Molecular spin switches are attractive candidates for controlling the spin polarization developing at the interface between molecules and magnetic metal surfaces1,2, which is relevant for molecular spintronics devices3,4,5. However, so far, intrinsic spin switches such as spin-crossover complexes have suffered from fragmentation or loss of functionality following adsorption on metal surfaces, with rare exceptions6,7,8,9. Robust metal–organic platforms, on the other hand, rely on external axial ligands to induce spin switching10,11,12,13,14. Here we integrate a spin switching functionality into robust complexes, relying on the mechanical movement of an axial ligand strapped to the porphyrin ring. Reversible interlocked switching of spin and coordination, induced by electron injection, is demonstrated on Ag(111) for this class of compounds. The stability of the two spin and coordination states of the molecules exceeds days at 4 K. The potential applications of this switching concept go beyond the spin functionality, and may turn out to be useful for controlling the catalytic activity of surfaces15.
Subscribe to Journal
Get full journal access for 1 year
only $4.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
Djeghloul, F. et al. High spin polarization at ferromagnetic metal–organic interfaces: a generic property. J. Phys. Chem. Lett. 7, 2310–2315 (2016).
Gruber, M. et al. Spin-dependent hybridization between molecule and metal at room temperature through interlayer exchange coupling. Nano Lett. 15, 7921–7926 (2015).
Barraud, C. et al. Unravelling the role of the interface for spin injection into organic semiconductors. Nat. Phys. 6, 615–620 (2010).
Cinchetti, M., Dediu, V. A. & Hueso, L. E. Activating the molecular spinterface. Nat. Mater. 16, 507–515 (2017).
Delprat, S. et al. Molecular spintronics: the role of spin-dependent hybridization. J. Phys. D 51, 473001 (2018).
Gopakumar, T. G. et al. Electron-induced spin crossover of single molecules in a bilayer on gold. Angew. Chem. Int. Ed. 51, 6262–6266 (2012).
Miyamachi, T. et al. Robust spin crossover and memristance across a single molecule. Nat. Commun. 3, 938 (2012).
Bairagi, K. et al. Molecular-scale dynamics of light-induced spin cross-over in a two-dimensional layer. Nat. Commun. 7, 12212 (2016).
Knaak, T. et al. Fragmentation and distortion of terpyridine-based spin-crossover complexes on Au(111). J. Phys. Chem. C 123, 4178–4185 (2019).
Wäckerlin, C. et al. Controlling spins in adsorbed molecules by a chemical switch. Nat. Commun. 1, 61 (2010).
Seufert, K., Auwärter, W. & Barth, J. V. Discriminative response of surface-confined metalloporphyrin molecules to carbon and nitrogen monoxide. J. Am. Chem. Soc. 132, 18141–18146 (2010).
Wäckerlin, C. et al. Ammonia coordination introducing a magnetic moment in an on-surface low-spin porphyrin. Angew. Chem. Int. Ed. 52, 4568–4571 (2013).
Hermanns, C. F. et al. Huge magnetically coupled orbital moments of Co porphyrin molecules and their control by CO adsorption. Phys. Rev. B 88, 104420 (2013).
Gopakumar, T. G., Tang, H., Morillo, J. & Berndt, R. Transfer of Cl ligands between adsorbed iron tetraphenylporphyrin molecules. J. Am. Chem. Soc. 134, 11844–11847 (2012).
Sugiyasu, K., Ogi, S. & Takeuchi, M. Strapped porphyrin-based polymeric systems. Polym. J. 46, 674–681 (2014).
Venkataramani, S. et al. Magnetic bistability of molecules in homogeneous solution at room temperature. Science 331, 445–448 (2011).
Matino, F. et al. Single azopyridine-substituted porphyrin molecules for configurational and electronic switching. Chem. Commun. 46, 6780–6782 (2010).
Momenteau, M. & Reed, C. A. Synthetic heme–dioxygen complexes. Chem. Rev. 94, 659–698 (1994).
Gazeau S., Pecaut J. & Marchon J.-C. Nickel porphyrin nanotweezers. Chem. Commun. 1644–1645 (2001).
Zhang, X. et al. Ultrafast stimulated emission and structural dynamics in nickel porphyrins. J. Phys. Chem. A 111, 11736–11742 (2007).
Duval, H., Bulach, V., Fischer, J. & Weiss, R. Four-coordinate, low-spin (S = 0) and six-coordinate, high-spin (S = 1) nickel(ii) complexes of tetraphenylporphyrins with β-pyrrole electron-withdrawing substituents: porphyrin-core expansion and conformation. Inorg. Chem. 38, 5495–5501 (1999).
