Chem. Sci., 2025, Accepted Manuscript DOI: 10.1039/D5SC06168G, Edge Article Manik Lal Maity, Sayan Chandra, Samyadeb Mahato, Subhajit Bandyopadhyay We have synthesized for the first time, a library of negative photochromic dimethyldihydropyrene phosphonium salts (DHPPs) that can be activated by red and far-red (up to 740 nm) photons in...