Azaporphyrin phosphorus(v) complexes: synthesis, structure, and modification of optical properties

Azaporphyrinoids, such as phthalocyanines (Pcs), tetraazaporphyrins (TAPs), and tetrabenzotriazacorroles (TBCs), are some of the most well-known and successful artificial dyes and pigments in modern material chemistry. Modifications of the macrocyclic core, periphery, and central element have attracted a great deal of interest in materials sciences due to generation of unique optical and electronic properties. However, the synthesis of most azaporphyrinoids with novel physical properties generally needs long, tedious procedures. On the other hand, the introduction of a phosphorus(v) atom into simple (known) azaporphyrin macrocycles is not necessarily difficult and can generate changes in the structural and optical properties. This paper provides an overview of the recent development of azaporphyrin phosphorus(v) complexes with unique structural and optical properties. Optical properties are discussed based on a combination of experimental absorption spectra, electrochemical properties, and theoretical molecular orbital calculations. These complexes are relatively easy to synthesize, are robust and free from transition metals, and have predictable properties.