SELECTIVE SWITCHING SURFACES, INTERFACES AND NANOSYSTEMS We employed low-temperature scanning tunneling microscopy to observe SYNCHROTRON SOLEIL HIGHLIGHTS 2020 and control the individual complexes. The complexes self-assemble into highly ordered arrays. Each molecule of an array can be separately addressed and reversibly switched between two states by applying a positive or negative voltage. A sequence of switching events is shown DEIMOS BEAMLINE in Figure 3, where the lower left molecule appears significantly brighter after electron injection. The molecule is then converted back to its pristine Associated publication state by depopulating the dx2-y2orbital of the Ni ion.The molecule is in the low-spin state in the pristine form as evident from the XA data (Figure Reversible coordination-induced spin- 2). The change of spin state upon manipulation has been confirmed by state switching in complexes on metal surfaces. further spectroscopic measurements performed with the microscope. A. Köbke, F. Gutzeit, F. Röhricht, FIGURE 2 A. Schlimm, J. Grunwald, F. Tuczek, M. Studniarek, D. Longo, F. Choueikani, E. Otero, P. Ohresser, S. Rohlf, S. Johannsen, F. Diekmann, K. Rossnagel, A. Weismann, T. Jasper-Toennies, C. Näther, R. Herges, R. Berndt & M. Gruber. Nature Nanotechnology, 15, 18 (2020). References [1] Molnar etal., J. Mater. Chem. C 2, 1360 (2014). [2] Gruber & Berndt, Magnetochemistry FIGURE 3 6, 35 (2020). [3] Wäckerlin et al., Angew. Chem. Int. Ed. 52, 4568 (2013). Corresponding authors Manuel Gruber Faculty of physics, University Duisburg-Essen, Duisburg - Germany manuel.gruber@uni-due.de CONCLUSION Rainer Herges Otto-Diels-Institut für Organische We have designed a new type of molecular spin switch interlocking spin Chemie, Christian-Albrechts-Universität and coordination states. The concept has been verified on three derivatives zu Kiel, Germany using various methods including x-ray absorption spectroscopy and x-ray rherges@oc.uni-kiel.de magnetic circular dichroism. The spin state of individual molecules on a Ag(111) surfaces is controllably toggled with the help of the tip of a low- Captions temperature scanning tunneling microscope. Besides their importance FIGURE 1: The hairclip concept essentially consists in the field of molecular spintronics, these findings may prove useful to in coupling the spin state (high/low), the coordination number (5/4) and the shape of the porphyrin (flat/ruffled). control catalytic activity of surfaces, which is expected to depend on Spin transition may be achieved by modification of any of the spin and accessibility of the Ni ion. these properties. FIGURE 2: X-ray absorption spectra revealing the Acknowledgement spin-state of three derivatives implementing the hairclip We are grateful to the SOLEIL staff, and in particular to the staff of the concept. Minor modifications between the derivatives allow to tune the spin ground state of the complexes on DEIMOS beamline, for the smooth running of the facility. We acknowledge Ag(111). funding by the Deutsche Forschungsgemeinschaft (DFG) via SFB 677. This project has received funding from the European Union’s Horizon FIGURE 3: High-resolution scanning-tunneling microscopy image evidencing the reversible, selective 2020 research and innovation programme under grant no. 766726. switching of the lower left molecule from the pristine low-spin to the high-spin state and back to the low-spin state. Current pulses were applied between the images. 23