Direct monitoring of spin transitions in a dinuclear triple-stranded helicate iron(<scp>ii</scp>) complex through X-ray photoelectron spectroscopy

Li, Li; Craze, Alexander R.; Akiyoshi, Ryohei; Tsukiashi, Asami; Hayami, Shinya; Mustonen, Outi; Bhadbhade, Mohan; Bhattacharyya, Saroj; Marjo, Christopher E.; Wang, Yun; Lindoy, Leonard F.; Aldrich‐Wright, Janice R.; Li, Feng

doi:10.1039/c7dt04190j

Cited by 26 publications

(18 citation statements)

References 30 publications

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“…(Fe 2p 1/2 )-B.E. (Fe 2p 3/2 ) = 13.2 eV, is also in accordance with a high-spin ferric state with increased spin-orbit coupling [61], or ∆ values typically observed for spin-crossover complexes [62,63]. The fitting of the Fe 2p multiplet ('Fe 2p 1-3') and the shake-up satellite ('Fe 2p 4') is illustrated in Figure 7a, the selected binding energy data from the fitted component peaks are listed in Table S1.…”

Section: Characterization Of the Complex As A Solid Ad-layer On Indiusupporting

confidence: 79%

An Iron(III) Complex with Pincer Ligand—Catalytic Water Oxidation through Controllable Ligand Exchange

et al. 2020

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Pincer ligands occupy three coplanar sites at metal centers and often support both stability and reactivity. The five-coordinate [FeIIICl2(tia-BAI)] complex (tia-BAI− = 1,3-bis(2’-thiazolylimino)isoindolinate(−)) was considered as a potential pre-catalyst for water oxidation providing the active form via the exchange of chloride ligands to water molecules. The tia-BAI− pincer ligand renders water-insolubility to the Fe–(tia-BAI) assembly, but it tolerates the presence of water in acetone and produces electrocatalytic current in cyclic voltammetry associated with molecular water oxidation catalysis. Upon addition of water to [FeIIICl2(tia-BAI)] in acetone the changes in the Fe3+/2+ redox transition and the UV-visible spectra could be associated with solvent-dependent equilibria between the aqua and chloride complex forms. Immobilization of the complex from methanol on indium-tin-oxide (ITO) electrode by means of drop-casting resulted in water oxidation catalysis in borate buffer. The O2 detected by gas chromatography upon electrolysis at pH 8.3 indicates >80% Faraday efficiency by a TON > 193. The investigation of the complex/ITO assembly by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) before and after electrolysis, and re-dissolution tests suggest that an immobilized molecular catalyst is responsible for catalysis and de-activation occurs by depletion of the metal.

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Section: Characterization Of the Complex As A Solid Ad-layer On Indiusupporting

confidence: 79%

An Iron(III) Complex with Pincer Ligand—Catalytic Water Oxidation through Controllable Ligand Exchange

et al. 2020

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“…The majority of SCO dinuclear triple helicates reported previously exhibit such incompleteness, and, to the best of our knowledge, only the systems of Kruger and co-workers[54,72] as well as our laboratory[73] display a full transition of the two Fe(II) sites of the dinuclear triple helicate architecture. The distortion required of the two spin-centres in semi-rigid dinuclear triple helicates makes a complete [HS-HS]↔[LS-LS] transition difficult to achieve.…”

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confidence: 66%

Solvent Effects on the Spin-Transition in a Series of Fe(II) Dinuclear Triple Helicate Compounds

et al. 2018

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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 [FeII2L3](BF4)4(CH3CN)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).

