I11-High Resolution Powder Diffraction
I19-Small Molecule Single Crystal Diffraction
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Inigo J.
Vitórica-Yrezábal
,
Craig A.
Mcanally
,
Matthew P.
Snelgrove
,
Mark R.
Warren
,
Adrian H.
Hill
,
Stephen P.
Thompson
,
Martin
Quinn
,
Sam
Mottley
,
Stephen
Mottley
,
Ashleigh J.
Fletcher
,
Lee
Brammer
Open Access
Abstract: Separation of CO2 from gas mixtures is important in applications such as CH4 gas purification and blue hydrogen production. Here we report selective CO2 uptake by a family of flexible silver coordination polymers (AgCPs) that are ostensibly non-porous but exhibit latent porosity to CO2 above a gate pressure, through a mechanism akin to dissolution in fluoroalkanes. The CO2 sorption properties are rationally modified by changing the perfluoroalkyl chain length of the constituent perfluorocarboxylate ligands. The AgCPs do not take up CH4 owing to failure of the dissolution mechanism, consistent with alkane–perfluoroalkane immiscibility. In situ single-crystal and powder X-ray diffraction enable direct visualization of the CO2 molecule binding domains. These techniques also reveal associated structural changes in the AgCPs and confirm the gating mechanism of CO2 uptake. The combination of perfluoroalkylcarboxylate ligands with the flexible silver(I) coordination sphere generates highly fluorinated but mobile regions of the crystals that play an integral role in the selective uptake of CO2 over CH4.
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Oct 2025
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[23480]
Open Access
Abstract: We report the synthesis of a right-handed (Δ-stereochemistry of strand crossings) trefoil knot from a single molecular strand containing three pyrazine-2,5-dicarboxamide units adjacent to point-chiral centers and six pyridine moieties. The oligomeric ligand strand folds into an overhand (open-trefoil) knot through the assistance of coordinatively dynamic Co(II) “chaperones” that drive the formation of a three-metal-ion circular helicate. The entangled structure is kinetically locked by oxidation to Co(III) and covalently captured by ring-closing olefin metathesis to generate a trefoil knot of single topological handedness. The stereochemistry of the strand crossings in the metal-coordinated overhand knot is governed by the stereochemistry of the point-chiral carbon centers in the ligand strand. The overhand and trefoil knots were characterized by NMR spectroscopy, mass spectrometry, and X-ray crystallography. Removal of the metal ions from the knot, followed by hydrogenation of the alkene, yielded the wholly organic trefoil knot. The metal-free knot and parent ligand were investigated by circular dichroism (CD) spectroscopy. The CD spectra indicate that the topological stereochemistry of the knot has a greater effect on the asymmetry of the chromophore environment than do the point-chiral centers of the strand.
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Jul 2024
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I19-Small Molecule Single Crystal Diffraction
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Jiangnan
Li
,
Xinran
Zhang
,
Mengtian
Fan
,
Yinlin
Chen
,
Yujie
Ma
,
Gemma
Smith
,
Inigo
Vitórica-Yrezábal
,
Daniel
Lee
,
Shaojun
Xu
,
Martin
Schroeder
,
Sihai
Yang
Diamond Proposal Number(s):
[34413]
Open Access
Abstract: Optimization of active sites and stability under irradiation are important targets for sorbent materials that might be used for iodine (I2) storage. Herein, we report the direct observation of I2 binding in a series of Cu(II)-based isostructural metal–organic frameworks, MFM-170, MFM-172, MFM-174, NJU-Bai20, and NJU-Bai21, incorporating various functional groups (–H, −CH3, – NH2, –C≡C–, and −CONH–, respectively). MFM-170 shows a reversible uptake of 3.37 g g–1 and a high packing density of 4.41 g cm–3 for physiosorbed I2. The incorporation of −NH2 and –C≡C– moieties in MFM-174 and NJU-Bai20, respectively, enhances the binding of I2, affording uptakes of up to 3.91 g g–1. In addition, an exceptional I2 packing density of 4.83 g cm–3 is achieved in MFM-174, comparable to that of solid iodine (4.93 g cm–3). In situ crystallographic studies show the formation of a range of supramolecular and chemical interactions [I···N, I···H2N] and [I···C≡C, I–C═C–I] between −NH2, –C≡C– sites, respectively, and adsorbed I2 molecules. These observations have been confirmed via a combination of solid-state nuclear magnetic resonance, X-ray photoelectron, and Raman spectroscopies. Importantly, γ-irradiation confirmed the ultraresistance of MFM-170, MFM-174, and NJU-Bai20 suggesting their potential as efficient sorbents for cleanup of radioactive waste.
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May 2024
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I19-Small Molecule Single Crystal Diffraction
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Zhipeng
Zhou
,
Lei
Zhang
,
Yonghang
Yang
,
Inigo J.
