Synthesis, Structure and (Photo)Catalytic Behavior of Ce-MOFs Containing Perfluoroalkylcarboxylate Linkers: Experimental and Theoretical Insights.

Cerium-based Metal-Organic frameworks (Ce-MOFs) are attracting increasing interest due to their similar structural features to zirconium MOFs. The redox behavior of Ce(III/IV) adds a range of properties to the compounds. Recently, perfluorinated linkers have been used in the synthesis of MOFs to introduce new characteristic into the structure. We report the synthesis and structural characterization of Ce(IV)-based MOFs constructed using two perfluorinated alkyl linkers. Their structure, based on hexanuclear Ce6O4(OH)4 12+ clusters linked to each other by the dicarboxylate ions, has been solved ab-initio from X-ray powder diffraction data and refined by the Rietveld method. The crystallization kinetics and the MOF formation mechanism was also invesitigated by Synchrotron radiation with XAS spectroscopies (EXAFS and XANES). The MOFs present the same fcu cubic topology as observed in MOF-801 and UiO-66, and they showed good stability in water at different pH conditions. The electronic structure of these MOFs has been studied by DFT calculations in order to obtain insights into the density of states structure of the reported compounds, resulting in band gaps in the range of 2.8-3.1 eV. Their catalytic properties were tested both thermally and under visible light irradiation for the degradation of methyl orange (MO) dye.

Synthesis, Crystal Structure, and Photocatalytic Properties of Two Isoreticular Ce(IV)-MOFs with an Infinite Rod-Shaped Inorganic Building Unit.

The use of the V-shaped linker molecules 4,4'-oxydibenzoic acid (H2ODB) and 4,4'-carbonyldibenzoic acid (H2CDB) led to the discovery of two isoreticular Ce(IV)-based metal-organic frameworks (MOFs) of composition [CeO(H2O)(L)], L = ODB2-, CDB2-, denoted CAU-58 (CAU = Christian-Albrechts-University). The recently developed Ce-MOF synthesis approach in acetonitrile as the solvent proved effective in accessing Ce(IV)-MOF structures with infinite rod-shaped inorganic building units (IBUs) and circumventing the formation of the predominantly observed hexanuclear [Ce6O8] cluster. For the structure determination of the isoreticular MOFs, three-dimensional electron diffraction (3D ED) and powder X-ray diffraction (PXRD) data were used in combination with density functional theory (DFT) calculations. [CeO(H2O)(CDB)] shows reversible H2O adsorption by stirring in water and thermal treatment at 190 °C, which leads to a unit cell volume change of 11%. The MOFs feature high thermal stabilities (T > 290 °C), which exceed those of most Ce(IV)-MOFs and can be attributed to the infinite rod-shaped IBU. Surface and bulk oxidation states of the cerium ions were analyzed via X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy (XANES). While Ce(III) ions are observed by the highly surface-sensitive XPS method, the bulk material contains predominantly Ce(IV) ions according to XANES. Application of the MOFs as catalysts for the catalytic degradation of methyl orange in aqueous solutions was also studied. While degradation activity for both MOFs was observed, only CAU-58-ODB revealed enhanced photocatalytic activity under ultraviolet (UV) light. The photocatalytic mechanism likely involves a ligand-to-metal charge transfer (LMCT) from the linkers to the Ce(IV) centers. Analyses by XANES and inductively coupled plasma-optical emission spectroscopy (ICP-OES) demonstrate that leaching of Cerium ions as well as partial reduction of Ce(IV) to Ce(III) takes place during catalysis. At the same time, PXRD data confirm the structural stability of the remaining MOF catalysts.

In†Situ X-ray Diffraction Investigation of the Crystallisation of Perfluorinated CeIV -Based Metal-Organic Frameworks with UiO-66 and MIL-140 Architectures*.

