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A series of Gd3+ complexes (Gd1-Gd3) with the general formula GdL3(EtOH)2, where L is a β-diketone ligand with polycyclic aromatic hydrocarbon substituents of increasing size (1-3), was studied by combining time-resolved electron paramagnetic resonance (TR-EPR) spectroscopy and DFT calculations to rationalize the anomalous spectroscopic behavior of the bulkiest complex (Gd3) through the series. Its faint phosphorescence band is observed only at 80 K and it is strongly red-shifted (∼200 nm) from the intense fluorescence band. Moreover, the TR-EPR spectral analysis found that triplet levels of 3/Gd3 are effectively populated and have smaller |D| values than those of the other compounds. The combined use of zero-field splitting and spin density delocalization calculations, together with spin population analysis, allows us to explain both the large red shift and the low intensity of the phosphorescence band observed for Gd3. The large red shift is determined by the higher delocalization degree of the wavefunction, which implies a larger energy gap between the excited S1 and T1 states. The low intensity of the phosphorescence is due to the presence of C-H groups which favor non-radiative decay. These groups are present in all complexes; nevertheless, they have a relevant spin density only in Gd3. The spin population analysis on NaL models, in which Na+ is coordinated to a deprotonated ligand, mimicking the coordinative environment of the complex, confirms the outcomes on the free ligands.

The similar reactivity of lanthanides generally leads to statistically populated polynuclear complexes, making the rational design of ordered hetero-lanthanide compounds extremely challenging. Here we report on the site selectivity in hetero-lanthanide tetranuclear complexes afforded by the relatively simple ditopic pyterpyNO ligand (4'-(4-pyridil)-2,2':6',2"-terpyridine N-oxide). The sequential room temperature reaction of RE

A family of homodinuclear Ln3+ (Ln3+ = Gd3+, Eu3+) luminescent complexes with the general formula [Ln2(β-diketonato)6(N-oxide)y] has been developed to study the effect of the β-diketonato and N-oxide ligands on their thermometric properties. The investigated complexes are [Ln2(tta)6(pyrzMO)2] (Ln = Eu (1·C7H8), Gd (5)), [Ln2(dbm)6(pyrzMO)2] (Ln = Eu (2), Gd (6)), [Ln2(bta)6(pyrzMO)2] (Ln = Eu (3), Gd (7)), [Ln2(hfac)6(pyrzMO)3] (Ln = Eu (4), Gd (8)) (pyrzMO = pyrazine N-oxide, Htta = thenoyltrifluoroacetone, Hdbm = dibenzoylmethane, Hbta = benzoyltrifluoroacetone, Hhfac = hexafluoroacetylacetone, C7H8 = toluene), and their 4,4′-bipyridine N-oxide (bipyMO) analogues. Europium complexes emit a bright red light under UV radiation at room temperature, whose intensity displays a strong temperature (T) dependence between 223 and 373 K. This remarkable variation is exploited to develop a series of luminescent thermometers by using the integrated intensity of the 5D0 → 7F2 europium transition as the thermometric parameter (Δ). The effect of different β-diketonato and N-oxide ligands is investigated with particular regard to the shape of thermometer calibration (Δ vs T) and relative thermal sensitivity curves: i.e.. the change in Δ per degree of temperature variation usually indicated as Sr (% K–1). The thermometric properties are determined by the presence of two nonradiative deactivation channels, back energy transfer (BEnT) from Eu3+ to the ligand triplet levels and ligand to metal charge transfer (LMCT). In the complexes bearing tta and dbm ligands, whose triplet energy is ca. 20000 cm–1, both deactivation channels are active in the same temperature range, and both contribute to determine the thermometric properties. Conversely, with bta and hfac ligands the response of the europium luminescence to temperature variation is ruled by LMCT channels since the high triplet energy (>21400 cm–1) makes BEnT ineffective in the investigated temperature range., A family of homodinuclear Eu3+ luminescent complexes with the general formula [Ln2(β-diketonato)6(N-oxide)y] (y = 2, 3) was developed to study the effect of the β-diketonato and N-oxide ligands on the thermometric properties of the complexes. In this way, an effective tuning of the system’s thermometric properties can be achieved.

Tuning the plasmonic response with an external magnetic field is extremely promising to achieve active magnetoplasmonic devices, such as next generation refractometric sensors or tunable optical components. Noble metal nanostructures represent an ideal platform for studying and modeling magnetoplasmonic effects through the interaction of free electrons with external magnetic fields, even though their response is relatively low at the magnetic field intensities commonly applied in standard magneto-optical spectroscopies. Here we demonstrate a large magnetoplasmonic response of silver nanoparticles by performing magnetic circular dichroism spectroscopy at high magnetic fields, revealing a linear response to the magnetic field up to 30 T. The exploitation of such high fields allowed us to probe directly the field-induced splitting of circular plasmonic modes by performing absorption spectra with static circular polarizations, giving direct experimental evidence that the magneto-optical activity of plasmonic nanoparticles arises from the energy shift of field-split circular magnetoplasmonic modes.

We report the thermally controlled synthesis of Cr doped ZnGa2O4 thin films and the evolution of their morphology, crystallinity, and optical luminescence tracked with X-ray Absorption Near Edge Structure (XANES) and X-ray Excited Optical Luminescence (XEOL). It is found that the as-prepared ZnGa2O4 thin films doped with/without Cr are amorphous and exhibits no luminescence while annealing induces crystallization which markedly improves crystallinity at higher temperatures. SEM, XRD and O K-edge, Zn and Ga L-edge, and Cr K-edge XANES show disorder to order phase transition upon annealing which is accompanied by the appearance of the N2 line (696 nm) characteristic of the luminescence from Cr-doped ZnGa2O4 where Cr3+ occupies the octahedral Ga3+ site. The N2 line correlates with the crystallinity of the sample in that the higher the annealing temperature, the better the crystallinity and the brighter the N2 line. It is also interesting to note that the optical luminescence from the host ZnGa2O4, which appears in the blue (420 nm), is completely quenched and the energy is transferred to the N2 luminescence in the red (696 nm). These results and their implications are discussed.

