New Hybrid Layered Molybdates Based on 2/∞[MonO3n+1]2– Units (n = 7, 9) with Systematic Organic–Inorganic Interfaces

Coordination Polymer Based on a Triangular Carboxylate Core {Fe(μ3-O)(μ-O2CR)6} and an Aliphatic Diamine

Interaction of the pre-organized complex of iron(II) trimethylacetate and 1,10-phenanthroline (phen) [Fe2(piv)4(phen)2] (1) (piv = (Me)3CCO2-)) with 1,6-diaminohexane (dahx) in anhydrous acetonitrile yielded a 1D coordination polymer [Fe3O(piv)6(dahx)1.5]n (2) and an organic salt of pivalic acid (H2dahx)(piv)2 (3). The structure of the obtained compounds was determined by single-crystal X-ray diffraction analysis. The phase purity of the complexes was determined by powder X-ray diffraction analysis. According to the single-crystal X-ray analysis, coordination polymer 2 is formed due to the binding of a triangular carboxylate core {Fe3(μ3-O)(μ-piv)6} with an aliphatic diamine ligand. Thermal behavior was investigated for compounds 1 and 2 in an argon atmosphere.

Hybrid bronzes: mixed-valence organic-inorganic metal oxides as a tunable material platform

We demonstrate that mixed-valence layered organic-inorganic metal oxides of the form (L)zHxMO3 (L = neutral ligand; M = Mo, W; z = 0.5, 1; 0 < x < 2), which we call hybrid bronzes, can be readily synthesized through mild solution-state self-assembly reactions to integrate the stability and electronic utility of inorganic metal oxide bronzes with the chemical diversity and functionality of organic molecules. We use single-crystal and powder X-ray diffraction coupled with X-ray, electronic, and vibrational spectroscopies to show that the products of aqueous pre-, mid-, or post-synthetic reduction are mixed-valence versions of highly crystalline layered hybrid oxides. Pillaring, bilayered, or canted bilayered arrangements of molecular arrays relative to inorganic sheets are dictated by judicious choice of organic ligands that can also incorporate chemical, redox, or photoactive handles. Significantly, bond-valence sum analysis and diffuse reflectance spectroscopy indicate relatively delocalized electronic behavior and four-point variable-temperature electrical transport measurements show that hybrid bronzes have comparable conductivity to their all-inorganic parent compounds. This work establishes a solution-processable, inexpensive, air- and water-stable, and non-toxic material family whose electronic bands can be readily tuned and doped, thereby positioning hybrid bronzes to address myriad material challenges.

Photochemical and gas adsorption studies of Keggin polyoxometalate functionalized porous melamine terephthaldehyde material

A compound containing a microporous melamine-terephthaldehyde framework is protonated by grinding with acetic acid, resulting in a mesoporous protonated melamine-terephthaldehyde network. The Keggin polyanion [PMo12O40]3- is then immobilized into this protonated melamine-terephthaldehyde network through a solid-state reaction. The polyanion interacts with the protonated microporous organic network through electrostatic interaction. Three different Keggin-melamine-terephthaldehyde materials were synthesized by varying the Keggin anion loading of 10 wt%, 15 wt% and 20 wt%. The Keggin-melamine-terephthaldehyde materials exhibit photochromism on irradiation with sunlight. The photochromism of the POM-organic hybrid material is due to reduction of the Keggin anion. The resulting blue reduced Keggin-melamine-terephthaldehyde materials are oxidized back by treatment with hydrogen peroxide. The N2, CO2 and H2 adsorption properties of all the synthesized materials, including protonated melamine-terephthaldehyde materials, were studied. The materials were characterized by IR, PXRD, DRS, TGA, EPR spectroscopy, and FESEM electron microscopy. The elemental composition was analysed with a CHN analyser and ICP-OES analysis.

Sonochemical synthesis of inorganic cryogel Ag2Mo3O10@Ag/AgO: structural characterization, antibacterial activity, and dye adsorption properties

An additive-free ultrasonic-assisted synthesis of a multi-layered Ag₂Mo₃O₁₀@Ag/AgO cryogel (SMSSO) nanocomposite has been developed, and a possible formation mechanism of multi-layered SMSSO was proposed based on characterization results of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman spectroscopy, and diffuse reflection spectroscopy (DRS). The FE-SEM images demonstrated the formation process of the multi-layered SMSSO cryogel over time under sonication, starting with the growth of Ag₂Mo₃O₁₀ nanowires, and the formation of spherical nuclei which turn into an octahedron in the presence of excess silver ions. The antibacterial activity of the synthesized cryogel and its adsorption behavior for hazardous pollutant removal were explored. The results revealed that SMSSO exhibits excellent adsorption properties, with a maximum adsorption capacity of 277.77 mg g⁻¹ and removal of 99/95% for 150 mg L⁻¹ methylene blue (MB) by 0.005 g adsorbent doses at 60 °C and pH 9. It was also confirmed that the synthesized cryogels have good antibacterial activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The selective adsorption capability of the cryogel toward cationic dye molecules and antibacterial activity makes it a competent candidate for water purification.

