From Aqua Green to Deep Red in One Step: Targeted Design of a Highly Luminescent Phosphacyclic Vat Orange 3 Dye.

Silver-mediated phosphacyclic ring expansion with strategic placement of phosphorus and dimethyl acetylenedicarboxylate (DMAD) on Vat Orange 3 was carried out. The target compounds possess narrow HOMO-LUMO energy gaps as low as 2.02 eV, with pronounced absorption across the visible region of the optical spectrum and intense luminescence at 691 nm, with impressive quantum yields of up to 70%. Moreover, the P-based conjugated materials exhibit reversible reduction events as low as -0.98 V.