(Invited) Theoretical Insight into New Strategies of Carbon Nanotube Functionalization

Abstract

An intentional introduction of quantum defects to the single-walled carbon nanotube (SWCNT) surface leads to unique photoluminescence properties that may be useful for a wide range of optoelectronic, sensing, imaging and quantum communication applications. Quantum-chemical simulations help to rationalize spectroscopic observation and fine tune synthetic strategies. I will overview photosynthetic control of chemical binding configurations of quantum defects through the spin multiplicity of photoexcited intermediates. Here photoexcited aromatics react with SWCNT sidewalls to undergo a singlet-state pathway in the presence of dissolved oxygen, leading to ortho binding configurations of the aryl group on the nanotube. In contrast, the oxygen-free photoreaction activates previously inaccessible para configurations through a triplet-state mechanism. To understand the atomistic mechanism of these photo-activated reactions and their dependence on spin multiplicity, we have modeled the reaction with and without triplet quenching using density functional theory. Computed reaction pathways demonstrate selectivity and dependence of outcomes of the photo-activated reaction on the presence or absence of triplet quenching, corresponding to presence or absence of oxygen, respectively. Such spin-selective photochemistry diversifies SWCNT emission tunability by controlling the morphology of the emitting sites.