A Theoretical Exploration of the 1,3-Dipolar Cycloadditions onto the Sidewalls of (n,n) Armchair Single-Wall Carbon Nanotubes

Abstract

The viability of 1,3-dipolar cycloadditions of a series of 1,3-dipolar molecules (azomethine ylide, ozone, nitrone, nitrile imine, nitrile ylide, nitrile oxide, diazomethane, and methyl azide) onto the sidewalls of carbon nanotubes has been assessed theoretically by means of a two-layered ONIOM approach. The theoretical calculations predict the following: (i) other than the 18-valence-electron azomethine ylide and ozone, the 16-valence-electron nitrile ylide and nitrile imine are the best candidates for experimentalists to try; (ii) upon 1,3-dipolar cycloaddition, a 1,3-diople molecule is di-sigma-bonded to a pair of carbon atoms on the sidewall of SWNT, forming a five-membered ring surface species; (iii) the as-formed 1,3-dipole-SWNT bonding is much weaker than that in the products of the molecular 1,3-DC reactions and can be plausibly broken by heating at elevated temperatures; (iv) the sidewalls of the armchair (n,n) SWNTs (n = 5-10) are subject to the 1,3-DCs of ozone and azomethine ylides; (v) both the 1,3-DC reactivity and retro-1,3-DC reactivity are moderately dependent on the diameters of SWNTs, implying the feasibility of making use of the heterogeneous 1,3-DC chemistry to purify and separate SWNTs diameter-specifically.

Functional Covalent Chemistry of Carbon Nanotube Surfaces

“…[103] Moreover, all of these approaches have been assessed theoretically as means of purifying, opening sidewalls, and separating SWNTs diameter-specifically. [104,105] In addition, theoretical calculations [106] predict that nitrene and carbene (2 þ 1) cycloaddition reactions on narrow-diameter tubes can recover, as a consequence of bond cleaving, the ''ideal'' conductance of original pristine tubes. Metallic tubes subjected to covalent sidewall functionalization of CCl 2 experience a band gap opening as the functionalization concentration increases to 11% followed by a continuation of the bandgap trend with rising functionalization levels up to 33.3%.…”

Cycloaddition Reactions of Butadiene and 1,3‐Dipoles to Curved Arenes, Fullerenes, and Nanotubes: Theoretical Evaluation of the Role of Distortion Energies on Activation Barriers

“…Lu and co-workers studied the Diels-Alder reaction theoretically by means of the ONIOM approach. [43] They observed that the 1,3-butadiene addition to (5,5) carbon nanotubes was disfavored, but the cycloaddition of o-quinodimethane was feasible due to the aromatic stabilization of the adducts.…”

“…[43] They found that the addition of formoazomethine ylide to (5,5) SWCNT has a reaction energy of À39.3 kcal mol À1 and an activation barrier of 3.4 kcal mol 1.7 À21.7 17.8 26.5 C 60 [5,6] À34.4 1. , respectively (as compared to the B3LYP energies). This indicates that the use of the AM1 method as the low level method within the ONIOM approach leads to an underestimation of reaction and activation energies in comparison with the values obtained for the treatment of all atoms at the high level of theory.…”

Indices of the fullerenes reactivity

“…the constraints of the carbon skeleton are increasing with the decrease in diameters of nanotubes that can be detected with the increase of θ P values. 44 The influence of SWNT diameter on the ozonation of SWNT 45 which was studied theoretically ( Figure 13) has been confirmed by experimental observation of the main drawing of small-diameter nanotubes in the reaction of ozonolysis. Figure 13.…”