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While Eu2+ → Eu3+ energy transfer is well known, in this study the energy transfer from Eu3+ to Eu2+ is reported for the first time. The predominant condition for Eu3+ → Eu2+ energy transfer is a Eu2+ 4f55d band at lower energy than the position of the Eu3+ 4f6[5D0] level, which is fulfilled in Eu‐doped CaO. X‐ray powder diffraction, Eu Mössbauer spectroscopy and optical absorption measurements are employed to determine the Eu3+ and Eu2+ concentrations in the prepared CaO:1at.%Eu samples. Synthesis in an H2/N2 atmosphere and addition of graphite powder as a reducing agent to the starting mixture are found to result in respective Eu3+ and Eu2+ concentrations of 0.6–0.7% and 0.3–0.4%. For this sample, the Eu3+ → Eu2+ energy transfer efficiency is estimated to be high (> 90%). This is explained by the high oscillator strength of the 4f7 → 4f65d excitation transition of the Eu2+ ion to which energy is transferred. As the Eu2+ 4f55d band lies below the Eu3+ 4f6[5D0] level, Eu3+ does not act as a killer center for the near‐infrared (NIR) Eu2+ emission at about 720 nm. Therefore, a full reduction of Eu3+ is not required to attain a high quantum efficiency. Implications of the demonstrated Eu3+ → Eu2+ energy transfer for application of long wavelength Eu2+ phosphors are discussed. [ABSTRACT FROM AUTHOR]

The solid‐state syntheses and the structures of three new europium carbodiimide chlorides are reported: Eu4(NCN)3Cl3=Eu(3+)Eu3(2+)(NCN)3Cl3 (1), LiEu2(NCN)Cl3 (2) and Na2Eu14(NCN)3Cl24 (3). 1 is the second example of mixed‐valent rare‐earth carbodiimide after Eu4F5(NCN)2. 2 belongs to a group of mixed carbodiimide compounds related to the Bideauxite group. 3 being the first Na‐containing rare‐earth carbodiimide. Syntheses in the field of rare‐earth carbodiimides benefit from the usage of different alkali carbodiimides to direct reaction pathway into individual compounds. High‐yield syntheses of 1–3, their crystal structures, and the photoluminescence properties of 3 are reported. [ABSTRACT FROM AUTHOR]

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The reaction of manganese halides with polydentate Schiff bases obtained by the condensation of 3-ethoxysalicylaldehyde and different amino alcohols, resulting in a NO3 set of donors, yielded a series of manganese clusters with {MnIII6MnIINa2}, {MnIII3MnIINa}, and {MnIII3} metallic cores. The influence of the ligand substituents and the halide on the final nuclearity has been studied. Analysis of their static magnetic behaviour confirms the ground states of 19/2 for the {MnIII6MnIINa2} complexes, 7/2 for the {MnIII3MnIINa} clusters, and 12/2 for the triangular {MnIII3} systems, and a weak field induced a slow relaxation of the magnetization for the trinuclear complexes. [ABSTRACT FROM AUTHOR]

This study reports the serendipitous discovery of intermolecular anionic mixed‐valence (MV) and π‐dimer species in ortho‐pentannulated BisAzaCoroneneDiimides (BACDs) during their electrochemical reduction in a non‐aqueous solvent. A library of nitrogen‐containing extended PDIs was synthesized via an aza‐benzannulation reaction followed by a Pd‐catalysed ortho‐pentannulation reaction. Ortho‐pentannulated BACDs revealed strong aggregation abilities in solution. Concentration‐dependent UV/Vis absorption spectra, variable temperature 1H NMR experiments, and atomic force microscopy coupled to molecular dynamics support their self‐assembly into columnar aggregates. Cyclic voltammetry experiments in dichloromethane reveal prominent splitting of the first reduction wave, attributed to the formation of unprecedented intermolecular anionic MV and π‐dimers in organic solvent. These species were thoroughly characterized by real‐time spectroelectrochemistry, electrochemical simulations and theoretical calculations. Remarkably, this work underscores the tuneable nature of AzaBenzannulatedPerylene Diimides (AzaBPDIs) and BACDs, emphasizing their potential as a promising scaffold for designing supramolecular materials with long‐range radical anion delocalization. The observation of this phenomenon provides insights into the fundamental behaviour of supramolecular organic semiconductors, thereby paving the way for the development of novel electronic devices and electron‐deficient materials. [ABSTRACT FROM AUTHOR]

Fe-MOFs of mixed valence was synthesized by a solvothermal method via the in-situ reduction of ethylene glycol (EG) pre-coordination with the proper ratio of Fe2+/Fe3+ between 0.83 and 2.46. Synchronously with copper introduction, the Fe/Cu MOFs of mixed valence (Fe/Cu-MVMOFs) was then one pot acquired to remarkably improve the affinity of Fe2+ and Cu+ to H2O2 and promote the conversion efficiency of Fe2+/Fe3+ via the electron transfer among Fe-Cu bimetal clusters (XPS and XRD). Hence, the maximum reaction rate of H2O2 with Fe/Cu-MVMOFs reached 16.65 M·s−1, along with Km as low as 0.0479 mM. H2O2 and glutathione (GSH) were efficiently detected, ranging from 0.25 to 60 µM and from 0.2 to 40 µM, respectively. The investigation of catalyzation selectivity and practical serum detection by Fe/Cu-MVMOFs illustrated the efficacy and efficiency, denoting Fe/Cu-MVMOFs as the promising peroxidase candidate. [ABSTRACT FROM AUTHOR]

The crystal structures of three mixed‐valence copper cyanide alkanolamine polymers are presented, together with thermogravimetric analysis (TGA) and electron spin resonance (ESR) data. In all three structures, a CuII moiety on a crystallographic center of symmetry is coordinated by two alkanolamines and links two CuICN chains via cyanide bridging groups to form diperiodic sheets. The sheets are linked together by cuprophilic CuI–CuI interactions to form a three‐dimensional network. In poly[bis(μ‐3‐aminopropanolato)tetra‐μ‐cyanido‐dicopper(I)dicopper(II)], [Cu4(CN)4(C3H8NO)2]n, 1, propanolamine bases have lost their hydroxyl H atoms and coordinate as chelates to two CuII atoms to form a dimeric CuII moiety bridged by the O atoms of the bases with CuII atoms in square‐planar coordination. The ESR spectrum is very broad, indicating exchange between the two CuII centers. In poly[bis(2‐aminopropanol)tetra‐μ‐cyanido‐dicopper(I)copper(II)], [Cu3(CN)4(C3H9NO)2]n, 2, and poly[bis(2‐aminoethanol)tetra‐μ‐cyanido‐dicopper(I)copper(II)], [Cu3(CN)4(CH7NO)2]n, 3, a single CuII atom links the CuICN chains together via CN bridges. The chelating alkanolamines are not ionized, and the OH groups form rather long bonds in the axial positions of the octahedrally coordinated CuII atoms. The coordination geometries of CuII in 2 and 3 are almost identical, except that the Cu—O distances are longer in 2 than in 3, which may explain their somewhat different ESR spectra. Thermal decomposition in 2 and 3, but not in 1, begins with the loss of HCN(g), and this can be correlated with the presence of OH protons on the ligands in 2 and 3, which are not present in 1. [ABSTRACT FROM AUTHOR]

