Hu Hui, Zhao Bin, Hamon Mark A, Kamaras Katalin, Itkis Mikhail E, Haddon Robert C
Center for Nanoscale Science and Engineering, Departments of Chemistry and Chemical & Environmental Engineering, University of California, Riverside, CA 92521-0403, USA.
J Am Chem Soc. 2003 Dec 3;125(48):14893-900. doi: 10.1021/ja0356737.
We report the sidewall functionalization of soluble HiPco single-walled carbon nanotubes (SWNTs) by addition of dichlorocarbene. The dichlorocarbene-functionalized SWNTs [(s-SWNT)CCl(2)] retain their solubility in organic solvents such as tetrahydrofuran and dichlorobenzene. The degree of dichlorocarbene functionalization was varied between 12% and 23% by using different amounts of the dichlorocarbene precursor. Because the addition of dichlorocarbene saturates the carbon atoms on the sidewall of the SWNTs and effectively replaces the delocalized partial double bonds with a cyclopropane functionality, the optical spectra of the SWNTs change dramatically. We estimate that the saturation of 25% of the pi-network electronic structure of the SWNTs is sufficient to remove all vestiges of the interband transitions in the infrared spectrum. The transitions at the Fermi level in the metallic SWNTs that appear in the far-infrared (FIR) region of the spectrum show a dramatic decrease of intensity on dichlorocarbene functionalization. The FIR region of the spectrum allows a clear differentiation between the covalent and the ionic chemistry of SWNTs. In contrast with covalent functionalization, we show that reaction of the SWNTs with bromine vapor leads to a strong increase in absorptions at the Fermi level that is observable in the FIR due to hole doping of the semiconducting SWNTs. Thermal treatment of the (s-SWNT)CCl(2) above 300 degrees C resulted in the breakage of C-Cl bonds, but did not restore the original electronic structure of the SWNTs.
我们报道了通过添加二氯卡宾对可溶性HiPco单壁碳纳米管（SWNTs）进行侧壁功能化。二氯卡宾功能化的单壁碳纳米管[（s-SWNT）CCl₂]在诸如四氢呋喃和二氯苯等有机溶剂中仍保持其溶解性。通过使用不同量的二氯卡宾前体，二氯卡宾功能化的程度在12%至23%之间变化。由于二氯卡宾的添加使单壁碳纳米管侧壁上的碳原子饱和，并有效地用环丙烷官能团取代了离域的部分双键，单壁碳纳米管的光谱发生了显著变化。我们估计，单壁碳纳米管π网络电子结构25%的饱和足以消除红外光谱中所有带间跃迁的痕迹。光谱远红外（FIR）区域中金属性单壁碳纳米管费米能级处的跃迁在二氯卡宾功能化后强度显著降低。光谱的FIR区域能够清晰地区分单壁碳纳米管的共价化学和离子化学。与共价功能化相反，我们表明单壁碳纳米管与溴蒸气的反应导致费米能级处的吸收强烈增加，这在FIR中是可观察到的，这是由于半导体单壁碳纳米管的空穴掺杂。在300℃以上对（s-SWNT）CCl₂进行热处理导致C-Cl键断裂，但并未恢复单壁碳纳米管的原始电子结构。