We report on the results of an in situ synchrotron powder X-ray diffraction study of the crystallisation in aqueous medium of two recently discovered perfluorinated CeIV -based metal-organic frameworks (MOFs), analogues of the already well investigated ZrIV -based UiO-66 and MIL-140A, namely, F4_UiO-66(Ce) and F4_MIL-140A(Ce). The two MOFs were originally obtained in pure form in similar conditions, using ammonium cerium nitrate and tetrafluoroterephthalic acid as reagents, and small variations of the reaction parameters were found to yield mixed phases. Here, we investigate the crystallisation of these compounds, varying parameters such as temperature, amount of the protonation modulator nitric acid and amount of the coordination modulator acetic acid. When only HNO3 is present in the reaction environment, only F4_MIL-140A(Ce) is obtained. Heating preferentially accelerates nucleation, which becomes rate determining below 57 °C. Upon addition of AcOH to the system, alongside HNO3 , mixed-phased products are obtained. F4_UiO-66(Ce) is always formed faster, and no interconversion between the two phases occurs. In the case of F4_UiO-66(Ce), crystal growth is always the rate-determining step. A higher amount of HNO3 favours the formation of F4_MIL-140A(Ce), whereas increasing the amount of AcOH favours the formation of F4_UiO-66(Ce). Based on the in situ results, a new optimised route to achieving a pure, high-quality F4_MIL-140A(Ce) phase in mild conditions (60 °C, 1 h) is also identified.

"Shake 'n Bake" Route to Functionalized Zr-UiO-66 Metal-Organic Frameworks.

We report a novel synthetic procedure for the high-yield synthesis of metal-organic frameworks (MOFs) with fcu topology with a UiO-66-like structure starting from a range of commercial ZrIV precursors and various substituted dicarboxylic linkers. The syntheses are carried out by grinding in a ball mill the starting reagents, namely, Zr salts and the dicarboxylic linkers, in the presence of a small amount of acetic acid and water (1 mL total volume for 1 mmol of each reagent), followed by incubation at either room temperature or 120 °C. Such a simple "shake 'n bake" procedure, inspired by the solid-state reaction of inorganic materials, such as oxides, avoids the use of large amounts of solvents generally used for the syntheses of Zr-MOF. Acidity of the linkers and the amount of water are found to be crucial factors in affording materials of quality comparable to that of products obtained under solvo- or hydrothermal conditions.

Amino-Functionalized Layered Crystalline Zirconium Phosphonates: Synthesis, Crystal Structure, and Spectroscopic Characterization.

Two new layered zirconium phosphonates functionalized with amino groups were synthesized starting from aminomethylphosphonic acid in the presence of different mineralizers, and their structures were solved from powder X-ray diffraction data. Their topologies are unprecedented in zirconium phosphonate chemistry: the first, of formula ZrH[F3(O3PCH2NH2)], prepared in the presence of hydrofluoric acid, features uncommon ZrO2F4 units and a remarkable thermal stability; the second, of formula Zr2H2[(C2O4)3(O3PCH2NH2)2]·2H2O, prepared in the presence of oxalic acid, is based on ZrO7 units with oxalate anions coordinated to the metal atom, which were never observed before in any zirconium phosphonate. In addition, the structure of another compound based on (2-aminoethyl)phosphonic acid is reported, which was the object of a previously published study. This compound has layered α-type structure with -NH3(+) groups located in the interlayer space. All of the reported compounds were further characterized by means of vibrational spectroscopy, which provided important information on fine structural details that cannot be deduced from the powder X-ray diffraction data.

Water-mediated proton conduction in a robust triazolyl phosphonate metal-organic framework with hydrophilic nanochannels.

