2D COSY NMR Correlation Spectroscopy

COSY turns a one-dimensional proton NMR spectrum into a two-dimensional correlation map: peaks sit on the diagonal exactly as in a 1D spectrum, but protons that are scalar-coupled through 2–3 bonds throw off symmetric off-diagonal cross-peaks. This 2D canvas version renders that correlation map the way real acquisition software (TopSpin, MestReNova) actually displays it — a flat contour/heatmap of intensity over the (δ₁, δ₂) plane — for three real spin systems (1-propanol, ethyl acetate, ethylbenzene), each with a different J-coupling network. Adjust the acquisition linewidth and intensity gain, toggle the cross-peaks on and off to isolate the diagonal, and click directly on any peak to see which proton it is, or which two coupled protons a cross-peak connects and where that bond sits in the molecule's structure.