7 results on '"Marjo, Christopher E."'
Search Results
2. Spin Crossover Induced by Changing the Identity of the Secondary Metal Ion from PdII to NiII in a Face‐Centered FeII8MII6 Cubic Cage**.
- Author
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Min, Hyunsung, Craze, Alexander R., Wallis, Matthew J., Tokunaga, Ryuya, Taira, Takahiro, Hirai, Yutaka, Bhadbhade, Mohan M., Fanna, Daniel J., Marjo, Christopher E., Hayami, Shinya, Lindoy, Leonard F., and Li, Feng
- Subjects
SPIN crossover ,SCRAP metals ,METAL ions ,MOSSBAUER spectroscopy ,MAGNETIC susceptibility ,SECONDARY ion mass spectrometry - Abstract
Discrete spin crossover (SCO) heteronuclear cages are a rare class of materials which have potential use in next‐generation molecular transport and catalysis. Previous investigations of cubic cage [Fe8Pd6L8]28+ constructed using semi‐rigid metalloligands, found that FeII centers of the cage did not undergo spin transition. In this work, substitution of the secondary metal center at the face of the cage resulted in SCO behavior, evidenced by magnetic susceptibility, Mössbauer spectroscopy and single crystal X‐ray diffraction. Structural comparisons of these two cages shed light on the possible interplay of inter‐ and intramolecular interactions associated with SCO in the NiII analogue, 1 ([Fe8Ni6L8(CH3CN)12]28+). The distorted octahedral coordination environment, as well as the occupation of the CH3CN in the NiII axial positions of 1, prevented close packing of cages observed in the PdII analogue. This led to offset, distant packing arrangements whereby important areas within the cage underwent dramatic structural changes with the exhibition of SCO. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
3. A complementary characterisation technique for spin crossover materials; the application of X-ray photoelectron spectroscopy for future device applications.
- Author
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Craze, Alexander R., Marjo, Christopher E., and Li, Feng
- Subjects
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X-ray photoelectron spectroscopy , *SPIN crossover , *SURFACE analysis , *THIN films , *SURFACES (Technology) - Abstract
Spin crossover (SCO) materials have long been studied for their inherent electronic switchability, which has been well investigated for potential application in electronic and switching devices. As the technologies for the fabrication of thin films and monolayers continue to develop at an exceedingly rapid pace, an emerging challenge for the SCO community has become the characterisation of spin transitions in the surface layers of a material, as well as understanding the origins of discrepancies observed between SCO in thin films and that of the bulk material. For the manufacture of such devices to become a reality, it is crucial to understand how spin crossover is affected by interactions with the substrate material and within thin films. As such, detailed analysis of the surface layers without interference from the substrate material emerged as a critical area of characterisation for future developments in SCO devices. In this regard, X-ray Photoelectron Spectroscopy (XPS) has emerged as a complementary technique for the analysis of SCO in the surface layers of a material, becoming an essential part of a multi-technique protocol that is driving advances in the field. Here we describe the complementary application of XPS to a variety of SCO materials, review major developments and provide illustrative examples of innovations made through surface analysis with XPS. [ABSTRACT FROM AUTHOR]
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- 2022
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4. A mixed-spin spin-crossover thiozolylimine [Fe L ] cage
- Author
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Li, Li, Craze, Alexander R., Mustonen, Outi, Zenno, Hikaru, Whittaker, Jacob J., Hayami, Shinya, Lindoy, Leonard F., Marjo, Christopher E., Clegg, Jack K., Aldrich-Wright, Janice R., and Li, Feng
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Materials science ,010405 organic chemistry ,010402 general chemistry ,01 natural sciences ,Molecular physics ,Temperature induced ,0104 chemical sciences ,3. Good health ,law.invention ,Condensed Matter::Soft Condensed Matter ,Inorganic Chemistry ,SQUID ,Condensed Matter::Materials Science ,X-ray photoelectron spectroscopy ,law ,Spin crossover ,Physics::Atomic and Molecular Clusters ,Condensed Matter::Strongly Correlated Electrons ,Physics::Chemical Physics ,Cage ,Spin (physics) - Abstract
A mixed-spin spin-crossover thiozolylimine [Fe L ] tetrahedral cage is reported., The self-assembly of a mixed-spin [Fe L ] tetrahedral cage is reported. The cage undergoes temperature induced spin-crossover with a 29 K hystereisis. Variable temperature X-ray photoelectron spectroscopy (VT-XPS), combined with SQUID data, allowed differentiation between the surface and bulk magnetic properties.
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- 2019
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5. Direct monitoring of spin transitions in a dinuclear triple-stranded helicate iron(ii) complex through X-ray photoelectron spectroscopy.
- Author
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Li, Li, Craze, Alexander R., Akiyoshi, Ryohei, Tsukiashi, Asami, Hayami, Shinya, Mustonen, Outi, Bhadbhade, Mohan M., Bhattacharyya, Saroj, Marjo, Christopher E., Wang, Yun, Lindoy, Leonard F., Aldrich-Wright, Janice R., and Li, Feng
- Subjects
SPIN crossover ,IRON compounds ,METAL complexes - Abstract
A dinuclear helical iron(ii) complex of a new ditopic thiazolylimine ligand (L) has been synthesised via supramolecular assembly. The resulting dinuclear helical cylinder [Fe
2 L3 ]·4BF4 was investigated by variable temperature X-ray crystallography, ESI high resolution mass spectrometry, CHN analysis, FT-IR and UV-Vis spectroscopy. The nature of the spin transition was investigated by magnetic susceptibility measurements, and confirmed by VT-SCXRD and X-ray photoelectron spectroscopy. [Fe2 L3 ]·4BF4 displays a complete spin transition with a gradual-abrupt character at T1/2 = 348 K and represents a new example of a dinuclear iron(ii) complex exhibiting a spin transition at high temperature. Both VT-SCXRD and XPS measurements show excellent correlation with the magnetic susceptibility experiments, demonstrating the power of XPS not just to confirm, but also to clearly follow the spin-state transition in Fe(ii) SCO complexes. [ABSTRACT FROM AUTHOR]- Published
- 2018
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6. Investigation of the Spin Crossover Properties of Three Dinulear Fe(II) Triple Helicates by Variation of the Steric Nature of the Ligand Type.
