An unsuccessful synthesis attempt of ScFMoO4 utilizing CsBr as fluxing agent led to platelet shaped single crystals of the composition CsSc[MoO4]2, which crystallize in the trigonal space group P m1 (a = 581.05(4), c = 804.74(6) pm) with one formula unit per unit cell. A following synthesis attempt to obtain the respective indium compound CsIn[MoO4]2 did not yield the desired compound but to equally platelet shaped crystals with the composition Cs2InBr[MoO4], crystallizing in the trigonal space group R m (a = 585.49(3), c = 3228.2(3) pm) with three formula units per unit cell. There are similarities found in both structures, such as trigonal pyramidal [MoO4]2− anions, octahedrally coordinated Sc3+ or In3+ cations, respectively, and kagome nets built up by some of the oxide anions. Differences are found in the cesium-oxygen partial structure, namely pseudo-close-packed layers in the structure of CsSc[MoO4]2 and honeycomb layers for Cs2InBr[MoO4]2. Furthermore, due to the presence of the bromide anions, anti CdCl2-type layers, according to contribute to the structure of Cs2InBr[MoO4]2. Besides the crystal structure determination, single crystal Raman spectra of the title compound were recorded as well.
Although charge-transfer (CT) cocrystals based on 1,2,4,5-tetracyanobenzene (TCNB) and anthracene derivatives have been extensively explored, the development of new donor–acceptor systems with diverse supramolecular architectures and tunable optical properties remains highly desirable. Herein, a new anthracene-based benzhydrazide derivative, benzoic acid (2E)-2-(9-anthracenylmethylene)hydrazide (APHD), containing a hydrazone linkage connecting anthracene and benzohydrazide units, was synthesized as an electron donor (D). Through supramolecular self-assembly with TCNB as an electron acceptor (A), a CT cocrystal (APTC) was obtained. The phase behavior and formation feasibility of APTC were investigated by an experimentally determined ternary phase diagram, which revealed the stable region of the pure cocrystal phase. Single crystal X-ray diffraction (SC-XRD) analysis revealed an alternating donor-acceptor stacking arrangement in APTC, primarily stabilized by face-to-face π···π interactions along with additional weak intermolecular interactions. The formation of the pure cocrystal phase was further confirmed by powder X-ray diffraction (PXRD) and Fourier-transform infrared (FT-IR) spectra. Compared with pristine APHD, APTC exhibited broadened and red-shifted absorption bands, accompanied by an approximately 103 nm bathochromic emission shift, enhanced quantum efficiency, and prolonged lifetime. Density functional theory (DFT) calculations demonstrated that CT interactions induced electronic redistribution, reduced the bandgap, and modulated excited-state properties. This work elucidated the impact of CT cocrystal formation on the optical properties of anthracene-based hydrazone derivatives with extended π-conjugated systems, providing new insights into the rational design of anthracene-based fluorescent CT cocrystal materials.
The synthesis results, structural characteristics, and physical properties of a series of ruthenium gallides with the composition R2Ru3Ga4 (R = Sm, Gd, Tb, Dy) are presented. All compounds are isostructural and crystallize in the Np2Tc3Si4 (Pu2Tc3Si4) structure type. The crystal structure of Sm2Ru3Ga4 was determined from single-crystal X-ray diffraction data: monoclinic unit cell parameters a = 6.9504(5) Å, b = 8.2241(6) Å, c = 5.7444(4) Å, β = 103.701(2)°, V = 319.01(4) Å3, space group P21/c (No. 14). The structure features a three-dimensional framework [Ru3Ga4]∞, within which alternating layers of Ru1[Ga6] distorted octahedra and Ru2[Ga5] triangular bipyramids can be distinguished. The rare-earth atoms occupy voids in this framework and coordinate eight Ga and two Ru atoms, forming R[Ga8Ru2] polyhedra. The relatively short Ru–Ga distances (2.544–2.601 Å) and the unusually short Sm–Ru distance (2.889 Å) indicate a significant covalent contribution to the chemical bonding. Magnetic susceptibility measurements for Dy2Ru3Ga4 revealed a ferromagnetic ordering below T = 10 K.
