I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[35994]
Open Access
Abstract: A series of previously unknown bis(acylhydrazone)s with aliphatic (zero to four CH2 units) and aromatic (phenylene substituted) linkers was synthesized and structurally characterized. Aliphatic derivatives exhibited distinct conformational geometries and packing motifs, with linker length critically affecting hydrogen bond interactions and energies. Aromatic derivatives revealed three polymorphs of the meta-substituted structure with two of the forms related by temperature. Additionally, a bis(acylhydrazone) low-molecular-weight gelator was crystallized, revealing a unique and impressive hydrogen-bonded framework with large water channels (952 Å3) and strong aliphatic and aromatic stacking interactions. These findings highlight the potential of bis(acylhydrazone)s in crystal engineering and supramolecular chemistry, especially in coformer design and selection, and supramolecular gelator applications.
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Dec 2025
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[40347]
Open Access
Abstract: We report a comparative high-pressure study of two fluorite-type rare-earth oxides with increasing configurational entropy, (CePr)O2–δ and (CePrLa)O2–δ. Synchrotron-based powder X-ray diffraction and Raman spectroscopy were carried out up to 30 and 20 GPa, respectively. Both compounds retain the cubic fluorite structure throughout the pressure range explored, although an anomaly is observed between 9 and 16 GPa, characterized by a compressibility plateau and changes in vibrational modes. This behavior is attributed to local lattice distortions and a progressive bond angle bending rather than abrupt phase transitions. In (CePrLa)O2−δ, the onset of amorphization is observed above 22 GPa, highlighting its reduced structural stability. The bulk modulus of both systems shows a slight decrease after the onset of the anomaly, suggesting subtle lattice softening. Raman spectroscopy reveals suppression of the F2g mode intensity with increasing cationic disorder, and under compression, partial reordering is evidenced by an increase in the RE–O mode intensity. Our results highlight the complex interplay between configurational entropy, cation size, and pressure in determining the structural stability and vibrational properties of rare-earth high-entropy oxides and provide insight into the mechanisms governing their resilience and local disorder under extreme conditions.
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Dec 2025
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Open Access
Abstract: Using elementary concepts of chemical reaction kinetics, the rates of primary homogeneous organic crystal nucleation from supersaturated solutions are modeled as nucleation with first order kinetics from large solute density fluctuations (LSDFs). Solute density fluctuations are modeled as diffusively driven many-body collisions of weakly interacting solvated solute molecules. The first order rate constant is a system-specific supersaturation-independent rate constant for nucleation in LSDFs. It is shown for several solute–solvent systems that the temperature-dependence of this nucleation rate constant exhibits Arrhenius behavior. The activation enthalpy (ΔH⧧) and activation entropy (ΔS⧧) for homogeneous nucleation is determined from an Eyring–Polanyi analysis of temperature-dependent nucleation rates. The steps of the Eyring–Polanyi analysis are described in detail for the homogeneous nucleation of l-histidine from aqueous solutions. The analysis is also applied to temperature-dependent homogeneous nucleation rates of salicylic acid in four different solvents. For all systems, the supersaturation- and the temperature-dependence of the primary homogeneous nucleation rates are completely reproduced by reference to temperature-dependent solubility data through the activation parameters ΔH⧧ and ΔS⧧. ΔH⧧ is for all examined systems approximately 12 times the enthalpy of solution determined from solubility data, suggesting that nucleation from LSDFs resembles, at the molecular level, a reverse dissolution process. Within the temperature ranges used for measuring nucleation rates, the Gibbs energy of activation ΔG⧧ does not vary strongly, resulting in an inverse correlation between enthalpies and entropies of activation. The Eyring–Polanyi framework thus provides, for the first time, a method for semiquantitative predictions of homogeneous nucleation rates from temperature-dependent solubilities.
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Dec 2025
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[30280]
Open Access
Abstract: Solvothermal reaction of N,N′-bis(5-isophthalic acid)naphthalenediimide (H4BINDI) with zinc(II) nitrate hexahydrate in dimethylformamide (DMF) in the presence of trifluoroacetic acid as a modulator gives rise to a self-catenated Metal–organic framework (MOF) termed BINDI-ZnSC of unprecedented topological complexity. Using the “all node” method, the topology is assigned as a six-nodal net with point symbol {4.102}2{4.122}{4.6.8}{42.6.8.106}{6.102}. In contrast to interpenetrated and other self-catenated MOFs that often exhibit limited pore volume, BINDI-ZnSC exhibits a total of 3730 Å3 (62.5% of the unit cell) of solvent-filled channels per unit cell, suggesting that the material is potentially capable of encapsulating not only single molecules but also molecular clusters of some small molecules.
