A gold nanocluster/MIL-100(Fe) bimodal nanovector for the therapy of inflammatory disease through attenuation of Toll-like receptor signaling.

A better understanding of the molecular and cellular events involved in the inflammation process has opened novel perspectives in the treatment of inflammatory diseases, particularly through the development of well-designed nanomedicines. Here we describe the design of a novel class of anti-inflammatory nanomedicine (denoted as Au@MIL) synthesized through a one-pot, cost-effective and green approach by coupling a benchmark mesoporous iron(III) carboxylate metal organic framework (MOF) (i.e. MIL-100(Fe)) and glutathionate protected gold nanoclusters (i.e. Au25SG18 NCs). This nano-carrier exhibits low toxicity and excellent colloidal stability combined with the high loading capacity of the glucocorticoid dexamethasone phosphate (DexP) whose pH-dependent delivery was observed. The drug loaded Au@MIL nanocarrier shows high anti-inflammatory activity due to its capacity to specifically hinder inflammatory cell growth, scavenge intracellular reactive oxygen species (ROS) and downregulate pro-inflammatory cytokine secretion. In addition, this formulation has the capacity to inhibit the Toll-like receptor (TLR) signaling cascade namely the nuclear factor kappa B (NF-κB) and the interferon regulatory factor (IRF) pathways. This not only provides a new avenue for the nanotherapy of inflammatory diseases but also enhances our fundamental knowledge of the role of nanoMOF based nanomedicine in the regulation of innate immune signaling.

Interfacing metal organic frameworks with polymers or carbon-based materials: from simple to hierarchical porous and nanostructured composites.

In the past few years, metal organic frameworks (MOFs) have been assembled with (bio)polymers and a series of carbon-based materials (graphene, graphene oxide, carbon nanotubes, carbon quantum dots, etc.) leading to a wide range of composites differing in their chemical composition, pore structure and functionality. The objective was mainly to overcome the limitations of MOFs in terms of mechanical properties, chemical stability and processability while imparting novel functionality (electron conductivity, (photo)catalytic activity, etc.) and hierarchical porosity. These composites were considered for numerous applications including gas/liquid adsorption and separation, (photo)catalysis, biomedicine, energy storage, conversion and so on. The performance of such composites depends strongly on their microstructural and physico-chemical properties which are mainly driven by the chemical strategies used to design and process such composites. In this perspective article, we propose to cover this topic and provide a useful survey of recent progress in the synthesis and design of MOFs-carbon material composites. This article will describe the development of composites with increasing complexity in terms of porous architecture, spatial structuration and organisation, and functionality.

Hierarchical superparamagnetic metal-organic framework nanovectors as anti-inflammatory nanomedicines.

Among a plethora of drug nanocarriers, biocompatible nanoscale metal-organic frameworks (nanoMOFs) with a large surface area and an amphiphilic internal microenvironment have emerged as promising drug delivery platforms, mainly for cancer therapy. However, their application in biomedicine still suffers from shortcomings such as a limited chemical and/or colloidal stability and/or toxicity. Here, we report the design of a hierarchically porous nano-object (denoted as USPIO@MIL) combining a benchmark nanoMOF (that is, MIL-100(Fe)) and ultra-small superparamagnetic iron oxide (USPIO) nanoparticles (that is, maghemite) that is synthesized through a one-pot, cost-effective and environmentally friendly protocol. The synergistic coupling of the physico-chemical and functional properties of both nanoparticles confers to these nano-objects valuable features such as high colloidal stability, high biodegradability, low toxicity, high drug loading capacity as well as stimuli-responsive drug release and superparamagnetic properties. This bimodal MIL-100(Fe)/maghemite nanocarrier once loaded with anti-tumoral and anti-inflammatory drugs (doxorubicin and methotrexate) shows high anti-inflammatory and anti-tumoral activities. In addition, the USPIO@MIL nano-object exhibits excellent relaxometric properties and its applicability as an efficient contrast agent for magnetic resonance imaging is herein demonstrated. This highlights the high potential of the maghemite@MOF composite integrating the functions of imaging and therapy as a theranostic anti-inflammatory formulation.

In Operando Spectroscopic Ellipsometry Investigation of MOF Thin Films for the Selective Capture of Acetic Acid.