The development of water-mediated proton-conducting materials operating above 100 °C remains challenging because the extended structures of existing materials usually deteriorate at high temperatures. A new triazolyl phosphonate metal-organic framework (MOF) [La3L4(H2O)6]Cl⋅x H2O (1, L(2-) = 4-(4H-1,2,4-triazol-4-yl)phenyl phosphonate) with highly hydrophilic 1D channels was synthesized hydrothermally. Compound 1 is an example of a phosphonate MOF with large regular pores with 1.9 nm in diameter. It forms a water-stable, porous structure that can be reversibly hydrated and dehydrated. The proton-conducting properties of 1 were investigated by impedance spectroscopy. Magic-angle spinning (MAS) and pulse field gradient (PFG) NMR spectroscopies confirm the dynamic nature of the incorporated water molecules. The diffusivities, determined by PFG NMR and IR microscopy, were found to be close to that of liquid water. This porous framework accomplishes the challenges of water stability and proton conduction even at 110 °C. The conductivity in 1 is proposed to occur by the vehicle mechanism.

A layered mixed zirconium phosphate/phosphonate with exposed carboxylic and phosphonic groups: X-ray powder structure and proton conductivity properties.

A novel mixed zirconium phosphate/phosphonate based on glyphosine, of formula Zr2(PO4)H5(L)2·H2O [L = (O3PCH2)2NCH2COO], was synthesized in mild conditions. The compound has a layered structure that was solved ab initio from laboratory PXRD data. It crystallizes in the monoclinic C2/c space group with the following cell parameters: a = 29.925(3), b = 8.4225(5), c = 9.0985(4) Å, and ß = 98.474(6)°. Phosphate groups are placed inside the sheets and connect the zirconium atoms in a tetradentate fashion, while uncoordinated carboxylate and P-OH phosphonate groups are exposed on the layer surface. Due to the presence of these acidic groups, the compound showed remarkable proton conductivity properties, which were studied in a wide range of temperature and relative humidity (RH). The conductivity is strongly dependent on RH and reaches 1 × 10(-3) S cm(-1) at 140 °C and 95% RH. At this RH, the activation energy of conduction is 0.15 eV in the temperature range 80-140 °C. The similarities of this structure with related structures already reported in the literature were also discussed.

Insight into the synthesis of LDH using the urea method: morphology and intercalated anion control.

Layered double hydroxides (LDHs) are a class of layered solids applied in many application fields. The study of synthetic methods able to control the interlayer composition and morphology of LDH is an open issue. The urea method, which exploits the thermal decomposition of urea, is known for yielding highly crystalline LDH in the carbonate form. This form is highly stable and, to replace carbonate ions with more easily exchangeable anions, a second step is required. In this work, we modified the urea method to obtain MgAl and ZnAl LDH in the chloride or nitrate form through a one-step synthesis. The effects of the urea/(Al + M(II)) molar ratio (R), reaction time and metal salt concentrations were deeply investigated. We found that LDH in chloride and nitrate forms can be prepared from solutions of metal salts not exceeding 1 M by adjusting R and maintaining the reaction time at 48 hours. The morphology of these products was found to depend on the R value and on the metal salts used in the synthesis. A high R value and nitrate salts favoured the formation of sand-rose crystals, while chloride salts induced the formation of plate-like crystals. The crystal growth mechanism and the parameters influencing the morphology are discussed with reference to ZnAl LDH by monitoring the synthesis over time.

Cellulose Nanocrystals and Lignin Nanoparticles Extraction from Lemna minor L.: Acid Hydrolysis of Bleached and Ionic Liquid-Treated Biomass.

Using biomass to develop and obtain environmentally friendly and industrially applicable biomaterials is increasingly attracting global interest. Herein, cellulose nanocrystals (CNCs) and lignin nanoparticles (LNPs) were extracted from Lemna minor L., a freshwater free-floating aquatic species commonly called duckweed. To obtain CNCs and LNPs, two different procedures and biomass treatment processes based on bleaching or on the use of an ionic liquid composed of triethylammonium and sulfuric acid ([TEA][HSO4]), followed by acid hydrolysis, were carried out. Then, the effects of these treatments in terms of the thermal, morphological, and chemical properties of the CNCs and LNPs were assessed. The resulting nanostructured materials were characterized by using Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, thermo-gravimetric analysis (TGA), and scanning electron microscopy (SEM). The results showed that the two methodologies applied resulted in both CNCs and LNPs. However, the bleaching-based treatment produced CNCs with a rod-like shape, length of 100-300 nm and width in the range of 10-30 nm, and higher purity than those obtained with ILs that were spherical in shape. In contrast, regarding lignin, IL made it possible to obtain spherical nanoparticles, as in the case of the other treatment, but they were characterized by higher purity and thermal stability. In conclusion, this research highlights the possibility of obtaining nanostructured biopolymers from an invasive aquatic species that is largely available in nature and how it is possible, by modifying experimental procedures, to obtain nanomaterials with different morphological, purity, and thermal resistance characteristics.

