This book presents the most advanced review available of all aspects of -electron systems, including novel structures, new synthetic protocols, chemical and physical properties, spectroscopic and computational insights, molecular engineering, device properties and physiological properties. -Electron systems are ubiquitous in nature. Plants convert light energy into chemical energy by photosynthetic processes, in which chlorophylls and other porphyrinoids play an important role. On the one hand, research to learn about photosynthesis from nature has led to understanding of electron and...