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

A library of novel naphtho[2,1-e]-fused 1,2-azaphosphorine-2-oxides that contain electron-withdrawing and -donating substituents on the 3-phenyl groups have been designed, prepared and characterized. This new family of phosphorus- and nitrogen-containing heterocycles are found to be brightly fluorescent with tuneable emission wavelengths (l_em = 441−493nm, F_F = 0.19−0.93). Their strong self-dimerization behaviours through N−H and P=O hydrogen bond donors/acceptors were investigated experimentally and theoretically. It has been demonstrated that the pendant phenyl groups can be used to modify the intrinsic optoelectronic properties as well as the self-association of heterocycles. These results presented herein are expected to enable the development of new photofunctional materials and provide important insights in diverse areas of supramolecular chemistry.