The reaction of manganese halides with polydentate Schiff bases obtained by the condensation of 3-ethoxysalicylaldehyde and different amino alcohols, resulting in a NO3 set of donors, yielded a series of manganese clusters with {MnIII6MnIINa2}, {MnIII3MnIINa}, and {MnIII3} metallic cores. The influence of the ligand substituents and the halide on the final nuclearity has been studied. Analysis of their static magnetic behaviour confirms the ground states of 19/2 for the {MnIII6MnIINa2} complexes, 7/2 for the {MnIII3MnIINa} clusters, and 12/2 for the triangular {MnIII3} systems, and a weak field induced a slow relaxation of the magnetization for the trinuclear complexes.

A solid solution of the mineral feiite (Fe3TiO5) was recently discovered in a shock-induced melt pocket of the Shergotty martian shergottite. It is particularly interesting for its potential as an indicator of pressure-temperature (P-T) and oxygen fugacity in martian crustal and mantle material. To date, complete crystallographic analysis of feiite has not been conducted, as the mineral was previously analyzed by electron backscatter diffraction on micrometer-size grains (Ma et al. 2021). Here we report a convergent crystal-structure model for feiite based on synchrotron single-crystal X-ray diffraction data collected on three grains of feiite synthesized at 12 GPa and 1200 °C. Feiite adopts the CaFe3O5 structure type (Cmcm, Z = 4), which is composed of two octahedral M1 and M2 sites and one trigonal prismatic M3 site (M = metal) in a ratio of 1:2:1. The three feiite grains with composition Ti0.46–0.60Fe3.54–3.40O5 were best modeled by substituting Ti4+ into only the octahedral M2 site, accounting for 30% of this site. Comparisons of the measured average bond lengths in the coordination polyhedra with the optimized Ti4+–O, Fe2+–O, and Fe3+–O bond lengths suggest that ferrous iron occupies the trigonal M3 site, while iron is mixed valence in the octahedral M1 and M2 sites. The Ti4+ and Fe3+ content constrained by our crystal-chemical analyses suggests that at least ~30% of the available iron must be ferric (i.e., Fe3+/Fetotal = 0.3) for the sample synthesized at 12 GPa and 1200 °C and higher P-T conditions may be needed to form the end-member feiite F e 3 2 + T i O 5 [ABSTRACT FROM AUTHOR]

Intelligent materials occupy a special place among the huge number of known materials and those, which are being created all the time. Despite the impressive number of publications, no attempt has yet been made to classify compounds with a valence-unstable rare-earth element (R.E.) as smart materials. In this review paper, we show that the valence of the R.E. in some compounds can be changed by external and internal factors, such as temperature, pressure, changes in the occupation of d- and f-levels, and changes in the coordination polyhedra of atoms. Changing the valence of the R.E. may significantly alter the electrical and magnetic properties of compounds. [ABSTRACT FROM AUTHOR]

We investigated the magnetocaloric and electrical transport properties of the Eu8CuNi2.5Si42.5 clathrate compound, synthesized by an arc melting and annealing method. X-ray photoemission spectroscopy revealed a mixed valence state of Eu2+ and Eu3+. The low-field and low-temperature magnetic measurements indicated a multiple magnetic transition, from ferromagnetic near 35 K to antiferromagnetic at 25 K. Increasing the magnetic field led to the broadening of antiferromagnetic peaks and a final ferromagnetic state under high magnetic fields, indicative of spin reorientation. The transition from a ferromagnetic to an antiferromagnetic state was further corroborated by specific heat measurements. We noted spontaneous magnetization at low temperatures via magnetic hysteresis and Arrott plot analysis. The coexistence of an antiferromagnetic ground state (attributed to the Eu2+ ions) and ferromagnetic clusters (associated with the Ni2+ ions) was supported by spontaneous magnetization at low temperatures in the antiferromagnetic state. The magnetocaloric analyses revealed a high spin entropy change over a broad temperature range for Eu8CuNi2.5Si42.5, which implies its potential as a robust low-temperature magnetocaloric material, distinguished by its high refrigerant capacity.

A series of trimetallic cyanidometal‐bridged compounds [MenCp(dppe)FeII‐(μ‐NC)‐RuII(MeOpy)4‐(μ‐CN)‐FeII(dppe)CpMen] ‐ [PF6]2 (N[PF6]2, n=0, N =1; n=1, N=2; n=3, N=3; Cp=cyclopentadiene, dppe=1,2‐bis(diphenylphosphino)ethane, MeOpy=4‐methoxypyridine) and their one‐ and two‐electron oxidized compounds N3+ and N4+ were synthesized and characterized. Meanwhile, a series of corresponding linear cyanido‐bridged pentanuclear compounds [MenCp(dppe)FeIII‐(μ‐NC)‐RuII(MeOpy)4‐(μ‐NC)‐AgI‐(μ‐CN)‐RuII(MeOpy)4‐(μ‐CN)‐FeIII(dppe)CpMen][BF4]5 (M[BF4]5, n=0, M=4; n=1, M=5; n=3, M=6) were also obtained and well characterized. The investigations suggest that in the trinuclear system there exists remote interaction between the two Fe centers, but no significant interactions exist across the central silver unit between the metals on the two sides of the silver center in the pentanuclear system. In both the trinuclear N4+ and the pentanuclear M5+ complexes, there exists the neighboring RuII→FeIII MM′CT transitions, and the MM'CT energy in the corresponding trinuclear system is higher than those in the pentanuclear system in which no remote metal‐metal interaction occurs. Meanwhile, as the substituted methyl groups on the cyclopentadiene increases, the redox potential of the ruthenium in the trinuclear N4+ series increases, but that in the pentanuclear M5+ complexes decreases. [ABSTRACT FROM AUTHOR]

