Preserving π-conjugation in covalently functionalized carbon nanotubes for optoelectronic applications

Abstract

Covalent functionalization tailors carbon nanotubes for a wide range of applications in varying environments. Its strength and stability of attachment come at the price of degrading the carbon nanotubes sp2 network and destroying the tubes electronic and optoelectronic features. Here we present a non-destructive, covalent, gram-scale functionalization of single-walled carbon nanotubes by a new [2+1] cycloaddition. The reaction rebuilds the extended π-network, thereby retaining the outstanding quantum optoelectronic properties of carbon nanotubes, including bright light emission at high degree of functionalization (1 group per 25 carbon atoms). The conjugation method described here opens the way for advanced tailoring nanotubes as demonstrated for light-triggered reversible doping through photochromic molecular switches and nanoplasmonic gold-nanotube hybrids with enhanced infrared light emission.

Scalable Production of Nanographene and Doping via Nondestructive Covalent Functionalization

“…This suggests a considerable weakening of the CC bond and π‐overlap at the bridge site upon addition of the triazine functional group. In accordance with literature, the CC bond at the bridge site is in fact broken, meaning the bridge site carbon atoms are not sp 3 hybridized. This is supported by analysis of the valence electronic structure, which displays a nodal plane between the two atoms in the highest occupied molecular orbital (Figure b).…”

“…Additional components appear in the C1s spectrum of nGTrz that are assigned to the CN and CN bonds of the triazine functional groups. Furthermore, the N1s spectrum shows two distinct nitrogen species assigned to the nitrogen atoms at the bridge site and in the triazine ring, with a peak area ratio of 1:3 (Figure S5, Supporting Information), similar to previously reported results . Most significantly, NEXAFS results show no noticeable decrease in the content of sp 2 carbon atoms, demonstrating that the π‐conjugated system of nGTrz is preserved (Figure f and Table S2, Supporting Information).…”

“…Doping effects can be observed when a heteroatom is conjugated with the π‐conjugated system of graphene. As has been reported with carbon nanotubes, this is possible when the nitrogen‐containing three‐membered rings of nGTrz has an open form (Figure b and Figure S1b, Supporting Information). Coherent with our computational results, the conjugated nature of the π‐system is not impaired by the covalent functionalization, as the sp 2 character of the involved carbon atoms is retained (Figure a).…”

Controlling the Decoration of the Reduced Graphene Oxide Surface with Pyrene‐Functionalized Gold Nanoparticles

“…To this purpose, we realized a novel set of nanohybrids incorporating SWCNTs and analyzed them through photoluminescence (PL) spectroscopy. Close proximity between gold nanoparticles and SWCNTs has already been demonstrated to enhance the SWCNT emission yield . We accordingly prepared two set of samples, namely SWCNTs coated just with the pyrene‐derivative (SWCNTs‐Py) and SWCNTs coated with PyAuNPs (2 nm; SWCNTs‐PyAuNPs).…”

Sensor Technologies Empowered by Materials and Molecular Innovations

“…In addition to the swelling of the random nanowire network, SWCNTs also display conductance changes induced by charge transfer or dipolar pinning/scattering caused by the analyte.P inning and charge transfer result in ar eduction of the mobile charge carriers,and this feature can be detected by changes in the threshold gate voltages in field-effect transistor (FET) devices. [27] Functionalization of SWCNTs to impart selectivity is key;h owever, the chemistry is complicated by the fact that core characterization methods like solution NMR spectroscopy and crystal structure determination are not possible with these nanomaterials.H owever,t he field continues to evolve with the refinement of methods for the attachment of functional groups with greater precision [28] and that can undergo subsequent functionalization [29] to add recognition elements. [30] Theu se of nanowires for chemical sensing has recently been reviewed.…”