Lattice-Directed Stabilization of Different Spin-State Phases in Metallo-Supramolecular Chains on Au Surfaces

Abstract

Controlled construction of molecule-based nanostructures with specific spin-state ordering is significant for design of spintronic devices and magnetic materials. Here, we report on the fabrication of metallo-supramolecular chains featuring varied spin-state phases on different lattice planes of the Au substrate. The one-dimensional molecular structures are formed by coordination between deprotonated tetrahydroxybenzene and Ni on Au(100) and Au(110). By employing scanning tunneling microscopy/spectroscopy and density functional theory calculations, we identify Ni atoms in the coordination chains on Au(100) and Au(110) at a low-spin (LS, S = 0) and high-spin (HS, S = 1) state, respectively, giving rise to the LS phase on Au(100) and the HS phase on Au(110). We demonstrate that the selective stabilization of the different spin-state orderings on the Au substrates stems from the distinct ground states of the spin-state phase at varied Ni–Ni separations in the chains on the different Au surfaces. Such a lattice-plane-dependent variation in Ni–Ni distance is revealed as a result of the chain-substrate commensurability. These findings provide insights into the key role of the substrate effect in tuning the magnetic properties of surface-confined supramolecular systems.

On-Surface Synthesis: A New Route Realizing Single-Layer Conjugated Metal–Organic Structures

“…This phenomena in 1D-cMOF chains of THB and Ni atoms synthesized on different Au substrates [Au(111), Au(110) and Au(100)] are studied using STM, STS under magnetic field and DFT calculations. 37 Distinct STM topographies of the 1D-cMOFs are observed on the three Au surfaces (Figure 2a). 37 Specifically, a collective SCO in the 1D-cMOF chains prepared on Au(111) is demonstrated using tip excitations.…”

“…37 Distinct STM topographies of the 1D-cMOFs are observed on the three Au surfaces (Figure 2a). 37 Specifically, a collective SCO in the 1D-cMOF chains prepared on Au(111) is demonstrated using tip excitations. 36 By applying voltage pulses, the brightness of multiple Ni atoms in the same coordination chain, which representing their spin states, are found to switch collectively (Figure 2d and e).…”

“…Benzene-based molecules have been used to react with metal atoms (Scheme ). − All these molecules are based on a phenyl ring with four radicals: (i) zwitterionic quinone (ZQ) functionalized by 2 amine groups and two carboxylic groups, (ii) tetrahydroxy benzene (THB), and (iii) 2,5-diamino-1,4-benzoquinonediimines (2HQDI). The formation of 1D-cMOFs from these molecules proceeds by successive deprotonation/metalation steps in which two covalent bonds and two coordinative bonds are formed between the metal center and two adjacent molecules.…”

“…As presented above, in the case of ZQ-Fe 1D-cMOF, the epitaxial relationship between the spin chain and the substrate can be used to strain the molecular wire, forcing it to change spin state from S = 1 to S = 2 (Figure ). These phenomena in 1D-cMOF chains of THB and Ni atoms synthesized on different Au substrates [Au(111), Au(110) and Au(100)] are studied using STM, STS under magnetic field, and DFT calculations . Distinct STM topographs of the 1D-cMOFs are observed on the three Au surfaces (Figure a) .…”

“…STM images of the coordination chains on Au(111) (d) before and (e) after the tip-induced collective SCO switching. Panels a and c are adapted with permission from ref . Copyright 2021 American Chemical Society.…”