Polyoxovanadates (POV) are a subgroup of polyoxometalates (POM), which are nanosized clusters with reported biological activities. This manuscript describes the first toxicity evaluation of a mixed-valence polyoxovanadate, pentadecavanadate, (Me4N)6[V15O36Cl], abbreviated as V15. Cytotoxicity experiments using peripheral blood mononuclear cells (PBMC), larvae of Artemia salina Leach, and in vivo oral acute and repeated 28-day doses in mice was carried out. The LC50 values in PBMC cells and A. salina were 17.5 ± 5.8 μmol L−1, and 17.9 µg L−1, respectively, which indicates high cytotoxic activity. The toxicity in mice was not observed upon acute exposure in a single dose, however, the V15 repeated 28-day oral administration demonstrated high toxicity using 25 mg/kg, 50 mg/kg and, 300 mg/kg doses. The biochemical and hematological analyses during the 28-day administration of V15 showed significant alteration of the metabolic parameters related to the kidney and liver, suggesting moderate toxicity. The V15 toxicity was attributed to the oxidative stress and lipid peroxidation, once thiobarbituric acid (TBAR) levels significantly increased in both males and females treated with high doses of the POV and also in males treated with a lower dose of the POV. This is the first study reporting a treatment-related mortality in animals acutely administrated with a mixed-valence POV, contrasting with the well-known, less toxic decavanadate. These results document the toxicity of this mixed-valence POV, which may not be suitable for biomedical applications. [ABSTRACT FROM AUTHOR]

Antimony oxides are important materials for catalysis and flame-retardant applications. The two most common phases, α -Sb2O3 (senarmontite) and β -Sb2O3 (valentinite), have been studied extensively. Specific focus has been placed recently on their lattice dynamics properties and how they relate to the α - β phase transformation and their potential anharmonicity. However, there has not been any direct investigation of anharmonicity in these systems, and a surprising lack of low-temperature structural information has prevented further study. Here, we report the powder neutron diffraction data of both phases of Sb2O3, as well as structural information. α -Sb2O3 behaved as expected, but β -Sb2O3 revealed a small region of zero thermal expansion along the c axis. Additionally, while the β phase matched well with reported atomic displacement parameters, the α phase displayed a marked deviation. This data will enable further investigations into these systems. [ABSTRACT FROM AUTHOR]

The syntheses and magnetic properties of organometallic heterometallic compounds [K(THF)6]{CoI[(μ3‐HAN)RE2Cp*4]2} (1‐RE) and [K(Crypt)]2{CoI[(μ3‐HAN)RE2Cp*4]2} (2‐RE) containing hexaazatrinaphthylene radicals (HAN⋅3−) and four rare earth (RE) ions are reported. 1‐RE shows isolable species with ligand‐based mixed valency as revealed by cyclic voltammetry (CV) thus leading to the isolation of 2‐RE via one‐electron chemical reduction. Strong electronic communication in mixed‐valency supports stronger overall ferromagnetic behaviors in 2‐RE than 1‐RE containing Gd and Dy ions. Ac magnetic susceptibility data reveal 1‐Dy and 2‐Dy both exhibit slow magnetic relaxation. Importantly, larger coercive field was observed in the hysteresis of 2‐Dy at 2.0 K, indicating the enhanced SMM behavior compared with 1‐Dy. Ligand‐based mixed‐valency strategy has been used for the first time to improve the magnetic coupling in lanthanide (Ln) SMMs, thus opening up new ways to construct strongly coupled Ln‐SMMs. [ABSTRACT FROM AUTHOR]

Flocculation is widely applied for dye wastewater treatment, due to its low cost, high efficiency and convenient operation. However, finding novel flocculant with high performance and low cost is still a challenge. Therefore, a fully characterized bivanadyl capped, highly reduced Keggin polyoxometalate (Et 3 NH) 5 [PMoV 6 MoVI 6 O 40 (VIVO) 2 ] (PMoV2) was explored as flocculant for the treatment of simulated cationic dye wastewater. The effect of initial pH, PMoV2 dosage, and concentrations of dyes and inorganic salts on the flocculation rate of methylene blue (MB)/ crystal violet (CV)/rhodamine B (RhB) was investigated. Under the optimum conditions, the flocculation rates of MB, CV and RhB were 99.7 %, 99.8 % and 99.7 % in 5 min, respectively. In addition, PMoV2 and dyes could be easily recovered from flocs. PMoV2 exhibited high selectivity for CV in the binary systems of CV-MB and CV-MO. Even after five recycling tests, PMoV2 still kept high flocculation rate of MB/CV/RhB. The possible flocculation mechanisms for MB/CV/RhB single system, and MB-CV and MO-CV binary systems were charge neutralization, charge neutralization and π-π interaction, and charge neutralization and electrostatic interaction, respectively. PMoV2 was better than the reported flocculants in the respect of easy availability and operation conditions, reusability and high flocculation rate. The cost effectiveness, eco-friendly nature and excellent flocculation performance in individual and binary dye systems made PMoV2 competitive in the field of water environment remediation and material development. This is the first report about the flocculation activities of bivanadyl capped, highly reduced Keggin polyoxometalate. [Display omitted] • A bi-capped and reduced Keggin polyoxometalate (PMoV2) was firstly explored as flocculant. • Almost all CV/MB/RhB in the solution could be flocculated by PMoV2. • PMoV2 has great practical application to flocculate dye. • Charge neutralization effect was the driving force behind flocculation. • PMoV2 showed good stability and reusability. [ABSTRACT FROM AUTHOR]

Synthesis and characterization of two centrosymmetric cobalt(III/II/III) compounds, [CoII{(μ-L1)(μ-OOCCH2CH2COOH)CoIII(DMF)}2](ClO4)2 (1) and [CoII{(μ-L2)(μ-OOCCH2CH2COOH)CoIII(DMF)}2](ClO4)2·2CH3CHO (2) with two tetradentate ligands, H2L1 (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(phenol) and H2L2 (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(4-chlorophenol), and succinate as anionic co-ligands have been reported. Single crystal X-ray diffraction studies have confirmed the structures of the compounds.

The excited‐state version of the Creutz–Taube ion was prepared via visible light excitation of [(NH3)5RuII(μ‐pz)RuII(NH3)5]4+. The resulting excited state is a mixed valence {RuIII–δ(μ‐pz⋅−)RuII+δ} transient species, which was characterized using femtosecond transient absorption spectroscopy with vis‐NIR detection. Very intense photoinduced intervalence charge transfers were observed at 7500 cm−1, revealing an excited‐state electronic coupling element HDA=3750 cm−1. DFT calculations confirm a strongly delocalized excited state. A notable consequence of strong electron delocalization is the nanosecond excited state lifetime, which was exploited in a proof‐of‐concept intermolecular electron transfer. The excited‐state Creutz–Taube ion is established as a reference, and demonstrates that electron delocalization in the excited state can be leveraged for artificial photosynthesis or other photocatalytic schemes based on electron transfer chemistry. [ABSTRACT FROM AUTHOR]

