Iron-based trinuclear metal-organic nanostructures on a surface with local charge accumulation

Abstract

Coordination chemistry relies on harnessing active metal sites within organic matrices. Polynuclear complexes—where organic ligands bind to several metal atoms—are relevant due to their electronic/magnetic properties and potential for functional reactivity pathways. However, their synthesis remains challenging; few geometries and configurations have been achieved. Here, we synthesise—via supramolecular chemistry on a noble metal surface—one-dimensional metal-organic nanostructures composed of terpyridine (tpy)-based molecules coordinated with well-defined polynuclear iron clusters. Combining low-temperature scanning probe microscopy and density functional theory, we demonstrate that the coordination motif consists of coplanar tpyʼs linked via a quasi-linear tri-iron node in a mixed (positive-)valence metal–metal bond configuration. This unusual linkage is stabilised by local accumulation of electrons between cations, ligand and surface. The latter, enabled by bottom-up on-surface synthesis, yields an electronic structure that hints at a chemically active polynuclear metal centre, paving the way for nanomaterials with novel catalytic/magnetic functionalities.

Selective on-surface covalent coupling based on metal-organic coordination template

“…The topograph indicates that there is one additional spot (white “ × ”) located beside the central spot (black “ × ”) and in the bay of each tpy terminal. The recent reports have presented similar Fe-tpy coordination chains on Ag(111) 53,54 , where the Fe trinuclear cluster was unambiguously demonstrated. Thus, we tentatively assign the three “ × ” spots within an L-mode link to three linearly distributed Fe atoms.…”

“…Thus, we tentatively assign the three “ × ” spots within an L-mode link to three linearly distributed Fe atoms. The central Fe atom exhibits a bright feature relative to other two Fe atoms, distinct from the scenario on Ag(111) 53,54 , where the central Fe atom displayed a relatively dim contrast. To interpret this feature, we have carried out DFT calculations (see Supplementary Note 4 and Supplementary Fig.…”

Long‐Range Surface‐Assisted Molecule‐Molecule Hybridization

“…NcAFM maps were smoothed by convolution with a Gaussian function, followed by a Laplace edge detection and a minimum filter. [44] DFT Calculations: DFT calculations were performed for gas-phase MgPc and MgPc on Ag(100) using the SIESTA [57] simulation tool with periodic boundary conditions, Troullier-Martins norm-conserving pseudopotentials (with relativistic corrections [58] for Ag), and the RPBE exchange-correlation [59] functional with van der Waals corrections (Grimme's method). [60] Kohn-Sham orbitals were represented by a DZP basis set with an energy shift of 0.01 and 0.02 Ry for the gas phase and Ag(100), respectively.…”

“…This technique enables real-space intramolecular structural characterisation with chemical bond resolution. [44,45] Both the single molecule and "++" dimer cases show very similar fourfold rotationally symmetric morphologies, with the four distinguishable isoindole units identical to their Lewis structure.…”

1D Coordination π–d Conjugated Polymers with Distinct Structures Defined by the Choice of the Transition Metal: Towards a New Class of Antiaromatic Macrocycles

“…Pure organic 1D materials can be obtained through catalyzed C−C coupling reactions on surface from halogenated precursors [7, 8] . Alternatively, 1D coordination‐polymers (CPs) can be isolated through coordination chemistry, the covalent bond formation resulting from on‐surface reactions between metal atoms and suitable linker groups [9–14] . One major advantage of this approach is the possibility to tune the properties of the wires by changing the nature of the metal and/or the ligand.…”