J-coupling (spin-spin coupling)

J-coupling, or spin-spin coupling, is an interaction between neighboring nuclear spins in molecules, detectable through nuclear magnetic resonance (NMR) spectroscopy. When nuclei like hydrogen atoms are close within a molecule, their magnetic moments influence each other, causing slight shifts in their magnetic signals. This interaction leads to the splitting of NMR signals into multiple peaks, revealing how atoms are connected. Essentially, J-coupling provides information about the molecular structure by indicating which nuclei are near each other and how they are bonded, making it a valuable tool for understanding complex chemical compounds.