This book presents the important facts about the synthesis and biological studies of macrocyclic transition metal complexes. A detailed synthetic discussion of the reaction steps in each mechanism and their relationship with transition metal complexes has been considered. Macrocyclic ligands and their transition metal complexes depends upon the nature of reactants and the corresponding metal ion. The macrocyclic ligand are a growing class of compounds with varying chemistry a wide range of different molecular topologies and set of donor atoms. Aza type ligands appear as very promising to be used as antifertile, antibacterial, antifungal and other biological properties. Macrocyclic metal complexes play a central role in the construction of molecular materials, which display magnetic properties and find applications in material and supramolecular chemistry and biochemistry. It is believed that the present book will provide a succinct and clear introduction to synthesis, characterization and biological studies macrocyclic ligands with transition metal complexes that meets the needs of researchers at a variety of levels in several disciplines.