Spin Crossover in a Vacuum-Deposited Submonolayer of a Molecular Iron(II) Complex

Bernien, Matthias; Wiedemann, Dennis; Hermanns, Christian Felix; Krüger, Alex; Rolf, Daniela; Kroener, Wolfgang; Müller, Paul; Grohmann, Andreas; Kuch, W.

doi:10.1021/jz3011805

Cited by 99 publications

(157 citation statements)

References 24 publications

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“…We found anedge jump of 2.3%,which is lower than the ones reported for another Fe(III)-based molecular system prepared by monolayer self-assembly 36 ,and for 0.8 monolayers of another SCO complex on HOPG. 27 As detailed in Figure S11 in Supporting Information, this edge jump, being 100 times smaller than the ones found for the bulk and thick film samples, gives an approximate coverage about 0.03 to 0.14 monolayers, thus allowing to safely exclude the presence of multilayer islands that would moreover be clearly visible on STM images.…”

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confidence: 84%

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Temperature- and Light-Induced Spin Crossover Observed by X-ray Spectroscopy on Isolated Fe(II) Complexes on Gold

Warner¹,

Oberg²,

Gill³

et al. 2013

J. Phys. Chem. Lett.

153

202

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Using X-ray absorption techniques, we show that temperature-and light-induced spin crossover properties are conserved for a sub-monolayer of the [Fe(H 2 B(pz) 2 ) 2 (2,2'-bipy)] complex evaporated onto a Au(111) surface. For a significant fraction of the molecules, we see changes in the absorption at the L 2,3 edges that are consistent with those observed in bulk and thick film references. Assignment of these changes to spin crossover is further supported by multiplet calculations to simulate the x-ray absorption spectra. As others have observed in experiments on monolayer coverages, we find that many molecules in our submonolayer system remain pinned in one of the two spin states. Our results clearly demonstrate that temperature-and light-induced spin-crossover is possible for isolated molecules on surfaces, but that interactions with the surface may play a key role in determining when this can occur. TOC X-ray absorption techniques evidenced that temperature-and light-induced spin crossover properties were conserved for a sub-monolayer of the [Fe(H 2 B(pz) 2 ) 2 (2,2'-bipy)] complex evaporated on a Gold surface KEYWORDS: spin crossover,·UHV evaporation,·submonolayer,·X-ray absorption,·iron complexes 3 Spin Crossover (SCO) complexes are promising building blocks for spintronic 1 Using variable temperature X-ray absorption spectra, we examined a submonolayer coverage evaporated in situ under UHV conditions on Au(111), before and after irradiation with visible laser light. We compare these results to those obtained from two other samples: 1) a 5 single crystal finely scratched on gold foil, which we use as a spectroscopic bulk reference; and 2) a 300 nm thick film sublimedex situ on copper foil, to check the preservation of structure and properties of the complex. Experimental spectra were then compared to the ones obtained using multiplet calculations. 37-39The variation of the L 2,3 edge spectra for the bulk sample over the range of the thermal spin crossover (100-300 K) is reported in Figure 1a(see also Figure S1 in Supplementary Information Spectra measured on the thick film prepared ex situ are similar to the bulk, and show comparable temperature dependence (Figure 1b and Figure S1). Nevertheless, the thick film spectrum is slightly differentfrom the bulk compound: shoulders on the high-energy side (at 300 K) or at the low-energy side (at 100 K) of the L 3 absorption peak, are likely associated with a small fraction of decomposition product, which maybe caused by air exposure of this sample prepared ex situ.The analysis of the temperature-dependent spectra as weighted sums of the bulk spectra at 300 K and 100 K, chosen as representative of the HS and LS state respectively, allows for the extraction of the temperature dependence of the HS fraction (Table S2). For the thick film, the shoulder signals were found to be temperature independent, and thus do not affect the switching behavior. We extracted this spurious contribution ( Figures S3 and S4) and subtracted it from all spectra before evaluating...

