I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[36775, 26668]
Open Access
Abstract: A variable-temperature and pressure single-crystal diffraction study of hybrid improper ferroelectric Sr3Sn2O7 is reported. In combination with symmetry analysis, we reveal that the application of pressure and temperature induce distinct phase transition pathways, driven by a differing response of the octahedral rotations to these stimuli. Contrary to what has been previously predicted, we observe the ferroelectric to paraelectric phase transition between 10.17(18) and 12.13(14) GPa, meaning the hybrid improper ferroelectric phase remains stable to significantly higher pressures than expected.
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Jun 2025
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I19-Small Molecule Single Crystal Diffraction
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Karen
Robertson
,
Mark R.
Warren
,
Lois E.
Wayment
,
Pollyanna
Payne
,
C. Daniel
Scott
,
Chick C.
Wilson
,
Lucy K.
Saunders
,
Graeme
Winter
,
Benjamin
Williams
,
Lauren E.
Hatcher
,
David R.
Allan
Diamond Proposal Number(s):
[22497, 21301]
Open Access
Abstract: Serial crystallography has revolutionalised our ability to analyse protein crystals; crystal structures can be uncovered by combining data from multiple crystals mitigating radiation damage through overexposure to the X-ray beam. With synchrotron sources becoming even brighter radiation damage is ever more pertinent for small molecule crystals as well. Combining serial crystallography with flow crystallisation, we pave the way to exploring high-throughput screening and kinetic studies, and application to small molecule crystals of up to mm-scale. Here we present the first known example of single crystal X-ray diffraction of small molecule crystals in a flow crystallisation environment. In situ single-crystal X-ray diffraction has been achieved on a series of growing singular crystals through use of segmented flow cooling crystallisation, holding crystals in the X-ray beam for 4.2 s whilst they freely rotate whilst flowing inside tubing. Upon triggering of a passing slug at the analysis point, the tubing is moved in the opposite direction to the flow, enabling the crystal to remain within the X-ray beam whilst maintaining the free rotation of the crystal due to fluid movement. Structure solution of paracetamol Form I has been achieved with 0.8 Å resolution using data combined from 13 crystals whilst unit cell information can be extracted from a single crystal.
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Jun 2025
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I19-Small Molecule Single Crystal Diffraction
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Milos
Dubajic
,
James R.
Neilson
,
Johan
Klarbring
,
Xia
Liang
,
Stephanie A.
Bird
,
Kirrily C.
Rule
,
Josie E.
Auckett
,
Thomas A.
Selby
,
Ganbaatar
Tumen-Ulzii
,
Yang
Lu
,
Young-Kwang
Jung
,
Cullen
Chosy
,
Zimu
Wei
,
Yorrick
Boeije
,
Martin V.
Zimmermann
,
Andreas
Pusch
,
Leilei
Gu
,
Xuguang
Jia
,
Qiyuan
Wu
,
Julia C.
Trowbridge
,
Eve M.
Mozur
,
Arianna
Minelli
,
Nikolaj
Roth
,
Kieran W. P.
Orr
,
Arman
Mahboubi Soufiani
,
Simon
Kahmann
,
Irina
Kabakova
,
Jianning
Ding
,
Tom
Wu
,
Gavin J.
Conibeer
,
Stephen P.
Bremner
,
Michael P.
Nielsen
,
Aron
Walsh
,
Samuel D.
Stranks
Diamond Proposal Number(s):
[33123]
Open Access
Abstract: Lead halide perovskites have emerged as promising materials for solar energy conversion and X-ray detection owing to their remarkable optoelectronic properties. However, the microscopic origins of their superior performance remain unclear. Here we show that low-symmetry dynamic nanodomains present in the high-symmetry average cubic phases, whose characteristics are dictated by the A-site cation, govern the macroscopic behaviour. We combine X-ray diffuse scattering, inelastic neutron spectroscopy, hyperspectral photoluminescence microscopy and machine-learning-assisted molecular dynamics simulations to directly correlate local nanoscale dynamics with macroscopic optoelectronic response. Our approach reveals that methylammonium-based perovskites form densely packed, anisotropic dynamic nanodomains with out-of-phase octahedral tilting, whereas formamidinium-based systems develop sparse, isotropic, spherical nanodomains with in-phase tilting, even when crystallography reveals cubic symmetry on average. We demonstrate that these sparsely distributed isotropic nanodomains present in formamidinium-based systems reduce electronic dynamic disorder, resulting in a beneficial optoelectronic response, thereby enhancing the performance of formamidinium-based lead halide perovskite devices. By elucidating the influence of the A-site cation on local dynamic nanodomains, and consequently, on the macroscopic properties, we propose leveraging this relationship to engineer the optoelectronic response of these materials, propelling further advancements in perovskite-based photovoltaics, optoelectronics and X-ray imaging.
