A Facile Strategy for Preparation of Fluorescent SWNT Complexes with High Quantum Yields Based on Ion Exchange

Abstract

AbstractThe fluorescent imidazolium salt (1,3‐bis(9‐anthracenylmethyl)imidazolium chloride, [bamim]Cl) has been grafted onto the surfaces of single‐walled carbon nanotubes (SWNTs) using an ion exchange strategy based on metathesis of the K+ ion in CO2K derivatized SWNTs with [bamim]+. The resulting SWNT‐[bamim] complex has been characterized with high‐resolution transmission electron microscopy (HR‐TEM), X‐ray photoelectron spectroscopy (XPS), elemental mapping, and elemental linear profiles analysis. A blue light emission can be observed at 392, 414 and 438 nm for SWNT‐[bamim] upon being excited at 254 nm. The quantum yield (QY) of the SWNT‐[bamim] complex (0.40) is much higher than that of SWNT/[bamim]Cl (0.02), used as a control, and prepared using a π‐π stacking method, indicating that ion exchange is a far more effective strategy for retaining a high QY. Additionally, UV‐Vis‐NIR and Raman spectroscopy show that the SWNT‐[bamim] complex can maintain the one‐dimensional electronic states of SWNTs. Other imidazolium salts have also been successfully grafted onto SWNTs via the same strategy, indicating that the ion exchange process can serve as a universal strategy for the functionalization of SWNTs.