Installation of cationic phosphorus on dimethyldihydropyrene photoswitches: expanding the atomic repertoire towards far-red photoswitching in water

We have synthesized for the first time a small library of negative photochromic dimethyldihydropyrene phosphonium salts (DHPPs) that can be activated by red and far-red (up to 740 nm) photons in a quantitative manner in the so-called "biological window". The intriguing feature of this particular class is their remarkably fast response in fully aqueous media with an improved ring-opening quantum yield. Additionally, the reversal can be activated upon visible (blue) light irradiation and also under thermal conditions in a quantitative manner, achieving efficient bidirectional visible light-mediated switching rendering this particular class of photoswitches even more attractive towards their potential application in biological premises. Additionally, all-photonic orthogonal photoswitching of a mixture of conventional unsubstituted DHP and one of our modified DHPP derivatives provides a demonstration of multifunctional molecular logic operations.