On-surface synthesized magnetic nanoclusters of ferrocene derivatives

Abstract

On-surface molecular self-assembly in solution can produce two-dimensional (2D) materials with unique surface nanostructures that have the potential to create new functionalities. The surface completely differs from the uniform flat surface of conventional 2D materials such as graphene, MoS₂, and 2D van der Waals nanosheets. The recently developed on-surface chemical synthesis of amino-ferrocene (AFc) nanoclusters on a graphene oxide (GO) nanosheet is a technique based on molecular self-assembly. Here, this method is applied to other ferrocene derivatives whose ferrocene units are covalently bonded to an amino group and several other molecules. The structure of the on-surface synthesized nanoclusters is analyzed by high-resolution transmission electron microscopy and atomic force microscopy. The molecules in the nanoclusters are densely and regularly arranged, and the distance between the Fe ions of the constituent molecules is longer than that in the AFc nanoclusters. Band-through electron transfer occurs between the Fe ions and the GO nanosheet, generating unpaired 3d electrons whose magnetic state is in the high spin state (S = 5/2). The present study demonstrates the feasibility of the design and synthesis of functional molecular nanostructures with molecular precision by on-surface chemistry, leading to the fabrication of nanoscale building blocks with molecular precision and 2D platforms for next-generation molecular spintronic and neuromorphic devices.

Keywords

On-surface chemistry / ferrocene derivative / nanocluster / high spin state / charge transfer / 2D materials

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