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Abstract: Modifying glass compositions is key to creating silicate-based glasses for technologies including optical fibres, catalytic supports, protective coatings and separation membranes. Here we extend this concept to metal–organic framework (MOF) glasses by modifying the MOF glass former ZIF-62 with Li(bim) and Na(bim) as compatible glass modifiers (benzimidazolate, bim−). Melt-quenching of physical mixtures with increasing Na(bim) content yields modified MOF glasses that exhibit a systematic decrease in the glass transition temperature (Tg), accompanied by increased liquid fragility, configurational heat capacity at Tg and density: paralleling silicate glass chemistry through partial network depolymerization. Structural and spectroscopic analysis, coupled with density-functional theory calculations, confirm that Na(bim) is incorporated homogeneously into the MOF glass framework rather than the pores and reveal the presence of undercoordinated sodium ion environments. Finally, extraction of the modifier by water treatment increases glass porosity, akin to established borosilicate glass processes. This work introduces a transferable approach for tailoring the structure and properties of MOF glasses.

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Abstract: The Ga₂S₃–Sb₂S₃ quasi-binary system has been investigated for its potential to yield stable chalcogenide glasses with tailored thermal and structural properties. Using melt-quenching techniques, a series of (Ga₂S₃)ₓ(Sb₂S₃)₁₋ₓ compositions (0.0 ≤ x ≤ 0.5) were synthesized, and their glass-forming domain was mapped. The latter extends up to approximately x ≤ 0.40, as confirmed by X-ray diffraction and DSC analyses, with the x = 0.4 composition exhibiting a glass-ceramic character. Density measurements, combined with calculations of molar volume and packing density, revealed a continuous structural densification as Ga₂S₃ content increased. Differential scanning calorimetry showed an increase in glass transition temperature (Tg), with the best thermal stability observed for x = 0.2, as assessed by the Hruby criterion. Electrical conductivity measurements demonstrated thermally activated behaviour following the Arrhenius law, with maximum activation energy also centred at x = 0.2. Raman spectroscopy and DFT modelling were used to decipher the structural contributions of Sb–S and Ga–S bonding. The emergence of vibrational modes characteristic of Ga-based structural units, especially beyond x > 0.2, suggests a structural reorganization from Sb-centred pyramidal units to Ga-centred tetrahedral. This was corroborated by high-energy X-ray diffraction, which showed significant changes in intermediate-range order with increasing Ga content, particularly in the first sharp diffraction peak and partial coordination environments.

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Abstract: Molecular single-source precursors are a promising way of obtaining multi-element extended solids directly. We show that thermal decomposition of well-defined mono-, bi- and trimetallic polyoxovanadates (POVs) proceeds through a series of intermediate amorphous and crystalline species which we characterise using solid-state NMR spectroscopy, pair-distribution function (PDF) analysis and in-situ X-ray diffraction, before forming crystalline V2O5 and BiVO4 products. This synthetic strategy enables the formation of phases inaccessible using other routes, including a previously unknown polymorph of BiVO4 which we name β-BiVO4 due to its similarity to β-SnWO4. Local structure information also reveals the temperature dependent incorporation of Zn do pants into BiVO4. The study also explores the electrochemical properties of amorphous mixed-valence vanadium oxides as Li-ion battery electrodes. We suggest that careful analysis of the thermal decomposition of molecular species may be a way of obtaining hitherto unknown kinetically stabilised polymorphs and amorphous variants of extended solids.

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Abstract: The development of high-performance infrared (IR) nonlinear optical (NLO) crystals is fundamentally challenged by the conflicting requirements for a large NLO coefficient, a high laser damage threshold (LDT), and a broad IR transparency range. We establish a structure–property relationship governing nonlinear optical response in diamond-like compounds, namely, a sixth-power scaling relation between the NLO coefficient dijk and average flexibility index F, i.e., dijk ∝ F6. Based on this relation, a multiple flexible-group synergistic polarization strategy is proposed, which successfully guided the discovery of an exceptional IR NLO crystal, Cd2In3Si2P7 (CISP). CISP exhibits the largest recorded SHG effect (8.8 × AgGaS2 (AGS) and 2.5 × ZnGeP2 (ZGP) @ 2050 nm) among reported pnictide NLO crystals, high NLO coefficients (d22 and d23 = 137.6 and 89.3 pm/V @ 1500 nm, respectively), a high LDT (10.3 × AGS), a moderate birefringence (0.098 @ 2050 nm), and a broad IR transmission range (0.62–18.0 μm). The outstanding comprehensive performances underscore its significant potential as a promising IR NLO material. This work not only provides a strategy for the design of IR NLO crystals but also introduces a straightforward yet powerful descriptor for understanding the structure–property correlation in polarizable functional materials.

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Abstract: The persistent contamination of water sources by perfluorooctanoic acid (PFOA) poses a major environmental and public health challenge. PFOA is a representative member of per- and polyfluoroalkyl substances (PFAS), a class of compounds characterized by high chemical stability, bioaccumulation potential, and toxicity. Conventional water treatment processes are not fully effective in removing PFOA, underscoring the urgent need for advanced remediation strategies. Here, we report the development of Fe-MOF-808, a novel porous material obtained by incorporating binuclear iron species into the Zr6O8 nodes of the MOF-808 framework. Comprehensive structural characterization was performed, including ex/in situ synchrotron-based techniques combined with computational modeling. The results confirm successful iron integration without compromising the structural integrity and accessibility of the porous network. Moreover, the presence of multiple, spatially accessible binding sites enables Fe-MOF-808 to capture PFAS through a combination of electrostatic, hydrophobic and coordinative interactions. This resulted in high removal efficiencies across various water matrices and for a wide range of PFAS pollutants and concentrations. Fe-MOF-808 notably achieves complete PFOA removal within minutes and demonstrates excellent recyclability over multiple adsorption cycles. The material also reaches experimental uptake and a maximum Langmuir adsorption capacity of 2081 and 3120 mg PFOA g–1, respectively, vastly outperforming the pristine MOF-808 and other state-of-the-art MOF materials. Overall, mechanistic insights gained from this study highlight the critical role of designing specific chemical environments within MOFs to maximize pollutant-sorbent interactions.