I19-Small Molecule Single Crystal Diffraction
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Deepak
Asthana
,
Dean
Thomas
,
Selena J.
Lockyer
,
Adam
Brookfield
,
Grigore A.
Timco
,
Iñigo J.
Vitorica-Yrezabal
,
George F. S.
Whitehead
,
Eric J. L.
Mcinnes
,
David
Collison
,
David A.
Leigh
,
Richard E. P.
Winpenny
Open Access
Abstract: Polymer beads have been used as the core of magnetic particles for around twenty years. Here we report studies to attach polymetallic complexes to polymer beads for the first time, producing beads of around 115 microns diameter that are attached to 1014 hybrid inorganic-organic [2]rotaxanes. The bead is then formally a [1014] rotaxane. The number of complexes attached is counted by EPR spectroscopy after including TEMPO radicals within the thread of the hybrid [2]rotaxanes.
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Jun 2022
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B22-Multimode InfraRed imaging And Microspectroscopy
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Bing
An
,
Zhe
Li
,
Zi
Wang
,
Xiangdi
Zeng
,
Xue
Han
,
Yongqiang
Chen
,
Alena M.
Sheveleva
,
Zhongyue
Zhang
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
Mark D.
Frogley
,
Anibal J.
Ramirez-Cuesta
,
Louise S.
Natrajan
,
Cheng
Wang
,
Wenbin
Li
,
Sihai
Yang
,
Martin
Schroeder
Diamond Proposal Number(s):
[23782]
Abstract: Natural gas, consisting mainly of methane (CH4), has a relatively low energy density at ambient conditions (~36 kJ l−1). Partial oxidation of CH4 to methanol (CH3OH) lifts the energy density to ~17 MJ l−1 and drives the production of numerous chemicals. In nature, this is achieved by methane monooxygenase with di-iron sites, which is extremely challenging to mimic in artificial systems due to the high dissociation energy of the C–H bond in CH4 (439 kJ mol−1) and facile over-oxidation of CH3OH to CO and CO2. Here we report the direct photo-oxidation of CH4 over mono-iron hydroxyl sites immobilized within a metal–organic framework, PMOF-RuFe(OH). Under ambient and flow conditions in the presence of H2O and O2, CH4 is converted to CH3OH with 100% selectivity and a time yield of 8.81 ± 0.34 mmol gcat−1 h−1 (versus 5.05 mmol gcat−1 h−1 for methane monooxygenase). By using operando spectroscopic and modelling techniques, we find that confined mono-iron hydroxyl sites bind CH4 by forming an [Fe–OH···CH4] intermediate, thus lowering the barrier for C–H bond activation. The confinement of mono-iron hydroxyl sites in a porous matrix demonstrates a strategy for C–H bond activation in CH4 to drive the direct photosynthesis of CH3OH.
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Jun 2022
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B18-Core EXAFS
B22-Multimode InfraRed imaging And Microspectroscopy
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Yujie
Ma
,
Wanpeng
Lu
,
Xue
Han
,
Yinlin
Chen
,
Ivan
Da Silva
,
Daniel
Lee
,
Alena M.
Sheveleva
,
Zi
Wang
,
Jiangnan
Li
,
Weiyao
Li
,
Mengtian
Fan
,
Shaojun
Xu
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
Yongqiang
Cheng
,
Svemir
Rudic
,
Pascal
Manuel
,
Mark D.
Frogley
,
Anibal J.
