An organic-organometallic CO-releasing material comprising 4,4'-bipyridine and molybdenum subcarbonyl building blocks.

Over the past two decades, following the discovery of the important biological roles of carbon monoxide (CO), metal carbonyl complexes have been intensively studied as CO-releasing molecules (CORMs) for therapeutic applications. To improve the properties of "bare" low molecular weight CORMs, attention has been drawn to conjugating CORMs with macromolecular and inorganic scaffolds to produce CO-releasing materials (CORMAs) capable of storing and delivering large payloads of the gasotransmitter. A significant obstacle is to obtain CORMAs that retain the beneficial features of the parent CORMs.

Tricarbonyl-Pyrazine-Molybdenum(0) Metal-Organic Frameworks for the Storage and Delivery of Biologically Active Carbon Monoxide.

Metal-organic frameworks (MOFs) have high potential as nanoplatforms for the storage and delivery of therapeutic gasotransmitters or gas-releasing molecules. The aim of the present study was to open an investigation into the viability of tricarbonyl-pyrazine-molybdenum(0) MOFs as carbon monoxide-releasing materials (CORMAs). A previous investigation found that the reaction of Mo(CO) with excess pyrazine (pyz) in a sealed ampoule gave a mixture comprising a major triclinic phase with pyz-occupied hexagonal channels, formulated as -Mo(CO)(pyz)·1/2pyz (), and a minor dense cubic phase, formulated as -Mo(CO)(pyz) ().

Enhanced thermal and photo-stability of a -substituted dicumyl ketone intercalated in a layered double hydroxide.

A ketodiacid, 4,4'-dicarboxylate-dicumyl ketone (), has been intercalated into a Zn, Al layered double hydroxide (LDH) by a coprecipitation synthesis strategy. The structure and chemical composition of the resultant hybrid material (LDH-KDA3) were characterized by powder X-ray diffraction (PXRD), FT-IR, FT-Raman and solid-state C{H} NMR spectroscopies, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), and elemental analysis (CHN). PXRD showed that the dicarboxylate guest molecules assembled into a monolayer to give a basal spacing of 18.

A hafnium-based metal-organic framework for the entrapment of molybdenum hexacarbonyl and the light-responsive release of the gasotransmitter carbon monoxide.

A carbon monoxide-releasing material (CORMA) has been prepared by inclusion of molybdenum hexacarbonyl in a hafnium-based metal-organic framework (MOF) with the UiO-66 architecture. Mo(CO) was adsorbed from solution to give supported materials containing 6.0-6.

A Molybdenum Trioxide Hybrid Decorated by 3-(1,2,4-Triazol-4-yl)adamantane-1-carboxylic Acid: A Promising Reaction-Induced Self-Separating (RISS) Catalyst.

3-(1,2,4-Triazol-4-yl)adamantane-1-carboxylic acid (tradcH), a heterobifunctional organic ligand in which carboxylic acid and 1,2,4-triazole groups are united through a rigid 1,3-adamantanediyl spacer, was employed for the synthesis of a Mo oxide organic hybrid. The ligand crystallized from water as tradcH·HO (), possessing a two-dimensional hydrogen-bonding network, and from ethanol as a cyclic molecular solvate with the composition (tradcH)·2EtOH (). Treatment of tradcH with MoO under hydrothermal conditions afforded a new Mo trioxide hybrid, [MoO(tradcH)]·HO (), which was structurally characterized.

A hydrogen-bonded assembly of cucurbit[6]uril and [MoOCl(HO)] with catalytic efficacy for the one-pot conversion of olefins to alkoxy products.

The reaction of the macrocyclic cavitand cucurbit[6]uril (CB[6]) and the diaqua complex [MoOCl(HO)] in hydrochloric acid solution gave a water insoluble supramolecular compound with the general composition 2[MoOCl(HO)]·CB[6]·xHO·yHCl·z(CHCOCH) (2). Single crystal X-ray diffraction (XRD) analysis revealed the presence of barrel-shape supramolecular entities, {CB[6]·10(HO)}, aligned in layers which are shifted relative to adjacent layers to form a brick-like pattern. The CB[6]/water hydrogen-bonded entities further engage in intermolecular interactions with water, HCl and [MoOCl(HO)] molecules to form a three-dimensional (3D) framework.

