Naphtho[2,1‑e]‑1,2-azaphosphorine 2‑Oxide Derivatives: Synthesis, Optoelectronic Properties, and Self-Dimerization Phenomena

A family of naphtho­[2,1-e]-fused 1,2-azaphosphorine 2-oxides that contain electron-withdrawing and -donating substituents on the 3-phenyl groups has been prepared and characterized. This new series of phosphorus- and nitrogen-containing heterocycles is brightly fluorescent with tunable emission wavelengths (λem = 441–493 nm, ΦF = 0.19–0.93). Their strong self-dimerization behavior through N–H and PO hydrogen bond donors/acceptors was investigated experimentally and theoretically. The pendant phenyl group can be used to modify the intrinsic optoelectronic properties as well as the self-association of the PN-heterocycles. The results presented herein are expected to enable the development of new photofunctional materials and provide important insights in diverse areas of supramolecular chemistry.