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.

New 1D hybrid nano-systems are elaborated with photo-active -conjugated molecules (PAM) either encapsulated into the hollow core of single-wall carbon nanotubes or non-covalently functionalized at their outer surface. The physical properties can be tuned by modifying the structural properties, providing practical routes to fit different requirements for potential applications. In this study, we report results obtained by functionalizing single wall carbon nanotubes with quathertiophene (4T) and phathlocyanine (MPc) molecules. The structural properties are investigated mainly by x-ray diffraction and/or Transmission Electron Microscopy and Raman spectroscopy. We evidence that the supramolecular organizations of confined oligothiophenes (from 1 to 3 chains into a nanotube section) depend on the nanocontainer size whereas phthalocyanine encapsulation leads the formation of a 1D-phase for which the angle between the molecule ring and the nanotubes axis is close to 32°. Confined MPc molecules display Raman spectra hardly altered with respect to the bulk phase, suggesting a rather weak interaction with the tubes. In 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.

We report an experimental study on the confinement of oligothiophene derivatives into single-walled carbon nanotubes over a large range of diameter (from 0.68 to 1.93 nm). We evidence by means of Raman spectroscopy and transmission electron microscopy that the supramolecular organizations of the confined oligothiophenes depend on the nanocontainer size. The Raman Radial Breathing Mode frequency is shown to be monitored by both the number of confined molecules into a nanotube section and the competition between oligothiophene/oligothiophene and oligothiophene/tube wall interactions. We finally propose simple Raman criteria to characterize oligothiophene supramolecular organization at the nanoscale.

The study of hybrid systems MPA@SWNT of peapods kind involving photoactive molecules (MPA) confined in single-walled carbon nanotubes (SWNT) find its motivation in the possibility of modulating the physical properties of the nanotubes. Many experimental studies using vibrational spectroscopy in particular are interested in the physical properties of these hybrid systems. The key point of this issue is the nature of the interaction between the nanoconfinement matrix and MPAs, and the complexity of its study requires a comparison between experimental data and modelizations. In this work, we study the hybrid systems MPA@SWNT through modeling performed in different settings ranging from the use of molecular dynamics (MD) to that of the density functional theory (DFT). The limiting factor in DFT calculations is the computation time. the latter which varies in N3 (N is the number of atoms) increases drastically when N exceeds a hundred atoms for energy minimizations calculation, and even more for phonons calculations. In this context, the study of hybrid systems with organic MPAs is delicate. Indeed, the MPAs are complex molecules generally comprising side chains for the solubility of the system. For example, the smallest hybrid system studied, which consists on encapsulating a single molecule of thiophene oligomer functionalized with methyl groups at the edges inside an (11,0) nanotube contains 344 atoms. For the computation time not to be prohibitive, we tested different methods of simulation of the vibrational spectra of MPA@SWCNT: molecular dynamics, tight binding, and hybrid calculations MD/DFT. We discuss in details the results comparing models with experimental data for 1D thiophene oligomer molecules encapsulated inside nanotubes.

Phthalocyanine molecules (Pc) are encapsulated into the hollow core of single-wall carbon nanotubes (NT) in order to tailor the opto-electronic properties of the 1D hybrid systems (Pc@NT). Non covalent functionalization at the outer surface of the tube is also investigated as reference sample (PcNT). Phthalocyanine molecules are used as they display strong absorption in the red visible range (around 670 nm). Encapsulation efficiency are investigated by Transmission Electron Microscopy and x-ray diffraction. The x-ray diffractograms strongly suggest a specific structural organization close to the -phase inside the nanotubes. Infrared spectra of confined phthalocyanine molecules confirm the structural properties suggested by x-ray diffraction. Raman spectra display significant differences depending on the molecule localization (either inside or outside the nanotubes). Into the hollow core of the NT, Pc molecule exhibits a “free-like” behavior. By contrast, at the outer surface of the nanotubes, the shift of the high frequency modes suggests a strong interaction between the central metal atom and the nanotubes walls. The nature of the central atom also influences the physical interaction between the confined molecule and the host carbon nanotubes.

Photo-active molecules are confined into single-wall carbon nanotubes to create 1D hybrid systems with new and original opto-electronic properties. This work deals with the encapsulation of quaterthiophene derivative and phthalocyanine molecules. They display strong optical absorption in the visible range, respectively around 400 and 670 nm. Encapsulation efficiency is investigated through Transmission Electron Microscopy. The physical interactions are mainly investigated by optical spectroscopies. The Raman spectra of the oligothiophene hybrid systems exhibit a striking dependence with the excitation energy which is correlated to the optical absorption energy of the photo-active molecule. Close to the molecule resonance, the results suggest a significant photo-induced charge transfer between the photo-active molecules and the nanotubes. In addition, the resonance window of the confined molecules depends on the nanotube diameter. The Raman spectra of the phthalocyanine based systems depend on the optical resonance conditions of the encapsulated molecules and on the structural properties of the hybrid system.

The influence of ultrasound radiation on graphite structure was studied by laser light scattering, X-ray diffraction, Raman spectroscopy and Transmission Electron Microscopy. Irradiations of polycrystalline graphite powder suspensions at frequencies of 20 kHz and 500 kHz, were carried out in three different solvents: water (as the best medium for cavitation), a surfactant (OMImBr) aqueous solution and also a mixture of sulfuric and nitric acids which caused the exfoliation by intercalation. The average basal particle size of 168 lm was reduced to 4 lm after ultrasonication delivering a huge energy density up to 1.2 MW/m2. Change of the sonication time and the nature of the solvents produced different reduction of the graphite crystals dimensions, affecting the out of plane thickness and the basal width as well. The ultrasonication promoted the disordering of the graphite tridimensional stacking for all solvents used, with the strongest effect in acidic medium. Turbostratic structures formation and exfoliation of graphene flakes have been observed after the use of surfactant for sonication medium. Intercalation in acid medium prior to the ultrasound treatment produced similar effects.