Successively Regioselective Electrosynthesis and Electron Transport Property of Stable Multiply Functionalized [60]Fullerene Derivatives

Abstract

<jats:p>With the recent advance in chemical modification of fullerenes, electrosynthesis has demonstrated increasing importance in regioselective synthesis of novel fullerene derivatives. Herein, we report successively regioselective synthesis of stable tetra- and hexafunctionalized [60]fullerene derivatives. The cycloaddition reaction of the electrochemically generated dianions from [60]fulleroindolines with phthaloyl chloride regioselectively affords 1,2,4,17-functionalized [60]fullerene derivatives with two attached ketone groups and a unique addition pattern, where the heterocycle is rearranged to a [5,6]-junction and the carbocycle is fused to an adjacent [6,6]-junction. This addition pattern is in sharp contrast with that of the previously reported biscycloadducts, where both cycles are appended to [6,6]-junctions. The obtained tetrafunctionalized compounds can be successively manipulated to 1,2,3,4,9,10-functionalized [60]fullerene derivatives with an intriguing “<jats:italic>S</jats:italic>”-shaped configuration <jats:italic>via</jats:italic> a novel electrochemical protonation. Importantly, the stability of tetrafunctionalized [60]fullerene products allows them to be applied in planar perovskite solar cells as efficient electron transport layers.</jats:p>

Electrochemically Promoted Benzylation of [60]Fullerooxazolidinone

“…On balance, we carried out our experiments on 1 (0.01 mmol) at a lower temperature of 15 • C. By controlled potential electrolysis (CPE) of 1 at −1.09 V in 1,2-C 6 H 4 Cl 2 solution containing 0.1 M tetra-n-butylammonium perchlorate (TBAP) at 15 • C under an atmosphere of argon, dianion 1 2− was generated after acceptance of two electrons. Similar to other dianionic C 60 -fused heterocycles, the ring-opened singly-bonded fullerenyl dianion was attained after addition of two electrons [26][27][28][29][30][31][32][33][34][35][36][37], as confirmed by the very different CV of dianion 1 2− (Figure S21) compared to that of neutral 1 (Figure 1). Then, 1 2− was treated with 20 equiv.…”

“…Our group demonstrated the electrosynthesis of the 1,2,3,16adducts from fulleroindoline and alkyl bromides, acyl chlorides, or chloroformates [26,27]. Subsequently, we reported the electrochemical reactions of the fulleroindolines with 1,2bis(bromomethyl)benzene or phthaloyl chloride, which regioselectively provided 1,2,4,17adducts [28,29], while the bulky alkyl bromides, such as 2,4,6-tris(bromomethyl)mesitylene and diphenylbromomethane, were also exploited to functionalize fulleroindolines, and afforded 1,2,3,16-adducts and a rare 1,4,9,12-adduct [30]. All of these reactions involved the rearrangement of the indoline moiety from a [6,6]-bond to a [5,6]-bond.…”

Unexpected formation of 1,2- and 1,4-bismethoxyl Sc3N@Ih-C80 derivatives via regioselective anion addition: an unambiguous structural identification and mechanism study

“… 15,16,40 But there is an exception that the electrochemical reaction of a C 60 derivative reported by Wang's group follows a “stepwise one-electron reduction and protonation” mechanism, in which the monoanionic intermediate was protonated to generate a free radical on the adjacent carbon. 41 The anion radical relay mechanism of methoxylation of Sc 3 N@C 80 follows the electron transfer process proposed in most electrochemical reactions, but is followed by a process in which the anion is directly oxidized to a free radical.…”

Cu(I)-Catalyzed Synthesis of [60]Fullerene-Fused Lactams and Further Electrochemical Functionalization

“…Fullerene derivatives have been applied to perovskite solar cells (PSCs) . Thus, 3a was selected as the overcoating layer of the electron-transporting layer in n-type perovskite solar cell with the configuration ITO/SnO 2 / 3a /MAPbI 3 /Spiro-OMeTAD/Ag (Figure a).…”