On-surface synthesis via covalent coupling of adsorbed molecules on metal surfaces has attracted significant attention in recent years due to its potential to fabricate low-dimensional carbon materials with atomic precision. To understand and control the surface-chemistry-driven synthesis, many efforts have been made to design smart precursors, explore novel reaction schemes, and utilize templating effects from the substrate. My presentation focuses on high-resolution scanning probe microscopy experiments combined with density functional theory to demonstrate recent highlights on the assembly of surface-supported low-dimensional molecular structures.