Vitórica-Yrezábal
,
Honglei
Wang
,
Fanglin
Tan
,
Li
Gong
,
Yuyao
Li
,
Pohua
Chen
,
Xin
Dong
,
Zihao
Liang
,
Jing
Yang
,
Chao
Wang
,
Yuexian
Hong
,
Yi
Qiu
,
Armin
Gölzhäuser
,
Xudong
Chen
,
Haoyuan
Qi
,
Sihai
Yang
,
Wei
Liu
,
Junliang
Sun
,
Zhikun
Zheng
Diamond Proposal Number(s):
[31627]
Abstract: A core feature of covalent organic frameworks (COFs) is crystallinity, but current crystallization processes rely substantially on trial and error, chemical intuition and large-scale screening, which typically require harsh conditions and low levels of supersaturation, hampering the controlled synthesis of single-crystal COFs, particularly on large scales. Here we report a strategy to produce single-crystal imine-linked COFs in aqueous solutions under ambient conditions using amphiphilic amino-acid derivatives with long hydrophobic chains. We propose that these amphiphilic molecules self-assemble into micelles that serve as dynamic barriers to separate monomers in aqueous solution (nodes) and hydrophobic compartments of the micelles (linkers), thereby regulating the polymerization and crystallization processes. Disordered polyimines were obtained in the micelle, which were then converted into crystals in a step-by-step fashion. Five different three-dimensional COFs and a two-dimensional COF were obtained as single crystals on the gram scale, with yields of 92% and above.
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Apr 2023
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[23480]
Open Access
Abstract: Ethylene-bridged oligoureas are dynamic foldamers in which the polarity of a coherent chain of intramolecular hydrogen bonds may be controlled by intra- or intermolecular interactions with hydrogen-bond donors or acceptors. In this paper, we describe the way that supramolecular interactions between ethylene-bridged oligoureas bearing a 3,5-bis(trifluoromethyl)phenylurea (BTMP) terminus leads to higher-order structures both in the crystalline state and in solution. The oligoureas self-assemble by head-to-tail hydrogen bonding interactions to form either supramolecular ‘nanorings’ with cyclic hydrogen bond chain directionality, or supramolecular helical chains of hydrogen bonds. The self-assembly process features a cascade of cooperative positive allostery, in which each intermolecular hydrogen bond formation at the BTMP terminus switches the native hydrogen bond chain directionality of monomers, favouring further assembly. Monomers with a benzyl urea terminus self-assemble into nanorings, whereas monomers with a N-ethyl urea terminus form helical chains. In the crystal state, parallel helices have identical handedness and polarity, whereas antiparallel helices have opposite handedness. The overall dipole moment of crystals is zero due to the antiparallel arrangements of local dipoles in the crystal packing. Supramolecular interactions in solution were also examined by VT and DOSY NMR spectroscopy, up to the point of crystal formation. The size of higher aggregates in dichloromethane was estimated by their hydrodynamic radius. The relative orientation of the monomers within the aggregates, determined by 2D ROESY NMR, was the same as in the crystals, where syn-orientations lead to the formation of rings and anti-orientations result in chains. Overall, the switch of hydrogen bond polarity propagates intermolecularly in crystal and solution states, constituting an example of intermolecular communication within supramolecular polymers.
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Nov 2022
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B22-Multimode InfraRed imaging And Microspectroscopy
I19-Small Molecule Single Crystal Diffraction
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Weiyao
Li
,
Jiangnan
Li
,
Thien D.
Duong
,
Sergey A.
Sapchenko
,
Xue
Han
,
Jack D.
Humby
,
George F. S.
Whitehead
,
Inigo J.
Vitórica-Yrezábal
,
Ivan
Da Silva
,
Pascal
Manuel
,
Mark D.
Frogley
,
Gianfelice
Cinque
,
Martin
Schroeder
,
Sihai
Yang
Diamond Proposal Number(s):
[28479, 23480]
Open Access
Abstract: The development of efficient sorbent materials for sulfur dioxide (SO2) is of key industrial interest. However, due to the corrosive nature of SO2, conventional porous materials often exhibit poor reversibility and limited uptake toward SO2 sorption. Here, we report high adsorption of SO2 in a series of Cu(II)-carboxylate-based metal–organic framework materials. We describe the impact of ligand functionalization and open metal sites on the uptake and reversibility of SO2 adsorption. Specifically, MFM-101 and MFM-190(F) show fully reversible SO2 adsorption with remarkable capacities of 18.7 and 18.3 mmol g–1, respectively, at 298 K and 1 bar; the former represents the highest reversible uptake of SO2 under ambient conditions among all porous solids reported to date. In situ neutron powder diffraction and synchrotron infrared microspectroscopy enable the direct visualization of binding domains of adsorbed SO2 molecules as well as host–guest binding dynamics. We have found that the combination of open Cu(II) sites and ligand functionalization, together with the size and geometry of metal–ligand cages, plays an integral role in the enhancement of SO2 binding.
