A crystallographic study of the solid-state photodimerization of 7-methoxy coumarin

Recent investigations of compounds with relatively short intramolecular oxygen-oxygen separations such as B-diketones and B-hydroxyketones have sugges•ted the occurrence of dynamic hydrogen exchange bet;,veen these oxygen a•toms in the solid state.Evidence for this phenomenon is provided by the results of solid state nuclear magnet.icresonance, nuclear quadrupole resonance, and X-ray diffraction experiments.s•tructural and spectroscopic da•ta point out the role of both intra-and intermolecular interactions in influencing this phenomenon.