An ultrasonic-assisted synthesis of Ag₂Mo₃O₁₀@Ag/AgO cryogel (SMSSO) nanocomposite was developed, and a possible formation mechanism of multi-layered SMSSO was proposed based on characterization results of SEM, EDX, XRD, Raman spectroscopy, and DRS.

Preparation of 2D supramolecular material doping with TiO2 for degradation of tetracycline

Anatase TiO₂ photocatalyst supported on [BMPP]₂[2D-Mo₁₈O₅₆] (BMPP = 1, 3-bis(4-methylpyridine) propane dibromide) was successfully prepared by hydrothermal method. The composites were characterized by field emission scanning electron microscopy (SEM), X-ray diffractometer (XRD), infrared spectroscopy (IR) and energy-dispersive X-ray spectrometer (EDS). The results show that the high content anatase nanoparticles are uniformly loaded on the polyacid supramolecules to form the composite material. The photocatalytic activity of TiO₂/Mo₉O₂₈-BMPP towards the tetracyclines (TCs), a model pollutant, has been investigated. The results show that under a 500W high-pressure xenon lamp, 0.15 g TiO₂/MoB can degrade 97% of 20 mL (25 mg/L) Tc after 115 min, showing high catalytic activity. In addition, 0.15-TiO₂/MoB can be easily separated from the reaction system by centrifugation, and the catalyst still maintains high photocatalytic activity after 3 cycles of tests under the same conditions. This shows that it has the potential for recycling. This research provides a new way for the development of new supported catalysts.

Significant enhancement of conductance of a hybrid layered molybdate semiconductor by light or heat

Introduction of the viologen cation, a well-known electron acceptor, into molybdate layers led to a dramatic change in the conductance of the 2D hybrid material in the process of photo-induced and thermo-induced coloration.

Hydrogen bonds and van der Waals forces as tools for the construction of a herringbone pattern in the crystal structure of hexane-1,6-diaminium hexane-1,6-diyl bis-(hydrogen phospho-nate)

The asymmetric unit of the title salt, [H3N(CH2)6NH3][(HO)O2P(CH2)6PO2(OH)], consists of one half of a hexane-1,6-diaminium dication and one half of a hexane-1,6-diyl bis-(hydrogen phospho-nate) dianion. Both are located around different centres of inversion (Wyckoff sites: 2a and 2d) of the space group P21/c. The shape of the hexane-1,6-diaminium cation is best described as a double hook. Both aminium groups as well as the two attached CH2 groups are turned out from the plane of the central four C atoms. In contrast, all six C atoms of the dianion are almost in a plane. The hydrogen phospho-nate (-PO3H) groups of the anions and the aminium groups of the cations form two-dimensional O-H⋯ and O-H⋯N hydrogen-bonded networks parallel to the ac plane, built up from ten-membered and twelve-membered ring motifs with graph-set descriptors R33(10) and R54(12), respectively. These networks are linked by the alkyl-ene chains of the anions and cations. The resulting three-dimensional network shows a herringbone pattern, which resembles the parent structures 1,6-di-amino-hexane and hexane-1,6-di-phospho-nic acid.

Two new molybdates based on ∞[MonO3n+1]2− units (n = 11, 4) with proton conduction under ionothermal

Two new members of the _∞[Mo_nO_3n+1]²⁻ family with high proton conduction synthesized under ionothermal condition.

Organic-inorganic hybrid rare earth complexes based on polymolybdates with intrinsic photosensitive properties

A series of organic–inorganic hybrid rare earth complexes {[RE2(PO)2(H2O)10][H2Mo36O112(OH2)12(PO)4]}·5PO·2(CH3CN)·nH2O [n = 23–42, RE(III) = Nd(III), 1; Sm(III), 2; Eu(III), 3; Gd(III), 4; Dy(III), 5; Er(III), 6; Tm(III), 7; Yb(III), 8; Lu(III), 9; Y(III), 10; PO = piperidin-2-one] have been synthesized and fully characterized by single-crystal X-ray diffraction, powder X-ray diffraction, elemental analysis, IR spectra, thermogravimetric analysis and UV-vis spectra. Structural analysis reveals that compounds 1-10 are isostructural and crystallize in the monoclinic P2(1)/n space group. Each compound contains a centrosymmetric anionic cluster [Mo36O112(OH2)12(PO)4](8-), which could be described as the derivative of [Mo36O112(OH2)16](8-) with four water molecules substituted by organic PO molecules. Each {Mo18} subunit connects with one RE(III) ion via its two terminal O atoms from two independent {MoO6} octahedra. The eight coordinated RE(III) ion with a distorted tetragonal antiprism coordination geometry is also surrounded by another six oxygen atoms, five of them from five water molecules and the final one from one PO molecule. Compounds 1-10 show considerable photosensitive behavior under visible light excitation. In addition, compound 3 exhibits three emission bands at 580, 595 and 617 nm in the solid state, which could be assigned to (5)D0→(7)F0, (5)D0→(7)F1 and (5)D0→(7)F2 transitions of Eu(III) ions, respectively.