Introduction and Classification of Organic Molecule Based Magnetic Materials

Molecular magnetism, deals with the research and development activities of organic molecule based magnetic materials that are rapidly evolving with discoveries which find possible applications in molecular spintronics, quantum technologies, and energy storage. The future of molecular spintronics will be based on molecular materials consisting of one or a few molecules commonly known as single-molecule magnets. Similarly, qubits based on the molecular spin with larger quantum coherence time have reached certain milestones in quantum computation technology. Further, molecular compounds in the form of open framework structures like Prussian blue analogues or others have shown promising applications in energy storage. Overall, molecule compounds with attractive physical properties and new functionalities are the basis of molecular magnetism which opens a multidisciplinary area linking physics, chemistry, and material science. The rational design, successful synthesis and physical characterization as well as the theoretical modeling of isolated molecules or assemblies of molecules containing one or more magnetic centers is the main objective of the field of molecular magnetism. Single chain magnets, single molecular magnets and spin crossover compounds are examples of molecular magnets which are synthesized in a definite framework or low dimensionalities giving unusual magnetic properties or exhibiting synergistic combinations of properties. The cross-over from 3-D to 2-D or 1-D also provides an opportunity to study the phenomenon of low dimensional magnetism in molecular magnetism. In this chapter, the introduction and classification of molecule based magnetic materials will be presented in detail. The main emphasis will be given to the magnetic properties and magnetic parameters commonly used for understanding molecular magnetism. Subsequently, the classifications of molecular magnetic materials, based on the nature of the ligands and structural dimensionalities are also presented. A few examples of molecule based magnetic materials are also presented to discuss their multifunctional properties.