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Jun 2025
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[29890]
Open Access
Abstract: Interwoven molecular structures underpin the functions of many biomolecules, yet synthesizing artificial topologically complex structures in high yield remains challenging. Here we describe a streamlined, high-yield one-pot synthesis of knotted cage frameworks by using a subcomponent designed to bridge over the faces of a predesigned cage framework. A ZnII4L3 (where L corresponds to a tritopic pyridyl-imine ligand that coordinates to the metal vertices) open-faced cage framework was employed as the basis for a topologically chiral perplexane, and a ZnII4L4 tetrahedron was built into a topologically chiral trefoil tetrahedron. Both interwoven architectures can be prepared through one-pot subcomponent self-assembly from a trialdehyde, the bridging triamine and a zinc(II) salt. The trefoil tetrahedron was observed to mechanically lock guests inside the cavity, resulting in a guest exchange half-life 17,000 times longer than that of the original tetrahedral cage. Both cage frameworks were reduced and demetallated to yield metal-free interwoven structures, with the perplexane producing an achiral product and the trefoil tetrahedron maintaining its topological chirality. Our strategy may enable the knotting of many existing cage frameworks produced using subcomponent self assembly, enhancing their robustness and ability to lock guests inside.
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Jun 2025
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[36775]
Abstract: Polar metals are an intriguing class of materials that feature a polar crystal structure while also exhibiting metallic conductivity. The unique properties of polar metals challenge expectations, making way for the exploration of exotic phenomena such as unconventional magnetism, hyperferroelectric multiferroicity, and the development of multifunctional devices that can leverage both the material's polar structure and its asymmetry in the spin conductivity, that arises due to the Rashba effect. Here, via a high-pressure single-crystal diffraction study, we report the pressure-induced enhancement of polar distortions in such a metal, Ca3Ru2O7. Our density functional theory calculations highlight that naive assumptions about the linear dependency between polar distortion amplitudes and the magnitude of the Rashba spin splitting may not be generally valid.
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May 2025
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[29890]
Open Access
Abstract: Herein we utilize the binding of fluoride to boron atoms to functionalize the interior of a boron-containing trigonal prismatic capsule that incorporates two triangular and three rectangular ligands, enabling the tuning of its guest binding properties. The methyl groups of the triangular ligands guide the rectangular ligands to adopt a ‘landscape’ orientation to avoid steric hindrance. This small structural change gives rise to an enlarged interior cavity volume for guest encapsulation, as compared with a previously-reported trigonal prismatic capsule, where the same rectangular ligand took a ‘portrait’ orientation with a non-methylated triangular ligand of similar size. The methylated triangular ligand contains a boron core, which can bind fluoride ions that point inward. These bound fluorides serve as hydrogen bond acceptors, which increases the affinity of the capsule for hydrogen-bond-donating alcohols, which are bound in preference to ketones of similar sizes. Moreover, this boron-containing trigonal prism selectively binds perrhenate over perchlorate, while fluoride binding modulates the cavity charge, leading to perrhenate ejection. These and similar endo-functionalized capsules may thus be of use in the fields of molecular recognition and separation.
