On-Surface Synthesis (OSS) has demonstrated its enormous potential for the bottom-up synthesis of a wide variety of atomically-precise materials at the nanoscale with exotic properties. This is achieved through the realization of chemical reactions catalyzed by the surfaces, which have been demonstrated to facilitate certain reactions by reducing the activation barriers. Additionally, OSS presents other unique characteristics that affords the synthesis of otherwise unattainable low dimensional nanostructures, like the use of controlled ultra-high vacuum (UHV) conditions that ensure an ultra-clean interface and a completely inert atmosphere, allowing the exploration of a wider temperature range before molecular degradation . These ideal UHV conditions, together with the use of "perfect" single crystalline substrates and theoretical firstprinciples calculations, allow for the complete modeling and rationalization of their properties and the reaction mechanisms involved at the atomic and molecular scale.