6-Ethynylisoquinoline is primarily used in organic synthesis and medicinal chemistry as a versatile building block for the development of complex molecules. Its ethynyl group allows for click chemistry reactions, particularly the copper-catalyzed azide-alkyne cycloaddition (CuAAC), making it valuable for creating biologically active compounds. This chemical is also employed in the design of pharmaceuticals, especially in the synthesis of potential drug candidates targeting neurological disorders or cancer. Additionally, it serves as a key intermediate in the preparation of fluorescent probes and imaging agents, aiding in biochemical research and diagnostics. Its unique structure contributes to the development of materials with specific electronic or photophysical properties, useful in organic electronics and optoelectronics.