Fluorescence properties of aromatic amine adsorbed on metallic and semiconducting single-walled carbon nanotubes

Semiconducting single-walled carbon nanotubes (SWNTs) have been enriched by 1-aminopyrene treatment of the mildly oxidized SWNTs due to removal of metallic SWNTs having a higher affinity for 1-aminopyrene. The enrichment was caused by the differences in the adsorption properties of 1-aminopyrene on the metallic and semiconducting SWNTs. The fluorescence properties of 1-aminopyrene adsorbed on the metallic and semiconducting SWNTs have been investigated in order to clarify its adsorption mechanism. 1-Aminopyrene was adsorbed on the metallic SWNTs through the interaction of the amino group with the graphene surface and through a hydrogen bonding interaction between the amino group and the carboxyl group on the graphene surface. On the other hand, in the case of semiconducting SWNTs, 1-aminopyrene was adsorbed through a π–π interaction on the graphene surface in addition to the hydrogen bonding interaction with the carboxyl groups.