Iron phosphate materials have attracted a lot of attention due to their potential as cathode materials for lithium-ion rechargeable batteries. It has been shown that lithium insertion or extraction depends on the Fe mixed valence and reduction or oxidation of the Fe ions' valences. In this paper, we report a new synthesis method for the Fe3(PO3OH)4(H2O)4 mixed valence iron phosphate. In addition, we perform temperature-dependent measurements of structural and physical properties in order to obtain an understanding of electronic–structural interplay in this compound. Scanning electron microscope images show needle-like single crystals of 50 μm to 200 μm length which are stable up to approximately 200 °C, as revealed by thermogravimetric analysis. The crystal structure of Fe3(PO3OH)4(H2O)4 single crystals has been determined in the temperature range of 90 K to 470 K. A monoclinic isostructural phase transition was found at ~213 K, with unit cell volume doubling in the low temperature phase. While the local environment of the Fe2+ ions does not change significantly across the structural phase transition, small antiphase rotations occur for the Fe3+ octahedra, implying some kind of electronic order. These results are corroborated by first principle calculations within density functional theory, which also point to ordering of the electronic degrees of freedom across the transition. The structural phase transition is confirmed by specific heat measurements. Moreover, hints of 3D antiferromagnetic ordering appear below ~11 K in the magnetic susceptibility measurements. Room temperature visible light absorption is consistent with the Fe2+/Fe3+ mixed valence. [ABSTRACT FROM AUTHOR]

Whilst 2‐ or 5‐OMe groups on the bridging phenylene ring in [{Cp*(dppe)RuC≡C}2(μ‐1,3‐C6H4)]+ have little influence on the electronic structure of this weakly coupled mixed‐valence complex, a 4‐OMe substituent enhances ground state electron delocalization, and increases the intensity of the IVCT transition. Vibrational frequency and TDDFT calculations (LH20t‐D3(BJ), def2‐SVP, COSMO (CH2Cl2)) on ([{Cp*(dppe)RuC≡C}2(μ‐1,3‐C6H3‐n‐OMe)]+ (n=2, 4, 5) models are in excellent agreement with the experimental results. The stronger ground state coupling is attributed to the change in composition of the β‐HOSO brought about by the 4‐OMe group, which is ortho or para to each of the metal fragments. The intensity of the IVCT transition increases with the greater overlap of the β‐HOSO and β‐LUSO, whilst the relative phases of the β‐HOSO and β‐LUSO in the 4‐OMe substituted complex are consistent with predictions of constructive quantum interference from molecular circuit rules. [ABSTRACT FROM AUTHOR]

Temperature dependent magnetic, electrical transport and thermal properties of polycrystalline orthorhombic CeFe 2 Al 8 intermetallic compound have been studied along with its isostructural La counterpart, LaFe 2 Al 8 . For the cerium compound, low field dc magnetization exhibits an antiferromagnetic like ordering ( T ) ∼ 4 K. The main feature of the magnetic susceptibility plot is a broad hump spanning a large temperature range, indicating mixed valence of Ce in the compound, in good agreement with reported literature. However, contrary to the reported observations we find that the mixed valence state is very robust and was evident even up to very high magnetic fields (> 2 T). Further, in this work we report 3d core level photoemission spectra of cerium in CeFe N ) ∼ 4 K. The main feature of the magnetic susceptibility plot is a broad hump spanning a large temperature range, indicating mixed valence of Ce in the compound, in good agreement with reported literature. However, contrary to the reported observations we find that the mixed valence state is very robust and was evident even up to very high magnetic fields (> 2 T). Further, in this work we report 3d core level photoemission spectra of cerium in CeFe 2 Al 8 , to understand the valence state of cerium ions in this system. Additionally, from resistivity measurements it is found that, CeFe 2 Al 8 is metallic with no indication of any anomaly, till the lowest temperature of measurement. Specific heat measurements show very low value of heat capacity and electronic contribution. The isostructural La analogue, LaFe 2 Al 8 compound shows broadness in susceptibility with maxima around 44 K which may be attributed to ordering of Fe moments. The comparison of Ce and La compounds brings out the role of Fe magnetic moments which may be responsible for competing with cerium moments and resulting in the dilution of long-range magnetic order, also contributing to magnetic frustration in CeFe 2 Al 8 ., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Polyoxovanadates (POV) are a subgroup of polyoxometalates (POM), which are nanosized clusters with reported biological activities. This manuscript describes the first toxicity evaluation of a mixed-valence polyoxovanadate, pentadecavanadate, (Me4N)6[V15O36Cl], abbreviated as V15. Cytotoxicity experiments using peripheral blood mononuclear cells (PBMC), larvae of Artemia salina Leach, and in vivo oral acute and repeated 28-day doses in mice was carried out. The LC50 values in PBMC cells and A. salina were 17.5 ± 5.8 μmol L−1, and 17.9 µg L−1, respectively, which indicates high cytotoxic activity. The toxicity in mice was not observed upon acute exposure in a single dose, however, the V15 repeated 28-day oral administration demonstrated high toxicity using 25 mg/kg, 50 mg/kg and, 300 mg/kg doses. The biochemical and hematological analyses during the 28-day administration of V15 showed significant alteration of the metabolic parameters related to the kidney and liver, suggesting moderate toxicity. The V15 toxicity was attributed to the oxidative stress and lipid peroxidation, once thiobarbituric acid (TBAR) levels significantly increased in both males and females treated with high doses of the POV and also in males treated with a lower dose of the POV. This is the first study reporting a treatment-related mortality in animals acutely administrated with a mixed-valence POV, contrasting with the well-known, less toxic decavanadate. These results document the toxicity of this mixed-valence POV, which may not be suitable for biomedical applications.

The asymmetrical dinuclear [{(trpy*)Ru}2(μ‐adc‐Salph)Cl](PF6) 1(PF6), trpy*=4,4',4"‐tri‐tert‐butyl‐2,6,2',6"‐terpyridine, adc‐Salph=1‐benzoyl‐2‐salicyloylhydrazido(3‐), and the related symmetrical dinuclear [{Cl(trpy*)Ru}2(μ,η2 : η2‐adc‐Ph)](PF6) 2(PF6), adc‐Ph=1,2‐bis(benzoyl)hydrazido(2‐), were synthesized and structurally characterized. Both paramagnetic compounds were compared with the previously reported symmetrical [{(trpy*)Ru}2(μ,η3 : η3‐adc‐Sal)](PF6) 3(PF6) containing the bis‐tridentate bridge 1,2‐bis(salicyloyl)hydrazido(4‐). Molecular structures and magnetic resonance features (1H NMR, EPR) indicate spin density distribution over the metal(s) and the bridging ligand. Reversible one‐electron reduction and oxidation were possible in all instances yielding comproportionation constants Kc of about 109 for the paramagnetic intermediates 1+–3+. Structural results, spin density distribution and UV‐Vis‐NIR spectroelectrochemistry were analyzed for 1+ with the help of TD‐DFT calculations for a model compound (tert‐Bu→Me). Intense absorptions around λmax=1450–1650 nm for the cations were assigned to mixed metal/ligand transitions with significant inter‐valence charge transfer (IVCT) character. For both the symmetrical and asymmetrical arrangements the cationic intermediates can be described as considerably mixed metal/ligand systems. [ABSTRACT FROM AUTHOR]