- Author
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Craze, Alexander R., Sciortino, Natasha F., Badbhade, Mohan M., Kepert, Cameron J., Marjo, Christopher E., and Feng Li
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SPIN crossover ,LIGANDS (Chemistry) ,SCHIFF bases ,CHEMICAL synthesis ,COMPLEX compounds - Abstract
The investigation of new spin-crossover (SCO) compounds plays an important role in understanding the key design factors involved, informing the synthesis of materials for future applications in electronic and sensing devices. In this report, three bis-bidentate ligands were synthesized by Schiff base condensation of imidazole-4-carbaldehyde with 4,4-diaminodiphenylmethane (L
1 ), 4,4'-diaminodiphenyl sulfide (L2 ) and 4,4'-diaminodiphenyl ether (L3 ) respectively. Their dinuclear Fe(II) triple helicates were obtained by complexation with Fe(BF4 )2 .6H2 O in acetonitrile. The aim of this study was to examine the influence of the steric nature of the ligand central atom (-X-, where X = CH2 , S or O) on the spin-crossover profile of the compound. The magnetic behaviours of these compounds were investigated and subsequently correlated to the structural information from single-crystal X-ray crystallographic experiments. All compounds [Fe2 (L1 )3 ](BF4 )2 (1), [Fe2 (L2 )3 ](BF4 )2 (2) and [Fe2 (L3 )3 ](BF4 )2 (3), demonstrated approximately half-spin transitions, with T1/2 ↓ values of 155, 115 and 150 K respectively, corresponding to one high-spin (HS) and one low-spin (LS) Fe(II) centre in a [LS-HS] state at 50 K. This was also confirmed by crystallographic studies, for example, bond lengths and the octahedral distortion parameter (∑) at 100 K. The three-dimensional arrangement of the HS and LS Fe(II) centres throughout the crystal lattice was different for the three compounds, and differing extents of intermolecular interactions between BF4 - counter ions and imidazole N-H were present. The three compounds displayed similar spin-transition profiles, with 2 (-S-) possessing the steepest nature. The shape of the spin transition can be altered in this manner, and this is likely due to the subtle effects that the steric nature of the central atom has on the crystal packing (and thus inter-helical Fe-Fe separation), intermolecular interactions and Fe-Fe intra-helical separations. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
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7. Solvent Effects on the Spin-Transition in a Series of Fe(II) Dinuclear Triple Helicate Compounds.
- Author
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Craze, Alexander R., Li, Feng, Bhadbhade, Mohan M., Marjo, Christopher E., Kepert, Cameron J., and Lindoy, Leonard F.
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SPIN crossover ,CRYSTALLOGRAPHY ,SOLVENTS - Abstract
This work explores the effect of lattice solvent on the observed solid-state spin-transition of a previously reported dinuclear Fe(II) triple helicate series 1–3 of the general form [Fe
II 2 L3 ](BF4 )4 (CH3 CN)n , where L is the Schiff base condensation product of imidazole-4-carbaldehyde with 4,4-diaminodiphenylmethane (L1 ), 4,4′-diaminodiphenyl sulfide (L2 ) and 4,4′-diaminodiphenyl ether (L3 ) respectively, and 1 is the complex when L = L1 , 2 when L = L2 and 3 when L = L3 (Craze, A.R.; Sciortino, N.F.; Bhadbhade, M.M.; Kepert, C.J.; Marjo, C.E.; Li, F. Investigation of the Spin Crossover Properties of Three Dinuclear Fe(II) Triple Helicates by Variation of the Steric Nature of the Ligand Type. Inorganics.2017, 5 (4), 62). Desolvation of 1 and 2 during measurement resulted not only in a decrease in T1/2 and completeness of spin-crossover (SCO) but also a change in the number of steps in the spin-profile. Compounds 1 and 2 were observed to change from a two-step 70% complete transition when fully solvated, to a single-step half complete transition upon desolvation. The average T1/2 value of the two-steps in the solvated materials was equivalent to the single T1/2 of the desolvated sample. Upon solvent loss, the magnetic profile of 3 experienced a transformation from a gradual SCO or weak antiferromagnetic interaction to a single half-complete spin-transition. Variable temperature single-crystal structures are presented and the effects of solvent molecules are also explored crystallographically and via a Hirshfeld surface analysis. The spin-transition profiles of 1–3 may provide further insight into previous discrepancies in dinuclear triple helicate SCO research reported by the laboratories of Hannon and Gütlich on analogous systems (Tuna, F.; Lees, M. R.; Clarkson, G. J.; Hannon, M. J. Readily Prepared Metallo-Supramolecular Triple Helicates Designed to Exhibit Spin-Crossover Behaviour. Chem. Eur. J.2004, 10, 5737–5750 and Garcia, Y.; Grunert, C. M.; Reiman, S.; van Campenhoudt, O.; Gütlich, P. The Two-Step Spin Conversion in a Supramolecular Triple Helicate Dinuclear Iron(II) Complex Studied by Mössbauer Spectroscopy. Eur. J. Inorg. Chem.2006, 3333–3339). [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
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