Mononuclear rare-earth tris-β-diketonato complexes RE(tta)

A series of Gd3+ complexes (Gd1–Gd3) with the general formula GdL3(EtOH)2, where L is a β-diketone ligand with polycyclic aromatic hydrocarbon substituents of increasing size (1–3), was studied by combining time-resolved electron paramagnetic resonance (TR-EPR) spectroscopy and DFT calculations to rationalize the anomalous spectroscopic behavior of the bulkiest complex (Gd3) through the series. Its faint phosphorescence band is observed only at 80 K and it is strongly red-shifted (∼200 nm) from the intense fluorescence band. Moreover, the TR-EPR spectral analysis found that triplet levels of 3/Gd3 are effectively populated and have smaller |D| values than those of the other compounds. The combined use of zero-field splitting and spin density delocalization calculations, together with spin population analysis, allows us to explain both the large red shift and the low intensity of the phosphorescence band observed for Gd3. The large red shift is determined by the higher delocalization degree of the wavefunction, which implies a larger energy gap between the excited S1 and T1 states. The low intensity of the phosphorescence is due to the presence of C–H groups which favor non-radiative decay. These groups are present in all complexes; nevertheless, they have a relevant spin density only in Gd3. The spin population analysis on NaL models, in which Na+ is coordinated to a deprotonated ligand, mimicking the coordinative environment of the complex, confirms the outcomes on the free ligands., A series of Gd3+ complexes (Gd1−Gd3) were studied by combining TR-EPR spectroscopy and DFT calculations to rationalize the deviant spectroscopic behavior of the bulkiest complex (Gd3). The combination of ZFS calculations and the spin density delocalization analysis ascribed the larger red shift to the higher degree of delocalization of the wavefunction and the low intensity of the phosphorescence band to the presence of C−H groups with relevant spin density that favor non-radiative decay.

Two homometallic Coordination Polymers (CPs) with composition [Ln(hfac)3bipy]n (Ln3+ = Eu3+, 1, and Tb3+, 2, hfac = hexafluoroacetylacetonato, bipy = 4,4′-bipyridine) were used to develop a family of ratiometric luminescent thermometers containing Eu3+ and Tb3+ as red and green emitters, respectively. The thermometric properties of pure CPs and of their mixtures having an Eu3+/Tb3+ molar ratio of 1:1, 1:3, 1:5, and 1:10 (samples: Eu1Tb1, Eu1Tb3, Eu1Tb5, and Eu1Tb10) were studied in the 83–383 K temperature range. Irrespective of the chemical composition, we observed similar thermometric responses characterized by broad applicative temperature ranges (from 100 to 165 K wide), and high relative thermal sensitivity values (Sr), up to 2.40% K−1, in the physiological temperature range (298–318 K). All samples showed emissions endowed with peculiar and continuous color variation from green (83 K) to red (383 K) that can be exploited to develop a colorimetric temperature indicator. At fixed temperature, the color of the emitted light can be tuned by varying composition and excitation wavelength.

The use of alkynyl gold(I) complexes covers different research fields, such as bioinorganic chemistry, catalysis, and material science, considering the luminescent properties of the complexes. Regarding this last application, we report here the synthesis of three novel dinuclear gold(I) complexes of the general formula [(diNHC)(Au-C≡CPh)2]: two Au-C≡CPh units are connected by a bridging di(N-heterocyclic carbene) ligand, which should favor the establishment of semi-supported aurophilic interactions. The complexes can be easily synthesized through mechanochemistry upon reacting the pristine dibromido complexes [(diNHC)(AuBr)2] with phenylacetylene and KOH. Interestingly, we were also able to isolate the monosubstituted complex [(diNHC)(Au-C≡CPh)(AuBr)]. The gold(I) species were fully characterized by multinuclear NMR spectroscopy and mass spectrometry. The emission properties were also evaluated, and the salient data are comparable to those of analogous compounds reported in the literature.

A theoretical protocol combining density functional theory (DFT) and multireference (CAS) calculations is proposed for a Eu3+ complex. In the complex, electronic levels of the central Eu3+ ion are correctly calculated at the CASPT2 level of theory, and the effect of introducing different numbers of states in the configuration interaction matrices is highlighted as well as the shortcomings of DFT methods in the treatment of systems with high spin multiplicity and strong spin-orbit coupling effects. For the 5D0 state energy calculation, the inclusion of states with different multiplicity and the number of states considered for each multiplicity are crucial parameters, even if their relative weight is different. Indeed, the addition of triplet and singlets is important, while the number of states is relevant only for the quintets. The herein proposed protocol enables a rigorous, full ab initio treatment of Eu3+ complex, which can be easily extended to other Ln3+ ions.

We report the study of two-dimensional graphitic carbon nitride (GCN) functionalized with copper single atoms as a catalyst for the reduction of CO2 (CO2RR). The correct GCN structure, as well as the adsorption sites and the coordination of the Cu atoms, was carefully determined by combining experimental techniques, such as X-ray diffraction, transmission electron microscopy, X-ray absorption, and X-ray photoemission spectroscopy, with DFT theoretical calculations. The CO2RR products in KHCO3 and phosphate buffer solutions were determined by rotating ring disk electrode measurements and confirmed by 1H-NMR and gas chromatography. Formate was the only liquid product obtained in bicarbonate solution, whereas only hydrogen was obtained in phosphate solution. Finally, we demonstrated that GCN is a promising substrate able to stabilize metal atoms, since the characterization of the Cu-GCN system after the electrochemical work did not show the aggregation of the copper atoms.

