XAS and XMCD of Single Molecule Magnets

Sessoli, Roberta; Mannini, Matteo; Pineider, Francesco; Cornia, Andrea; Sainctavit, Philippe

doi:10.1007/978-3-642-04498-4_10

Cited by 13 publications

(9 citation statements)

References 92 publications

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“…The charge distribution of the bulk phase of 1 – 3 has been assessed using temperature- and light-dependent XAS. In the past, XAS was shown to be an unmatched tool for analysis of thermally and optically triggered transitions of bistable molecular materials, affording spectral analysis of the processes with atomic selectivity and sensitivity to investigate bulk and surface-confined molecular assemblies . More specifically, it has been employed to study the electronic and structural features of switchable materials like polycyanometallates and Fe II complexes , as well as to investigate the effect of surface confinement on their bistability. , In the case of VT materials, it helped in clarifying the electronic states involved in the pressure-, entropy-, , and light-driven conversions and revealed X-ray light as an optical source of photoconversion, though the microscopic mechanism involved in the excitation process remained to be clarified .…”

Section: Resultsmentioning

confidence: 99%

Magnetic and Spectroscopic Investigation of Thermally and Optically Driven Valence Tautomerism in Thioether-Bridged Dinuclear Cobalt–Dioxolene Complexes

et al. 2013

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A series of dinuclear cobalt complexes of general formula [Co(Mentpa)(diox-S-diox)Co(Mentpa)](PF6)2·MeOH (n = 0, 2, 3) was prepared through the synthesis of the bis-bidentate ligand 6,6'-((1,4-phenylenebis(methylene))bis(sulfanediyl))bis(3,5-di-tert-butyl-benzene-1,2-diol) (diox-S-diox). The ancillary ligands Mentpa are obtained by the tripodal tris(2-pyridylmethyl)amine (tpa) ligand through successive introduction of methyl groups into the 6 position of the pyridine moieties. As expected, the steric hindrance induced by this substitution modulates the redox properties of the metal acceptor, determining the charge distribution of the metal-dioxolene adduct at room temperature. Magnetic measurements and X-ray photoelectron and X-ray absorption spectroscopies indicate that the charge distributions low-spin-Co(III)-catecholate and high-spin-Co(II)-semiquinonate characterize the complexes formed by the tpa and Me3tpa tetradentate ligands, respectively. The complex formed by the Me2tpa ligand undergoes a thermal- and light-induced interconversion of the two states, in agreement with the existence of a valence tautomeric equilibrium. All complexes were stable and behaved reproducibly under X-ray irradiation. This work points out a fast and simple chemical approach to structurally and electronically modify the catechol ring while leaving its coordination capabilities unaffected. These findings afford a robust chemical method to prepare sulfur-functionalized dioxolene ligands as new molecular bricks for chemical functionalization of noble metal surfaces with this class of molecular switches.

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Section: Resultsmentioning

confidence: 99%

Magnetic and Spectroscopic Investigation of Thermally and Optically Driven Valence Tautomerism in Thioether-Bridged Dinuclear Cobalt–Dioxolene Complexes

et al. 2013

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“…XMCD spectra were obtained with a similar averaging procedure 54 from circularly polarised (left and right) absorption spectra measured at the temperature of 2 K and under an applied magnetic field of 50 kOe parallel to the X-ray propagation vector. The same set-up was used to record the XMCD dependence on the magnetic field (hysteresis curves) as a function of sample orientation and temperature, as well as field sweeping rate.…”

Section: Methodsmentioning

confidence: 99%

Magnetic behaviour of TbPc2 single-molecule magnets chemically grafted on silicon surface

et al. 2014

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Single-molecule magnets (SMMs) are among the most promising molecular systems for the development of novel molecular electronics based on the spin transport. Going beyond the investigations focused on physisorbed SMMs, in this work the robust grafting of Terbium(III) bis(phthalocyaninato) complexes to silicon surface from a diluted solution is achieved by rational chemical design yielding the formation of a partially oriented monolayer on the conducting substrate. Here, by exploiting the surface sensitivity of X-ray circular magnetic dichroism we evidence an enhancement of the magnetic bistability of this single-molecule magnet, in contrast to the dramatic reduction of the magnetic hysteresis that characterises monolayer deposits evaporated on noble and ferromagnetic metals. Photoelectron spectroscopy investigations and density functional theory analysis suggest a non-innocent role played by the silicon substrate, evidencing the potentiality of this approach for robust integration of bistable magnetic molecules in electronic devices.

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“…Experimental insight into the electronic structure and magnetic behavior of a surface-supported Fe 4 Ph submonolayer was obtained through synchrotron-based X-ray absorption techniques, a key tool for the investigation of thin films of magnetic molecules. , Surface selectivity and sensitivity to submonolayer coverages are in fact achieved by measuring the absorption in the total electron yield (TEY) mode, which is based on the emission of secondary electrons and the detection of the draining current. Moreover, X-ray absorption based experiments involve core orbitals and are element selective and oxidation-state sensitive.…”

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confidence: 99%

Magnetic Bistability in a Submonolayer of Sublimated Fe₄ Single-Molecule Magnets

et al. 2014

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We demonstrate that Fe4 molecules can be deposited on gold by thermal sublimation in ultra-high vacuum with retention of single molecule magnet behavior. A magnetic hysteresis comparable to that found in bulk samples is indeed observed when a submonolayer film is studied by X-ray magnetic circular dichroism. Scanning tunneling microscopy evidences that Fe4 molecules are assembled in a two-dimensional lattice with short-range hexagonal order and coexist with a smaller contaminant. The presence of intact Fe4 molecules and the retention of their bistable magnetic behavior on the gold surface are supported by density functional theory calculations.

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XAS and XMCD of Single Molecule Magnets

Cited by 13 publications

References 92 publications

Magnetic and Spectroscopic Investigation of Thermally and Optically Driven Valence Tautomerism in Thioether-Bridged Dinuclear Cobalt–Dioxolene Complexes

Magnetic and Spectroscopic Investigation of Thermally and Optically Driven Valence Tautomerism in Thioether-Bridged Dinuclear Cobalt–Dioxolene Complexes

Magnetic behaviour of TbPc2 single-molecule magnets chemically grafted on silicon surface

Magnetic Bistability in a Submonolayer of Sublimated Fe₄ Single-Molecule Magnets

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XAS and XMCD of Single Molecule Magnets

Cited by 13 publications

References 92 publications

Magnetic and Spectroscopic Investigation of Thermally and Optically Driven Valence Tautomerism in Thioether-Bridged Dinuclear Cobalt–Dioxolene Complexes

Magnetic and Spectroscopic Investigation of Thermally and Optically Driven Valence Tautomerism in Thioether-Bridged Dinuclear Cobalt–Dioxolene Complexes

Magnetic behaviour of TbPc2 single-molecule magnets chemically grafted on silicon surface

Magnetic Bistability in a Submonolayer of Sublimated Fe4 Single-Molecule Magnets

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Magnetic Bistability in a Submonolayer of Sublimated Fe₄ Single-Molecule Magnets