Interactions of functionalized carbon nanotubes with tethered pyrenes in solution

Abstract

Single-wall carbon nanotubes (SWNTs) were functionalized by oligomeric species containing derivatized pyrenes. Absorption and emission properties of the pyrene moieties tethered to the functionalized SWNTs were studied in homogeneous solution. The absorption spectra suggest no significant ground-state complexation between the pyrenes and nanotubes. The fluorescence and fluorescence excitation results show that the tethered pyrenes form “intramolecular” (intra-nanotube) excimers and that the excimer formation is predominantly dynamic in nature. The time-resolved fluorescence results show that the pyrene monomer and excimer emissions are significantly quenched by the attached SWNTs. The quenching is explained in terms of a mechanism in which carbon nanotubes serve as acceptors for excited-state energy transfers from the tethered pyrene moieties.