Structure Characterization of Materials by Association of the Raman Spectra and X-Ray Diffraction Data

Supramolecular chemistry, which can be described as the chemistry beyond the covalent bonds, has become a very interesting focus of investigation in the last years. The main purpose of this kind of studies is the strategic construction of specific arrangements, and the complete comprehension of the connection between structure and physical–chemical properties. However, in the solid state there are several weak interactions, as hydrogen bonds and -stacking, which can play a decisive role in orientation of the crystallization processes (Carlucci et al., 2003). Essentially, common features of all of the supramolecular systems are non-covalent interactions, which provide the clips linking the building blocks, leading to well organized superstructures (Yan et al., 2007). The term “Supramolecular chemistry” was introduced by Jean-Marie Lehn and it is defined as “the chemistry beyond the molecule”. While a covalent bond normally has a homolytic bond dissociation energy that ranges between 20 and 100 kcal mol-1, noncovalent interactions are generally weak and vary from less than 1 kcal mol-1 for van der Waals forces, through approximately 25 kcal mol-1 for hydrogen bonds, to 60 kcal mol-1 for Coulomb interactions (Hoeben et al., 2005). In this sense, the most important interactions in solid organic compounds are the hydrogen bonds. The kind and strength of these interactions added to the molecular arrangement are responsible for the crystal structure of these compounds. The change in production and/or storage conditions of solids may modify the hydrogen bonding design and the balance between them and van der Waals interactions. These modifications give rise several changes in the solid state, like phase transitions (Wang et al., 2009). Weak attractive forces are important in deciding the conformation of organic compounds and 3D structure of biomacromolecules. Among molecular interactions, the van der Waals force, electrostatic interactions and hydrogen bonds are the most important (Takahashi et al., 2010). Apart of hydrogen bonds, another type of interaction that plays an important role in the design of supramolecular materials is - interactions. Attractive non-bonded interactions between aromatic rings are seen in many areas of chemistry, and hence are of interest to all realms of chemistry. The strength as well as the causes of these interactions, however, varies. In water the stacking interaction between aromatic molecules is mainly caused by the