Synthesis and Characterization of ZIF-90 Nanoparticles as Potential Brain Cancer Therapy.

Human glioblastoma is probably the most malignant and aggressive among cerebral tumors, of which it represents approximately 80% of the reported cases, with an overall survival rate that is quite low. Current therapies include surgery, chemotherapy, and radiotherapy, with associated consistent side effects and low efficacy. The hardness in reaching the site of action, and overcoming the blood-brain barrier, is a major limitation of pharmacological treatments. In this paper, we report the synthesis and characterization of ZIF-90 (ZIF, Zeolitic Imidazolate Framework) nanoparticles as putative carriers of anticancer drugs to the brain. In particular, we successfully evaluated the biocompatibility of these nanoparticles, their stability in body fluids, and their ability to uptake in U251 human glioblastoma cell lines. Furthermore, we managed to synthesize ZIF-90 particles loaded with berberine, an alkaloid reported as a possible effective adjuvant in the treatment of glioblastoma. These findings could suggest ZIF-90 as a possible new strategy for brain cancer therapy and to study the physiological processes present in the central nervous system.

Synthesis, crystal structure, and proton conductivity of one-dimensional, two-dimensional, and three-dimensional zirconium phosphonates based on glyphosate and glyphosine.

The reaction of two small phosphono-amino acids based on glycine (glyphosine and glyphosate) with zirconium under mild conditions led to the attainment of three related zirconium derivatives with 1D, 2D, and 3D structures of formulas ZrF[H3(O3PCH2NHCH2COO)2] (1), Zr3H8[(O3PCH2)2NCH2COO]4·2H2O (2), and Zr[(O3PCH2)(HO3PCH2)NHCH2COOH]2·2H2O (3), respectively, whose structures were solved by X-ray powder and single-crystal diffraction data. The glyphosate derivative has 1D ribbon-type structure whereas the dimensionality of the glyphosine-derived materials (2D and 3D) can be tuned by changing the synthesis conditions. The low-dimensional compounds (1 and 2) can be directly produced in the form of nanoparticles with different size and morphology whereas the 3D compound (3) has a higher crystallinity and can be obtained as single crystals with a prismatic shape. The different structural dimensionality reflects the shape and size of the crystals and also differently affects the proton conductivity properties, measured over a wide range of temperature at 95% relative humidity. Their high thermal and chemical stability together with the small size may promote their use as fillers for polymeric electrolyte membranes for fuel cells applications.

Coupling physical chemical techniques with hydrotalcite-like compounds to exploit their structural features and new multifunctional hybrids with luminescent properties.

Hydrotalcite-like compounds (HTlc), belonging to the large class of Layered Double Hydroxides (LDH), have excited wide interest owing to the incredible number of their potential and achieved applications in physical, chemical and bio-chemical fields. This perspective review deals with recent advances in the application of physical-chemical techniques for the study of HTlc structure and for the design and synthesis, using intercalation chemistry routes, of new hybrid materials. Firstly, a rapid survey on the most common synthetic strategies for the attainment of HTlc with different crystallinity degree and crystal size and for their modification to obtain hybrids has been made, and the use of coupled techniques (XRPD, luminescence, Solid State MAS NMR and Molecular Dynamics) to gain structural information is reported. Then, the design, synthesis and photophysical characterization of azoic dyes-intercalated and co-intercalated HTlc hybrid materials are described. Hybrids constituted of ZnAl-HTlc, co-intercalated with stearate anions and methyl orange or methyl yellow dyes, have been used as nanofillers of hydrophobic polymers. The polymeric nano-composites obtained have been characterized by means of XRPD patterns, Thermo-Gravimetric Analysis and Confocal Fluorescence Microscopy. This latter technique has been found to be an excellent, complementary and non-invasive tool to probe the dispersion degree of the fluorescent fillers into the polymeric matrices and their stability in the compounding process. Finally, the synthesis and spectroscopic characterization of nanoparticle (NP) decorated HTlc for advanced antimicrobial and photo-catalytic applications are also reported. The review terminates with a concluding short note and future trends.

