Solid‐State NMR Applications in the Structural Elucidation of Small Molecules

Solid materials play an important role in the lives of human beings and understanding their properties better contributes to an improved comprehension of the universe we live in. Solids exhibit specific mechanical, magnetic, electric, thermal, optic, and also biological properties. Insight into the structure and dynamics of solids over a range of length and time scales is key to rationalizing, engineering, and improving these properties. A plethora of spectroscopic techniques is at our disposal for studying solids at the molecular level, mostly based on their electronic structure. Solid-state nuclear magnetic resonance (ssNMR) spectroscopy is a well-established method for studying the inter- and intramolecular interactions based on the magnetic and electric properties of the molecules, and is much used to study molecular dynamics over a wide range of time scales. Molecules are the building blocks of extended systems, such as coordination polymers or supramolecular entities arranged in the space through non-covalent interactions, for example, drug/pesticide organic molecules or inorganic complexes. Many reviews are available on the applications of ssNMR to the study of materials and polymers. In this chapter, however, we focus on the use of ssNMR for studying small molecules (roughly molecules of molecular weight under 800 Da). We shall highlight the main applications of the technique, providing structural insight into a broad family of small molecules commonly employed in multiple applications of general interest to the scientific community. The use of small molecules to alter or tune the activity or functions of porous materials, biomaterials, or nanomaterials is also a very important topic. Thus, a few case studies are presented, where small molecules are used as spy entities to gain specific information on materials or used as surface modifiers of existent materials to enhance their catalytic or biological activities.