ORCID Profile
0000-0002-0880-3225
Current Organisations
University of Manchester
,
University of Melbourne
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Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/CH14166
Abstract: Polyoxometalates are robust and versatile multidentate oxygen-donor ligands, eminently suitable for coordination to trivalent lanthanoid ions. To date, 10 very different structural families of such complexes have been found to exhibit slow magnetic relaxation due to single-molecule magnet (SMM) behaviour associated with the lanthanoid ions. These families encompass complexes with between one and four of the later lanthanoid ions: Tb, Dy, Ho, Er, and Yb. The lanthanoid coordination numbers vary between six and eleven and a range of coordination geometries are evident. The highest energy barrier to magnetisation reversal measured to date for a lanthanoid–polyoxometalate SMM is Ueff/kB = 73 K for the heterodinuclear Dy–Eu compound (Bu4N)8H4[DyEu(OH)2(γ-SiW10O36)2].
Publisher: Wiley
Date: 07-2016
Publisher: American Chemical Society (ACS)
Date: 15-12-2016
DOI: 10.1021/ACS.INORGCHEM.6B02312
Abstract: Inelastic neutron scattering (INS) has been used to investigate the crystal field (CF) magnetic excitations of the analogs of the most representative lanthanoid-polyoxometalate single-molecule magnet family: Na
Publisher: Springer Science and Business Media LLC
Date: 14-12-2020
Publisher: American Chemical Society (ACS)
Date: 15-11-2016
DOI: 10.1021/ACS.INORGCHEM.6B02218
Abstract: Eight new members of a family of mixed-metal (Mo,W) polyoxometalates (POMs) with amino acid ligands have been synthesized and investigated in the solid state and solution using multiple physical techniques. While the peripheral POM structural framework is conserved, the different analogues vary in nuclearity of the central metal-oxo core, overall redox state, metal composition, and identity of the zwitterionic α-amino acid ligands. Structural investigations reveal site-selective substitution of Mo for W, with a strong preference for Mo to occupy the central metal-oxo core. This core structural unit is a closed tetrametallic loop in the blue reduced species and an open trimetallic loop in the colorless oxidized analogues. Density functional theory calculations suggest the core as the favored site of reduction and reveal that the corresponding molecular orbital is much lower in energy for a tetra- versus trimetallic core. The reduced species are diamagnetic, each with a pair of strongly antiferromagnetically coupled Mo
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9SC03431E
Abstract: Halide abstraction chemistry is performed on a series of trigonal lanthanide(III) complexes to provide bent complexes that contain only two N-donor ligands.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9DT01069F
Abstract: In three structurally related series of nine-coordinate lanthanide( iii ) complexes, solution NMR studies and DFT/CASSCF calculations have provided key information on the magnetic susceptibility anisotropy.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D2SC05797B
Abstract: Magnetoelastic coupling has been investigated using inelastic neutron scattering. This has allowed the spin–phonon coupling of the candidate qubit Na 9 [Ho(W 5 O 18 ) 2 ]·35D 2 O to be determined in the absence of an applied magnetic field.
Publisher: American Chemical Society (ACS)
Date: 27-09-2017
DOI: 10.1021/JACS.7B07094
Abstract: Bleaney's long-standing theory of magnetic anisotropy has been employed with some success for many decades to explain paramagnetic NMR pseudocontact shifts, and has been the subject of many subsequent approximations. Here, we present a detailed experimental and theoretical investigation accounting for the anomalous solvent dependence of NMR shifts for a series of lanthanide(III) complexes, namely [LnL
Publisher: American Chemical Society (ACS)
Date: 18-04-2019
DOI: 10.1021/ACS.INORGCHEM.9B00060
Abstract: Knowledge of the crystal structure of a monometallic inorganic molecule is often sufficient to calculate its electronic structure and interpret its magnetic properties. Here we show that for a series of nine-coordinate lanthanide complexes based on the 1,4,7-tris[(6-carboxypyridin-2-yl)methyl]-1,4,7-triazacyclononane ligand, the electronic structure is hypersensitive to geometric structure and to the presence of noncoordinated lattice solvent, which renders the magnetic and spectroscopic properties very difficult to interpret. We explore possible explanations for the peculiar electron paramagnetic resonance (EPR) spectra and conclude that a number of entangled factors are at play across the s les. Hence, great care should be taken in the interpretation of EPR spectra for systems with small magnetic anisotropy, even when the molecular structure is known.