CeO 2 /ZnO heterostructure with optimized composition has improved structural and electronic properties for photocatalytic degradation of azo dyes. [Display omitted] • Various compositions of CeO 2 /ZnO heterostructure were prepared. • The morphological, chemical and electronic properties of these heterostructures were determined. • Photocatalytic degradation of methylene blue dye was carried out up to 99.28% with CeO 2 /ZnO heterostructure. • The mechanism of photocatalytic degradation was thoroughly discussed. Organic pollutants pose a significant challenge due to their toxicity and potential carcinogenicity, thereby posing a severe threat to the environment and human health. Heterogeneous photocatalysts offer promising advantages over traditional water purification methods due to their tunable electronic properties such as bandgap, easy separation from the reaction solution and formidable nanostructures. Herein, we prepare a CeO 2 /ZnO heterostructure via simple hydrothermal synthesis. The electronic structure of this nanocomposite was tuned to achieve a band gap of ∼2.94 eV, which was between the individual bandgaps of CeO 2 and ZnO nanoparticles. In addition, the mixed valence character of Ce further enhanced the electronic properties of the CeO 2 /ZnO heterostructure. The photocatalytic performance of CeO 2 , ZnO and CeO 2 /ZnO heterostructure was evaluated and it was found that CeO 2 /ZnO heterostructure with a Zn/Ce ratio of 0.2 exhibited the highest photocatalytic activity, where the degradation efficiency was 99.28 % after irradiation for 60 min. It was mainly ascribed to the heterojunction structure of the CeO 2 /ZnO nanocomposite, leading to a higher separation efficiency of electron-hole pairs and generating more superoxide radicals, which in turn improved the photocatalytic activity effectively. [ABSTRACT FROM AUTHOR]

• A new mixed valent cobalt complex [L 3 CoIICoIII 2 (CH 3 COO)(OCH 3)] (2) has been synthesized and characterized. • 2 is an efficient bio-functional model of catechol oxidase. • 2 takes 10 min for complete conversion of 3,5-DTBC to 3,5-DTBQ. • In solution, 2 may dissociate into a mononuclear moietiy which act as the catalytically active species. • A metal centric SET mechanism has been proposed for catecholic oxidation by 2. A trinuclear mixed valence cobalt complex, [L 3 CoIICoIII 2 (CH 3 COO)(OCH 3)] (2), has been synthesized using a Schiff base ligand (H 2 L, 1). The ligand was prepared via 1:1 condensation of 3-Chloro salicylaldehyde and 3-Amino-1-propanol in methanol. The structure of 2 has been elucidated by single crystal X-ray crystallography. Comparing each set of the corresponding data of bond lengths and bond angles, presence of two different oxidation states (+2 and +3) of the cobalt metal ions was understood. Again the occurrence of mixed valence has been confirmed by X-ray photoelectron spectroscopy (XPS) study of 2. Interestingly, 2 acted as an efficient bio-mimic of catechol oxidase toward oxidation of 3,5-di‑ tert- butyl catechol (3,5-DTBC) to 3,5-di‑ tert- butyl quinone (3,5-DTBQ). Two different solvents, methanol (CH 3 OH) and acetonitrile (CH 3 CN), have been utilized as media for exploring catecholase activity of 2 and acetonitrile was observed to be a better medium since furnished greater turn-over number. 1HNMR spectroscopy suggests completion of the oxidation process within just ten minutes in acetonitrile. The ESI-MS spectrum of the substrate-catalyst mixtures in acetonitrile confirmed formation of Co(III)-3,5-DTSQ (3,5-DTSQ = 3,5-di‑ tert butyl semiquinone) intermediates in the time scale of mass spectrum which could stand as a supporting evidence for the catalytic function of 2. However, all the substrate bound intermediates observed are mononuclear which indicates that the complex probably undergoes a dissociation in acetonitrile to generate mononuclear fragments for binding the substrate. Thus, on the basis of ESI-MS, 2 may be suggested as a pre-catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

The compound Ca 2 MnTiO 6 , synthesized using a two-step solid-state reaction method, has been studied for its structural, spectroscopic (XPS) and magnetic properties, as part of our efforts to understand the correlation between mixed metal oxide bonds and magnetism in double perovskite oxides. Room temperature diffraction studies shows that the compound is in orthorhombic structure at room temperature and remains so till low temperatures, although the variation in global instability index (GII) indicated little instability of the structure as the temperature is lowered from room temperature (∼300 K) to 3 K. The compound exhibits interesting behavior in magnetic susceptibility, as it exhibits magnetization reversal or negative magnetic susceptibility at low applied fields which turns positive for higher fields. Magnetic susceptibility also exhibits two anomalies at T N1 ∼ 8.2 K and another one around, T N2 , between 121 – 124 K. Magnetization as a function of field reveals weak antiferromagnetism in the system, as M varies non-linearly, but sluggishly below T <150 K, with no signature of saturation with respect to H. Overall, magnetization studies show that there is inherent magnetic frustration in the system and lack of long-range magnetic order, which is supported by low temperature neutron diffraction studies too. The XPS studies quantify the oxidation states of mixed valent Mn and Ti. A comparison of the structural and physical properties of double perovskite compound is presented here to understand the strong correlation between structural, spectroscopic and magnetic properties. [ABSTRACT FROM AUTHOR]

Antimony oxides are important materials for catalysis and flame-retardant applications. The two most common phases, α-Sb2O3 (senarmontite) and β-Sb2O3 (valentinite), have been studied extensively. Specific focus has been placed recently on their lattice dynamics properties and how they relate to the α-β phase transformation and their potential anharmonicity. However, there has not been any direct investigation of anharmonicity in these systems, and a surprising lack of low-temperature structural information has prevented further study. Here, we report the powder neutron diffraction data of both phases of Sb2O3, as well as structural information. α-Sb2O3 behaved as expected, but β-Sb2O3 revealed a small region of zero thermal expansion along the c axis. Additionally, while the β phase matched well with reported atomic displacement parameters, the α phase displayed a marked deviation. This data will enable further investigations into these systems.