Ramirez-Cuesta
,
Martin
Schroeder
,
Sihai
Yang
Diamond Proposal Number(s):
[19850]
Open Access
Abstract: The presence of active sites in metal–organic framework (MOF) materials can control and affect their performance significantly in adsorption and catalysis. However, revealing the interactions between the substrate and active sites in MOFs at atomic precision remains a challenging task. Here, we report the direct observation of binding of NH3 in a series of UiO-66 materials containing atomically dispersed defects and open Cu(I) and Cu(II) sites. While all MOFs in this series exhibit similar surface areas (1111–1135 m2 g–1), decoration of the −OH site in UiO-66-defect with Cu(II) results in a 43% enhancement of the isothermal uptake of NH3 at 273 K and 1.0 bar from 11.8 in UiO-66-defect to 16.9 mmol g–1 in UiO-66-CuII. A 100% enhancement of dynamic adsorption of NH3 at a concentration level of 630 ppm from 2.07 mmol g–1 in UiO-66-defect to 4.15 mmol g–1 in UiO-66-CuII at 298 K is observed. In situ neutron powder diffraction, inelastic neutron scattering, and electron paramagnetic resonance, solid-state nuclear magnetic resonance, and infrared spectroscopies, coupled with modeling reveal that the enhanced NH3 uptake in UiO-66-CuII originates from a {Cu(II)···NH3} interaction, with a reversible change in geometry at Cu(II) from near-linear to trigonal coordination. This work represents the first example of structural elucidation of NH3 binding in MOFs containing open metal sites and will inform the design of new efficient MOF sorbents by targeted control of active sites for NH3 capture and storage.
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May 2022
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I11-High Resolution Powder Diffraction
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Tian
Luo
,
Lili
Li
,
Yinlin
Chen
,
Jie
An
,
Chengcheng
Liu
,
Zheng
Yan
,
Joseph H.
Carter
,
Xue
Han
,
Alena M.
Sheveleva
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
Chiu C.
Tang
,
Martin
Schroeder
,
Sihai
Yang
Diamond Proposal Number(s):
[15972]
Open Access
Abstract: Construction of C-C bonds via reductive coupling of aldehydes and ketones is hindered by the highly negative reduction potential of these carbonyl substrates, particularly ketones, and this renders the formation of ketyl radicals extremely endergonic. Here, we report the efficient activation of carbonyl compounds by the formation of specific host-guest interactions in a hydroxyl-decorated porous photocatalyst. MFM-300(Cr) exhibits a band gap of 1.75 eV and shows excellent catalytic activity and stability towards the photoreductive coupling of 30 different aldehydes and ketones to the corresponding 1,2-diols at room temperature. Synchrotron X-ray diffraction and electron paramagnetic resonance spectroscopy confirm the generation of ketyl radicals via confinement within MFM-300(Cr). This protocol removes simultaneously the need for a precious metal-based photocatalyst or for amine-based sacrificial agents for the photochemical synthesis.
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Jun 2021
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I11-High Resolution Powder Diffraction
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Martin
Schroeder
,
Louis
Kimberley
,
Alena M.
Sheveleva
,
Jiangnan
Li
,
Joseph H.
Carter
,
Xinchen
Kang
,
Gemma L.
Smith
,
Xue
Han
,
Sarah J.
Day
,
Chiu C.
Tang
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
Sihai
Yang
Open Access
Abstract: Selective oxidation of benzylic C‐H compounds to ketones is important for the production of a wide range of fine chemicals, and is often achieved using toxic or precious metals catalysts. Here, we report the efficient oxidation of benzylic C‐H groups in a broad range of substrates under mild conditions over a robust metal‐organic framework material, MFM‐170, incorporating redox‐active [Cu2II(O2CR)4] paddlewheel nodes. A comprehensive investigation employing electron paramagnetic resonance (EPR) spectroscopy and synchrotron X‐ray diffraction has identified the critical role of the paddlewheel moiety in activating the oxidant tBuOOH (t‐butyl hydroperoxide) via partial reduction to [CuIICuI(O2CR)4] species.
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Apr 2021
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I11-High Resolution Powder Diffraction
I20-EDE-Energy Dispersive EXAFS (EDE)
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Longfei
Lin
,
Mengtian
Fan
,
Alena M.
Sheveleva
,
Xue
Han
,
Zhimou
Tang
,
Joseph H.
Carter
,
Ivan
Da Silva
,
Christopher
Parlett
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
German
Sastre
,
Svemir
Rudic
,
Hamish
Cavaye
,
Stewart F.
Parker
,
Yongqiang
Cheng
,
Luke L.
Daemen
,
Anibal J.
Ramirez-Cuesta
,
Martin P.
Attfield
,
Yueming
Liu
,
Chiu C.