A theoretical protocol combining density functional theory (DFT) and multireference (CAS) calculations is proposed for a Eu3+ complex. In the complex, electronic levels of the central Eu3+ ion are correctly calculated at the CASPT2 level of theory, and the effect of introducing different numbers of states in the configuration interaction matrices is highlighted as well as the shortcomings of DFT methods in the treatment of systems with high spin multiplicity and strong spin–orbit coupling effects. For the 5D0 state energy calculation, the inclusion of states with different multiplicity and the number of states considered for each multiplicity are crucial parameters, even if their relative weight is different. Indeed, the addition of triplet and singlets is important, while the number of states is relevant only for the quintets. The herein proposed protocol enables a rigorous, full ab initio treatment of Eu3+ complex, which can be easily extended to other Ln3+ ions., A theoretical protocol combining density functional theory and multireference calculations is proposed for a Eu3+ complex. For the 5D0 state energy calculation, the inclusion of states with different multiplicity and the number of states considered for each multiplicity are crucial parameters. The herein proposed protocol enables a rigorous, full ab initio treatment of Eu3+ complex, which can be easily extended to other Ln3+ ions.

Density functional theory-based methods have been exploited to look into the structural, vibrational and electronic properties of antenna ligands, all of them being crucial factors for the reliable design of customized luminescent lanthanide (Ln3+) complexes. The X-ray structures, UV-Vis absorption spectra and triplet (T1) energies of three novel β-diketone ligands with a thienyl group and naphthyl (L1), phenanthryl (L2), and pyrenyl (L3) polycyclic aromatic hydrocarbons as substituents have been modelled. Vibronic progressions provide a strong contribution to the L1 and L2 absorption spectra, while the L3 absorption spectrum needs the assumption of different conformational isomers in solution. T1 energies have been estimated either through the vertical- or the adiabatic-transition approach. The comparison with the phosphorescence spectra of Gd3+ complexes allowed us to infer that the latter approach is the most suitable one, in particular when sizable ligands are involved. Results obtained for the isolated antennas can be directly compared with those of the corresponding Ln3+ complexes, due to the unanimously accepted assumption that the excitation is ligand-centred.

The aim of Lab-on-a-chip systems is the downscaling of analytical protocols into microfluidic devices, including optical measurements. In this context, the growing interest of the scientific community in opto-microfluidic devices has fueled the development of new materials. Recently, lithium niobate has been presented as a promising material for this scope, thanks to its remarkable optical and physicochemical properties. Here, we present a novel microfluidic device realized starting from a lithium niobate crystal, combining engraved microfluidic channels with integrated and self-aligned optical waveguides. Notably, the proposed microfabrication strategy does not compromise the optical coupling between the waveguides and the microchannel, allowing one to measure the transmitted light through the liquid flowing in the channel. In addition, the device shows a high versatility in terms of the optical properties of the light source, such as wavelength and polarization. Finally, the developed opto-microfluidic system is successfully validated as a probe for real-time pH monitoring of the liquid flowing inside the microchannel, showing a high integrability and fast response.

Oxidized carbon nanohorn water based nanofluids are attracting more and more attention for solar harvesting applications because of their peculiar features: stable suspension without any surfactant, higher solar absorbance values as compared to the base fluid, etc. However, these nanofluids are still matter of research because not all their properties have been comprehensively studied yet. This paper is focused on the wettability properties of the carbon nanohorn water based nanofluids on different metal surfaces. The static contact angle was measured for ten nanofluids with concentrations ranging from 0.002%wt to 0.1% wt, five of those used non-oxidized carbon nanohorns while the other five used oxidized carbon nanohorns. Moreover, this work investigates a novel use of the oxidized carbon nanohorn nanofluids to deposit an ultra-thin layer via pool boiling. The realized coating was proved to be stable and found to slightly affect the wettability of the nanofluids. Finally, the solar reflectance of the coated aluminum sample was measured and found to be from 2 to 10 times lower as compared to a reference aluminum surface.

Single-crystal-to-single-crystal post-synthetic modifications (PSMs) of Lanthanide Organic Frameworks (LOFs) {[Ln2(H2L)3(DMF)4]·2DMF}n (Ln = Gd, 1 and Eu, 2; H4L = 2,5-dihydroxyterephthalic acid; DMF = dimethylformamide), carried out by treatment with (a) chloroform or (b) an imidazole solution in chloroform, yielded respectively isostructural {[Ln2(H2L)3(DMF)4]·CHCl3}n (Ln = Gd, 3; Eu, 4) or {[Ln2(H2L)3(Im)4][Ln2(H2L)3(Im)2(H2O)2]·6Im·2CHCl3}n (Ln = Gd, 5; Eu, 6). Single crystal X-ray diffraction studies of 5 showed two different regularly alternating dimeric units in the LOF and two regularly alternating cavities with different guest molecules. All compounds revert to the parent LOF, 1 or 2, when treated with DMF at 90 °C for 8 h. Europium-LOFs (2, 4 and 6) showed a faint red emission that progressively gained intensity upon cooling from RT to liquid nitrogen temperature. This behaviour was exploited to develop a family of luminescent thermometers whose characteristics were affected by the structural and coordinative modifications induced by PSMs.

A new model with the aim to predict the temperature dependence of europium emission in coordination systems is presented. The model has been developed from a library of Eu(3+)complexes of general formulaEuL(3)A(2), whereLis a beta-diketone, andAis an ancillary ligand. Three possible deactivation channels have been considered: two competitive metal-related terms describing the primary deactivation channels,i. e. back energy transfer and multiphonon quenching, and a third ligand-related term to describe non-radiative deactivation of the antenna triplet. As many parameters as possible are taken from measurable chemical-physical properties, such as ligand triplet and multiphonon quenching energies. The other parameters have been deduced from selectedEuL(3)A(2)compounds and used asone-size-fits-allvalues. The model proved to be very effective in describing the interplay between back energy transfer and multiphonon deactivation channels. Finally, the model has been implemented in a freeware standalone MATLAB application. Users need to input only the energy of the sensitizer triplet level and choose the coordinated quencher, if present. It simulates the range of applicability of the molecular thermometers and the shape of the thermometric sensitivity curveS(r)employing as thermometric parameter either emission intensity or lifetime.

