This thesis investigates spin interactions in atomically precise organic nanostructures synthesized on metal substrates using on-surface synthesis techniques. While magnetism is usually associated with transition metals, it can also emerge in light elements like carbon through π-magnetism, driven by unpaired p-shell electrons. Magnetic carbon-based nanostructures are expected to exhibit unique properties such as enhanced spin delocalization and long coherence times, making them promising candidates for spintronics and quantum information applications. We employ scanning probe microscopy techniques—mainly scanning tunneling microscopy (STM) and spectroscopy (STS)—along with theoretical simulations to study various organic systems with differing numbers of unpaired π electrons: a non-planar organic diradical (2-OS); a triradical nanographene (TTAT), formed by joining three [3]triangulenes via a nitrogen-doped triangulene core; and a [3]triangulene-based macrocycle (TNS), accumulating twelve unpaired electrons. Finally, we explore strategies for fabricating two-dimensional covalent networks using open-shell triangulene units, with the aim of creating extended organic spin architectures.
