Introduction of fluorine in the structure of pharmaceuticals has been an effective strategy for tuning their pharmacodynamic properties with more than 40 new drugs accessing the market in last 15 years. In this context 19F NMR can be viewed as a useful probe for investigating the host-guest chemistry of pharmaceuticals in nanosize drug delivery systems. Although the interest in confined crystallisation, nanosize devices and porous catalysts is gradually increasing, understanding of the complex phase behavior of organic molecules confined within nano-chambers or nano-reactors is still lacking. Using 19F MAS NMR, we achieved detailed mechanistic insight into the crystallization of flufenamic acid (FFA) in a confined environment of mesoporous silicas with different pore diameters (3.2 to 29 nm), providing a direct experimental proof of the formation of a molecular liquid-like layer in addition to the crystalline confined FFA form I.
- Mesoporöses SiO2