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ABSTRACT: Overlapping absorption edges will occur when an element is present in multiple oxidation states within a material. DetOx is a program for partitioning overlapping X-ray absorption spectra into contributions from individual atomic species and computing the dependence of the anomalous scattering factors on X-ray energy. It is demonstrated how these results can be used in combination with X-ray diffraction data to determine the oxidation state of ions at specific sites in a mixed-valance material, GaCl(2).
Journal of Synchrotron Radiation 01/2013; 20(Pt 1):200-4. · 2.73 Impact Factor
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ABSTRACT: The dedicated small-molecule single-crystal X-ray diffraction beamline (I19) at Diamond Light Source has been operational and supporting users for over three years. I19 is a high-flux tunable-wavelength beamline and its key details are described in this article. Much of the work performed on the beamline involves structure determination from small and weakly diffracting crystals. Other experiments that have been supported to date include structural studies at high pressure, studies of metastable species, variable-temperature crystallography, studies involving gas exchange in porous materials and structural characterizations that require analysis of the diffuse scattering between Bragg reflections. A range of sample environments to facilitate crystallographic studies under non-ambient conditions are available as well as a number of options for automation. An indication of the scope of the science carried out on the beamline is provided by the range of highlights selected for this paper.
Journal of Synchrotron Radiation 05/2012; 19(Pt 3):435-41. · 2.73 Impact Factor
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ABSTRACT: The first example of a [2]-rotaxane in which a perylene diimide acts as a recognition site has been synthesised and characterised. The interlocked nature of the compound has been verified by both NMR studies and an X-ray structure determination. Electrochemical investigations confirm that the nature of the redox processes associated with the perylene diimide are modified by the complexation process and that it is possible to mono-reduce the [2]-rotaxane to give a radical anion based rotaxane. Further reduction of the compound leads to de-threading of the macrocycle from the reduced PTCDI recognition site. Our synthetic strategies confirm the potential of PTCDI-based rotaxanes as viable targets for the preparation of complex interlocked species.
Chemistry 12/2011; 17(52):14746-51. · 5.93 Impact Factor
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Thomas B Faust,
Valerio Bellini,
Andrea Candini,
Stefano Carretta,
Giulia Lorusso,
David R Allan,
Laura Carthy,
David Collison,
Rebecca J Docherty,
Jasbinder Kenyon, [......],
Christopher A Muryn, Harriott Nowell,
Robin G Pritchard,
Simon J Teat,
Grigore A Timco,
Floriana Tuna,
George F S Whitehead,
Wolfgang Wernsdorfer,
Marco Affronte,
Richard E P Winpenny
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ABSTRACT: We present a synthetic, structural, theoretical, and spectroscopic study of a family of heterometallic ring dimers which have the formula [{Cr(7)NiF(3)(Etglu)(O(2)CtBu)(15)}(2)(NLN)], in which Etglu is the pentadeprotonated form of the sugar N-ethyl-D-glucamine, and NLN is an aromatic bridging diimine ligand. By varying NLN we are able to adjust the strength of the interaction between rings with the aim of understanding how to tune our system to achieve weak magnetic communication between the spins, a prerequisite for quantum entanglement. Micro-SQUID and EPR data reveal that the magnetic coupling between rings is partly related to the through-bond distance between the spin centers, but also depends on spin-polarization mechanisms and torsion angles between aromatic rings. Density functional theory (DFT) calculations allow us to make predictions of how such chemically variable parameters could be used to tune very precisely the interaction in such systems. For possible applications in quantum information processing and molecular spintronics, such precise control is essential.
Chemistry 11/2011; 17(50):14020-30. · 5.93 Impact Factor
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ABSTRACT: The metal-organic frameworks NOTT-400 and NOTT-401, based on a binuclear [Sc(2)(μ(2)-OH)(O(2)CR)(4)] building block, have been synthesised and characterised; the desolvated framework NOTT-401a shows a BET surface area of 1514 m(2) g(-1) with a total H(2) uptake of 4.44 wt% at 77 K and 20 bar.
Chemical Communications 06/2011; 47(29):8304-6. · 6.17 Impact Factor
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Andrew McRobbie,
Asad R Sarwar,
Steven Yeninas, Harriott Nowell,
Michael L Baker,
David Allan,
Marshall Luban,
Christopher A Muryn,
Robin G Pritchard,
Ruslan Prozorov,
Grigore A Timco,
Floriana Tuna,
George F S Whitehead,
Richard E P Winpenny
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ABSTRACT: Hexametallic chromium(III) chains can act as fluoride donor ligands to lanthanide ions giving {(Cr(6))Ln(x)}(n) complexes; preliminary spectroscopic studies are reported.
Chemical Communications 06/2011; 47(22):6251-3. · 6.17 Impact Factor
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ABSTRACT: A new carboxylic acid functionalised cavitand forms [Cu(3)L(2)] metallo-cryptophanes with Cu(OAc)(2) that can be linked together into dimers with the bridging ligand 1,2-bis(4-pyridyl)ethylene. Reaction of the cavitand with Co(OAc)(2) gives a metallo-cryptophane with a central Co(7) cluster.
Chemical Communications 01/2011; 47(1):176-8. · 6.17 Impact Factor
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ABSTRACT: Metal-organic frameworks, typically built by bridging metal centres with organic linkers, have recently shown great promise for a wide variety of applications, including gas separation and drug delivery. Here, we have used them as a scaffold to probe the photophysical and photochemical properties of metal-diimine complexes. We have immobilized a M(diimine)(CO)(3)X moiety (where M is Re or Mn, and X can be Cl or Br) by using it as the linker of a metal-organic framework, with Mn(II) cations acting as nodes. Time-resolved infrared measurements showed that the initial excited state formed on ultraviolet irradiation of the rhenium-based metal-organic framework was characteristic of an intra-ligand state, rather than the metal-ligand charge transfer state typically observed in solution, and revealed that the metal-diimine complexes rearranged from the fac- to mer-isomer in the crystalline solid state. This approach also enabled characterization of the photoactivity of Mn(diimine)(CO)(3)Br by single-crystal X-ray diffraction.
Nature Chemistry 08/2010; 2(8):688-94. · 20.52 Impact Factor