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May 2025
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I19-Small Molecule Single Crystal Diffraction
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Abstract: We present the successful encapsulation of a number small organic guest moieties within the molecular cavities of pseudo [M7] (M = Co(II), Ni(II) and Zn(II)) metallocalix[6]arene hosts and include the complexes [(2-fur)Zn(II)7(OMe)6(L)6](NO3)2.3H2O (1), [(3-fur)Co(II)7(OH)6(L)6](NO3)2 .4.5H2O (6), [(bzal)Zn(II)7(OMe)6(L)6](NO3)2.5H2O (7), [(2-acetylfuran)⊂[Ni(II)7(OMe)6L6(NO3)2].3H2O (12) and [(coumarin)⊂[Ni(II)7(OH)6(L)6(NO3)2.3H2O (20) (where LH = 2-Methoxy-6-[(E)-(methylimino)methyl]phenol). Guest inclusion of the species 2- and 3-furaldehyde, benzaldehyde, 2-thiophenecarboxaldehyde, 2-acetylfuran, acetophenone, 1-indanone and coumarin was evidenced through a combination of FT-IR, solid state NMR, X-ray diffraction studies and TGA measurements. Guest packing coefficients were produced for a cross-section of these materials to give values ranging from 34% (in [(3-Fur)Ni(II)7(OH)6(L)6](NO3)2.3H2O (5)) to 75% (in [(2-acetylfuran)⊂[Co(II)7(OMe)6(L)6](NO3)2.7H2O (13)).
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May 2025
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[36069]
Open Access
Abstract: Core-twisted perylene diimides (PDIs) are chiral organic dyes that may be exploited for self-assembled chiroptical materials or for the enantioselective recognition and sensing of chiral substrates. Discrete self-assembled dimers and host–guest complexes of core-twisted perylene diimides are important for furthering our understanding of this supramolecular chemistry, yet they are rare because the twisted perylene core significantly weakens intermolecular π–π interactions with the PDI's π-surface. To address this challenge, we have installed hydrogen bond donor groups in the PDI's bay positions, which direct the formation of a robust, co-facial and homochiral intermolecular PDI dimer. The structure of this discrete dimer is distinct from previous aggregates of non-planar PDIs that utilize the imide position for hydrogen bonding. We also uncover the potential of core-twisted, dicationic PDIs for the enantioselective recognition and chiroptical sensing of chiral anions and investigate the basis of this response via chiral complementarity in the discrete host–guest complex.
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May 2025
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I11-High Resolution Powder Diffraction
I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[26668, 34452, 39378]
Open Access
Abstract: The absorption spectra of a series of Ce-oxo clusters (molecular nanoparticles) with sizes ranging from 3 to 100 Ce atoms per cluster are reported. The O 2p to Ce 4f charge-transfer absorption onset in these systems is unaffected by size and almost identical to that of 5 nm CeO(2−x) particles and other Ce based materials such as the metal–organic framework Ce-UiO-66. This clearly demonstrates that in CeO2 based systems, with highly localized 4f LUMO orbitals, quantum confinement effects are not influential on electronic structure. Importantly, this allows the use of ultrasmall ceria particles in (visible light) photochemical applications without detrimental band-gap enlarging size-effects. Changes in colour in CeO2 materials and these Ce-oxo clusters are instead clearly attributed to the presence of (defective) surface sites. Surface Ce(III) sites in mixed-valence clusters contribute a Ce(III)/Ce(IV) intervalence charge transfer transition in the visible region, which affects their colour. Ce24 clusters with a range of aliphatic and aromatic carboxylate ligands are studied, to compare the effect of surface ligands on the electronic structure. Ligand influence on the absorption spectra is only observed when highly conjugated (naphthyl) or strongly electron donating substituents (anisole or aniline) are present.
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May 2025
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[30375]
Abstract: We present a combined experimental and density functional theory study that characterizes the charge and spin density in NiX2(3,5-lutidine)4 (X = Cl, Br and I). In this material, magnetic exchange interactions occur via Ni2+–halide⋯halide–Ni2+ pathways, forming one-dimensional chains. We find evidence for weak halide⋯halide covalency in the iodine system, which is greatly reduced when X = Br and is absent for X = Cl; this is consistent with the reported `switching-on' of magnetic exchange in the larger-halide cases. Our results are benchmarked against density functional theory calculations on [NiHF2(pyrazine)2]SbF6, in which the primary magnetic exchange is mediated by F–H–F bridging ligands. This comparison indicates that, despite the largely depleted charge density found at the centre of halide⋯halide bonds, these through-space interactions can support strong magnetic exchange gated by weak covalency and enhanced by significant electron density overlapping that of the transition metal centres.
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Apr 2025
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