The Porphyrin Handbook, Volume 18: Multiporphyrins, Multiphthalocyanines and Arrays provides information pertinent to every aspect of the chemistry, synthesis, spectroscopy, and structure of phthalocyanines. This book examines the biology and medical implications of porphyrin systems. Organized into five chapters, this volume begins with an overview of the results obtained in the research concerning the properties and formation of a class of metal phthalocyanine derivatives containing of two macrocyclic units. This text then examines the luminescence and photophysical data of multiporphyrin systems in which the chromophore centers are held together by weak, medium, or strong bonding interactions. Other chapters consider the intensive electronic absorption and circular dichroism properties of chiral phthalocyanines. This book discusses as well the chemistry porphyrin and corrin systems. The final chapter deals with geoporphyrins or sedimentary porphyrins, which are the most abundant porphyrin derivatives on earth. This book is a valuable resource for research scientists, engineers, and clinicians.