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 sub-stituents 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 (lambda(em) = 441-493 nm, Phi(F) = 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.