On-Surface Synthesis of 2D Radical Frameworks

Abstract

The design of atom thick two-dimensional (2D) frameworks by on-surface synthesis has recently contributed to the development of advanced materials with high control over their structural, electronic, optical and magnetic properties. Countless 2D frameworks, with a large variety of applications, can be synthesized made of purely organic molecules (covalent organic and supramolecular frameworks) or combining both metals and organic molecules (metalorganic frameworks). Here, we focus on the design and synthesis of radical 2D frameworks, composed of open-shell nanographenes equipped with azaindole units, on an Au(111) surface. Interestingly, the deposition of transition metal atoms on such frameworks allow the tuning of their magnetic properties, expanding their possible applications. The structural, electronic and magnetic characterization of the frameworks was performed by scanning tunneling microscopy/spectroscopy (STM/STS) and non-contact atomic force microscopy, and supported by density functional theory (DFT) calculations. Additionally, the magnetic characterization was complemented by nickelocene-functionalized tips investigations, which act as a magnetic sensor that unveils the magnetism of the frameworks at the single molecule level.