Control of the Near Infrared Photoluminescence of Locally Functionalized Single-Walled Carbon Nanotubes via Doping by Azacrown-Ether Modification

Doped semiconducting single-walled carbon nanotubes (SWNTs) through local chemical functionalization (lf-SWNTs) show fascinating photoluminescence (PL) that appears with a longer wavelength and enhanced quantum yield compared to the original PL of non-modified SWNTs. In this study, we introduce an azacrown ether moiety at the doped sites of lf-SWNTs (CR-lf-SWNTs), and observe selective PL wavelength shifts depending on different interaction modes of silver ion inclusion and protonation of the amino group in the ring. Interestingly, their different values of the wavelength shifts show a clear correlation with calculated electron density of the nitrogen atom in the azacrown moiety in case of the inclusion form and the protonated form. This newly-observed responsiveness based on molecular interactions is expected to create doped sites that can versatilely control the PL functions based on molecular systems.