The emission of polar volatile organic compounds (VOCs) is a major worldwide concern of air quality and equally impacts the preservation of cultural heritage (CH). The challenge is to design highly efficient adsorbents able to selectively capture traces of VOCs such as acetic acid (AA) in the presence of relative humidity (RH) normally found at storage in museums (40-80%). Although the selective capture of VOCs over water is still challenging, metal-organic frameworks (MOFs) possess highly tunable features (Lewis, Bronsted, or redox metal sites, functional groups, hydrophobicity, etc.) suitable to selectively capture a large variety of VOCs. In this context, we have explored the adsorption efficiency of a series of MOFs thin films (ZIF-8(Zn), MIL-101(Cr), and UiO-66(Zr)-2CF3) for the selective capture of AA based on a UV/vis and FT-IR spectroscopic ellipsometry in operando study (2-6% of relative pressure of AA under 40% of RH), namely conditions close to the realistic environmental storage conditions of cultural artifacts. For that purpose, optical quality thin films of MOFs were prepared by dip-coating, and their AA adsorption capacity and selectivity were evaluated under humid conditions by measuring the variation of the refractive index as a function of the vapor pressures while the chemical nature of the coadsorbed analytes (water and AA) was identified by FT-IR ellipsometry. While thin films of ZIF-8(Zn) strongly degraded upon exposure to AA/water vapors, films of MIL-101(Cr) and UiO-66(Zr)-2CF3 present a high chemical stability under those conditions. It was shown that MIL-101(Cr) presents a high AA adsorption capacity due to its high pore volume but exhibits a poor AA adsorption selectivity under humid conditions. In contrast, UiO-66(Zr)-2CF3 was shown to overpass MIL-101(Cr) in terms of AA/H2O adsorption selectivity and AA adsorption/desorption cycling stability because of its high hydrophobic character, suitable pore size for adequate confinement, and specific interactions.

Functionalization of Gold Nanoparticles by Inorganic Entities.

The great affinity of gold surface for numerous electron-donating groups has largely contributed to the rapid development of functionalized gold nanoparticles (Au-NPs). In the last years, a new subclass of nanocomposite has emerged, based on the association of inorganic molecular entities (IME) with Au-NPs. This highly extended and diversified subclass was promoted by the synergy between the intrinsic properties of the shell and the gold core. This review-divided into four main parts-focuses on an introductory section of the basic notions related to the stabilization of gold nanoparticles and defines in a second part the key role played by the functionalizing agent. Then, we present a wide range of inorganic molecular entities used to prepare these nanocomposites (NCs). In particular, we focus on four different types of inorganic systems, their topologies, and their current applications. Finally, the most recent applications are described before an overview of this new emerging field of research.

Metal-Organic Frameworks for Cultural Heritage Preservation: The Case of Acetic Acid Removal.

The removal of low concentrations of acetic acid from indoor air at museums poses serious preservation problems that the current adsorbents cannot easily address owing to their poor affinity for acetic acid and/or their low adsorption selectivity versus water. In this context, a series of topical water-stable metal-organic frameworks (MOFs) with different pore sizes, topologies, hydrophobic characters, and functional groups was explored through a joint experimental-computational exploration. We demonstrate how a subtle combination of sufficient hydrophobicity and optimized host-guest interactions allows one to overcome the challenge of capturing traces of this very polar volatile organic compound in the presence of humidity. The optimal capture of acetic acid was accomplished with MOFs that do not show polar groups in the inorganic node or have lipophilic but polar (e.g., perfluoro) groups functionalized to the organic linkers, that is, the best candidates from the list of explored MOFs are MIL-140B and UiO-66-2CF3. These two MOFs present the appropriate pore size to favor a high degree of confinement, together with organic spacers that allow an enhancement of the van der Waals interactions with the acetic acid. We establish in this work that MOFs can be a viable solution to this highly challenging problem in cultural heritage protection, which is a new field of application for this type of hybrid materials.

Iridium(III) soft salts from dinuclear cationic and mononuclear anionic complexes for OLED devices.

Two iridium(III) soft salts based on ion-paired dinuclear cationic and mononuclear anionic complexes were designed and investigated as phosphorescent emitters for solution processed OLEDs. New dinuclear cationic complexes were prepared with two different bridging ligands, a carbazole and a phenylene spacer. Best devices were designed with the soft salt bearing a carbazole moiety.

Dithiolate-appended iridium(III) complex with dual functions of reducing and capping agent for the design of small-sized gold nanoparticles.

The unprecedented combined reduction of chloroauric acid and capping of the resulting gold nanoparticles in the absence of an external reducing agent are demonstrated using a novel heteroleptic Ir(III) complex incorporating a 4,5-diazafluorenedithiolate ligand. The reduction process in basic medium results from a cascade mechanism involving oxidation of the ligand, reduction of the gold salt, and stabilization and functionalization of the gold nanoparticles.

Coordination chemistry approach for the end-to-end assembly of gold nanorods.