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Sep 2025
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I16-Materials and Magnetism
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Abstract: Four novel carbazole-based photopolymerizable liquid crystals (PLCs) incorporating diacrylates or nonconjugated dienes were designed and synthesized to study their mesomorphic behavior and photocuring properties, with a focus on future applications in 4D printing. A combined analysis protocol using polarized optical microscopy (POM), differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), and wide-angle X-ray scattering (WAXS) revealed a favorably wide range of nematic phases near room temperature and a slow tendency to crystallize. This should be advantageous in applications requiring good surface-alignment of the reactive mesogen in the nematic phase. This behavior could be attributed to the effects of polymerization under prolonged high temperatures for acrylates and the high entropy of long, branched, flexible alkyl chains in dienes. The polymerization process induces a kinetic competition between LC ordering and network formation. This work establishes protocols for real-time phase monitoring during polymerization, resolving longstanding ambiguities in LC phase identification under thermal polymerization. Furthermore, photocuring tests of the acrylate and diene monomers demonstrated high photopolymerization efficiency and good thermal stability, particularly for the acrylate monomers.
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Sep 2025
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I22-Small angle scattering & Diffraction
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Diamond Proposal Number(s):
[29532]
Open Access
Abstract: Ultrasound standing waves (USW) produce a force capable of displacing micrometer-sized free-flowing particles in a fluid, wherein this phenomenon is also referred to as acoustophoresis. However, the effect of acoustophoresis on dynamically changing and growing crystal networks is unclear. An example of such a system are monoglyceride (MG)-based oleogels, which are free-flowing lipids (e.g., vegetable oils) structured with a lipid-crystal network. In this work, we use MG oleogels as an example system to investigate the acoustophoretic effect on the structuration of a growing crystal network. For this purpose, multifaceted characterization is conducted utilizing optical and coded excitation scanning acoustic microscopy as well as small-angle X-ray scattering, respectively. The optical microscopy results show that USW produces local density differences of the structuring crystalline material and induces the orientation of the MG platelets. X-ray diffraction measurements confirm these findings and show a 23% average increase in MG platelet correlation length, which can be linked to platelet thickness, as well as an increase in the MG nanoplatelet surface smoothness. These findings produce a foundation for better understanding the effect of acoustophoresis in dynamically developing lipid-based materials and illuminate the mechanical changes that arise because of USW treatment.
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Jun 2025
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I22-Small angle scattering & Diffraction
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Diamond Proposal Number(s):
[34844]
Open Access
Abstract: Due to the increasing global demand for chocolate products and changes in consumer preferences, chocolate manufacturers have recently started to explore novel solutions to reformulate chocolate. Milk fat alternatives (MFA) are blends of triglycerides from different plant-based sources that resemble anhydrous milk fat in physical properties, particularly thermal behavior and solid fat content. However, in order to use MFA as potential ingredients for vegan milk chocolate formulations, it is necessary to understand their crystallization behavior, particularly in light of their chemical composition. Here, we applied synchrotron X-ray scattering, polarized light microscopy, and differential scanning calorimetry to investigate the crystallization behavior of four selected commercial MFAs (MF1, 2, 3, and 4), on their own and mixed with cocoa butter (CB). Chemical characterization revealed significant differences among samples and with both anhydrous milk fat (MF) and CB. POP-rich MF1 presented a specific polymorphic and thermal behavior, with the unstable β′ form persisting for longer times than all other samples. Sample MF2 exhibited a polymorphic behavior more similar to CB in terms of number, type, and melting behavior due to the compositional similarities (e.g., prevalence of both SOS and POP). SOS-rich MF3 was characterized by metastable forms γ and β′(3L), whereas MF4 at ambient conditions showed only β(2L) forms due to its specific composition. Mixtures of CB and all MFAs behaved similarly to CB and MF mixtures, with good miscibility at ambient temperature and a lower melting point. Despite significant differences in chemical composition, MF4 presented similar solid fat content compared to MF; this is due to the high amount of relatively long chain, unsaturated fatty acids and the broad distribution of different TAGs, which all lower the melting point of this sample.