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confidence: 84%

“…27 The latter complex shows a much more gradual SCO, hinting that cooperative interactions between the molecules may play a role in blocking SCO.…”

mentioning

confidence: 99%

Temperature- and Light-Induced Spin Crossover Observed by X-ray Spectroscopy on Isolated Fe(II) Complexes on Gold

Warner¹,

Oberg²,

Gill³

et al. 2013

J. Phys. Chem. Lett.

153

202

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“…One is that several molecules are grouped together, thus forming small islands [17,48]. However, if this were the case, one would not expect such a relatively narrow size distribution, unless specific geometries are preferred due to intermolecular interactions (for which we have no evidence).…”

Section: Adsorbate Characterisation By Stmmentioning

confidence: 97%

Thiocyanate Anchors for Salt-like Iron(II) Complexes on Au(111): Promises and Caveats

Stock

Erbe

Buck

et al. 2014

Zeitschrift Für Naturforschung B

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The formation of self-assembled monolayers (SAMs) on Au(111) from solution has been investigated for two ionic iron(II) complexes of the type [Fe(L)](BF 4 ) 2 , where L is tripodal hexadentate and contains three thiocyanate anchor groups. The ligands (L1, L2; donor set: N 6 ) are obtained by Schiff base condensation of a tripodal triamine (L1: tris-(2-aminoethyl)amine, 'tren'; L2: 1,1 ,1 -trimethyl(thiophosphoryl)trihydrazide) with 5-(4-thiocyanatobutoxy) pyridine-2-carbaldehyde. Layers of the complexes adsorbed on Au(111) from methanol solution have been characterised using scanning tunnelling microscopy (STM), infrared reflectance absorbance (IRRAS), X-ray photoelectron (XPS) and UV/Vis reflectance spectroscopies, as well as ellipsometry. Complex [Fe(L1)](BF 4 ) 2 deposits intact on a gold surface and retains its optical addressability. Elaboration of this result may provide access to a new class of self-assembled layers, employing salt-like tripodal coordination compounds with thiocyanate anchors. The second complex, [Fe(L2)](BF 4 ) 2 , which contains a sulphur atom in the ligand backbone, is not sufficiently stable under the same conditions.

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“…31 Synthesis of [FeL(NCS) 2 ] (1). In addition to the route starting from [Fe(NCS) 2 ( py) 4 ] ( py: pyridine), 17 …”

Section: Materials and Analytical Methodsmentioning

confidence: 99%

“…17 A possible explanation is the formation of a twodimensional HS lattice on HOPG through high-temperature vapour deposition. When cooling the sample, interactions with the surface do not allow for relaxation into the energetically most preferable LS arrangement, thereby lessening Δ SCO H m .…”

Section: Dalton Transactions Papermentioning

confidence: 99%

Bulk spin-crossover in the complex [FeL(NCS)₂] of a tris(pyridyl)ethane-derived N₄-ligand—a temperature-dependent crystallographic study

Wiedemann

Grohmann

2014

Dalton Trans.

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Spin Crossover in a Vacuum-Deposited Submonolayer of a Molecular Iron(II) Complex

Cited by 99 publications

References 24 publications

Temperature- and Light-Induced Spin Crossover Observed by X-ray Spectroscopy on Isolated Fe(II) Complexes on Gold

Temperature- and Light-Induced Spin Crossover Observed by X-ray Spectroscopy on Isolated Fe(II) Complexes on Gold

Thiocyanate Anchors for Salt-like Iron(II) Complexes on Au(111): Promises and Caveats

Bulk spin-crossover in the complex [FeL(NCS)₂] of a tris(pyridyl)ethane-derived N₄-ligand—a temperature-dependent crystallographic study

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Spin Crossover in a Vacuum-Deposited Submonolayer of a Molecular Iron(II) Complex

Cited by 99 publications

References 24 publications

Temperature- and Light-Induced Spin Crossover Observed by X-ray Spectroscopy on Isolated Fe(II) Complexes on Gold

Temperature- and Light-Induced Spin Crossover Observed by X-ray Spectroscopy on Isolated Fe(II) Complexes on Gold

Thiocyanate Anchors for Salt-like Iron(II) Complexes on Au(111): Promises and Caveats

Bulk spin-crossover in the complex [FeL(NCS)2] of a tris(pyridyl)ethane-derived N4-ligand—a temperature-dependent crystallographic study

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Bulk spin-crossover in the complex [FeL(NCS)₂] of a tris(pyridyl)ethane-derived N₄-ligand—a temperature-dependent crystallographic study