe 3 XRD patterns confirms that those are isomorphic. The compounds crystallize in the P1̅ space group, exhibiting a crystal structure constructed from inorganic layers pillared by Bpe ligands. The crystal structure contains intralayer and interlayer channels, in which the crystallization water molecules and Bpe guest molecules, respectively, are located. The solvent molecules establish a hydrogen bonding network with the coordinated water molecules. Thermodiffractometric and thermogravimetric studies showed that the loss of crystallization and coordinated water molecules takes place at different temperatures, giving rise to crystal structure transformations that involve important reduction of the interlayer distance, and strong reduction of crystallinity. The IR, Raman, and UV-vis spectra of the as-synthesized and heated compounds confirm that the structural building blocks and octahedral coordination environment of the metal centers are maintained after the structural transformations. The color change and reversibility of the water molecules uptake/removal were tested showing that the initial color is not completely recovered when the compounds are heated at temperatures higher than 200 °C. The thermal evolution of the magnetic susceptibility indicates one-dimensional antiferromagnetic coupling of the metal centers at high temperatures. For NiCoBpe 3 and NiBpe 4 compounds magnetic ordering is established at low temperatures, as can be judged by the maxima observed in the magnetic susceptibilities. CoNiBpe 2 was proved as catalyst being active for cyanosilylation reactions of aldehydes.

Enhancement of the luminescent properties of a new red-emitting phosphor, Mn2(HPO3)F2, by Zn substitution

The Mn(2)(HPO(3))F(2) phase has been synthesized as single crystals by using mild hydrothermal conditions. The compound crystallizes in the orthorhombic Pnma space group, with unit cell parameters of a = 7.5607(8), b = 10.2342(7), and c = 5.5156(4) Å, with Z = 4. The crystal structure consists of a three-dimensional framework formed by alternating (010) layers of [MnO(3)F(3)] octahedra linked up by three connected [HPO(3)] tetrahedra. Luminescence measurements were performed at different temperatures between 10 and 150 K. The 10 K emission spectrum of the octahedrally coordinated Mn(II) cation exhibits a broad band centered at around 615 nm corresponding to the (4)T(1) → (6)A(1) transition. In order to explore the effect of the Mn(II) concentration and the possibility of enhancing the luminescence properties of the Mn(II) cation in Mn(2)(HPO(3))F(2), different intermediate composition members of the finite solid solution with the general formula (Mn(x)Zn(1-x))(2)(HPO(3))F(2) were prepared and their luminescent properties studied. The magnetic and specific heat behavior of M(2)(HPO(3))F(2) (M = Mn, Fe) have also been investigated. The compounds exhibit a global antiferromagnetic ordering with a spin canting phenomenon detected at approximately 30 K. The specific heat measurements show sharp λ-type peaks at 29.7 and 33.5 K for manganese and iron compounds, respectively. The total magnetic entropy is consistent with spin S = 5/2 and S = 2 of Mn(II) and Fe(II) cations.

The cyclo-propylammonium cation as a templating agent for inorganic networks: Synthesis and structure of (C3H8N)2·Zn3(HPO3)4

The hydrothermal synthesis and single crystal structure of (C3H8N)2·Zn3(HPO3)4 are described. This compound is built up from ZnO4 tetrahedra and HPO3 pyramids sharing vertices to generate a three-dimensional 4:3 network containing 8-ring channels. The protonated organic cations occupy the channels in a head-to-tail arrangement and interact with the framework by way of N–H···O hydrogen bonds. Crystal data: C6H20N2O12P4Zn3, Mr = 632.23, monoclinic, P21/ n (No. 14), Z = 4, a = 9.6773 (2) Å, b = 13.8676 (2) Å, c= 15.4482 (3) Å, β = 90.039 (1)°, V = 2073.16 (7) Å3, R( F) = 0.028, wR( F2) = 0.062.