Non-covalent control of spin-state in metal-organic complex by positioning on N-doped graphene.

de la Torre, Bruno; Švec, Martin; Hapala, Prokop; Redondo, Jesus; Krejčí, Ondřej; Lo, Rabindranath; Manna, Debashree; Sarmah, Amrit et al. · Nat Commun · 2018

basic_science · Level V

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Abstract

Nitrogen doping of graphene significantly affects its chemical properties, which is particularly important in molecular sensing and electrocatalysis applications. However, detailed insight into interaction between N-dopant and molecules at the atomic scale is currently lacking. Here we demonstrate control over the spin state of a single iron(II) phthalocyanine molecule by its positioning on N-doped graphene. The spin transition was driven by weak intermixing between orbitals with z-component of N-dopant (p<sub>z</sub> of N-dopant) and molecule (d<sub>xz</sub>, d<sub>yz</sub>, d<sub>z</sub><sup>2</sup>) with subsequent reordering of the Fe d-orbitals. The transition was accompanied by an electron density redistribution within the molecule, sensed by atomic force microscopy with CO-functionalized tip. This demonstrates the unique capability of the high-resolution imaging technique to discriminate between different spin states of single molecules. Moreover, we present a method for triggering spin state transitions and tuning the electronic properties of molecules through weak non-covalent interaction with suitably functionalized graphene.