Single-walled carbon nanotube (SWCNT) hybrids with meso-5,10,15,20- tetrakis(N-methyl-4-pyridyl)porphyrin (TMPyP4) and meso-5,10,15,20- tetraphenylporphyrin (TPP) have been studied by the resonance Raman spectroscopy and by ab initio and molecular dynamic calculations. A comparison of the intensities of the bands assigned in the Raman spectrum to the radial breathing mode, as well as the relative band positions corresponding to the tangential modes of the hybrids with respect to the positions of these modes in the spectrum of the pristine SWCNT, indicates that the interaction of the nanotube with TMPyP4 is stronger than with TPP. A structure calculation (by the DFT/M05-2X method) of the TMPyP4 molecule adsorbed to a fragment of the zigzag (10,0) SWCNT surface shows that porphyrin adapts a saddled structure with the binding energy to the nanotube of -72.0 kcal/mol. The interaction energy in the complex of a TPP molecule with SWCNT, whose molecular structure is similar to TMPyP4, is only -19.3 kcal/mol and TPP does not adapt the saddled structure on the nanotube surface. The calculated interaction energies of the nanotube surface with the porphin core (-14.3 kcal/mol), the charged fragment of TMPyP4 (methylpyridinium) (-25.8 kcal/mol) and a neutral benzene molecule (-4.6 kcal/mol), which mimic the side residues of TMPyP4 and TPP, respectively, suggest that the stronger interaction between SWCNT and the TMPyP4 molecule is due to the cation-π interaction. The SWCNT:TMPyP4 complex formation in the aqueous solution has been modeled by the molecular dynamics method. The modeling showed that the hybrid is also stable in the water solution.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films