Weijie Huang

Interactions of functionalized carbon nanotubes with tethered pyrenes in solution

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.

Functionalization of Carbon Nanotubes with Bovine Serum Albumin in Homogeneous Aqueous Solution

Single-walled (SWNTs) and multiple-walled (MWNTs) carbon nanotubes were solubilized via the esterification of nanotube-bound carboxylic acids by oligomeric polyethylene glycol compounds. The water-soluble samples were used as starting materials in reactions with bovine serum albumin (BSA) protein in ambient aqueous solutions. The reaction conditions were designed for thermodynamically favorable transformation from ester to amide linkages, yielding SWNT-BSA and MWNT-BSA conjugates. The results show that the use of soluble starting nanotube materials in an indirect functionalization method represents a valuable approach to the biomodification of carbon nanotubes.

Luminescence anisotropy of functionalized carbon nanotubes in solution

Luminescence anisotropy of functionalized single-wall (SWNT) and multiple-wall (MWNT) carbon nanotubes in solution and in polymeric thin-film matrix was investigated. The results show that the absorption and emission dipole moments are intrinsically collinear, corresponding to the limiting positive anisotropy. The observation of strong luminescence polarization for the functionalized carbon nanotubes in room-temperature chloroform is consistent with the polymeric nature of these luminescent species; and the partial depolarization in solution is rationalized in terms of the flexibility of the nanotubes.

Intramolecular electron transfer in fullerene derivatives with multiple donors

Abstract Electronic absorption and emission properties of the fullerene derivatives with multiple electron donors, ( N , N -dimethylaniline) N -[60]fullerene ( N =0,1,2,4, and 6), were investigated. The results show that there are both ground-state and excited-state electron transfers from the dimethylaniline moiety to the fullerene and that the electron transfers are dependent on the number of intramolecular electron donors on the fullerene cage. The results also show that the absorption and emission properties of these molecules are extremely solvent polarity dependent, consistent with the presence of significant electron transfer processes.