Controlled synthesis of Mn-doped ZnO nanostructures with Mn concentrations of 1%, 3%, and 10% at. has been carried out using sol–gel methods and temperature treatments at 400, 600, and 800 °C. It is found that Mn is successfully introduced into the hcp oxide lattice of ZnO nanoparticles of a range of sizes from a few nm to 102 nm, depending on temperature conditions. It is also found that a secondary phase appears as the Mn concentration and processing temperature increase, most probably in the form appropriately described as MnOx clusters on the surface, although the dominant component remains hcp ZnO. The x-ray absorption near edge structure at all edges of interest reveals that the Mn2+ ion substitutes Zn2+ at the tetrahedral site and that the secondary phase exhibits a clear signature of the octahedral local environment at the Mn L3,2 and O K-edge. X-ray excited optical luminescence excited at 1085 eV (just above the Zn L3,2 edge) shows that the characteristic bandgap emission is slightly blue shifted and the luminescence from both the bandgap and defect emission is quenched somewhat with the latter significantly shifted to longer wavelengths in the region observed for surface and near surface defects. The Mn-doped samples processed at low temperature are poor light emitters due to the high degree of disorder and improve markedly with annealing at higher temperature. The magnetic properties of these systems were also investigated. The results suggest that Mn doping impedes radiative recombination, which is in favor of improved photocatalytic behavior. The implication of these findings is discussed.

Bi12O17Cl2/(BiO)2CO3 nanocomposite materials were studied as bifunctional systems for depuration of wastewater. They are able to efficiently adsorb and decompose rhodamine B (RhB) and methyl orange (MO), used as model pollutants. Bi12O17Cl2/(BiO)2CO3 nanocomposites were synthesized at room temperature and ambient pressure by means of controlled hydrolysis of BiCl3 in the presence of a surfactant (Brij 76). Cold treatments of the pristine samples with UV light or thermal annealing at different temperatures (370–500 °C) and atmospheres (air, Ar/30% O2) were adopted to modulate the relative amounts of Bi12O17Cl2/(BiO)2CO3 and hence the morphology, surface area, ζ-potential, optical absorption in the visible range, and the adsorption/degradation of pollutants. The best performance was achieved by (BiO)2CO3-rich samples, which adsorbed 80% of MO and decomposed the remaining 20% by visible light photocatalysis. Irrespective of the dye, all of the samples were able to almost complete the adsorption step within 10 min contact time. Bi12O17Cl2-rich composite materials displayed a lower adsorption ability, but thanks to the stronger absorption in the visible range they behaved as more effective photocatalysts. The obtained results evidenced the ability of the employed strategy to modulate sample properties in a wide range, thus pointing out the effectiveness of this approach for the synthesis of multifunctional inorganic materials for environmental remediation.

Insight into the ineffectiveness of a subcomponent self-assembly procedure between 4-aminopyridine (4-apy) and pyridine-2-carbaldehyde (2-pyA) led to a new aminal ligand (L). The combination of L with AgI gave a 2D luminescent network, in which the silver ions have a distorted triangular-pyramidal coordination geometry. The aminal is stable in acetonitrile and DMSO but decomposes in alcohol solvents. Moreover, we found that CuII also induced the decomposition of L, which led to Cu(pic)2, {[Cu(4-apy)4](ClO4)2}, and an unprecedented {[Cu4(pic)4(OH)2(H2O)6](ClO4)2} tetramer based on CuII ions and picolinic acid (Hpic) generated in situ. The decomposition pathway of L was clarified by a combination of single-crystal XRD analysis, NMR spectroscopy, and ESI-MS.

Solvent can play a crucial role in the synthesis of coordination polymers (CPs). Here, this study reports how the coordinating solvent approach (CSA) can be used as an effective tool to control the nature of the final CP. This study exploited the system Cu(II)-4,4&prime, bipyridine coupled to different coordinating solvents, such as DMA, DMF and DMSO. This allowed the isolation and structurally characterization of four new CPs: three 2D layered networks and one 1D chain. Moreover, it was evidenced that even adventitious water can play the role of the coordinating solvent in the final CP.

A dianiline derivative of a symmetric donor-acceptor-donor diketopyrrolopyrrole-based dye is employed for the two-sided covalent functionalization of liquid exfoliated few layers graphene flakes, through a direct arylation reaction. The resulting nanohybrid features the properties of a polymeric species, being solution-processed into homogeneous thin films, featuring a pronounced red-shift of the main absorption band with respect to the model dye unit and energy levels comparable to those of common diketopyrrolopyrrole-based polymers. A good electrical conductivity and the absence of radical signals generated after intense white light illumination, as probed through electron paramagnetic resonance, suggest a possible future application of this composite material in the field of photoprotective, antistatic layers with tunable colors.

Novel silver(I), gold(I), and palladium(II) complexes were synthesized with bidentate heteroditopic carbene ligands that combine an imidazol-2-ylidene (nNHC) with a 1,2,3-triazol-5-ylidene (tzNHC) connected by a propylene bridge. The silver(I) and gold(I) complexes were dinuclear species, [M-2(nNHC-tzNHC)(2)](PF6)(2) (M = Ag or Au), with the two bidentate ligands bridging the metal centers, whereas in the palladium(II) complex [Pd(nNHC-tzNHC)(2)]-(PF6)(2), the two ligands were chelated on the same metal center. Because of the presence of two different carbene units, isomers were observed for the gold(I) and palladium(II) complexes. The molecular structures of the head-to-tail isomer for gold(I) complexes, with a twisted or folded-syn conformation of the bridge between the carbene units, were determined by X-ray diffraction analysis. The study was completed with a systematic structural investigation through density functional theory (DFT) calculations. For palladium(II) species, the head-to-head form was structurally characterized. The dinuclear gold(I) complexes were emissive in the solid state in the blue region (PLQY up to 8%); time-dependent density functional theory (abbreviated as TD-DFT) calculations disclosed that the absorption bands have metal-to-ligand-charge-transfer character and evidenced that the emission occurs from the T-1 level (phosphorescence).