Tang
,
Buxing
Han
,
Sihai
Yang
Diamond Proposal Number(s):
[2359]
Open Access
Abstract: Optimising the balance between propene selectivity, propene/ethene ratio and catalytic stability and unravelling the explicit mechanism on formation of the first carbon–carbon bond are challenging goals of great importance in state-of-the-art methanol-to-olefin (MTO) research. We report a strategy to finely control the nature of active sites within the pores of commercial MFI-zeolites by incorporating tantalum(V) and aluminium(III) centres into the framework. The resultant TaAlS-1 zeolite exhibits simultaneously remarkable propene selectivity (51%), propene/ethene ratio (8.3) and catalytic stability (>50 h) at full methanol conversion. In situ synchrotron X-ray powder diffraction, X-ray absorption spectroscopy and inelastic neutron scattering coupled with DFT calculations reveal that the first carbon–carbon bond is formed between an activated methanol molecule and a trimethyloxonium intermediate. The unprecedented cooperativity between tantalum(V) and Brønsted acid sites creates an optimal microenvironment for efficient conversion of methanol and thus greatly promotes the application of zeolites in the sustainable manufacturing of light olefins.
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Feb 2021
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I19-Small Molecule Single Crystal Diffraction
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Helen M.
O’connor
,
Sergio
Sanz
,
Aaron J.
Scott
,
Mateusz B.
Pitak
,
Wim T.
Klooster
,
Simon J.
Coles
,
Nicholas F.
Chilton
,
Eric J. L.
Mcinnes
,
Paul J.
Lusby
,
Høgni
Weihe
,
Stergios
Piligkos
,
Euan K.
Brechin
Diamond Proposal Number(s):
[11238]
Open Access
Abstract: Three new heterometallic [CrIII8NiII6] coordination cubes of formulae [CrIII8NiII6L24(H2O)12](NO3)12 (1), [CrIII8NiII6L24(MeCN)7(H2O)5](ClO4)12 (2), and [CrIII8NiII6L24Cl12] (3) (where HL = 1-(4-pyridyl)butane-1,3-dione), were synthesised using the paramagnetic metalloligand [CrIIIL3] and the corresponding NiII salt. The magnetic skeleton of each capsule describes a face-centred cube in which the eight CrIII and six NiII ions occupy the eight vertices and six faces of the structure, respectively. Direct current magnetic susceptibility measurements on (1) reveal weak ferromagnetic interactions between the CrIII and NiII ions, with JCr-Ni = + 0.045 cm−1. EPR spectra are consistent with weak exchange, being dominated by the zero-field splitting of the CrIII ions. Excluding wheel-like structures, examples of large heterometallic clusters containing both CrIII and NiII ions are rather rare, and we demonstrate that the use of metalloligands with predictable bonding modes allows for a modular approach to building families of related polymetallic complexes. Compounds (1)–(3) join the previously published, structurally related family of [MIII8MII6] cubes, where MIII = Cr, Fe and MII = Cu, Co, Mn, Pd.
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Feb 2021
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B18-Core EXAFS
B22-Multimode InfraRed imaging And Microspectroscopy
I11-High Resolution Powder Diffraction
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Shaojun
Xu
,
Xue
Han
,
Yujie
Ma
,
Thien D.
Duong
,
Longfei
Lin
,
Emma K.
Gibson
,
Alena
Sheveleva
,
Sarayute
Chansai
,
Alex
Walton
,
Duc-The
Ngo
,
Mark D.
Frogley
,
Chiu C.