A Comparative Study of Molybdenum Carbonyl and Oxomolybdenum Derivatives Bearing 1,2,3-Triazole or 1,2,4-Triazoles in Catalytic Olefin Epoxidation.

The molybdenum(0)-carbonyl-triazole complexes [Mo(CO)₃(L)₃] [L = 1,2,3-triazole (1,2,3-trz) or 1,2,4-triazole (1,2,4-trz)] have been prepared and examined as precursors to molybdenum(VI) oxide catalysts for the epoxidation of -cyclooctene. Reaction of the carbonyl complexes with the oxidant -butyl hydroperoxide (TBHP) (either separately or in situ) gives oxomolybdenum(VI) hybrid materials that are proposed to possess one-dimensional polymeric structures in which adjacent oxo-bridged dioxomolybdenum(VI) moieties are further linked by bidentate bridging triazole (trz) ligands. A pronounced ligand influence on catalytic performance was found and the best result (quantitative epoxide yield within 1 h at 70 °C) was obtained with the 1,2,3-triazole oxomolybdenum(VI) hybrid.

Molybdenum(0) tricarbonyl and tetracarbonyl complexes with a cationic pyrazolylpyridine ligand: synthesis, crystal structures and catalytic performance in olefin epoxidation.

The synthesis of molybdenum(0) tricarbonyl and tetracarbonyl complexes of the form [Mo(CO)(ptapzpy)Br] (1) and -[Mo(CO)(ptapzpy)]Br (2) is reported, where ptapzpy = 2-(1-propyltrimethylammonium-3-pyrazolyl)pyridine. Preparation of these derivatives was accomplished either through thermal replacement of CO in Mo(CO) (for 1) or substitution under milder conditions of piperidine ligands in the precursor -[Mo(CO)(pip)] (for 2). The crystal structures of the ligand [ptapzpy]Br and complexes 1 and 2 were determined.

Interactions and Supramolecular Organization of Sulfonated Indigo and Thioindigo Dyes in Layered Hydroxide Hosts.

Supramolecularly organized host-guest systems have been synthesized by intercalating water-soluble forms of indigo (indigo carmine, IC) and thioindigo (thioindigo-5,5'-disulfonate, TIS) in zinc-aluminum-layered double hydroxides (LDHs) and zinc-layered hydroxide salts (LHSs) by coprecipitation routes. The colors of the isolated powders were dark blue for hybrids containing only IC, purplish blue or dark lilac for cointercalated samples containing both dyes, and ruby/wine for hybrids containing only TIS. The as-synthesized and thermally treated materials were characterized by Fourier transform infrared, Fourier transform Raman, and nuclear magnetic resonance spectroscopies, powder X-ray diffraction, scanning electron microscopy, and elemental and thermogravimetric analyses.

Ferrocene and ferrocenium inclusion compounds with cucurbiturils: a study of metal atom dynamics probed by Mössbauer spectroscopy.

Temperature-dependent Fe Mössbauer effect (ME) spectroscopic studies were carried out on ferrocene (Fc), 1,1'-dimethylferrocene (1,1'(CH)Fc) and ferrocenium hexafluorophosphate (FcPF) guest species in cucurbit[n]uril (n = 7, 8) inclusion complexes. The solid inclusion complexes were isolated by freeze-drying of dilute aqueous solutions and/or microwave-assisted precipitation from concentrated mixtures. The presence of genuine 1 : 1 (host : guest) inclusion complexes in the isolated solids was supported by liquid-state H and solid-state C{H} MAS NMR, elemental and thermogravimetric analyses, powder X-ray diffraction, FTIR spectroscopy, and diffuse reflectance UV-Vis spectroscopy.

Triazolyl, Imidazolyl, and Carboxylic Acid Moieties in the Design of Molybdenum Trioxide Hybrids: Photophysical and Catalytic Behavior.