We present an approach toward sequence-dependent materials based on a stepwise assembly on a silica surface of rare earth cations (RE: Y3+, Eu3+ and Tb3+) and the 1,4-benzenedicarboxylate (terephthalate, T2-) ligand, organized in an ordered sequence RE1-T-RE2. The first RE was grafted to silica through a reaction of its N,N-dibutylcarbamato derivative, [RE1(O2CNBu2)(3)], with the surface silanols. The residual carbamato groups in the metal coordination sphere were then substituted by HT- through a reaction with H2T in pyridine. The BrOnsted acidity of the pendant COOH groups was successively exploited for the anchorage of the second metal ion (RE1 = Eu, RE2 = Tb; RE1 = Y, RE2 = Tb). The choice of pyridine as the solvent, able to dissolve both H2T and the secondary product [NH2Bu2](2)[T]H2T, was crucial for achieving success with this method. The emission properties of the materials were modulated by modifying the order of the synthetic steps. Metal complexes and materials were characterized by IR, EDX, ICP and photoluminescence. We used Tb3+ to Eu3+ energy transfer (ET) to study the RE3+ spatial distribution and intermetal distances to prove the formation of a RE1-T-RE2 sequence. Photoluminescence was used as a multi-tool technique to characterize the functional properties of the materials and to obtain structural information supporting the sequence growth.

The synthesis of heterobimetallic complexes remains a synthetic challenge in the field of organometallic chemistry. A possible approach in this regard might be the use of a bidentate heteroditopic bis(carbene) ligand that combines an imidazol-2-ylidene (nNHC) with a 1,2,3-triazol-5-ylidene (tzNHC) connected by an organic spacer. The optimized strategy to heterobimetallic complexes with this type of ligand involves a 3-step procedure: (i) Coordination of the nNHC, functionalized with a 1,2,3-triazole ring, to a metal center, (ii) formation of the triazolium ring by alkylation of the triazole N-3, (iii) deprotonation of the tzNHC precursor and coordination of the second metal center. Following this procedure, a novel Au(I)-Ag(I) dinuclear complex was isolated and its properties were compared to the analogous homobimetallic Ag(I)-Ag(I) and Au(I)-Au(I) complexes. The study was completed by the determination of the molecular structures of some synthetic intermediates.

The ability to tune and enhance the properties of luminescent materials is essential for enlarging their application potential. Recently, the modulation of the photoluminescence emission of lanthanide-doped ferroelectric perovskites by applying an electric field has been reported. Herein, we show that the ferroelectric order and, more generally the polar order, has a direct effect on the photoluminescence of Eu

The coordination polymers [ Ln ( β - dik ) 3 bpy ] ∞ 1 ·C7H8 (Ln = Eu, β-dik = dbm, tta, hfac; Ln = Tb; β-dik = dbm; Hdbm = dibenzoylmethane, Htta = thenoyltrifluoroacetone, Hhfac: hexafluoroacetylacetone) were easily assembled in mild conditions and high yields starting from the anhydrous lanthanide β-diketonates as nodes and 4,4′-bipyridine (bpy) as connector. X-ray single crystal studies have shown zigzag extended chains where lanthanide centres are 8-coordinated in a distorted square-antiprismatic geometry. Photoluminescence studies show bright red europium emission and spectral features dependent on the topology of the polymeric chains.

The synthesis of dinuclear molecular complexes [Eu2(dbm)6(bipyMO)2], 1, [Tb2(dbm)6(bipyMO)2], 2, [Eu2(tta)6(bipyMO)2], 3 [Eu2(hfac)6(bipyMO)3], 4, [Tb2(hfac)6(bipyMO)3], 5 is here reported (bipyMO = 4,4?-bipyridine N-oxide, Hdbm = dibenzoylmethane, Htta = thenoyltrifluoroacetone, Hhfac = hexafluoroacetylacetone). The products were obtained in mild conditions and with high yields reacting anhydrous lanthanide ?-diketonates and bipyMO in 1:1 or 1.5 molar ratio in toluene. X-ray single crystal studies on 2, 3, 4 showed that the heterotopic ligands are hypodentate, bridging the two lanthanide centres exclusively through the oxygen atom. Photoluminescence studies show bright red emissions from europium derivatives with absolute quantum yields up to 44 %.

Heterotopic divergent ligand N-oxide-4,4'-bipyridine (bipyMO) has been herein exploited for the preparation of hetero-bimetallic coordination polymers where Ln(hfac)(3) and M(hfac)(2) nodes regularly alternate (Hhfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione), bipyMO being able to selectively use its two potential coordination sites to discriminate the metal ions. The synthesis of three coordination polymers, [Ln(hfac)(3)M(hfac)(2) (bipyMO)(2)](n) (Ln = Eu, M = Zn, 1; Ln = Eu, M = Cu, 2, Ln = Dy, M = Co, 3), was carried out by reacting the appropriate [M(hfac)(2)(bipyMO)](n) and [Ln(hfac)(3)] precursors in toluene in the presence of a given stoichiometric amount of bipyMO. The products were characterized by elemental analysis, X-ray powder diffraction, and FTIR spectroscopy. Single crystal X-ray diffraction studies carried out on 2 showed that it was formed by chains containing the hexa-coordinated 3d metal (Cu(hfac)(2)[N](2)) and the octa-coordinated lanthanide (Eu(hfac)(3)[O](2)) nodes, where [N] and [O] stand for the donor atom of the bridging divergent ligand. The X-ray powder diffraction patterns of the three compounds and the comparison of their cell constant values allowed establishing that the derivatives were isotypic. Photoluminescence (PL) studies on microcrystalline sample powders evidenced a bright red emission for 1 with an absolute PL quantum yield of 0.24. The sensitized emission of Eu3+ can be excited in a wide wavelength range, from UV to visible, up to approximate to 450 nm. Conversely, europium emissions are not detectable in 2 due to the presence of Cu(hfac)(2)(bipyMO) moieties whose strong absorption overlaps Eu3+ transitions. Magnetic measurements conducted on 3 revealed the presence of a weak ferromagnetic interaction below 2.1 K. An ac susceptibility study highlighted a slow relaxation of the magnetization of 3 with an applied static magnetic field of 0.1 T, which could be equally fitted with a Orbach-direct or a Raman-direct mechanism. No relaxation dynamics was detected without the application of a static magnetic field.

