Dual Photochemical Bond Cleavage for a Diarylethene-Based Phototrigger Containing both Methanolic and Acetic Sources

In this paper, we
present a novel concept for “smarter”
photolabile organic compounds combining not one but two caged functions.
As proof of principle, this diarylethene-based compound possesses
two inhibited chemical groups (OMe and OAc) and its efficient release
in different solvents is reported. In low- to medium-polarity media,
both MeOH and AcOH are released, with a slight preferential uncaging
of AcOH except in 1,4-dioxane, where MeOH is preferentially released.
In contrast, DMSO or DMF render AcOH release strongly dominating.
DFT calculations of the corresponding photoreactive conformations
not only afford strong support to the observed release of MeOH and
AcOH but also qualitatively explain the preferential release of acid
in terms of dispersive noncovalent interactions. Finally, mechanistic
aspects are discussed on the bases of the spectroscopic observations
and of the TD-DFT calculations.