Venegas Yazigi Diego A.
Historically, magnetism has been studied mainly by physicists. However, in the last two decades, chemists started to play an important role in this area of research, since they are able to design and characterize new compounds with interesting magnetic properties, which are different from those observed in the classical magnets.Initially, the area of molecular magnetism was focused on discrete systems (dimers, trimers) which were used as models to understand the magnetic exchange interactions. Then, chemists became more and more interested in designing systems with higher complexity, showing cooperative phenomena such as ferro- and ferrimagnetism. The final aim was to obtain systems showing magnetic ordering above room temperature. This challenge was finally achieved in heterometallic "Prussian Blue Materials".Other systems of interest were provided by discrete molecular entities exhibiting unusual behavior, as for example the so called Single Molecule Magnets (SMM). These molecular clusters show magnetic hysteresis at low temperature, and quantum effects due to their reduced size. They are now becoming one of the most important objects in applied molecular magnetism as they can, in principle, store information at a molecular level. They can be therefore of interest in Molecular Nanomagnetism.Finally the increase of complexity, together with the flexibility provided by the molecular approach, has afforded the production of new multifunctional materials combining magnetism with a second physical property of interest.In all these systems the chemist uses a molecular building block, known as Bottom Up approach. This approach can provide new magnetic molecular materials with controlled metal nuclearity, magnetic and structural dimensionality and magnetic exchange interactions, which can exhibit new properties or association of properties.