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“…Only four examples of Fe(II) dinuclear triple helicates have been reported with a full SCO at both Fe(II) sites of the complex, including our recent report of the magnetic properties of the thiazole derivative of the compounds presented in this study. − Such compounds are instead more commonly found to exhibit incomplete transitions, with either the [LS–HS] intermediate or a 50:50 mixture of [LS–LS]:[HS–HS] compounds stabilized at low temperatures. − In order to provide synthetic control, the design of dinuclear spin-switching architectures often utilizes semirigid bridging ligands. Previously, the often incomplete spin transition in similar dinuclear structures has been explained to be a consequence of intramolecular steric restrictions imposed by the semirigid ligands employed, whereby the ability to distort at both Fe(II) centers of the complex is restricted. − In regards to the potential of these materials in device or sensor applications, a full [HS–HS] ↔ [LS–LS] transition is desirable as a result of the larger electronic and structural changes exhibited .…”

Section: Introductionmentioning

confidence: 99%

A Rare Example of a Complete, Incomplete, and Non-Occurring Spin Transition in a [Fe₂L₃]X₄ Series Driven by a Combination of Solvent-and Halide-Anion-Mediated Steric Factors

et al. 2020

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A trend between the degree of steric congestion of the Fe(II) coordination environment and the extent of spin transition (percentage completeness) has been observed in a series of halide salts of a dinuclear triple helicate architecture with the general form [Fe2 L 3]X4 (where X = Cl– for 1, Br– for 2, and (I–)3/I3 – for 3, and L is (1E,1′E)-N,N′-(oxybis(4,1-phenylene))bis(1-(1H-imidazol-4-yl)methanimine). Crystal packing densities of adjacent helicates were found to decrease with increasing anion size. Greater steric congestion by neighboring helicates favored the [HS–HS] state of the dinuclear triple helicate architecture. As a result, the highly crowded Cl– salt (1) did not undergo spin-crossover (SCO), the more congested Br– salt (2) underwent an incomplete solvent-dependent transition, and the least crowded (I–)3/I3 – analogue (3) exhibited a full SCO from the [HS–HS] ↔ [LS–LS] state. Furthermore, an interesting two-step transition was observed in the Br– salt, exhibiting a 28 K thermal hysteresis in the higher temperature step, the largest thermal hysteresis reported to date for a Fe(II) dinuclear triple helicate system. Variable-temperature single-crystal X-ray diffraction (SCXRD) analysis of 2 demonstrated that this two-step profile was found to be the result of crystallographic parameters evolving in a two-step manner with temperature, rather than a crystallographic phase change.

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Direct monitoring of spin transitions in a dinuclear triple-stranded helicate iron(ii) complex through X-ray photoelectron spectroscopy

Cited by 26 publications

References 30 publications

An Iron(III) Complex with Pincer Ligand—Catalytic Water Oxidation through Controllable Ligand Exchange

An Iron(III) Complex with Pincer Ligand—Catalytic Water Oxidation through Controllable Ligand Exchange

Solvent Effects on the Spin-Transition in a Series of Fe(II) Dinuclear Triple Helicate Compounds

A Rare Example of a Complete, Incomplete, and Non-Occurring Spin Transition in a [Fe₂L₃]X₄ Series Driven by a Combination of Solvent-and Halide-Anion-Mediated Steric Factors

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Direct monitoring of spin transitions in a dinuclear triple-stranded helicate iron(ii) complex through X-ray photoelectron spectroscopy

Cited by 26 publications

References 30 publications

An Iron(III) Complex with Pincer Ligand—Catalytic Water Oxidation through Controllable Ligand Exchange

An Iron(III) Complex with Pincer Ligand—Catalytic Water Oxidation through Controllable Ligand Exchange

Solvent Effects on the Spin-Transition in a Series of Fe(II) Dinuclear Triple Helicate Compounds

A Rare Example of a Complete, Incomplete, and Non-Occurring Spin Transition in a [Fe2L3]X4 Series Driven by a Combination of Solvent-and Halide-Anion-Mediated Steric Factors

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A Rare Example of a Complete, Incomplete, and Non-Occurring Spin Transition in a [Fe₂L₃]X₄ Series Driven by a Combination of Solvent-and Halide-Anion-Mediated Steric Factors