Recent advances in the chemistry and applications of fluorinated metal-organic frameworks (F-MOFs).

Metal-organic frameworks are a class of porous crystalline materials based on the ordered connection of metal centers or metal clusters by organic linkers with comprehensive functionalities. The interest in these materials is rapidly moving towards their application in industry and real life. In this context, cheap and sustainable synthetic strategies of MOFs with tailored structures and functions are nowadays a topic widely studied from different points of view. In this review, fluorinated MOFs (F-MOFs) and their applications are investigated. The principal aim is to provide an overview of the structural features and the main application of MOFs containing fluorine atoms both as anionic units or as coordinating elements of more complex inorganic units and, therefore, directly linked to the structural metals or as part of fluorinated linkers used in the synthesis of MOFs. Herein we present a review of F-MOFs reported in the recent literature compared to benchmark compounds published over the last 10 years. The compounds are discussed in terms of their structure and properties according to the aforementioned classification, with an insight into the different chemical nature of the bonds. The application fields of F-MOFs, especially in sustainability related issues, such as harmful gas sorption and separation, will also be discussed. F-MOFs are compounds containing fluorine atoms in their framework and they can be based on: (a) fluorinated metallic or semi-metallic anionic clusters or: (b) fluorinated organic linkers or (c) eventually containing both the building blocks. The nature of a covalent C-F bond in terms of length, charge separation and dipole moment sensibly differs from that of a partly ionic M-F (M = metal) one so that the two classes of materials (points a and b) have different properties and they find various application fields. The study shows how the insertion of polar M-F and C-F bonds in the MOF structure may confer several advantages in terms of interaction with gaseous molecules and the compounds can find application in gas sorption and separation. In addition, hydrophobicity tends to increase compared to non-fluorinated analogues, resulting in an overall improvement in moisture stability.

On the high-temperature phase transition of a new chlorocadmate(ii) complex incorporating symmetrical Cd2Cl6 clusters: structural, optical and electrical properties.

In the present investigation, a new hybrid crystal, with the formula [(C4H9)4P]2Cd2Cl6 has been synthesized by the slow evaporation method at room temperature. It was characterized by X-ray diffraction (XRD), Hirshfeld surface, differential scanning calorimetry (DSC), optical measurement and complex impedance. Single crystal X-ray diffraction structural analysis revealed that the title compound crystallizes in the triclinic system with space group P1̄ and cell parameters: a = 11.972 (1) Å, b = 15.418 (1) Å, c = 15.426 (2) Å, αa = 68.71 (2) °, ß = 73.20 (3) ° and γ = 74.39 (2)°. The Hirshfeld surface analysis was conducted to investigate intermolecular interactions and associated 2D fingerprint plots, revealing quantitatively the relative contribution of these interactions in the crystal cohesion. DSC studies indicated one phase transition at about 348 K. Optical absorption spectra show that the band gap of [(C4H9)4P]2Cd2Cl6 is approximately 2.65 eV. The Nyquist plot showed only one semicircular arc, representing the grain effect in the electrical conduction. The thermal evolution of the conductivity of the grains presents an Arrhenius type behavior, demonstrating that charge carriers have to overcome different energy barriers while conducting and relaxing. Besides, the AC conductivity was analyzed by Jonscher's law and the conduction mechanism is well ensured by the correlated barrier hopping (CBH) model.

