Spiropyran-based photoswitchable dimethylaminopyridine†
Embedding of DMAP in a spiropyran derivative results in a molecular switch 1, which changes the coordination capability of the DMAP moiety upon exposure to external stimuli such as light and heat. In the closed form, 1c behaves as an isolated DMAP, complexing with zinc porphyrin (ZnP) with a high binding constant (K = 1.8 × 104 M−1). However, in the open form, 1o associates with ZnP with a much weaker binding strength (K = 0.5 × 104 M−1). Switching between 1c and 1o is fast and reversible. In the photostationary state under irradiation at 330 nm, 90% of 1 is transformed from 1c to 1o.