Gold nanorods synthesized by radiolysis were selectively end-functionalized by a fully conjugated thiol bearing a pendant terpyridine group; addition of ferrous ions led to the end-to-end 1D self-assembly of the nanorods. Similar results have been obtained when the preformed [(HStpy)Fe(tpySH)](2+) dithiol complex was directly added to the gold nanorods.

Tunable optical properties of chromophores derived from oligo(p-phenylene vinylene).

A series of 11 symmetric push-pull chromophores consisting of electron-accepting groups connected through a central pi-conjugated system derived from oligo(p-phenylene vinylene) (OPV) were designed and synthesized. Electronic and spectroscopic properties were investigated by UV-visible absorption, fluorescence spectroscopy, and cyclic voltammetry. By finely tuning the electron-withdrawing ability of the acceptors as well as the length of the pi-conjugated spacer, a wide range of dyes exhibiting strong absorption and emission were obtained.

Gold nanoparticles functionalized with gadolinium chelates as high-relaxivity MRI contrast agents.

Water-dispersible gold nanoparticles functionalized with paramagnetic gadolinium have been fully characterized, and the NMRD profiles show very high relaxivities up to 1.5 T. Characterization using TEM images and dynamic light scattering indicate a particle size distribution from 2 to 15 nm. The gold cores of the nanoparticles do not contribute significantly to the overall magnetic moment.

Electrochemical, linear optical, and nonlinear optical properties and interpretation by density functional theory calculations of (4-N,N-dimethylaminostyryl)-pyridinium pendant group associated with polypyridinic ligands and respective multifunctional metal complexes (Ru(II) or Zn(II)).

The synthesis, linear optical and nonlinear optical properties, as well as the electrochemical behavior of a series of pro-ligands containing the 4-(4-N,N-dimethylaminostyryl)-1-methyl pyridinium (DASP(+)) group as a push-pull moiety covalently linked to terpyridine or bipyridine as chelating ligands are reported in this full paper. The corresponding multifunctional Ru(II) and Zn(II) complexes were prepared and investigated. The structural, electronic, and optical properties of the pro-ligands and the ruthenium complexes were investigated using density functional theory (DFT) and time-dependent (TD) DFT calculations. A fairly good agreement was observed between the experimental and the calculated electronic spectra of the pro-ligands and their corresponding ruthenium complexes. A quenching of luminescence was evidenced in all ruthenium complexes compared with the free pro-ligands but even the terpyridine-functionalized metal complexes exhibited detectable luminescence at room temperature. Second order nonlinear optical (NLO) measurements were performed by Harmonic Light Scattering and the contribution of the DASP(+) moieties (and their relative ordering) and the metal-polypyridyl core need to be considered to explain the nonlinear optical properties of the metal complexes.

1,10-Phenanthroline and 1,10-phenanthroline-terminated ruthenium(II) complex as efficient capping agents to stabilize gold nanoparticles: application for reversible aqueous-organic phase transfer processes.

1,10-Phenanthroline (phen) and 1,10-phenanthroline-terminated ruthenium(II) complex [Ru-Lphen](2+) have been used to stabilize and functionalize gold nanoparticles (Au-NPs). The strong interaction between the nitrogen atoms of phen and the surface of Au-NPs allowed for the phase transfer of Au-NPs from toluene to aqueous phase containing [Ru-Lphen](2+). Reverse phase transfer of these Au-NPs from water to acetonitrile by substituting the Cl(-) counter anion by PF(-)(6) has also been demonstrated. Such facile post-functionalization, phase transfer and solvent transfer processes using metallic complexes bearing a terminal phenanthroline pendant group constitute a prerequisite for further studies of the electronic and optical properties of these NCs in various media.

New chelating stilbazonium-like dyes from Michler's ketone.

A series of "push-pull" salts substituted with an electron-donating bis(N,N-dimethyl)aniline unit and different electron-withdrawing methyl or chelating pyridinium units have been designed and synthesized from Michler's ketone. The spectroscopic and electronic properties were investigated and compared to their DAST homologues. The studies revealed that a lower HOMO-LUMO gap is obtained in all cases, showing the ability of our donor to increase the "push-pull" effect. Two chromophores with a terpyridine as acceptor end group have also been prepared.

Facile synthesis of silver nano/micro-ribbons or saws assisted by polyoxomolybdate as mediator agent and vanadium(IV) as reducing agent.

Original and effective syntheses of crystalline silver wires and saw bundles, using reduced Keggin polyoxomolybdovanadate (POM) as mediator and reducing agent, were performed in acetonitrile at room temperature; several parameters influencing the final silver 1D-structures, with micrometric length and nanometric thickness, were varied: the nature of the POM, silver salts, vanadium(iv) source and the mild conditions.

