Crystalline Thymine Dimers Splitting by an Interfacial Photomechanochemical Single Electron Transfer Chain Reaction

Splitting of the <i>cis, syn</i> thymine dimer (<b>TD</b>) into thymine (<b>T</b>) can be achieved in the solid state via an interfacial SET photomechanochemical reaction with <i>N</i>,<i>N</i>,<i>N</i>,<i>N</i>-tetramethyl-1,4-phenylenediamine (TMPD) as the photochemical reductant. Mechanical grinding enabled the uniform deposition of the TMPD sensitizer on the dimer surface, and photoirradiation of this solid-solid mixture (<b>TD</b>+TMPD) triggered electron transfer at the solid-solid interface that was propagated into the bulk of the crystal as a chain reaction. Variables explored included sensitizer loading and preparation strategies that included solid-solid mixing and the deposition of the photosensitizer onto the <b>TD</b> surface from solution. Clean solid-to-solid transformations were observed with product yields as high as ∼95%.