Uncovering the Role of Electronic Doping in Lead-free Perovskite (CH3 NH3 )2 CuCl4-x Brx and Solar Cells Fabrication.

Lead halide perovskites are attractive pigments to fabricate solar cells in the laboratory, owing to their high power conversion efficiency. However, given the presence of Pb, such materials also have a high level of toxicity and are carcinogenic for humans and aquatic life. Arguably, this hampers their acceptability for immediate commercialization. This study entails the synthesis, optoelectronic properties, and photovoltaic parameters of two-dimensional copper-based perovskites as an environmentally benign alternative to lead-based perovskites. The perovskites - (CH3 NH3 )2 CuCl4-x Brx with x=0.3 and 0.66 - are derivatives of the stable (CH3 NH3 )2 CuCl4 . The single crystals and powders diffractograms suggest compositions with variations in Cl/Br ratio and dissimilar bromine localization in the inorganic framework. The copper mixed halide perovskite exhibits a narrow absorption with a bandgap of 2.54-2.63 eV related to the halide ratio disparity (crystal color variation). These findings demonstrate the impact of halides to optimize the stability of methylammonium copper perovskites and provide an effective pathway to design eco-friendly perovskites for optoelectronic applications.

Cooperative CO2 adsorption mechanism in a perfluorinated CeIV-based metal organic framework.

Adsorbents able to uptake large amounts of gases within a narrow range of pressure, i.e., phase-change adsorbents, are emerging as highly interesting systems to achieve excellent gas separation performances with little energy input for regeneration. A recently discovered phase-change metal-organic framework (MOF) adsorbent is F4_MIL-140A(Ce), based on CeIV and tetrafluoroterephthalate. This MOF displays a non-hysteretic step-shaped CO2 adsorption isotherm, reaching saturation in conditions of temperature and pressure compatible with real life application in post-combustion carbon capture, biogas upgrading and acetylene purification. Such peculiar behaviour is responsible for the exceptional CO2/N2 selectivity and reverse CO2/C2H2 selectivity of F4_MIL-140A(Ce). Here, we combine data obtained from a wide pool of characterisation techniques - namely gas sorption analysis, in situ infrared spectroscopy, in situ powder X-ray diffraction, in situ X-ray absorption spectroscopy, multinuclear solid state nuclear magnetic resonance spectroscopy and adsorption microcalorimetry - with periodic density functional theory simulations to provide evidence for the existence of a unique cooperative CO2 adsorption mechanism in F4_MIL-140A(Ce). Such mechanism involves the concerted rotation of perfluorinated aromatic rings when a threshold partial pressure of CO2 is reached, opening the gate towards an adsorption site where CO2 interacts with both open metal sites and the fluorine atoms of the linker.

The structures, morphologies, and photophysical properties of multiluminescent layered lanthanide-phosphono-carboxylate nanoparticles.

A new family of layered metal(III)-phosphono-carboxylate nanostructures (M=Y, Eu, Tb, Er, and Yb) was hydrothermally synthesized and their structures and morphologies were characterized by X-ray powder diffraction and TEM. 4-[Bis(phosphonomethyl)amino]caproic acid and 4- [bis(phosphonomethyl)amino]undecanoic acid, with general formula (H(2)O(3)PCH(2))(2)NR (R=C(5)H(10)COOH(P2CAPR) and C(10)H(22)COOH(P2UND), respectively) were used as building blocks for the preparation of novel layered hybrid materials in which the inorganic layers were composed of MO(7) or MO(8) polyhedra and PO(3)C tetrahedra. The interlayer region was occupied by carboxyalkyl chains. These layered compounds were easily dispersed as stable solutions in alkylamine/water upon ultrasonication. These dispersions were constituted of rectangular elongated nanoparticles (NPs), which showed a distribution of sizes ranging from 20-500 nm. These new materials had interesting photophysical properties because they were multiluminescent compounds. These properties gave rise to several emission bands, which were spread over the broad spectroscopic region, from the near-UV up to the near-IR regions. Each emission band had a specific lifetime, which ranged from the sub-ps to the ms scale.

