HIGH ORDERING AND LOCAL CURVATURE OF PHTHALOCYANINE MOLECULES MONITORED BY SINGLE-WALLED CARBON NANOTUBES
Résumé
Metallo-phthalocyanine or metal free molecules are either encapsulated into the hollow core of single-wall carbon nanotubes or non-covalently functionalized at their outer surface in order to elaborate new 1D hybrid systems with tunable opto-electronic properties. The encapsulation efficiency is investigated by Transmission Electron Microscopy and x-ray diffraction. The x-ray diffraction patterns allow evidencing the structural organization of the molecules inside the nanotubes which can be envisaged as a “1D -phase”. The angle between the molecule ring and the nanotubes axis is close to 32° as determined from our calculations. The Raman spectra of the hybrid systems display an important dependence with the excitation energy associated to resonant process on both the inserted molecules and the host nanotubes. Confined molecules display Raman spectra hardly altered with respect to the bulk phase, suggesting a rather weak interaction with the tubes. By contrast, the vibrational properties of the molecules functionalized at the outer surface of tubes display important modifications. We assume a significant curvature of the phthalocyanine induced by the interaction with the tube walls and a change of the central atom position within the molecular ring, in good agreement with our DFT calculations.