ABSTRACT
This chapter introduces the concept of molecular materials by defining what they are and what distinguishes them from the more conventional atom-based systems. It talks about molecular materials that show magnetic, optical, or electrical properties, independently of the nature and complexity of the molecules that originate them. The concept of molecular materials, intended as materials built by functional molecules that retain their properties down to the molecular scale, also changed the way to conceive the construction of technological devices. The top-down approach, which consists in decreasing the dimension of bulk materials to prepare smaller objects without losing the material's performance, the so-called bottom-up approach represents the alternative strategy deriving from the concept of molecular materials. The physical properties of conventional atom-based inorganic materials, such as metals, and oxides, are strongly dependent on the dimensions of discrete object constituting the material, a particle, etc. The chapter also presents an overview of the key concepts discussed in this book.
