B(III)-subporphyrazines, B(III)-subporphyrins and their hybrids

In recent years, subporphyrazines and subporphyrins, as a class of fascinating ring-contracted porphyrinoids containing boron, have been widely developed as the promising functional dyes. They exhibit very interesting structural, photophysical and electrochemical properties, such as interesting cone-shaped structures, 14π-electron aromatic characters, highly tunable electronic features and unique nonlinear optical properties. This review provides an overview of the synthesis of subporphyrazines and subporphyrins, and summarizes the main structural modification methods of subporphyrazines and subporphyrins, such as changing the axial B-position substituents, meso-position substituents, and peripheral substituents. In addition, some fascinating subporphyrinoid analogues are also discussed in detail, such as subtriazachlorin, subchlorin, subbacteriochlorin and subpyriporphyrin. Furthermore, many interesting dimers and oligomers, hybrid systems and stable subporphyrin radicals have also been actively emphasized. Importantly, special attention has been paid to outstanding free base triphyrin(1.1.1) such as calix[3]pyrrole and free base subporphyrin, as well as hybrid subporphyrinoids. These corresponding impressive photophysical and electrochemical properties have also been emphasized, as a deep understanding of subporphyrinoids.