Spectroscopic probing of organic molecules encapsulated in functionalized carbon nanotubes in solution

Pyrene was introduced into cavities in functionalized single-walled and multiple-walled carbon nanotubes to be used as a molecular probe in the study of encapsulation. The solubility of these materials in common organic solvents allowed solution-phase absorption and emission spectroscopic measurements. The results, which are consistent with the formation of pyrene excimer, are explained in terms of high local pyrene concentrations and perhaps pyrene microcrystals inside the carbon nanotube cavities. The fluorescence decay results show that there is significant quenching of pyrene excited states by the hosting carbon nanotubes.