Three organic ligands bearing 1,2,4-triazolyl donor moieties, (S)-4-(1-phenylpropyl)-1,2,4-triazole (trethbz), 4-(1,2,4-triazol-4-yl)benzoic acid (trPhCOH), and 3-(1H-imidazol-4-yl)-2-(1,2,4-triazol-4-yl)propionic acid (trhis), were prepared to evaluate their coordination behavior in the development of molybdenum(VI) oxide organic hybrids. Four compounds, [MoO(trethbz)]·HO (1), [MoO(trPhCOH)]·0.5HO (2a), [MoO(trPhCOH)]·HO (2b), and [MoO(trhis)(trhisH)]·2HO (3), were synthesized and characterized.

Insights into the Photophysics and Supramolecular Organization of Congo Red in Solution and the Solid State.

Steady-state and time-resolved absorption and fluorescence measurements are reported for Congo Red (CR) in aqueous and dimethylsulfoxide (DMSO) solutions. The very low fluorescence quantum yield (≈10 ) for CR in dilute solutions together with the absence of a triplet state indicates that internal conversion is the dominant deactivation route with more than 99.99 % of the quanta loss (attributed to the energy gap law for radiationless transitions).

Solid-state study of the structure and host-guest chemistry of cucurbituril-ferrocene inclusion complexes.

Inclusion complexes of ferrocene (Fc) with cucurbit[n]urils (n = 7, 8) have been prepared via a rapid microwave-assisted hydrothermal approach. Solids were isolated and characterised by elemental analysis, powder X-ray diffraction (PXRD), spectroscopic, and thermoanalytical methods. The UV-Vis spectra support the presence of Fc in Fc@CB7 and a mixture of Fc and ferrocenium ions in Fc@CB8.

A recyclable ionic liquid-oxomolybdenum(vi) catalytic system for the oxidative desulfurization of model and real diesel fuel.

The oxidative desulfurization of model and real diesel has been studied using the complex [MoO2Cl2(4,4'-di-tert-butyl-2,2'-bipyridine)] as (pre)catalyst, aq. H2O2 as oxidant, and an ionic liquid as extraction solvent. Under moderate conditions (50 °C) and short reaction times (<3 h), dibenzothiophene, 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene could be completely removed from the model diesel.

Catalytic alcoholysis of epoxides using metal-free cucurbituril-based solids.

Metal-free cucurbit[7]uril (CB7) solid-state assemblies promote acid-catalysed alcoholysis of aliphatic and aromatic epoxides under mild conditions to give β-alkoxy alcohols, which are important intermediates for the synthesis of a vast range of compounds such as bioactive pharmaceuticals. The catalytic process is heterogeneous and the catalyst can be reused in consecutive runs without any reactivation treatment. The acid species responsible for the catalytic activity of CB7 may be entrapped hydronium ions.

Crystal structure of an organic-inorganic supra-molecular salt based on a 4,4'-methyl-enebis(3,5-dimethyl-1H-pyrazol-2-ium) cation and a β-octa-molybdate anion.

The asymmetric unit of the title compound, bis-[4,4'-methyl-enebis(3,5-dimethyl-1H-pyrazol-2-ium)] β-octa-molybdate, (C11H18N4)2[Mo8O26] or (H4mbdpz)2[Mo8O26], is composed of an H4mbdpz(2+) cation and half of the β-octa-molybdate anion which is completed by inversion symmetry. The organic mol-ecular units are engaged in a series of N-H⋯O hydrogen bonds with neighbouring anions, with N⋯O distances and N-H⋯O angles in the ranges 2.730 (2)-2.

Redetermination of the crystal structure of 3,5-di-methyl-pyrazolium β-octa-molybdate tetra-hydrate.

The title compound, (C5H9N2)4[Mo8O26]·4H2O, was reported previously from a room-temperature data collection from which only the metal atoms could be refined anisotropically [FitzRoy et al. (1989 ▸). Inorg.

Synthesis and Structural Elucidation of Triazolylmolybdenum(VI) Oxide Hybrids and Their Behavior as Oxidation Catalysts.