Survey on the phase transitions and their effect on the ion-exchange and on the proton-conduction properties of a flexible and robust Zr phosphonate coordination polymer.

The flexible zirconium tetraphosphonate coordination polymer with formula Zr(O(3)PCH(2))(2)N-C(6)H(10)-N(O(3)CH(2)P)(2)X(2-x)H(2+x)·nH(2)O (X = H, Li, Na, K, 0 < x < 1, 4 < n < 7.5) (1) possesses an open framework structure with 1D cavities decorated with polar and acids P═O and P-OH groups. 1 has been fully protonated by adding HCl and then subjected to several acid-base ion-exchange reactions with alkaline metals hydroxides. 1 is a very robust coordination polymer because it can be regenerated in H- form using strong acid solutions and ri-exchanged several times without hydrolysis and loss of crystallinity. The flexibility of 1 has been also studied by means of TDXD (temperature dependent X-ray diffraction) evidencing remarkable phase transformations that lead to a different disposition of the water molecules. These transformations also influence the accessibility of the cations on the P-OH groups placed inside the channels and thus the ion-exchange properties. The dependence of the proton conductivity properties on these phase transitions has been also investigated and discussed.

New insights on the incorporation of lanthanide ions into nanosized layered double hydroxides.

Nanosized Layered Double Hydroxides (LDH) were prepared in confined environment through the microemulsion method in the presence of different lanthanide cations (Ln(III) = Eu(III), Yb(III), Tb(III), and Nd(III)). To investigate the effects of lanthanide insertion in the sheets of LDH materials, several samples were prepared upon progressively increasing the content of Ln ions and properly reducing the Al(III) amount; the samples were characterized in terms of metal content, structure, morphology, thermal behavior, and spectroscopic properties. The data revealed that Ln(III) content in the LDH samples depends on the ionic radius of the lanthanide cations and on its concentration in the starting microemulsion. X-ray powder diffraction (XRPD) indicated that Eu(III) can be inserted into the LDH structure in average atomic percentages lower than 2.7%, leading to the formation of a low symmetry phase, as confirmed by steady state luminescence spectra; while Yb(III) can be incorporated into the layer structure up to about 10% forming a pure layered phase containing the lanthanide in the sheet. The incorporation of Yb(III) and Eu(III) into the LDH sheets is also supported by FT-IR measurements. Coupled thermogravimetrical (TG) and differential scanning calorimetric (DSC) studies indicated that water molecules are essential in the coordination sphere of incorporated Ln cations; this observation accounts for the lower thermal stability of Ln-doped LDH compared to the undoped ones. Furthermore, Eu-luminescence measurements indicates that the lanthanide inclusion does not compromise its luminescence although the spectral position and brightness can be tuned by the loading.

A simple and effective method to form metallic nanoparticles onto composites made up of organic polymers and layered inorganic ion exchangers as fillers.

A new easy method for the preparation of polymeric nanocomposites supporting metal nanoparticles is presented. The method concerns the use of a layered inorganic ion exchanger converted in the proper metallic form and exfoliated to act as filler of organic polymers with twofold aim of obtaining a composite (or nanocomposite) and to have metal ions that can be suitably reduced with a proper reducing agent to form metal nanoparticles. This strategy has been applied to the system polyvinylidene fluoride (PVDF) filled with layered a-zirconium phosphate in copper form. Several physical techniques (X-ray powder diffraction, atomic force microscopy, high resolution transmission electron microscopy) have been used to characterize the Cu-nanoparticles, whose dimensions range from 5 to 200 nm for those placed inside or on the surface of the polymeric matrix respectively, depending on the dispersion degree of the inorganic filler. The method is simple and can be used for different polymeric matrices and/or metal ions in order to produce metal/polymer systems with promising technological application.