Non covalent interactions through pi-stacking between carbon aromatic cores appear as an essential building block to engender the structural stability and electronic coupling of organic and biologic supramolecular assemblies (DNA, proteins, photosynthetic reaction center...). Interestingly pi-stacking functionalization has emerged as a rich and powerful way to synthesize hybrid compounds made from carbon nanotubes with organic molecules adsorbed on their sidewall. This scheme opens avenues for various applications including photo-voltaics, photo-detection, bio-sensing or imaging. In this context, we recently demonstrated that the decoration of nanotubes with dye molecules (porphyrins) brings remarkable properties including an efficient and ultrafast photo-induced energy transfer as well as good stability [1-3].

    In the present work, we unveil through a thermodynamics study an original diameter dependence of the interaction between nanotubes and porphyrin monomers, which favors the larger diameters. We extract parameters such as the reaction time constant and the Gibbs energy of the reaction, which can be described by the classical cooperative adsorption Hill model. Moreover, the evolution of the Gibbs energy as a function of the nanotube diameter is studied for 16 nanotube chiral species [4], and compared with DFT calculations [5].

Finally, we show how tiny changes in the molecules structure influence their self assembly around the nanotube.

References

[1] C. Roquelet, et al, ChemPhysChem 2010,  11, 1667
[2] G. Clave, G. Delport et al, Chem. Mat. 2013, 25, 2700
[3] C. Roquelet, et al, Appl. Phys. Lett. 2010, 97,141918
[4] F. Vialla, G. Delport et al, Nanoscale, accepted
[5] W. Orellana et al, J. Mater Sci 2015, 50, 898