Sapphyrins: New Life for an Old "Expanded Porphyrin"

Abstract
Sapphyrin, so called due to its intense blue-green color, is a 22 π-electron pentapyrrolic molecule known for over 20 years. This macrocycle can now be prepared in good yield and is becoming the subject of serious current study. Although planar and aromatic, the larger size of this "expanded porphyrin" endows it with some unexpected properties in comparison to the better-known porphyrins 1. Introduction 2. Synthesis 3. Anion Binding 4. Metal Complexation 5. Future Directions