PONy Dyes: Direct Addition of P(III) Nucleophiles to Organic Fluorophores

Nucleophilic addition of phosphinic acid, phosphites, sodium dialkyl phosphites, phosphoramidites, phosphinites, and phosphonites to highly polarized or cationic fluorophores, followed by oxidation, results in new “PONy” dyes with auxochromic phosphinate, phosphonate, or phosphonamidate groups. The reaction was applied to a wide variety of coumarins, (thio)­pyronins, and N-alkylacridinium and 5,6-dihydrobenzo­[c]­xanthen-12-ium salts as well as a meso-chlorinated BODIPY to provide compact dyes with red-shifted absorption and emission bands and Stokes shifts up to 8200 cm–1.