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Apr 2025
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[34800]
Open Access
Abstract: Three-dimensional (3D) electron diffraction (3D-ED) techniques can be used for structure determination, circumventing challenges posed to conventional and bulk X-ray diffraction techniques such as submicrometer-sized crystals, the strong effects of texture, the presence of defects, and polyphasic samples. Such challenges previously prevented the structure solution of xanthine, a purine base chemically similar to guanine that may also be found in organisms. In this work, we use 3D-ED to elucidate the crystal structure of xanthine. The electron diffraction data obtained from a single microcrystal is also of sufficient quality to determine hydrogen positions, confirming the presence of the 7H-tautomer, as expected. This study highlights the potential for the use of 3D-ED on biogenic nanocrystals, for example opening opportunities to understand the links between crystal anisotropy, birefringence, and organism characteristics.
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Feb 2025
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I22-Small angle scattering & Diffraction
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Diamond Proposal Number(s):
[9904]
Open Access
Abstract: Rare-earth element (REE) carbonates play a crucial role in geochemistry due to their prevalence in carbonatite ore deposits, which are extensively mined globally for REE extraction. Two primary mineral groups of interest are lanthanites (REE2(CO3)3·8H2O) and bastnäsites (REECO3(OH,F)), typically enriched in light REE. This study aims to elucidate the mechanisms and kinetics of La-, Ce-, Pr-, and Nd-carbonate crystallization reactions at the earliest stages. REE-carbonates were synthesized through homogeneous crystallization by combining CO32– and REE-bearing solutions at temperatures ranging from near-ambient to low hydrothermal conditions (5–80 °C). The crystallization processes were monitored in situ and in real-time using UV–vis spectrophotometry and synchrotron-based wide-angle X-ray scattering (WAXS). The characterization and quantification of the newly formed phases were conducted using a combination of conventional powder X-ray diffraction, high-resolution scanning electron microscopy with energy-dispersive spectroscopy and Fourier transform infrared spectroscopy. Our findings reveal a complex, multistep crystallization pathway specific to each REE, influenced by factors such as temperature, solution concentration and ratio, phase stability, and REE ionic potential. Additionally, the REE-carbonate crystallization pathways align with a progressive dehydration sequence involving multiple intermediate nanophases and reversible reactions. Notably, a reversible reaction between lanthanite and nanotengerite was observed at ambient temperature, involving structural rearrangements and hydration-dehydration processes. Our findings emphasize the importance of nanophase formation during the initial stages of REE-carbonate crystallization, with implications for the development of more efficient REE extraction methods.
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Feb 2025
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[19366]
Open Access
Abstract: In the crystalline state, xanthine plays a significant role in several biological systems. For example, pathological crystallization of xanthine causes renal stones in humans and bladder stones in cats and dogs, while xanthine crystals can also serve as functional optical materials, including their role as reflective mirrors in the eye-like organs of certain insects. To understand the role of crystalline xanthine in such biological processes and functions, knowledge of the crystal structure is essential. However, crystal structure determination has so far proved elusive, as xanthine is recalcitrant to the formation of crystals suitable for single-crystal XRD, and severe preferred orientation in powder samples of xanthine has prevented structure determination from powder XRD data. Here we report the crystal structure of xanthine based on the analysis of 3D electron diffraction (3D-ED) data recorded for microcrystals in a powder sample, in conjunction with periodic DFT-D calculations and the analysis of powder XRD data. In common with certain other purines, the crystal structure of xanthine is a layered structure containing planar hydrogen-bonded sheets in which all hydrogen-bond donor and acceptor groups are engaged in intermolecular hydrogen bonds. Considering the tautomeric form of xanthine in the crystal structure, analysis of the 3D-ED data supports the presence of the N7H tautomer (the tautomer of lowest energy for an isolated xanthine molecule). However, the corresponding crystal structure containing the N9H tautomer is essentially isostructural, as it differs from the structure containing the N7H tautomer only in the position of the H atom within each intermolecular N–H···N hydrogen bond in the structure. Interestingly, the difference in energy (per molecule of xanthine) between the crystal structures containing the N7H and N9H tautomers is significantly lower than the difference in energy of an isolated xanthine molecule in the N7H and N9H tautomers.
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Jan 2025
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