Pyrene-tethered bismoviologens for visible light-induced C(sp³)–P and C(sp²)–P bonds formation

Developing efficient photosensitizers for C–P bond construction is highly important and remains a challenge due to the urgently needed for the synthesis of modified nucleosides, nucleotides, and other phosphine-containing ligands. Herein, two pyrene-tethered bismoviologen derivatives (Py-BiV²⁺) were designed and synthesized for visible-light-induced C–P bonds formation. The photochemical and electrochemical properties of Py-BiV²⁺ were studied systemically, certifying fine-tunable opto-electronic properties through the number of pyrene groups (4, n = 1; 6, n = 2). The prepared Py-BiV²⁺ showed strong light absorption, while retaining good redox features and chromic response features that were inherent to viologens. 4 exhibited accelerated photoinduced electron transfer in the presence of the electron donor (pyrene) and the generated 4′ (radical cation) showed higher stability. Accordingly, Py-BiV²⁺ directly served as photosensitizers for the first time in the visible-light-induced C(sp³)–P and C(sp²)–P bonds formation. As expected, these novel viologen derivatives exhibited good catalytic performance and good substrate expansibility under ambient conditions.