Bi12O17Cl2/(BiO)2CO3 nanocomposite materials were studied as bifunctional systems for depuration of wastewater. They are able to efficiently adsorb and decompose rhodamine B (RhB) and methyl orange (MO), used as model pollutants. Bi12O17Cl2/(BiO)2CO3 nanocomposites were synthesized at room temperature and ambient pressure by means of controlled hydrolysis of BiCl3 in the presence of a surfactant (Brij 76). Cold treatments of the pristine samples with UV light or thermal annealing at different temperatures (370–500 °C) and atmospheres (air, Ar/30% O2) were adopted to modulate the relative amounts of Bi12O17Cl2/(BiO)2CO3 and hence the morphology, surface area, ζ-potential, optical absorption in the visible range, and the adsorption/degradation of pollutants. The best performance was achieved by (BiO)2CO3-rich samples, which adsorbed 80% of MO and decomposed the remaining 20% by visible light photocatalysis. Irrespective of the dye, all of the samples were able to almost complete the adsorption step within 10 min contact time. Bi12O17Cl2-rich composite materials displayed a lower adsorption ability, but thanks to the stronger absorption in the visible range they behaved as more effective photocatalysts. The obtained results evidenced the ability of the employed strategy to modulate sample properties in a wide range, thus pointing out the effectiveness of this approach for the synthesis of multifunctional inorganic materials for environmental remediation.

We describe a new organic/inorganic material emitting circularly polarized luminescence (CPL). The hybrid system was obtained by the following steps: (i) preliminary grafting of the europium N,N-dibutylcarbamate [Eu(O2CNBu2)3] complex onto silica, (ii) substitution of the residual carbamato groups with anionic 1,3-diphenyl-1,3-propanedionato ligands (dbm), and (iii) subsequent introduction of the neutral tridentate chiral ligand 2,6-bis(isopropyl2-oxazolin-2-yl)pyridine (iPr-PyBox) in the metal coordination sphere. The solid material is stable to air and does not leach either the metal or the ligand. Samples of both enantiomers have been studied, showing mirror-image CPL spectra. The molecular compounds [Eu(dbm)3-(S)-(iPr-PyBox)] and [Eu(dbm)3-(R)-(iPrPyBox)] were prepared for comparison purposes and their molecular structures studied by single-crystal X-ray diffraction, showing mononuclear derivatives with a coordination number of 9 for europium. Powder X-ray diffraction showed a single crystalline phase. Photoluminescence and CPL evidenced the presence of a single emitting species.

We describe the synthesis, computational analysis, photophysics, electrochemistry and electrochemiluminescence (ECL) of a series of compounds formed of two triphenylamines linked by a fluorene or spirobifluorene bridge. The phenylamine moieties were modified at the para-position of the two external rings by electron-withdrawing or electron-donating substituents. These modifications allowed for fine-tuning of the photoluminescence (PL) and ECL emission from blue to green, with an overall wavelength span of 73 (PL) and 67 (ECL) nm, respectively. For all compounds, we observed a very high PL quantum yield (79-89%) and formation of stable radical ions. The ECL properties were investigated by direct annihilation of the electrogenerated radical anion and radical cation. The radical-ion annihilation process is very efficient and causes an intense greenish-blue ECL emission, easily observable even by naked eye, with quantum yield higher than the standard 9,10-diphenylanthracene. The ECL spectra show one single band that almost matches the PL band. Because the energy of the annihilation reaction is higher than that required to form the singlet excited state, the S-route is considered the favored pathway followed by the ECL process in these molecules. All these features point to this type of molecular system as promising for ECL applications.

We describe herein the synthesis and photophysical characterization of new lanthanide complexes that consist of a (9,9-dimethylfluoren-2-yl)-2-oxoethyl or a (9,9'-spirobifluoren-2-yl)-2-oxoethyl unit as the antenna, covalently linked to a 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A) unit as the Ln(3+) (Gd(3+), Eu(3+), Sm(3+), Tb(3+), Dy(3+)) coordination site. We were able to translate the spectroscopic properties of the innovative bipartite ligands into the formation of highly luminescent europium complexes that exhibit efficient emission (ϕ(se)>0.1) upon sensitization in the near-visible region, that is, with an excitation wavelength above 350 nm. The luminescence of the Eu(3+) complexes is clearly detectable at concentrations as low as 10 pM. Furthermore, the structural organization of these bipartite ligands makes the complexes highly soluble in aqueous solutions and chemically stable over time.

