Handle-free conjugation of small molecules generates tunable emissive defects on carbon nanotubes

Few chemical methods controllably generate sp³ defects on single-walled carbon nanotubes (SWCNTs) in such a way as to preserve or modulate their excitonic photoluminescence. We describe herein a new substrate-catalyzed functionalization reaction that enables conjugation of diverse small molecules lacking traditional SWCNT conjugation handles, resulting in quantum well defects with tunable near-infrared emission properties. This reaction is highly versatile – we describe herein the conjugation of over 200 unique small molecules including alcohols, amines, carbonyls, phenyl groups, alkyl chains, amino acids and peptides. The optical properties of the resulting nanotubes can be precisely tuned through the choice of conjugated molecule, as the electronic structure of the attached group governs the relative configuration of defects within the graphitic lattice. These molecularly driven effects allow fine-tuning of the emission wavelength, enabling rational design of nanotube-based fluorophores across the near-infrared window.