Excited-state energy transfers in single-walled carbon nanotubes functionalized with tethered pyrenes

Single-walled carbon nanotubes were co-functionalized with pyrenemethanol and 3,5-dihexadecanyloxybenzyl alcohol in different ratios with the purpose of altering the content of pyrene moieties tethered to the nanotube surface. The functionalized nanotube samples were characterized by using established instrumental techniques. The absorption and emission results of the samples suggest that there are significant intramolecular excited-state energy transfers from both pyrene monomer and excimer to the linked nanotube, though the energy transfer efficiencies may be different between the monomer and excimer. The excimer formation can be limited by reducing the pyrenemethanol fraction to simplify the excited state processes, but contributions from the luminescence of the well-functionalized carbon nanotubes in the same wavelength region becomes an additional complication. Mechanistic implications of the photophysical results are discussed. (c) 2006 Elsevier B.V. All rights reserved.