Syntheses, structures and properties of different trinuclear mixed valence manganese(II/III) complexes with different Schiff bases were reported in literature. This review focuses light on relative merits and demerits of different synthetic procedures. At the same time, the structures and properties of these complexes were also compared. The review also identifies the less explored areas of applications of these mixed valence complexes. [Display omitted] • Rationalization of synthetic strategies of some trinuclear mixed valence manganese(II/III) Schiff base complexes. • Analysis of the structures of the complexes. • Discussion of few biological activities of the complexes. • Identification of the spaces where more work could be done. This review is focused on the synthetic strategies, structures and properties of few mixed valence trinuclear manganese(II/III) complexes with some Schiff base ligands. Few methods were applied by the researchers for the preparation of these mixed valence complexes. Aerial oxidation of manganese(II) to manganese(III) was identified as one of the important tools for such syntheses as manganese(II) Schiff bases complexes are air sensitive and easily oxidized to manganese(III) complexes. However, fragmentation of the mixed valence manganese(II/III) precursor followed by structural rearrangement was also identified as another synthetic route. Several properties like magnetic, DNA-binding, anti-proliferative, anti-microbial and catecholase-like activities, investigated by different groups are also highlighted in this review. The less explored areas of potential applications of these mixed valence complexes are also discussed. [ABSTRACT FROM AUTHOR]

Kinetics and mechanism of the oxygen reduction reaction (ORR) in an alkaline medium have been studied on La2BO4±δ (B: Ni, Co or Mn) various mixed conducting oxides (MIEC: mixed electronic and ionic conductor). The preparation of these materials was carried out using the citrate method. The purity, the surface chemical state and the morphology were investigated by X-ray diffraction, X-ray photon-electron spectrometry (XPS) and scanning electron microscopy, respectively. An iodometric titration was also performed to evaluate the oxygen (over)-stoichiometry. The catalytic activity of the La2NiO4±δ (L2NO), La2CoO4±δ (L2CO) and La2MnO4±δ (L2MO) oxides towards ORR in alkaline medium was evaluated using the rotating disc electrode in 0.5 M NaOH solution completed by various electrochemical techniques such as cyclic voltammetry, linear voltammetry, the Koutecky–Levich diffusion model and impedance spectroscopy. The La2NiO4±δ sample is pure and more porous, but the La2CoO4±δ and La2MnO4±δ samples show secondary phases and are less porous. The XPS analysis shows that the surface of the La2NiO4±δ material is rich in hydroxide ions (OH−) and the Ni3+/Ni2+ ratio is very low unlike La2CoO4±δ and La2MnO4±δ materials in which OH¯ are low. Porosity and percentages of OH¯ and B3+/B2+ ratio are parameters influencing the ORR mechanism and therefore favouring, for this purpose, a one-step mechanism on La2NiO4+δ and a two-step mechanism on La2CoO4±δ and La2MnO4±δ electrocatalysts. [ABSTRACT FROM AUTHOR]

A novel G-La 2 Si 2 O 7 : Eu phosphor has been synthesized through SiC-reduction assisted with sol-gel method. Divalent Eu2+ and trivalent Eu3+ luminescent centers coexist in G-La 2 Si 2 O 7 : Eu lattice. Furthermore, two types of Eu2+ luminescent centers exist in G-La 2 Si 2 O 7 : Eu lattice, labeled as Eu 1 and Eu 2 , arising from two La3+ crystallographic sites in G-La 2 Si 2 O 7 host. Eu 1 represents blue band emission while Eu 2 shows green-yellow emission. Eu2+ selective occupation introduces Eu2+ large-scale blue-yellow regulation. Eu3+ shows typical red sharp line emission mainly located at 593 nm and 611 nm assigned to 5D 0 →7F J (J = 1, 2) transitions. The luminescence process in G-La 2 Si 2 O 7 : Eu is discussed in details. Energy transfer processes from Eu3+ to Eu 1 and Eu 2 , Eu 1 to Eu 2 occurs in G-La 2 Si 2 O 7 : Eu lattice. The influence of Eu dopant concentration is explored. As Eu increases, the dominant emission changes from Eu2+ to Eu3+. The coexistence of Eu 1 , Eu 2 and Eu3+ brings G-La 2 Si 2 O 7 : Eu blue to red regulation. Fixing Eu doping at 0.5%, G-La 1.99 Si 2 O 7 : 0.01Eu sample shows a single-phased white light-emitting phosphor. At ultraviolet light 254 nm excitation, the emission spectrum approximate to full spectrum with a high rendering index of Ra = 91 is obtained using La 1.99 Si 2 O 7 : 0.01Eu sample at 254 nm excitation. Besides, G-La 2 Si 2 O 7 : Eu represents a good fluorescent thermal stability with luminous intensity keeping 80% (160 °C) of that at room temperature (30 °C), indicating G-La 2 Si 2 O 7 : Eu is a great potential single-matrix candidate in nUV-chip WLEDs. [ABSTRACT FROM AUTHOR]

We report the effect of the sintering temperature on the structure and valence states of Ru–Mn in Li2Mn0.9Ru0.1O3. These effects are explored by synchrotron X-ray diffraction patterns, Raman and X-ray absorption spectroscopy spectra (analysis of the Ru–M4, Mn–L2,3, and O–K edges). Ru doping at the Mn site in Li2MnO3 changes the lattice parameters of the parent Li2MnO3. Li2Mn0.9Ru0.1O3 sintered at 950oC shows two peaks of the Ru–M4 absorption edge. These peaks confirm the presence of mixed valence states Ru+4 and Ru+5. The compound Li2Mn0.9Ru0.1O3 sintered at 1050oC shows only one peak of the Ru–M4 absorption edge, which reveals the presence of the Ru+4 valence state. The Mn–L3 absorption edge of Li2Mn0.9Ru0.1O3 shifts towards lower energy in comparison to the absorption edge of Li2MnO3. The O–K absorption edge of Li2Mn0.9Ru0.1O3 shows the origin of a new peak in comparison to the absorption edge of Li2MnO3 due to the presence of Mn+3–O hybridization in Li2Mn0.9Ru0.1O3 sintered at 950oC. The Raman spectrum of Li2Mn0.9Ru0.1O3 shows splitting and peak shifting with the change in the sintering conditions. The presence of mixed valences Mn+3, Mn+4, Ru+4, and Ru+5 in the lattice of Li2Mn0.9Ru0.1O3 sintered at 950oC may affect the charge–discharge properties of the Li2Mn0.9Ru0.1O3 cathode. [ABSTRACT FROM AUTHOR]