A-RE-Tt-Q4 type 1:1:1:4 rare-earth-containing chalcogenides have attracted increasing attention owing to their well-defined compositions, tunable elemental constituents, and potential optical and magnetic responses. In this work, two layered heavy rare-earth thiogermanates, CsDyGeS4 and CsErGeS4, which have not yet been systematically investigated within the CsREGeS4 series, were successfully synthesized. Their crystal structures, phase compositions, optical properties, electronic structures, and magnetic behaviors were systematically studied. Single-crystal X-ray diffraction reveals that both compounds crystallize in the noncentrosymmetric orthorhombic space group P212121. Their structures are built from [GeS4] tetrahedra and [RES7] (RE = Dy or Er) mono-capped trigonal-prismatic polyhedra, which connect to form two-dimensional [REGeS4]- anionic layers, with Cs+ cations located between the layers for charge balance. Ultraviolet-visible (UV-Vis) spectroscopy diffuse reflectance spectra show that CsDyGeS4 and CsErGeS4 are wide-band-gap chalcogenide semiconductors with band gaps of 3.24 and 3.01 eV, respectively. First-principles calculations indicate that both compounds are indirect band-gap semiconductors. The valence band maximum is mainly contributed by S-3p orbitals, whereas the conduction band minimum is influenced by RE-4f, Ge-4p, and S-3p orbitals. Refractive-index dispersion calculations reveal obvious optical anisotropy. Magnetic measurements show typical rare-earth paramagnetic behavior from 2 to 300 K, mainly originating from localized 4f electron magnetic moments of Dy3+ and Er3+ ions.
As a vital basic amino acid in the human body, arginine plays an indispensable role in the generation and proliferation of immune cells including T lymphocytes, and its deficiency can result in impaired immune function and immunosuppression. Accordingly, the qualitative and quantitative detection of arginine is of great significance in biomedicine, food industry, environmental monitoring and other related fields. In this study, a novel ratiometric fluorescence probe (NU-1000@HOF@RhB) was rationally constructed by in-situ growth of a hydrogen-bonded organic framework (HOF) on a metal-organic framework (MOF) surface, followed by encapsulation of rhodamine B (RhB) within the composite matrix. The as-prepared probe presents distinct dual-emission characteristics upon excitation at 395 nm. Upon exposure to arginine (Arg), the fluorescence intensity at 470 nm is remarkably enhanced, while the emission signal at 590 nm is significantly quenched, accompanied by a distinguishable fluorescence color change from light pink to bright blue under 365 nm UV irradiation. Such a recognizable and intuitive response enables the specific and efficient identification of arginine, with favorable anti-interference capability and sensing performance. The limit of detection (LOD) for arginine is calculated to be 0.208 μM. Furthermore, a portable paper-based sensor is fabricated by immobilizing the composite probe, which displays obvious color changes corresponding to different arginine concentrations under UV light illumination.
The effect of isovalent V5+ substitution for Nb5+ on the crystal structure and oxide ion conductivity of Ba7Nb4-xVxMoO20 (x = 0.00, 0.05, 0.15) has been investigated. Despite no change in nominal oxide ion carrier concentration, a significantly reduced bulk oxide ion conductivity is observed below ∼ 400 °C upon increasing x, suggesting enhanced local oxide ion trapping. This may arise from the formation of defect associates between V5+ centres and interstitial oxide ions, creating energetically favourable trapping sites that reduce the population of mobile charge carriers available for long-range diffusion. This behaviour contrasts with that of Ba3Nb1-xVxMoO8.5, where moderate V5+ substitution significantly improves oxide ion transport. This suggests that oxide ion migration in Ba7Nb4MoO20 is more sensitive to local structural perturbations than the hexagonal perovskite derivative Ba3NbMoO8.5. At higher temperatures, thermal activation overcomes trapping effects, while lattice expansion and increased tetrahedral distortion promote oxide ion diffusion so that the conductivities of the substituted and unsubstituted compositions converge near 650 °C. These results highlight the importance of local structural chemistry in controlling oxide ion transport in hexagonal perovskite derivative oxide ion conductors.
Red phosphors hold great application prospects in the field of lighting. Nonetheless, their poor spectral matching with commercial blue chips, together with harsh synthesis conditions, severely restricts their practical application in LEDs. Therefore, the development of better-matched red phosphors and the exploration of mild synthesis strategies have become a key research focus. In this wok, high-purity CaS was synthesized from flue gas desulfurization gypsum and then used to prepare CaS:Eu2+-based red phosphors via a medium-temperature normal-pressure solid-state method. The phosphors exhibit the characteristic red emission of Eu2+ (peaking at 650 nm) under 475 nm blue light excitation. The introduction of Y3+ optimizes the local crystal field environment around Eu2+, effectively suppressing non-radiative transitions and thereby significantly enhancing the red emission intensity. In contrast, Nd3+ co-doping introduces trap levels, shortening the fluorescence lifetime to 0.33 μs and endowing the material with excellent long afterglow luminescence properties. Furthermore, after hydrophobic modification with octadecyltrichlorosilane, the contact angle of the phosphor increased to 113°, substantially improving its stability in humid environments. This study demonstrates that CaS:Eu2+, Nd3+/Y3+ phosphors, combining strong blue-light absorption, efficient red emission, and good environmental stability, hold great promise for applications in high color rendering index white LEDs and next-generation solid-state lighting.
