jp071604t_si_001.pdf (259.03 kB)
Retention of Intrinsic Electronic Properties of Soluble Single-Walled Carbon Nanotubes after a Significant Degree of Sidewall Functionalization by the Bingel Reaction
journal contribution
posted on 2007-07-12, 00:00 authored by Tomokazu Umeyama, Noriyasu Tezuka, Mitsuru Fujita, Yoshihiro Matano, Norihiko Takeda, Kei Murakoshi, Kaname Yoshida, Seiji Isoda, Hiroshi ImahoriSidewalls of acid-treated, shortened single-walled carbon nanotubes (SWNTs) with long alkyl chains at the
open ends and defect sites have been functionalized by Bingel reaction to examine the structures and
spectroscopic properties in detail for the first time. The microwave-assisted Bingel reaction has been successfully
applied to the sidewall functionalization of which the reaction rate is ca. 50 times faster than that under the
conventional conditions. The degree of the sidewall functionalization (one diester unit per 75−300 carbon
atoms of SWNTs) was found to be controllable by changing the output power of the microwave under the
same temperature. Atomic force microscopy and transmission electron microscopy showed the progressive
exfoliation of the SWNT bundles by the double chemical modification. Resonant Raman and UV−vis−NIR
absorption spectroscopies revealed that the electronic properties of SWNT are largely retained after a significant
degree of sidewall modification by the Bingel reaction without apparent selective reactivity for metallic and
semiconducting SWNTs. This is in remarkable contrast with the conventional sidewall functionalization of
SWNTs leading to the loss of their electronic properties (one functional group per 10−100 carbon atoms on
the sidewall). Thus, our covalent functionalization methodology can provide SWNT materials with both
excellent solubility and inherent electronic properties which are highly desirable in solution-phase processing
for the fabrication of SWNT-based molecular devices.