Publisher: American Chemical Society (ACS)
Date: 20-05-2016
DOI: 10.1021/ACS.INORGCHEM.6B00108
Abstract: Optimization of literature synthetic procedures has afforded, in moderate yield, homogeneous and crystalline s les of the five analogues Na11[{RE(OH2)}3CO3(PW9O34)2] (1-RE RE = Y, Tb, Dy, Ho, and Er). Phase-transfer methods have allowed isolation of the mixed salts (Et4N)9Na2[{RE(OH2)}3CO3(PW9O34)2] (2-RE RE = Y and Er). The isostructural polyanions in these compounds are comprised of a triangular arrangement of trivalent rare-earth ions bridged by a μ3-carbonate ligand and sandwiched between two trilacunary Keggin {PW9O34} polyoxometalate ligands. Alternating-current (ac) magnetic susceptibility studies of 1-Dy, 1-Er, and 2-Er reveal the onset of frequency dependence for the out-of-phase susceptibility in the presence of an applied magnetic field at the lowest measured temperatures. Inelastic neutron scattering (INS) spectra of 1-Ho and 1-Er exhibit transitions between the lowest-lying crystal-field (CF) split states of the respective J = 8 and (15)/2 ground-state spin-orbit multiplets of the Ho(III) and Er(III) ions. Complementary ab initio calculations performed for these two analogues allow excellent reproduction of the experimental magnetic susceptibility and low-temperature magnetization data and are in reasonable agreement with the experimental INS data. The ab initio calculations reveal that the slight difference in coordination environments of the three Ln(III) ions in each complex gives rise to differences in the CF splitting that are not insignificant. This theoretical result is consistent with the observation of multiple relaxation processes by ac magnetic susceptibility and the broadness of the measured INS peaks. The ab initio calculations also indicate substantial mixing of the MJ contributions to the CF split energy levels of each Ln(III) ion. Calculations indicate that the CF ground states of the Ho(III) centers in 1-Ho are predominantly comprised of contributions from small MJ, while those of the Er(III) centers in 1-Er are predominantly comprised of contributions from large MJ, giving rise to slow magnetic relaxation. Although no direct evidence for intramolecular RE···RE magnetic coupling is observed in either magnetic or INS studies, on the basis of the ab initio calculations, we find noncollinear magnetic axes in 1-Er that are coplanar with the erbium triangle and radially arranged with respect to the triangle's centroid thus, we argue that the absence of magnetic coupling in this system arises from dipolar and antiferromagnetic superexchange interactions that cancel each other out.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8CC04995E
Abstract: The second coordination sphere determines ligand field in lanthanide coordination complexes.
Publisher: Wiley
Date: 09-09-2014
Abstract: The first members of a promising new family of hybrid amino acid-polyoxometalates have emerged from a search for modular functional molecules. Incorporation of glycine (Gly) or norleucine (Nle) ligands into an yttrium-tungstoarsenate structural backbone, followed by crystallization with p-methylbenzylammonium (p-MeBzNH3(+)) cations, affords (p-MeBzNH3)6K2(GlyH)[As(III)4(Y(III)W(VI)3)W(VI)44Y(III)4O159(Gly)8(H2O)14]⋅47 H2O (1) and enantiomorphs (p-MeBzNH3)15(NleH)3[As(III)4(Mo(V)2Mo(VI)2)W(VI)44Y(III)4O160(Nle)9(H2O)11][As(III)4(Mo(VI)2W(VI)2)W(VI)44Y(III)4O160(Nle)9(H2O)11] (generically designated 2: L-Nle, 2 a D-Nle, 2 b). An intensive structural, spectroscopic, electrochemical, magnetochemical and theoretical investigation has allowed the elucidation of site-selective metal substitution and photoreduction of the tetranuclear core of the hybrid polyanions. In the solid state, markedly different crystal packing is evident for the compounds, which indicates the role of noncovalent interactions involving the amino acid ligands. In solution, mass spectrometric and small-angle X-ray scattering studies confirm maintenance of the structure of the polyanions of 2, while circular dichroism demonstrates that the chirality is also maintained. The combination of all of these features in a single modular family emphasizes the potential of such hybrid polyoxometalates to provide nanoscale molecular materials with tunable properties.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5CC07541F
Abstract: Ab initio calculations of the electronic structure of Na 9 [Tb(W 5 O 18 ) 2 ] have allowed interpretation of the inelastic neutron scattering spectra, revealing the subtle relationship between molecular geometry and magnetic properties of two isostructural species.
Location: Italy
Location: United Kingdom of Great Britain and Northern Ireland
Location: Italy
Start Date: 2014
End Date: 2015
Funder: Australian Nuclear Science and Technology Organisation
View Funded ActivityStart Date: 2015
End Date: 2015
Funder: Australian Nuclear Science and Technology Organisation
View Funded Activity