Synthesis and Regiochemistry of [60]Fullerenyl 2-Methylmalonate Bisadducts and their Facile Electron-Accepting Properties

Abstract

A simple one-pot reaction using in situ chemically generated Na-naphthalenide as an electron reductant in the preferential generation of C 60 2− is described. Trapping of C 60 2− intermediate with two molar equivalents of sterically hindered 2-bromo-2-methylmalonate ester afforded two singly bonded fullerenyl bisadducts C 60 [-CMe(CO 2 Et) 2 ] 2 in 35 and 7% yield, respectively. The regiochemistry of these two products were determined to be 1,4-and 1,16-bisadducts, respectively, by NMR, UV-Vis-NIR, LCMS, and X-ray single crystal structural analysis. The minor 1,16-bisadduct 2 exhibits long wavelength absorption bands in near-IR region and the prominent electron-accepting characteristics as compared with those of the major 1,4-bisadduct and pristine C 60 . As revealed by DFT calculation, we propose that the origin of these unusual characters of 2 arises from the moiety of [18π]-trannulene, in close resemblance to that of the highly symmetrical emerald green 1,16,29,38,43,60-hexaadduct of C 60 , EF-6MC n . Accordingly, we anticipate a fast progressive formation of plausible 1,16-bisadduct-like intermediate moieties on a C 60 cage as the precursor structure leading to the formation of EF-6MC n , by taking the corresponding regiochemistry and electronic properties into account.

Ionic conductivity of [Li+@C60](PF6−) in organic solvents and its electrochemical reduction to Li+@C60˙−

“…[9][10][11][12] In addition, the radial anion can serve as an important reaction intermediate for various unique chemical modifications of the fullerene cage. 13 Although many methods for the preparation of empty C 60 radical anion salts have been reported, 14 studies on endohedral fullerene radical anions are relatively stagnant.…”

“…The generated Li + @C 60 À was characterised by UV-vis-NIR and ESR spectroscopy. 7 Li and 13 C NMR, dynamic light scattering (DLS), and z potential distribution measurements did not furnish meaningful signals/results, probably because of the low concentration of the target species, in addition to paramagnetic relaxation. The UV-vis-NIR spectra of the solution collected from the cathode side after 3 days are shown in Fig.…”

Synthesizing 1,23-C60 Adducts with Improved Efficiency: A Type of Stable and Highly Soluble C60 Derivatives

“…However, the use of bulky addends would not necessarily result in the 1,23-adducts due to the complication caused by the side reactions . Reports on the 1,23-addition of carbon addends to C 60 are limited − and typically with a low yield as shown for the diethyl methylmalonate, where the 1,23-adducts were obtained only with 7% via either the Mn­(III)-medicated reactions or the reactions of C 60 dianion (C 60 2– ) . Notably, the addition pattern to fullerenes has a significant effect on the property of the compounds, and an isomeric effect is shown on the organic and perovskite solar cells .…”

Prediction of the experimental regioselectivity of C60 fullerene bis‐adducts

“…Efforts on the regioselective preparation of bis‐adducts have been recently reported, for example, the preparation of novel fullerenyl bis‐adducts . In addition, the formation of bis‐adducts using tethered organic fragments and double Diels–Alder cycloaddition has been reported.…”