A large family of bifunctional 1,2,4-triazole molecular tectons (tr) has been explored for engineering molybdenum(VI) oxide hybrid solids. Specifically, tr ligands bearing auxiliary basic or acidic groups were of the type amine, pyrazole, 1H-tetrazole, and 1,2,4-triazole. The organically templated molybdenum(VI) oxide solids with the general compositions [MoO3(tr)], [Mo2O6(tr)], and [Mo2O6(tr)(H2O)2] were prepared under mild hydrothermal conditions or by refluxing in water.

An Indigo Carmine-Based Hybrid Nanocomposite with Supramolecular Control of Dye Aggregation and Photobehavior.

Zn-Al layered double hydroxides (LDHs) containing solely indigo carmine (IC) or 1-hexanesulfonate (HS) anions, or a mixture of the two with different HS/IC molar ratios, were prepared by the direct synthesis method and characterized by various techniques. Hydrotalcite-type phases were obtained with basal spacings of 17.6 Å for the LDH intercalated by IC (IC-LDH) and 18.

Dichlorodioxomolybdenum(VI) complexes bearing oxygen-donor ligands as olefin epoxidation catalysts.

Treatment of the solvent adduct [MoO2Cl2(THF)2] with either 2 equivalents of N,N-dimethylbenzamide (DMB) or 1 equivalent of N,N'-diethyloxamide (DEO) gave the dioxomolybdenum(vi) complexes [MoO2Cl2(DMB)2] () and [MoO2Cl2(DEO)] (). The molecular structures of and were determined by single-crystal X-ray diffraction. Both complexes present a distorted octahedral geometry and adopt the cis-oxo, trans-Cl, cis-L configuration typical of complexes of the type [MoO2X2(L)n], with either the monodentate DMB or bidentate DEO oxygen-donor ligands occupying the equatorial positions trans to the oxo groups.

Crystal Structure and Catalytic Behavior in Olefin Epoxidation of a One-Dimensional Tungsten Oxide/Bipyridine Hybrid.

The tungsten oxide/2,2'-bipyridine hybrid material [WO3(2,2'-bpy)]·nH2O (n = 1-2) (1) has been prepared in near quantitative yield by the reaction of H2WO4, 2,2'-bpy, and H2O in the mole ratio of ca. 1:2:700 at 160 °C for 98 h in a rotating Teflon-lined digestion bomb. The solid-state structure of 1 was solved and refined through Rietveld analysis of high-resolution synchrotron X-ray diffraction data collected for the microcrystalline powder.

Controlling the fluorescence behavior of 1-pyrenesulfonate by cointercalation with a surfactant in a layered double hydroxide.

Zn-Al layered double hydroxides (LDHs) containing solely 1-pyrenesulfonate (PS) or 1-heptanesulfonate (HS) anions, or a mixture of the two with HS/PS molar ratios ranging between ca. 7.5 and 82, were prepared by the direct synthesis method and characterized by powder X-ray diffraction, thermal and elemental analyses, scanning electron microscopy, and FT-IR, FT-Raman, and (13)C{(1)H} CP MAS NMR spectroscopies.

Crystal structure and temperature-dependent luminescence of a heterotetranuclear sodium-europium(III) β-diketonate complex.

A heterotetranuclear Na2Eu2 complex with uncommon photoluminescence properties is reported. The complex exhibits good emission efficiency at ambient temperature, coupled with strong temperature dependence of the emission intensity and lifetime in the 273-333 K range, all of which are key features for non-contact luminescence-based thermometers capable of sensing and imaging temperatures in the physiological range.

Triazolyl-based copper-molybdate hybrids: from composition space diagram to magnetism and catalytic performance.

The multicomponent mixed-metal Cu(II)/Mo(VI) oxides/1,3-bis(1,2,4-triazol-4-yl)adamantane (tr2ad) system was thoroughly studied employing a compositional diagram approach. The concept allowed us to prepare three layered copper-molybdate hybrid solids [Cu(II)2(tr2ad)4](Mo8O26) (1), [Cu4(II)(μ4-O)(tr2ad)2(MoO4)3]·7.5H2O (2), and [Cu(I)2(tr2ad)2](Mo2O7)·H2O (3), and to elucidate the relationship between initial reagent concentration/stoichiometry and the stability of the resultant structural motifs.