Gold nanocomposites with rigid fully conjugated heteroditopic ligands shell as nanobuilding blocks for coordination chemistry.

Monodisperse and solvent adaptable gold nanoparticles stabilized by rigid and fully conjugated modified neocuproinium and terpyridinium salts have been characterized and further used as nanobuilding blocks for the synthesis of gold nanoparticles functionalized by polypyridyl ruthenium complexes.

Structure and magnetic properties of a non-heme diiron complex singly bridged by a hydroxo group.

The synthesis of the first singly bridged non-heme diiron complex with a mu-hydroxo bridging ligand, [{(salten)Fe}2(OH)][B(C6H5)4].(CH3CN)x.(H2O)y (1) [H2salten = 4-azaheptane-1,7-bis(salicylideneiminate)], is reported. The complex has been characterized with X-ray crystallography, FTIR, magnetic susceptibility measurements, and Mössbauer spectroscopy. The data have been compared with the results of DFT calculations on both 1 and a model with an unsupported mu-oxo bridge (2) to verify the formulation of the complex as a mu-hydroxo-bridged species. The X-ray structure [Fe-O(H) = 1.997(1) A and Fe-O(H)-Fe = 159 degrees ] is consistent with the DFT-optimized geometry of 1 [Fe-O(H) = 2.02 A and Fe-O(H)-Fe = 151 degrees ]; the Fe-O(H) distance in 1 is about 0.2 A longer than the Fe-O separations in the optimized geometry of 2 (1.84 A) and in the crystallographic structures of diiron(III) compounds with unsupported mu-oxo bridges (1.77-1.81 A). The formulation of 1 as a hydroxo-bridged compound is also supported by the presence of an O-H stretch band in the FTIR spectrum of the complex. The magnetic susceptibility measurements of 1 reveal antiferromagnetic exchange (J = 42 cm(-1) and H(ex) = JS(1).S(2)). Nearly the same J value is obtained by analyzing the temperature dependence of the Mössbauer spectra (J = 43 cm(-1); other parameters: delta = 0.49 mm s(-1), DeltaE(Q) = -0.97 mm s(-1), and eta = 0.45 at 4.2 K). The experimental J values and Mössbauer parameters agree very well with those obtained from DFT calculations for the mu-hydroxo-bridged compound (J = 46 cm(-1), delta = 0.48 mm s(-1), DeltaE(Q) = -1.09 mm s(-1), and eta = 0.35). The exchange coupling constant in 1 is distinctly different from the value J approximately 200 cm(-1) calculated for the optimized mu-oxo-bridged species, 2. The increased exchange-coupling in 2 arises primarily from a decrease in the Fe-O bond length.

Size controlled formation of silver nanoparticles by direct bonding of ruthenium complexes bearing a terminal mono- or bi-pyridyl group.

Two polypyridyl ruthenium complexes containing either a terminal pyridine or phenanthroline group have been used to coat silver nanoparticles and control their size depending on the Ag/[RuII] ratio.

Synthesis and characterization of [Mo(7)O(16)(O(3)PCH(2)PO(3))(3)]:(8-) a mixed-valent polyoxomolybdenum diphosphonate anion with octahedrally and tetrahedrally coordinated molybdenum.

Two new compounds containing the title diphosphono-polyoxometalate anion and diprotonated ethylenediamine (enH(2)) or piperazine (ppzH(2)) countercations have been hydrothermally synthesized and structurally characterized ((enH(2))(4)[Mo(7)O(16)(O(3)PCH(2)PO(3))(3)].7H(2)O, triclinic, P(-)1, Z = 2, a = 10.3455(7) A, b = 13.136(1) A, and c = 20.216(3) A, alpha = 93.247(6) degrees, beta = 96.434(6) degrees, and gamma = 111.900(6) degrees; (ppzH(2))(4)[Mo(7)O(16)(O(3)PCH(2)PO(3))(3)].8H(2)O, triclinic, P(-)1, Z = 2, a = 13.255(2) A, b = 13.638(2) A, and c = 16.874(4) A, alpha = 93.20(2) degrees, beta = 101.27(2) degrees, and gamma = 105.87(1) degrees). The anion is a ring of three pairs of edge-sharing octahedra of Mo(V)O(6) (with Mo(V)-Mo(V) bonds) that share corners with each other. The diphosphonate groups connect the pairs at the periphery. The ring is "capped" by a tetrahedron of Mo(VI)O(4). According to magnetic measurements, the compounds are diamagnetic.