The grafting and the postgrafting functionalization of lanthanide ions on commercial amorphous silica have been herein carried out by using as a precursor the terbium N,N-dibutylcarbamato derivative [Tb(O2CNBu2)3]. The reaction of the complex with the surface silanols involved only a fraction of the carbamato ligands. The following protolytic substitution of the residual carbamato ligands was carried out by exploiting the Bronsted's acidity of the beta-diketone dibenzoylmethane (Hdbm), in view of the antenna effect of the beta-diketonato groups, which are commonly used in lanthanide photoluminescence studies. The reaction proceeded at room temperature in a clean and easy way affording the introduction of the chosen functionality in the lanthanide coordination sphere. The same procedure has been followed by using as a precursor the X-ray characterized heterometallic N,N-dibutylcarbamato complex [NH2Bu2]2[Ln4(CO3)(O2CNBu2)12] (Ln = Eu, Tb, Tm). In both cases, X-ray photoelectron spectroscopy evidenced the chemical implantation of the lanthanide ions on the silica surface, and photoluminescence studies pointed out the potentiality of the proposed synthetic approach in the preparation of highly luminescent materials.

In this study, we present the aqueous solution behavior of two luminescent lanthanide antenna complexes (Eu3+ ⊂1, Dy3+ ⊂9) with different ligand topologies in the presence of dipicolinic acid (DPA, pyridine-2,6-dicarboxylic acid). Macrocyclic (1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid, DO3A, 9) and acyclic (1,4,7-triazaheptane-1,1,7,7-tetraacetic acid, DTTA, 1) ligands have been selected to form a ratiometric pair in which Dy3+ ⊂9 acts as a reference and Eu3+ ⊂1 acts as a probe for the recognition of DPA. The pair of luminescent complexes in water reveals the capability to work as a DPA luminescent sensor. The change of emission intensity of Eu3+ indicates the occurrence of a new sensitization path for the lanthanide cation through excitation of DPA. NMR evidence implies the presence of free 1 and mass spectrometry shows the formation of emitting [EuDPA2 ]- as a result of a ligand exchange reaction.

The present work is devoted to the preparation of Ag/TiO2 nanosystems by an original synthetic strategy, based on the radio-frequency (RF) sputtering of silver particles on titania-based xerogels prepared by the sol-gel (SG) route. This approach takes advantage of the synergy between the microporous xerogel structure and the infiltration power characterizing RF-sputtering, whose combination enables the obtainment of a tailored dispersion of Ag-containing particles into the titania matrix. In addition, the systems chemico-physical features can be tuned further through proper ex situ thermal treatments in air at 400 and 600 °C. The synthesized composites are extensively characterized by the joint use of complementary techniques, that is, X-ray photoelectron and X-ray excited Auger electron spectroscopies (XPS, XE-AES), secondary ion mass spectrometry (SIMS), glancing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), electron diffraction (ED), high-angle annular dark field scanning TEM (HAADF-STEM), energy-filtered TEM (EF-TEM) and optical absorption spectroscopy. Finally, the photocatalytic performances of selected samples in the decomposition of the azo-dye Plasmocorinth B are preliminarily investigated. The obtained results highlight the possibility of tailoring the system characteristics over a broad range, directly influencing their eventual functional properties.

The present study, focused on the sol-gel synthesis of rare-earth-doped zinc oxide, highlights the crucial points involved in the design and development of ZnO/Eu nanosystems. with peculiar and easily tunable photophysical. properties. ZnO nanopowders containing different europium amounts were prepared starting from zinc and europium acetate salts as the sol precursors. The densification process and the evolution of the structural-optical properties were studied as a function of annealing performed in air between 100 and 1000 degrees C. The microstructure and composition of the samples and their dependence on the synthesis procedure were investigated by X-ray diffraction and X-ray photoelectron spectroscopy, whereas the emission properties were studied by photoluminescence spectroscopy in the energy and time domains as a function of the structural evolution. Crystalline ZnO powders in the wurtzite structure were formed after heat treatment at 400 degrees C, with an average nanocrystal size of ca. 20 nm. Stronger annealing conditions allowed a more extended densification of the oxide-based network and the removal of most -OH groups but also promoted the crystallization of EU2O3 at 800 degrees C. The most intense emission bands around 600 nm due to Eu3+ transitions were clearly observed in the annealed samples (T >= 600 degrees C). Interestingly, the observed overlap of the typical Eu3+ red emission with the characteristic green luminescence of the nanostructured ZnO matrix can be synergistically exploited for single or multicolor emission through the proper choice of the excitation wavelength.

The present contribution is devoted to outlining some recent results from an innovative approach to metal oxide nanosystems. The proposed synthesis pathway is based on three successive steps: i) preparation of a porous xerogel layer (host) via sol–gel (SG); ii) CVD of a guest phase on the above matrix, making it possible to achieve an intimate host/guest intermixing; iii) ex situ thermal treatment under suitable conditions, aimed at tailoring the system properties as a function of the desired application. In particular, the above route has been adopted in two specific cases, LaCoO3 and CeO2–ZrO2 nanostructured thin films, which are acquiring increasing importance in the development of fuel cell technology. The most significant results, obtained by glancing incidence X-ray diffraction (GIXRD), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), and transmission electron microscopy (TEM), will be critically discussed, emphasizing the achievement of tailored material properties by design.

The suitability of the Ag+ Na+ ion exchange process was tested for the production of luminescent cover glasses with down-shifting properties suitable for solar cells. The photoluminescence properties were investigated as a function of the preparation parameters (i.e., Ag salt bath concentration, post-synthesis annealing temperature and duration). The performance of the samples was tested by measuring the output power of a Si solar cell covered with the treated glass slides and exposed to a solar simulator radiation; the photoluminescence quantum yield of the best performing samples was also estimated. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Neodymium and terbium pentafluorophenolates, containing 1,10-phenanthroline as ancillary ligand, [Ln(OC6F5)3(phen)3], (1 Ln = Nd, 2 Ln = Tb) have been synthesized by reacting the N,N-dibutylcarbamato complexes, [Ln(O2CNBu2)3], easily obtained from aqueous solutions of lanthanide salts, with C6F5OH in the presence of 1,10-phenanthroline. The formation of the sparingly soluble hydrated compound [Tb(OC6F5)3(phen)2(H2O)·phen], 3, was observed, due to fortuitous presence of water. Single crystal X-ray diffraction studies on compounds 1, 3 and 3·DME (DME = dimethoxyethane) showed coordination numbers (CN) 9 for neodymium in 1 and 8 for terbium in 3 and 3·DME, where only two 1,10-phenanthroline ligands are coordinated to terbium, the third forming two hydrogen bonds with the coordinated water. The structural characterisation of [NH2Bu2][C6F5O], 4, showed the organisation of the product in ionic quartets. The photoluminescence spectra of 1 and 2 displayed the typical emissions related to the lanthanide centre in the NIR and visible region, respectively.

