ortho-Substituted Aryldiazonium Design for the Defect Configuration-Controlled Photoluminescent Functionalization of Chiral Single-Walled Carbon Nanotubes.

Defect functionalization of single-walled carbon nanotubes (SWCNTs) by chemical modification is a promising strategy for near-infrared photoluminescence (NIR PL) generation at >1000 nm, which has advanced telecom and bio/medical applications. The covalent attachment of molecular reagents generates sp3-carbon defects in the sp2-carbon lattice of SWCNTs with bright red-shifted PL generation. Although the positional difference between proximal sp3-carbon defects, labeled as the defect binding configuration, can dominate NIR PL properties, the defect arrangement chemistry remains unexplored. Here, aryldiazonium reagents with π-conjugated ortho-substituents (phenyl and acetylene groups) were developed to introduce molecular interactions with nanotube sidewalls into the defect-formation chemical reaction. The functionalized chiral SWCNTs selectively emitted single defect PL in the wavelength range of ∼1230-1270 nm for (6,5) tubes, indicating the formation of an atypical binding configuration, different from those exhibited by typical aryl- or alkyl-functionalized chiral tubes emitting ∼1150 nm PL. Moreover, the acetylene-based substituent design enabled PL brightening and a subsequent molecular modification of the doped sites using click chemistry.

Azide modification forming luminescent sp2 defects on single-walled carbon nanotubes for near-infrared defect photoluminescence.

Azide functionalization produced luminescent sp2-type defects on single-walled carbon nanotubes, by which defect photoluminescence appeared in near infrared regions (1116 nm). Changes in exciton properties were induced by localization effects at the defect sites, creating exciton-engineered nanomaterials based on the defect structure design.

Solvatochromism of near infrared photoluminescence from doped sites of locally functionalized single-walled carbon nanotubes.

The doped sites of locally functionalized single-walled carbon nanotubes emit red-shifted and bright near-infrared photoluminescence compared to non-doped nanotubes. Here, we observe unique photoluminescent solvatochromism. Organic solvent environments induce photoluminescent energy shifts that linearly correlate with a solvent polarity function. A high responsiveness at the doped sites is found.