Jia, S.-L. et al. Axial coordination and conformational heterogeneity of nickel(ii) tetraphenylporphyrin complexes with nitrogenous bases. Inorg. Chem. 37, 4402–4412 (1998).
Gutzeit, F. et al. Structure and properties of a five-coordinate Ni(ii) porphyrin. Inorg. Chem. 58, 12542–12546 (2019).
Krasnikov, S. A. et al. Electronic structure of Ni(ii) porphyrins and phthalocyanine studied by soft X-ray absorption spectroscopy. Chem. Phys. 332, 318–324 (2007).
Gottfried, J. M. Surface chemistry of porphyrins and phthalocyanines. Surf. Sci. Rep. 70, 259–379 (2015).
Auwärter, W., Écija, D., Klappenberger, F. & Barth, J. V. Porphyrins at interfaces. Nat. Chem. 7, 105–120 (2015).
Ohresser, P. et al. DEIMOS: a beamline dedicated to dichroism measurements in the 350–2,500 eV energy range. Rev. Sci. Instrum. 85, 013106 (2014).
Joly, L. et al. Fast continuous energy scan with dynamic coupling of the monochromator and undulator at the DEIMOS beamline. J. Synchrotron Radiat. 21, 502–506 (2014).
Kappler, J.-P. et al. Ultralow-temperature device dedicated to soft X-ray magnetic circular dichroism experiments. J. Synchrotron Radiat. 25, 1727–1735 (2018).
Piamonteze, C. et al. X-treme beamline at SLS: X-ray magnetic circular and linear dichroism at high field and low temperature. J. Synchrotron Radiat. 19, 661–674 (2012).
We are grateful to the SOLEIL staff for the smooth running of the facility and to F. Leduc for technical assistance. We acknowledge funding by the Deutsche Forschungsgemeinschaft (DFG) via SFB 677. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant no. 766726.
Peer Review Information Nature Nanotechnology thanks Mirko Cinchetti and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Examples of switching procedures a–b from the LS to the HS state and c–d from the HS to the LS state. The tip is positioned over the center of the complex experiencing the switching, and the current feedback loop is active while the voltage is gradually varied as a function of time. While the switching from the LS to the HS state (HS to LS) occurs at a sample voltage of 2.5 V (\(-1.7\) V) for these examples, the voltage required to induce a transition varies from 2.1 to 2.7 V (\(-1.6\) to \(-2.1\) V), and the large voltage may need to be applied for several seconds to several minutes for transitions from the LS to the HS state. The large spread in the threshold voltages may be due to the exact positioning of the tip and details of the molecule’s environment. To increase the success rate of the switching from the LS to the HS state, we usually applied a sample voltage between 2.5 and 2.7 V with a current between 30 pA and 1 nA for approximately 5 min. While this procedure is very effective, it is at the cost of selectivity as neighboring molecules were usually switched as well. In contrast, HS to LS switching is relatively efficient. Sub-pA currents may be sufficient to induce the corresponding transition (see Extended Data Fig. 2). The arrows indicate the time at which the switching takes place.
a–e Constant-height STM topographs (1 V, 10 pA, 4.65 nm wide) describing the switching sequence of two complexes (compound 2) on Ag(111). In this example, a sample voltage of 2.7 V was applied for 30 s between the acquisition of topographs a and b, and between topographs b and c (tunneling current of 30 pA) to induce transitions from the LS to the HS state of the lower left and lower right complexes. The topographs a and b illustrate that the switching can be induced in neighboring molecules upon application of large voltages. Indeed, the tip was positioned on the top right molecule (white disk in a) while the lower right molecule is switched (lower right molecule in b). f, \(I-V\) curve recorded atop the lower right molecule in c leading to the switching from the HS to the LS state. Note that a current of \(\approx 250\) fA was sufficient to induce the transition highlighting the efficiency of the backward switching process.
About this article
Cite this article
Köbke, A., Gutzeit, F., Röhricht, F. et al. Reversible coordination-induced spin-state switching in complexes on metal surfaces. Nat. Nanotechnol. 15, 18–21 (2020). https://doi.org/10.1038/s41565-019-0594-8
Chemistry – A European Journal (2021)
Theoretical modeling of the singlet–triplet spin transition in different Ni(ii)-diketo-pyrphyrin-based metal–ligand octahedral complexes
Physical Chemistry Chemical Physics (2021)
Angewandte Chemie (2021)
Journal of Applied Physics (2021)
DFT computational insight into the mechanism of the monomer–trimer isomerism of Ni(II) bis-acetylacetonate
Inorganica Chimica Acta (2021)