Arylsulfanyl radical lifetime in nanostructured silica: dramatic effect of the organic monolayer structure

Nanostructured hybrid silicas, in which covalently anchored aromatic thiols are regularly distributed over the pores, enable a dramatic increase in the half-lives of the corresponding arylsulfanyl radicals. This enhancement is not only due to limited diffusion but also to the structure of the organic monolayer on the surface of the pores. Molecular dynamics modeling shows that at high loadings, in spite of their spatial vicinity, supramolecular interactions disfavor the coupling of arylsulfanyl radicals. As compared to phenylsulfanyl radical in solution, the half-life measured at 293 K can be increased by 9 orders of magnitude to reach 65 h.