Ricerc@Sapienza

Supramolecular chemistry is the chemistry of molecular aggregates assembled by intermolecular forces of different nature such as electrostatic (hydrogen and halogen bonds) and dispersive forces. Concerning the main components of DNA and RNA (cytosine, guanine, adenine, thymine and uracil), nucleobases are held together by non-covalent interactions determining highly specific functions, i.e. molecular recognition. Hydrogen bonds (and halogen bonds in non-canonical nucleobases), and dispersive interactions all need to be accurately described in order to explain and control RNA and DNA sequence, structure and flexibility which are still only partially understood. Moreover, unusual (epigenetic) DNA nucleobases, identified as 5-substituted cytosines, have been detected in brain cells very recently leading to a new research field that has only very little published literature as yet. In this project, we aim to combine single-crystal and powder X-ray diffraction (XRD), atomic force microscopy (AFM), molecular modeling and thermodynamic measurements to fully describe DNA/RNA old and newly-detected nucleobases (in homomers and heteromers association) in 2D and 3D aggregates. 2D systems are formed by immobilizing molecules on a substrate and the combined interactions among the adsorbates and the surface lead to molecular networks. 3D aggregates are obtained by growing single crystals or crystal powders. The detailed molecular-level investigation of these interactions is of significant importance in the study of the DNA/RNA structure and properties: a change in the interactions between nucleobases can lead to genetic mutation and tumor formation. Hence the investigation of these systems is critically relevant in a large and varied range of fields, such as medicine, genetics, biochemistry, bioengineering of nano-systems and material chemistry.