Tang
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
C. Richard A.
Catlow
,
Christopher
Hardacre
,
Sihai
Yang
,
Martin
Schroeder
Open Access
Abstract: Efficient catalytic conversion of NO2 to non-harmful species remains an important target for research. State-of-the-art deNOx processes are based upon ammonia (NH3)-assisted selective catalytic reduction (NH3-SCR) over Cu-exchanged zeolites at elevated temperatures. Here, we describe a highly efficient non-thermal plasma (NTP) deNOx process catalyzed by a Cu-embedded metal-organic framework, Cu/MFM-300(Al), at room temperature. Under NTP activation at 25°C, Cu/MFM-300(Al) enables direct decomposition of NO2 into N2, NO, N2O, and O2 without the use of NH3 or other reducing agents. NO2 conversion of 96% with a N2 selectivity of 82% at a turnover frequency of 2.9 h−1 is achieved, comparable to leading NH3-SCR catalysts that use NH3 operating at 250°C–550°C. The mechanism for the rate-determining step (NO→N2) is elucidated by in operando diffuse reflectance infrared Fourier transform spectroscopy, and electron paramagnetic resonance spectroscopy confirms the formation of Cu2+⋯NO nitrosylic adducts on Cu/MFM-300(Al), which facilitates NO dissociation and results in the notable N2 selectivity.
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Feb 2021
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B22-Multimode InfraRed imaging And Microspectroscopy
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Xue
Han
,
Wanpeng
Lu
,
Yinlin
Chen
,
Ivan
Da Silva
,
Jiangnan
Li
,
Longfei
Lin
,
Weiyao
Li
,
Alena M.
Sheveleva
,
Harry G. W.
Godfrey
,
Zhenzhong
Lu
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
Yongqiang
Cheng
,
Luke L.
Daemen
,
Laura J.
Mccormick Mcpherson
,
Simon J.
Teat
,
Mark D.
Frogley
,
Svemir
Rudic
,
Pascal
Manuel
,
Anibal J.
Ramirez-Cuesta
,
Sihai
Yang
,
Martin
Schroeder
Diamond Proposal Number(s):
[23782]
Abstract: Ammonia (NH3) is a promising energy resource owing to its high hydrogen density. However, its widespread application is restricted by the lack of efficient and corrosion-resistant storage materials. Here, we report high NH3 adsorption in a series of robust metal–organic framework (MOF) materials, MFM-300(M) (M = Fe, V, Cr, In). MFM-300(M) (M = Fe, VIII, Cr) show fully reversible capacity for >20 cycles, reaching capacities of 16.1, 15.6, and 14.0 mmol g–1, respectively, at 273 K and 1 bar. Under the same conditions, MFM-300(VIV) exhibits the highest uptake among this series of MOFs of 17.3 mmol g–1. In situ neutron powder diffraction, single-crystal X-ray diffraction, and electron paramagnetic resonance spectroscopy confirm that the redox-active V center enables host–guest charge transfer, with VIV being reduced to VIII and NH3 being oxidized to hydrazine (N2H4). A combination of in situ inelastic neutron scattering and DFT modeling has revealed the binding dynamics of adsorbed NH3 within these MOFs to afford a comprehensive insight into the application of MOF materials to the adsorption and conversion of NH3.
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Feb 2021
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B22-Multimode InfraRed imaging And Microspectroscopy
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Xinchen
Kang
,
Bin
Wang
,
Kui
Hu
,
Kai
Lyu
,
Xue
Han
,
Ben F.
Spencer
,
Mark D.
Frogley
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
Robert A. W.
Dryfe
,
Buxing
Han
,
Sihai
Yang
,
Martin
Schroeder
Diamond Proposal Number(s):
[19171]
Open Access
Abstract: Efficient electro-reduction of CO2 over metal–organic framework (MOF) materials is hindered by the poor contact between thermally synthesized MOF particles and the electrode surface, which leads to low Faradaic efficiency for a given product and poor electrochemical stability of the catalyst. We report a MOF-based electrode prepared via electro-synthesis of MFM-300(In) on an indium foil, and its activity for the electrochemical reduction of CO2 is assessed. The resultant MFM-300(In)-e/In electrode shows a 1 order of magnitude improvement in conductivity compared with that for MFM-300(In)/carbon-paper electrodes. MFM-300(In)-e/In exhibits a current density of 46.1 mA cm–2 at an applied potential of −2.15 V vs Ag/Ag+ for the electro-reduction of CO2 in organic electrolyte, achieving an exceptional Faradaic efficiency of 99.1% for the formation of formic acid. The facile preparation of the MFM-300(In)-e/In electrode, coupled with its excellent electrochemical stability, provides a new pathway to develop efficient electro-catalysts for CO2 reduction.
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Sep 2020
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