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Jul 2022
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[23480]
Open Access
Abstract: Herein, we report on the use of tetrathiavulvalene-tetrabenzoic acid, H4TTFTB, to engender semiconductivity in porous hydrogen-bonded organic frameworks (HOFs). By tuning the synthetic conditions, three different polymorphs have been obtained, denoted MUV-20a, MUV-20b, and MUV-21, all of them presenting open structures (22, 15, and 27%, respectively) and suitable TTF stacking for efficient orbital overlap. Whereas MUV-21 collapses during the activation process, MUV-20a and MUV-20b offer high stability evacuation, with a CO2 sorption capacity of 1.91 and 1.71 mmol g–1, respectively, at 10 °C and 6 bar. Interestingly, both MUV-20a and MUV-20b present a zwitterionic character with a positively charged TTF core and a negatively charged carboxylate group. First-principles calculations predict the emergence of remarkable charge transport by means of a through-space hopping mechanism fostered by an efficient TTF π–π stacking and the spontaneous formation of persistent charge carriers in the form of radical TTF•+ units. Transport measurements confirm the efficient charge transport in zwitterionic MUV-20a and MUV-20b with no need for postsynthetic treatment (e.g., electrochemical oxidation or doping), demonstrating the semiconductor nature of these HOFs with record experimental conductivities of 6.07 × 10–7 (MUV-20a) and 1.35 × 10–6 S cm–1 (MUV-20b).
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May 2022
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[23480]
Open Access
Abstract: The hexagonal-bipyramidal lanthanide(III) complex [Dy(OtBu)Cl(18-C-6)][BPh4] (1; 18-C-6 = 1,4,7,10,13,16-hexaoxacyclooctadecane ether) displays an energy barrier for magnetization reversal (Ueff) of ca. 1000 K in a zero direct-current field. Temperature-dependent X-ray diffraction studies of 1 down to 30 K reveal bending of the Cl–Ln–OtBu angle at low temperature. Using ab initio calculations, we show that significant bending of the O–Dy–Cl angle upon cooling from 273 to 100 K leads to a ca. 10% decrease in the energy of the excited electronic states. A thorough exploration of the temperature and field dependencies of the magnetic relaxation rate reveals that magnetic relaxation is dictated by five mechanisms in different regimes: Orbach, Raman-I, quantum tunnelling of magnetization, and Raman-II, in addition to the observation of a phonon bottleneck effect.
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Dec 2021
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I19-Small Molecule Single Crystal Diffraction
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Lucy K.
Saunders
,
Hamish H.-M.
Yeung
,
Mark
Warren
,
Peter
Smith
,
Stuart
Gurney
,
Stephen F.
Dodsworth
,
Inigo
Vitorica-Yrezabal
,
Adrian
Wilcox
,
Paul V.
Hathaway
,
Geoff
Preece
,
Paul
Roberts
,
Sarah A.
Barnett
,
David R.
Allan
Diamond Proposal Number(s):
[19670, 22964]
Open Access
Abstract: With the recent increase in research into ferroelectric, anti-ferroelectric and piezoelectric materials, studying the solid-state properties in situ under applied electric fields is vital in understanding the underlying processes. Where this behaviour is the result of atomic displacements, crystallographic insight has an important role. This work presents a sample environment designed to apply an electric field to single-crystal samples in situ on the small-molecule single-crystal diffraction beamline I19, Diamond Light Source (UK). The configuration and operation of the cell is described as well as its application to studies of a proton-transfer colour-change material.
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Oct 2021
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I11-High Resolution Powder Diffraction
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Xi
Chen
,
Zhongyue
Zhang
,
Jin
Chen
,
Sergei
Sapchenko
,
Xue
Han
,
Ivan
Da Silva
,
Ming
Li
,
Inigo
Vitorica-Yrezabal
,
George
Whitehead
,
Chiu C.
Tang
,
Kunio
Awaga
,
Sihai
Yang
,
Martin
Schroeder
Diamond Proposal Number(s):
[22138]
Abstract: MFM-722(Pb)-DMA undergoes a single-crystal-to-single-crystal (SCSC) transformation to give MFM-722(Pb)-H2O via ligand substitution upon exposure to water vapour. In situ single crystal impedance spectroscopy reveals an increase in proton conductivity due to this structural transition, with MFM-722(Pb)-H2O showing a proton conductivity of 6.61×10-4 S cm-1 at 50 °C and 98% RH. The low activation energy (Ea = 0.21 eV) indicates that the proton conduction follows a Grotthuss mechanism.
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Nov 2020
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