Defect-Free Chemical Functionalization of Magnetic Monolayers Based on Coordination Polymers

Chemical functionalization has demonstrated to be a powerful approach to tailor the physical and chemical properties of two-dimensional (2D) materials, to increase their processability and

stability, to add new functionalities and, even, to create new 2D materials. However, this post synthetic method – which involves the anchoring of molecules on the surface of an exfoliated 2D crystal – inevitably leads to defective materials, which lack long-range structural order. If defect-free functionalized monolayers are required, a radically new approach needs to be developed. Here we present a pre-synthetic method based on coordination chemistry that affords the isolation of crystalline functionalized monolayers. This involves functionalization of the ligand prior to the formation of the 2D material. The concept is illustrated using layered coordination polymers formed by reacting various benzimidazole derivatives with ferrocene. This surface tuneability, together with the robust magnetic and mechanical properties of these 2D materials, make them exceptional candidates for studying the magnetism in the 2D limit, as well as for developing membranes for selective molecular sensing.