Molecular recognition in a uradinyl-functionalized stable radical

Stable radical 2-(6-uradinyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1-oxyl (1) binds to hydrogen-bonding complement 2,6-di(propylamido)pyridine (DAP) in chloroform with Ka = 220 M−1 at 33 °C; ESI-MS shows not only 1∶DAP complementary dyad formation, but also 1∶(DAP)2 formation at higher concentrations of DAP.