Molecular Modelling of Aromatic Interactions between Pyrene Derivatives and Carbon Nanotubes: Materials for Biomedical Applications

In previous works, we investigated the possibility of using carbon nanotubes functionalized with organic molecules as effective contrast agents for Magnetic Resonance Imaging. This a very useful method for clinical diagnosis, whose effectiveness is conditioned by the development of new contrast agents increasing the quality, resolution, and specificity of the Magnetic Resonance images. Solubilization and functionalization of carbon nanotubes have been previously reported using pyrene derivatives through π–π interactions. In this work, we used dispersion-corrected Density Functional Theory calculations to analyze interactions between carbon nanotubes and several pyrene derivatives. We built two different positions of the aromatic molecule relative to the carbon nanotube (parallel and perpendicular) and calculated binding energies, electrostatic potential surfaces, and electronic charges, in order to shed some light on the interaction strength between both molecules and their preferred orientations. A good interaction between carbon nanotubes and pyrene derivatives is key for the synthesis of materials that work efficiently in biomedical imaging. The results clearly indicate a large influence of the nature of functional groups and orientation of the aromatic molecule relative to the carbon nanotube surface on the adhesion strength.