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Abstract: Supramolecular deep eutectic solvents (SUPRADESs), formed by combining cyclodextrins (CDs) with hydrogen bond donors, enhance solvation efficiency while retaining CD inclusion capabilities. This study presents the first detailed structural analysis of a SUPRADES composed of β-cyclodextrin (β-CD) and lactic acid (LA) (1:30 M ratio) using Molecular Dynamics simulations and X-ray scattering. Results reveal a well-dispersed system where LA molecules form stabilizing sheaths around isolated β-CDs, preventing coalescence through optimized hydrogen bonding and dispersive interactions. The SUPRADES significantly improved solubilisation and retention of water-insoluble trans-anethole (AN), demonstrating strong absorption capacity. While β-CD encapsulation of AN was limited, 2D ROESY NMR confirmed inclusion complex formation. These findings highlight the SUPRADES's unique microstructure and its potential as a sustainable, eco-friendly solvent for volatile organic compound (VOC) applications, offering insights for future green solvent design.

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Abstract: We report the solvent-free synthesis of a crystalline heterometallic imidazolate derivative with formula [Fe1Zn2(im)6(Him)2], designated MUV-25, incorporating both iron and zinc. The structure imposes strict positional constraints on the metal centres due to the lattice containing distinct geometric coordination sites, tetrahedral and octahedral. As a consequence, each metal is exclusively directed to its specific coordination site, ensuring precise spatial organization within the lattice. Atom locations were meticulously monitored utilizing X-ray diffraction (single crystal and total scattering) and XAS techniques, demonstrating that the tetrahedral sites are occupied exclusively by zinc, and the octahedral sites are occupied by iron. This combination of metal centres results, upon heating, in a structural phase transformation to the zni topology at a very low temperature. Further heating causes the melting of the solid, yielding a heterometallic MOF-derived glass. The methodology lays the groundwork for tailoring crystalline structures to advance the development of novel materials capable of melting and forming glasses upon cooling.

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Abstract: We present a structural characterization of a low-transition-temperature mixture (LTTM), consisting of thymol and carvacrol, at an equimolar ratio. Carvacrol and thymol are natural regioisomers of terpenes. When combined at an equimolar ratio, they form a liquid mixture at room temperature, with supercooling capability and glass transition at ca. 210 K. Using small- and wide-angle X-ray scattering and molecular dynamics, we describe the structural complexity within this system. X-ray scattering reveals a low-Q peak at around 0.6 Å–1, indicating the existence of mesoscale structural heterogeneities, likely related to the segregation of polar moieties engaged in hydrogen bond (HB) interactions within an aromatic, apolar matrix. These polar interactions are predominantly a result of HBs involving thymol as the HB donor species. The liquid structure is also driven by O–H···π interactions, prevalently due to the ability of the carvacrol π-site to engage in this type of weak interaction as a HB acceptor. Besides, dispersive interactions affect the local arrangement of molecules, with a propensity of carvacrol rings to orient their first neighbors with a perpendicular orientation, while thymol tends to induce a closer approach of other thymol molecules with a preferential parallel alignment. Overall, we observed a complex structural arrangement driven by the interplay of both conventional and weak hydrogen bond interactions, with the aromatic nature of the compounds playing a pivotal role in shaping the system’s architecture. Carvacrol and thymol, despite being very similar compounds, are characterized by distinctly different behavior in terms of the interactions they engage in with their neighbors, likely due to the different steric hindrance experienced by their hydroxyl groups, which are close to either a small methyl or a bulky isopropyl group, respectively. Such observations can provide useful hints to develop new solvents with tailored properties.

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Abstract: Metal-organic frameworks (MOFs) are a versatile class of hybrid inorganic-organic materials known for their adjustable chemical and physical properties, as well as their exceptional porosity. These characteristics render MOFs particularly valuable for applications requiring extensive surface areas, such as gas storage and catalysis. Despite being advantageous in many applications, the high porosity and specific bonding characteristics of crystalline MOFs can, however, make them susceptible to pore collapse and amorphisation under pressure. This limits the practical effectiveness of MOFs in their most commonly synthesised form of crystalline powders, as large-scale production and shaping of powders for industrial use often involves pressure and heating. This thesis examines how a range of MOFs behave under various high pressure and high pressure-temperature conditions to examine both their amorphisation mechanisms and amorphous phases formed. The MOFs were selected to fall within two groups: zirconium-based (UiO-66, MOF-808 and NU-1000) and zinc-based (ZIF-8, ZIF-4 and ZIF-62). The methods chosen for investigations were hydrostatic compression, non-hydrostatic compression, and ball-milling, as they are all used for industrial processing of powders: The former two are methods for shaping, and the latter for mixing. Hydrostatic compression of these MOFs is investigated in depth through in situ high pressure-temperature crystallographic and spectroscopic measurements, allowing real-time analysis on the MOFs’ collapse mechanisms. Both groups display partially reversible amorphisation under hydrostatic compression to certain pressures, indicating a displacive amorphisation transition into an amorphous phase topologically similar to the crystalline. Penetration of the pressure-transmitting media into the framework’s pores was also indicated in each MOF, with clear negative volume compressibility shown in the zinc-based MOFs. Ex situ investigations into non-hydrostatic compression then introduce the effect of shear stress so its effect on the MOFs can be highlighted, where the two groups demonstrate quite different behaviour attributed to differences in the connectivity of their inorganic components. Ball-milling is finally examined as a non-compression form of amorphisation with a high shear component. In both shear-based pressure states, decoordination of the organic components from the inorganic is seen as a driving factor of amorphisation. Understanding the collapse mechanisms and resultant amorphous phases from various amorphisation methods in these MOFs gives insight into trends in mechanical properties and stability within this class of materials, and is essential for the future industrialisation of MOFs.

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Abstract: ABX3-type hybrid organic–inorganic structures have recently emerged as a new class of meltable materials. Here, by the use of phenylphosphonium derivatives as A cation, we study liquid- and glass-forming behavior of a new family of hybrid structures, (RPh3P)[Mn(dca)3] (R = Me, Et, Ph; dca = dicyanamide). These new compounds melt at 196–237 °C (Tm) and then vitrify upon cooling to room temperature, forming glasses. In situ glass formation of this new family of materials was probed on a large scale using a variable-temperature PXRD experiment. Structure analyses of the crystalline and the glasses were carried out by solid-state nuclear magnetic resonance spectroscopy and synchrotron X-ray total scattering techniques for using the pair distribution function. The mechanical properties of the glasses produced were evaluated showing promising durability. Thermal and electrical conductivities showed low thermal conductivities (κ ∼ 0.07–0.09 W m–1 K–1) and moderate electrical conductivities (σ ∼ 10–4–10–6 S m–1) at room temperature, suggesting that by the precise control of the A cation, we can tune meltable hybrid structures from moderate conductors to efficient thermal insulators. Our results raise attention on the practical use of this new hybrid material in applications including, e.g., photovoltaic devices to prevent light-deposited heat (owing to low κRT), energy harvesting thermoelectric, etc., and advance the structure–property understanding.