We report the effect of the sintering temperature on the structure and valence states of Ru–Mn in Li2Mn0.9Ru0.1O3. These effects are explored by synchrotron X-ray diffraction patterns, Raman and X-ray absorption spectroscopy spectra (analysis of the Ru–M4, Mn–L2,3, and O–K edges). Ru doping at the Mn site in Li2MnO3 changes the lattice parameters of the parent Li2MnO3. Li2Mn0.9Ru0.1O3 sintered at 950oC shows two peaks of the Ru–M4 absorption edge. These peaks confirm the presence of mixed valence states Ru+4 and Ru+5. The compound Li2Mn0.9Ru0.1O3 sintered at 1050oC shows only one peak of the Ru–M4 absorption edge, which reveals the presence of the Ru+4 valence state. The Mn–L3 absorption edge of Li2Mn0.9Ru0.1O3 shifts towards lower energy in comparison to the absorption edge of Li2MnO3. The O–K absorption edge of Li2Mn0.9Ru0.1O3 shows the origin of a new peak in comparison to the absorption edge of Li2MnO3 due to the presence of Mn+3–O hybridization in Li2Mn0.9Ru0.1O3 sintered at 950oC. The Raman spectrum of Li2Mn0.9Ru0.1O3 shows splitting and peak shifting with the change in the sintering conditions. The presence of mixed valences Mn+3, Mn+4, Ru+4, and Ru+5 in the lattice of Li2Mn0.9Ru0.1O3 sintered at 950oC may affect the charge–discharge properties of the Li2Mn0.9Ru0.1O3 cathode. [ABSTRACT FROM AUTHOR]

Two trinuclear cobalt(III)-cobalt(II)-cobalt(III) complex has been synthesized and characterized. DFT calculations have been used to analysed the Cl···Cl interactions that result in the creation of a stable 2D supramolecular assembly in the solid state. [Display omitted] Two mixed-valence trinuclear cobalt(III)-cobalt(II)-cobalt(III) complexes, [CoII{(μ-L1)(μ-OOCC 6 H 5 NO 2)CoIII(N 3)} 2 ] (1) and [CoII{(μ-L2)(μ-OOCC 6 H 4 NO 2 CH 3)CoIII(N 3 } 2 ] (2) have been synthesized using two tetradentate N 2 O 2 donor 'reduced Schiff base' ligands, H 2 L1 {2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(4-chlorophenol}, and H 2 L2 {2-hydroxy-1,3-propanediyl)bis(iminomethylene)bis(4-chlorophenol}, and 3-nitrobenzoic benzoic acid or 4-methyl 3-nitrobenzoic benzoic acid as anionic co-ligands. The complexes have been characterized by spectroscopic measurements and their solid state structures have been determined by single crystal X-ray diffraction analysis. The trinuclear cobalt(III)-cobalt(II)-cobalt(III) skeleton of both the complexes are linear and centrosymmetric. Both the central cobalt(II) and terminal cobalt(III) of both the complexes are hexa -coordinated. DFT calculations have been used to analysed some supramolecular assemblies of the complex that have been observed in the solid state, specifically the Cl···Cl interactions that result in the creation of a stable 2D supramolecular assembly in the solid state. QTAIM and NCI Plot computational tools have been used to characterize the interactions. Thermo-gravimetric (TG) analysis was used to examine the thermal behaviour of both complexes. The redox behaviors of both the complexes were studied by using Cyclic Voltammetry (CV). [ABSTRACT FROM AUTHOR]

Reaction of 2-(anthracen-9-yl)phenol (HOPhAn, 1) with divalent Yb[N(SiMe3)2]2·2THF in THF–toluene mixtures affords the mixed-valence YbII–YbIII dimer {[2-(anthracen-9-yl)phenolato-κO]bis(tetrahydrofuran)ytterbium(III)}-tris[μ-2-(anthracen-9-yl)phenolato]-κ4O:O;κO:1,2-η,κO-{[2-(anthracen-9-yl)phenolato-κO]ytterbium(II)} toluene trisolvate, [Yb2(C20H13O)5(C4H8O)2]·3C7H7 or [YbIII(THF)2(OPhAn)](μ-OPhAn)3[YbII(OPhAn)]·3C7H7 (2), as the major product. It crystallized as a toluene trisolvate. The Yb—O bond lengths in the crystal structure of this dimer clearly identify the YbII and YbIII centres. Interestingly, the formally four-coordinate YbII centre shows a close contact with one anthracene C—C bond of a bridging OPhAn ligand, bringing the formal coordination number to five.

We investigated the magnetocaloric and electrical transport properties of the Eu 8 CuNi 2.5 Si 42.5 clathrate compound, synthesized by an arc melting and annealing method. X-ray photoemission spectroscopy revealed a mixed valence state of Eu 2+ and Eu 3+ . The low-field and low-temperature magnetic measurements indicated a multiple magnetic transition, from ferromagnetic near 35 K to antiferromagnetic at 25 K. Increasing the magnetic field led to the broadening of antiferromagnetic peaks and a final ferromagnetic state under high magnetic fields, indicative of spin reorientation. The transition from a ferromagnetic to an antiferromagnetic state was further corroborated by specific heat measurements. We noted spontaneous magnetization at low temperatures via magnetic hysteresis and Arrott plot analysis. The coexistence of an antiferromagnetic ground state (attributed to the Eu 2+ ions) and ferromagnetic clusters (associated with the Ni 2+ ions) was supported by spontaneous magnetization at low temperatures in the antiferromagnetic state. The magnetocaloric analyses revealed a high spin entropy change over a broad temperature range for Eu 8 CuNi 2.5 Si 42.5 , which implies its potential as a robust low-temperature magnetocaloric material, distinguished by its high refrigerant capacity., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

This paper reports on the synthesis of a new trinuclear homometalic mixed-valent iron carboxylate cluster with furan-2-carboxylic acid. The complex with the formula [Fe2IIIFeIIO(C4H3OCOO)6(H2O)3]∙0.5CH3CN•2.25H2O was characterized by X-ray analysis that revealed that the compound crystalizes in the triclinic centrosymmetric group P-1, with the following unit cell parameters: a = 10.2758(6)Å, b = 11.5991(9) Å, c = 19.7349(15) Å, α = 105.060(7)°, β = 94.216(6)°, γ = 101.662(6)°.

3D well‐crystallized metal–organic frameworks (MOFs), M‐THBQ (M=Fe, Co, Mn, THBQ=tetrahydroxybenzoquinone), are synthesized and characterized. Their structures are determined as cubic cell in the group of Pm3‾ from powder X‐ray diffraction data, and their properties of electronic, magnetic and spectroscopic are also investigated. They are all semiconductors, and Fe‐THBQ exhibits the air‐stable n‐type thermoelectric characteristic as its Seebeck coefficient reaches −130 μV K−1, and the electrical conductivity is 2.7×10−4 S cm−1 at 300 K. Additional, M‐THBQ are paramagnetic, and the value of Weiss constant of Fe‐THBQ is −219.37 K, indicating the existence of robust intramolecular antiferromagnetic exchanges. Meanwhile, they display strong absorption bands in the range of 220 to 1000 nm, suggest M‐THBQ could have the potential to become photoabsorbers, and Fe‐THBQ exhibits a narrow band gap of 0.63 eV according to the ultraviolet absorption edge spectrum. [ABSTRACT FROM AUTHOR]