As part of an ongoing investigation into group 2 germanium oxychalcogenides, a previously unreported compound, Sr3Ge3OS8, was identified. This compound crystallizes in the centrosymmetric Pnma space group. Sr3Ge3OS8 has lattice parameters a = 15.6628(6) Å, b = 13.9919(5) Å, c = 6.6687(3) Å, and Z = 4. Sr3Ge3OS8 does not adopt any known structure type, thus a new structure type has been discovered. DFT calculations predict that the material is a semiconductor with a band gap in the visible range, calculated at 2.55 eV.
A series of Sr-doped La0.8-xSrxCoO3 perovskite catalysts was fabricated via a citric acid sol-gel route for propane catalytic combustion under humid flue gas. The results show that an appropriate amount of Sr doping (x = 0.08) stabilizes the perovskite framework, suppresses grain agglomeration, and increases the specific surface area. Additionally, Sr2+ substitution triggers charge compensation, raising the surface Co2+/Co3+ ratio (0.26 → 0.36) and Oads/Olatt ratio (1.16 → 1.44), thereby generating abundant oxygen vacancies. The Raman red-shift and TPR β peak shift (356 °C → 340 °C) confirm weakened Co-O bond strength and enhanced lattice oxygen activity, while the upshifted γ peak (550 °C→ 579 °C) reflects that moderate Sr substitution reinforces bulk framework stability. Excessive Sr doping (x ≥ 0.16) leads to SrCO3 impurity formation, destabilizes the lattice, and significantly reduces both specific surface area and lattice oxygen activity. Compared with the undoped La0.8CoO3 catalyst, the optimally Sr-doped La0.72Sr0.08CoO3 catalyst exhibits significantly enhanced low-temperature activity and water resistance, outperforming most previously reported perovskite catalysts.
We report the modulation of phase structure and electronic transport properties of FeSe thin films through Se stoichiometry. The epitaxial FeSe thin films were grown on Al2O3(0001) substrates via molecular beam epitaxy, with systematic variation of the Se/Fe flux ratio from 1 to 10. A gradual phase evolution was observed, where tetragonal β–FeSe is stabilized for Se/Fe ≤ 3, while increasing Se content leads to the emergence and eventual dominance of hexagonal δ–FeSe. The β–FeSe films exhibit metallic-like conduction, whereas δ–FeSe-rich films display semiconducting-like behavior. Moreover, we reveal a shift from hole-dominated metallic transport in tetragonal films to electron-type conduction in hexagonal samples. This behavior suggests reduced carrier mobility and possible carrier localization or multi-band effects. These results offer valuable insights into phase-selective growth and carrier dynamics in chalcogenide-based thin films.
Metal–organic frameworks (MOFs) are considered ideal platforms for proton conduction, owing to their tunable pore architectures and abundant H-bonding sites that facilitate the formation of continuous transport pathways. Nevertheless, only limited efforts have been devoted to exploring MOFs whose proton-conducting performance can be modulated by altering the external measurement environment. The proton conductivity of a chosen Mn-based MOF, namely {[Mn3(m-MOD)2(H2O)6]·4H2O}n (Mn-MOF-COOH; m-MOD is 2-(3-methoxyphenyl)-1H-imidazole-4,5-dicarboxylic acid), was explored under humid conditions and aquaammonia vapor. Mn-MOF-COOH exhibits a six-lobed turbine-shaped 3D architecture along with multiple interpenetrating six-membered-ring honeycomb layers. Abundant coordinated and free water molecules, together with zigzag one-dimensional channels within the structure, collectively facilitate proton conduction. At 100 °C in 2 M aquaammonia vapor, Mn-MOF-COOH exhibits a peak proton conductivity of 3.40 × 10-3 S/cm, nearly two orders of magnitude above the highest conductivity (4.64 × 10-5 S/cm) measured under water vapor at 100 °C-98% RH. Based on structural characteristics, water vapor uptake capacity, specific surface area, and pore size distribution, the underlying reasons for the improved conductivity in aquaammonia vapor, along with the associated proton conduction mechanism, are systematically explored and thoroughly clarified.