We report the synthesis of three optical probes (Eu(3+)⊂1, Eu(3+)⊂2, and Eu(3+)⊂3) having a luminescent Eu complex (signaling unit) bonded in different positions to folic acid (FA), the folate receptor (FR) targeting unit. The structures of the two regioisomers Eu(3+)⊂1 and Eu(3+)⊂2 were assigned by mass spectrometric experiments. The optical properties and stability of these probes were assessed in phosphate-buffered saline, cell culture medium, rat serum, and cellular lysate, and results indicated that they are chemically and photophysically stable. Cytotoxicity was studied with ovarian cancer cells having high (SKOV-3), intermediate (OVCAR-3), low (IGROV-1), or null (A2780) expression of FRs. The internalized probe, evaluated in SKOV-3, IGROV-1, and A2780 cells, was in the order Eu(3+)⊂2 > Eu(3+)⊂1 > Eu(3+)⊂3. No internalization was observed for A2780 cells. Such results, together with those obtained in competition experiments of FA versus Eu(3+)⊂2 and FA or Eu(3+)⊂2 versus (3)H-FA, indicate that internalization is receptor-mediated and that Eu(3+)⊂2 shows high selectivity and specificity for FR.

Nanocomposite materials based on metal nanoparticles (NPs, guest) in/on oxide matrices (host) have attracted increasing attention thanks to their intriguing chemico-physical properties that can be tailored as a function of NP size, shape and mutual interactions. The possibility to obtain a controlled dispersion of metal particles in/on suitable oxides (inside- and outside-cluster systems, respectively) paves the way to a broad spectrum of technological applications, ranging from heterogeneous catalysis, to gas sensing and non-linear optics. The control of functional performances relies on tailoring the system properties by design through a suitable choice of the synthesis and processing routes. In this context, the present review provides a synoptic overview on our recent research activity concerning nanocomposites containing 11th group metal clusters (Cu, Ag and Au), dispersed in/on oxide matrices (SiO(2), TiO(2), Al(2)O(3)). We begin by briefly outlining the interest and size-dependent properties of such systems. Subsequently, the attention is switched to a survey on the preparation strategies previously adopted in the literature, focusing in particular on the use of soft methods, such as sol-gel (SG), RF-sputtering and their innovative combination. The most relevant results on M'/M(x)O(y) nanocomposites (where M' = Cu, Ag, An and M = Si, Ti, Al) obtained by these routes are then comparatively discussed, highlighting analogies and differences between them. Finally, the most attractive research perspectives in the field are briefly presented.

Pure and Ca-doped LaCoO3 nanopowders were prepared by a non-alkoxidic sol-gel route using cobalt(II) acetate, lanthanum(III) nitrate and calcium(II) acetate as oxide precursors. The structural evolution and magnetic properties of the samples were studied as a function of thermal treatments in air up to 1273 K. In particular, the microstructure and composition of the systems were analyzed by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS). Both pure and calcium-doped samples annealing at 973 K resulted in the formation of cubic LaCoO3 (average crystallite size

The preparation of sol–gel glasses is described wherein highly stable Eu(III) centres are anchored to the silica glass upon acidic hydrolysis and by using tetraethylorthosilicate (TEOS) as a silica source. The complex employed is Eu·1 and is obtained from bipartite ligand 1, which features a DO3A macrocycle as a hosting unit for the Eu(III) centre, a methoxy-acetophenone unit as an antenna chromophore, and an alkyl chain bearing one primary hydroxy group (DO3A is 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid). Eu·1 is linked to the forming silica glass through the –OH groups and a uniform distribution of the luminescent centres is obtained, as indicated by results from secondary ion mass spectrometry in-depth profiling. The luminescent efficiency of the Eu(III) centres in the solid matrix is evaluated to be 10%, which is comparable to that of Eu·1 in water solution and of a convenient reference complex, Eu·2 (2 is a ligand featuring the same hosting and antenna functionalities of 1, wherein the –OH residue is replaced by an unreactive group, a benzoylmethyl residue). A discussion is given of the photophysical properties exhibited by the complexes in the film and in solution.

The hydrolysis and polycondensation reactions of Al(OBu(s))3 have been studied by laser desorption/ionization (LDI), performed on the solid samples originating from different aluminum alkoxide solutions, prepared using the usual operating conditions employed in the sol-gel synthesis of Al2O3-based materials. CHCl3, CH3OH and CH3OH/H2O mixture were used as solvents. In the latter case different H2O/Al(OBu(s))3 molar ratios were adopted, i.e. 1:1, 1:2, and 1:4. The obtained hydrolysis and polycondensation species consist of polynuclear species containing < or =12 aluminum atoms. In the CHCl3 solutions, the formation of the observed hydrolysis products has been ascribed to the reaction with water present in the atmosphere during the LDI sample preparation and/or present at trace level in the solvent. When methanol is used as a solvent, extensive methanolysis reactions take place, thus originating oligomers with CH3O and OH substituents. The kinetics of formation of the various polynuclear species are dependent on the reaction environment and the reaction is faster in the presence of methanol. It is worth noticing that, regardless of the hydrolysis process, the polycondensation products can be considered as originating from a common tetrameric core [Al4O4(OBu)2(OH)2] around which different building blocks are condensed to form various oxo-polymeric species.