The evolution of the electron delocalization in the ferrous subspectra in a sample of mixed valence ferrous‐ferric freudenbergite has been followed by Mössbauer spectroscopy from 6 K to 650 K. The spectral changes do not involve the ferric component, leading to the conclusion that it is due to a thermally driven delocalization of the sixth d‐electron on the ferrous ions. The phenomenon does not occur in samples of pure ferrous freudenbergite. [ABSTRACT FROM AUTHOR]

During the last three decades, experimental chemists have forged a plethora of bimetallic molecular wires in which two redox‐active metal termini are linked by a carbon‐rich bridge. Their extensive redox chemistry with multiple, stepwise, one‐electron oxidation processes provide them with some interesting electronic and/or magnetic properties for potential applications. The nature of both the metal end‐groups and the carbon bridge has a significant effect on the redox process, which is of paramount importance for the design of these systems. Indeed, examples of mono‐oxidized complexes range from weakly coupled mixed‐valence species through more strongly coupled systems in which the bridging ligand can be intimately involved in electron transfer processes. Similarly, di‐oxidized species can encompass difference in magnetic behavior depending upon not only the nature of the framework of the systems but also the torsion angle between the terminal spin carriers, which allows the inversion of the singlet vs. triplet ground states. Theoretical quantum chemical computations have greatly assisted the development of this field of research. This review illustrates how, in synergy with experiments, computational results can provide additional valuable information on the nature of the localized vs. delocalized electronic communication in the mono‐oxidized mixed‐valence species, or the magnetic coupling differences and characteristics of the di‐oxidized complexes. [ABSTRACT FROM AUTHOR]

Recent evolutions, essentially in the last 15 years, are reviewed in the field of molecular mixed‐valent compounds and their properties. The considered systems are of the type Mn–BL–Mn where Mn is either a monometallic terminal site (n = 1) or a polymetallic cluster (n = 2, 3), and BL is a bridging ligand. A large variety of bridging ligands is considered: non‐innocent, long conjugated, ambidentate, cross‐conjugated, H‐bonded, switching. The theoretical descriptions are briefly reviewed and sorted according to their degree of complexity/accuracy: simple orbital models, modified Marcus–Hush diagrams, 3D diagrams with two nuclear degrees of freedom, and finally quantitative models (mainly from DFT) with geometrical optimization. With improved DFT functionals, the prediction of the class II or III nature of a symmetrical complex can now be addressed. Finally, applications in NIR electrochromism and molecular electronics are briefly reviewed. [ABSTRACT FROM AUTHOR]

The effects of Sn4+ substitution at Cr3+ sites on the thermoelectric and electronic properties of p-type delafossite CuCrO2 have been studied. CuCr1−xSnxO2 (x = 0.01, 0.03) samples were prepared via conventional solid-state reaction. The Seebeck coefficient results confirmed that all the samples exhibited p-type conduction. X-ray photoelectron spectroscopy verified the presence of Sn4+ ions and the appearance of mixed-state Cr3+/Cr2+ ions. The experimental results revealed that addition of Sn impacted the electrical conductivity due to the mixed Cu1+/Cu2+ states while the Seebeck coefficient was affected by the mixed Cr3+/Sn4+ states. The electrical conductivity was governed by the polaron hopping mechanism, and the large Seebeck coefficient was controlled by the spin and orbital degeneracy of the mixed Cr3+/Sn4+ ions. The electrical conductivity activation energy values were 0.410 eV and 0.407 eV while the thermal activation energy values were 0.208 eV and 0.160 eV, for x = 0.01 and 0.03, respectively. The results confirm that Sn4+ substitution at Cr3+ sites impacted the Seebeck coefficient and electronic behavior of delafossite CuCrO2 oxide even for low dopant levels of x = 0.01 and 0.03, resulting in p-type conduction and optically conducting materials. [ABSTRACT FROM AUTHOR]

A decanuclear cerium-oxo cluster CeIII 4 CeIV 6 featuring mixed valence was prepared by only using the trivalent cerium salt. Single-crystal structure and the distribution of Ce ions in different valence states are determined. The oxidation process and influencing factors of CeIII to CeIV was revealed. Based on the unique structure with mixed valence, the CeIII 4 CeIV 6 cluster exhibits efficient photocurrent response with photocurrent density 0.98 μA cm−2 at 0.5 V. [Display omitted] • A mixed valence cerium-oxo cluster CeIII 4 CeIV 6 only using the trivalent cerium salt was prepared. • The oxidation process of CeIII to CeIV in the initial reaction was revealed. • The unique structure and composition lead to the effective photocurrent response. Cerium-oxo clusters with mixed valence exhibit distinctive redox properties due to cerium ions switch between +3/+4 valence states. However, the design and synthesis of these clusters present formidable challenges, resulting in limited availability of such species, often necessitating the use of both CeIII and CeIV reactants. Herein, we successfully obtained a mixed valence cerium-oxo cluster CeIII 4 CeIV 6 (µ 3 -O) 4 (µ 4 -O) 4 (acac) 14 (CH 3 O) 6 (CH 3 OH) 2 (CeIII 4 CeIV 6 , Hacac = acetylacetone) through low-temperature crystallization only using the trivalent cerium salt. The coexistence as well as the distribution of Ce ions in different valence states have been determined from a multifaceted analysis. In addition, the stability of the synthesized cluster was confirmed by the HRESI-MS study through redissolution of the single crystal sample in fresh methanol. Importantly, Importantly, this study reveals the mechanism for the generation of +4 valence state. Under alkaline conditions, the presence of trace oxygen and the involvement of acetylacetone ligand facilitated the partial oxidation of CeIII to CeIV. The cluster CeIII 4 CeIV 6 has strong ultraviolet absorption and long visible light absorption. As the electrode precursor, CeIII 4 CeIV 6 showed clear photocurrent response and high photocurrent intensity due to CeIII/CeIV redox reaction. [ABSTRACT FROM AUTHOR]

We report the infrared charge dynamics of YbIn1-xAgxCu4 in a series of x- and T-dependent reflectivity measurements. Within the low-temperature coherent phase, characteristics of a low energy (0.25 eV) excitation appear to be controlled by the same Kondo scale, TK, which is relevant to the magnetic response (Phys. Rev. B 56 (1997) 7993). We show that the observed TK dependence of the frequency and strength of this excitation is consistent with an interpretation in terms of a coherent-to-incoherent quasiparticle transition between the correlation-induced bands of the periodic Anderson model (Phys. Rev. Lett. 92 (2004) 186405). Additionally, we consider an interpretation of x-dependence in the higher frequency optical response in terms of a rigid band structure picture where the filling is depleted by Ag doping, augmented by a Kondo resonance which tracks the x-dependent Fermi level. In addition to the properties of the low-temperature phase, our results also encompass the anomalous temperature dependent behavior in the vicinity of the electronic phase transition at low doping (x