Regioselectivity of the Pauson–Khand reaction in single-walled carbon nanotubes

Abstract

Chemical functionalization of nanotubes, in which their properties can be combined with those of other classes of materials, is fundamental to improve the physicochemical properties of nanotubes for potential technological applications. In this work, we theoretically and experimentally examine the Pauson-Khand reaction (PKR) on zig-zag, armchair, and chiral single-walled carbon nanotubes (SWCNTs). Our benchmarked density functional theory (DFT) calculations show that an alternative pathway to the widely accepted Magnus reaction pathway has significantly lower energy barriers, thus suggesting the use of this alternative pathway to predict whether a PKR on SWCNTs is favored or hampered. Accessible energy barriers of up to 16 kcal mol-1 are estimated and our results suggest that semiconducting SWCNTs react faster than metallic ones, although both types can be functionalized. Guided by our theoretical predictions, cyclopentenones are successfully attached to SWCNTs by heating and are, subsequently, characterized in the laboratory.

Covalent Functionalization of Single-Walled Carbon Nanotubes by the Bingel Reaction for Building Charge-Transfer Complexes

“…Selective formation of the open adducts with the binding configuration perpendicular to the nanotube axis was also found for (8,8)- and (10,5)-SWCNTs in an earlier computational study . Therefore, this reaction can lead to the functionalization of nanotubes in the position different from that observed in the [4 + 2] or [2 + 2] cycloaddition reactions, , and in the Pauson–Khand reaction . Moreover, the experimental study on the sidewall functionalization of HiPco SWCNTs using the Bingel reaction showed that the degree of sidewall functionalization (one group per 75–300 carbon atoms of SWCNTs) can be controlled by changing the output power of microwave heating …”

“…For example, the sidewall (4 + 2) cycloaddition reaction of zigzag SWCNTs leads to the addition of benzyne in the parallel position to the SWCNT axes . The parallel product is also formed in the [2 + 2 + 1] cycloaddition Pauson–Khand reaction . The computed Gibbs energies of all stationary points for the formation of par and obl products of the Bingel reaction are presented in Figure .…”

“…36 Therefore, this reaction can lead to the functionalization of nanotubes in the position different from that observed in the [4 + 2] or [2 + 2] cycloaddition reactions, 37,38 and in the Pauson−Khand reaction. 39 Moreover, the experimental study on the sidewall functionalization of HiPco SWCNTs using the Bingel reaction showed that the degree of sidewall functionalization (one group per 75−300 carbon atoms of SWCNTs) can be controlled by changing the output power of microwave heating. 23 (6,5)-Chiral SWCNTs.…”

“…37 The parallel product is also formed in the [2 + 2 + 1] cycloaddition Pauson-Khand reaction. 39 The computed Gibbs energies of all stationary points for the formation of par and obl products of the Bingel reaction are presented in…”

Decomposition of the electronic activity in competing [5,6] and [6,6] cycloaddition reactions between C60 and cyclopentadiene

“…As a result, it undergoes a variety of chemical organic reactions, the most important being the nucleophilic additions [4][5][6]. Moreover, C 60 reacts through many metal-catalysed processes like the Pauson-Khand reactions [7][8][9], the Suzuki-Miyaura reactions [10][11][12][13] or the [2 + 2 + 2] cycloadditions [14][15][16], among others. However, one of the most employed reactions for the functionalization of fullerenes and their derivatives is the Diels-Alder (DA) cycloaddition [17][18][19][20][21][22].…”