Aerobic Oxidations of C₆₀^2– in the Presence of PhCN and PhCH₂CN: Oxygenation versus Dehydrogenation Reactions

Aerobic oxidations of dianionic C60 were examined in PhCN and PhCH2CN, where dioxygen was activated to O2•– via the single-electron transfer from C602– and underwent oxygenation and dehydrogenation reactions, respectively. Addition of PhCH2Br led to further benzylation for the oxygenated product but not for the dehydrogenated one, suggesting that the initial two negative charges were preserved for the intermediates of the oxygenation reaction but not for those of the dehydrogenation reaction

Aerobic Oxidations of C₆₀^2– in the Presence of PhCN and PhCH₂CN: Oxygenation versus Dehydrogenation Reactions

Aerobic oxidations of dianionic C₆₀ were examined in PhCN and PhCH₂CN, where dioxygen was activated to O₂^•– via the single-electron transfer from C₆₀^2– and underwent oxygenation and dehydrogenation reactions, respectively. Addition of PhCH₂Br led to further benzylation for the oxygenated product but not for the dehydrogenated one, suggesting that the initial two negative charges were preserved for the intermediates of the oxygenation reaction but not for those of the dehydrogenation reaction

Impact of the Interlayer Distance between Graphene and MoS₂ on Raman Enhancement

Two-dimensional (2D) materials and their van der Waals (vdW) heterostructures, particularly graphene and graphene/MoS2, have attracted intense attention due to their potential application in surface-enhanced Raman spectroscopy (SERS). Herein, we report how to modulate the SERS response of 2D materials. First, we demonstrate that SERS based on graphene materials is inversely proportional to the functionalization degree. The covalent functionalization interrupts the conjugation of the graphene π-system, inhibiting the charge transfer between graphene and the probe molecule (Rhodamine 6G), thus reducing Raman enhancement. For graphene/MoS2 vdW heterostructures, the SERS enhancement is dominated by the vdW interaction between graphene and MoS2. A shorter interlayer distance, with stronger vdW interactions, improves the dipole–dipole interaction and the charge transfer, increasing the Raman enhancement. Moreover, the SERS intensity of graphene/MoS2 vdW heterostructures varies rapidly when the interlayer distances are less than 0.6 nm, while it varies less at interlayer distances longer than 0.6 nm. This study not only demonstrates the Raman enhancement dependence on the functionalization degree of graphene materials and the interlayer distance in graphene/MoS2 vdW heterostructures but also opens the door for controlling and predicting the SERS intensity based on 2D materials

Reductive Benzylation of C₆₀ Imidazoline with a Bulky Addend

Reductive benzylation of C60 imidazoline with a bulky addend affords two 1,2,3,16-adducts (2 and 4) and one 1,2,3,4-adduct (3). Experimental and computational results indicate that the sterically favored 2 is more stable than the electronically favored 3. However, an opposite stability order is shown for the dianions of 2 and 3

Reductive Benzylation of C₆₀ Imidazoline with a Bulky Addend

Reductive benzylation of C₆₀ imidazoline with a bulky addend affords two 1,2,3,16-adducts (<b>2</b> and <b>4</b>) and one 1,2,3,4-adduct (<b>3</b>). Experimental and computational results indicate that the sterically favored <b>2</b> is more stable than the electronically favored <b>3</b>. However, an opposite stability order is shown for the dianions of <b>2</b> and <b>3</b>

Reductive Benzylation of C₇₀ Imidazoline with a Bulky Addend

Reductive benzylation of C70 imidazolines bearing a bulky addend has been carried out under conditions similar to that reported for C60 analogues. However, different from the reaction of C60 analogues, the reaction of C70 imidazolines not only results in adducts with 1,2,3,16-configuration due to the steric effect, but also a considerable amount of dibenzylated and monobenzylated products with 1,2,3,4-configuration, demonstrating a reactivity difference between C60 and C70. Interestingly, the anions of the 1,2,3,16-C70 adduct are rather stable as shown by the electrochemical study, which is in contrast to the anions of 1,2,3,16-C60 counterparts, and can be rationalized by the electronic structure difference between C70 and C60 derivatives

Reductive Benzylation of Singly Bonded 1,2,4,15‑C₆₀ Dimers with an Oxazoline or Imidazoline Heterocycle: Unexpected Formation of 1,2,3,16‑C₆₀ Adducts and Insights into the Reactivity of Singly Bonded C₆₀ Dimers

Upon reduction, singly bonded 1,2,4,15-C₆₀ dimers with an oxazoline or imidazoline heterocycle dissociate into monoanionic 1,2,4-C₆₀ intermediates, which surprisingly leads to the formation of 1,2,3,16-C₆₀ rather than 1,2,4,15-C₆₀ adducts of the original configuration by further benzylation, even though the analogue of dibenzylated C₆₀ oxazoline with a 1,2,4,15-configuration is stable and has been obtained. These results are corroborated by computational calculations, which rationalize the reaction and clarify the structure of the 1,2,3,16-C₆₀ adducts, providing new insights into the intrinsic reactivity of singly bonded C₆₀ dimers

Hydroxide-Initiated Conversion of Aromatic Nitriles to Imidazolines: Fullerenes vs TCNE

Transformation of aromatic nitriles to imidazolines has been achieved under basic conditions with the electron-deficient C60 and C70 fullerenes, but not with the electron-deficient olefin of tetracyanoethylene (TCNE). In situ UV–vis–NIR indicates that the ability of RC60– to undergo single-electron transfer (SET) to C60 is crucial for the reaction

Preparation of a C₇₀ Bis-heterocyclic Derivative with High Chemio- and Regioselectivity

C₇₀ bis-heterocyclic derivative (<b>1</b>) bearing one oxazoline ring and one imidazoline ring with the 2 o’clock configuration is obtained with high chemio- and regioselectivity via the reaction of C₇₀ with hydroxide and benzonitrile quenched with I₂. Further study with benzylation experiment and theoretical calculations indicate that the oxazoline ring is the one first formed on the C₇₀ cage, while the imidazoline ring is the one formed after the addition of I₂ via a radical coupling reaction mechanism

Hydroxide-Initiated Conversion of Aromatic Nitriles to Imidazolines: Fullerenes vs TCNE

Transformation of aromatic nitriles to imidazolines has been achieved under basic conditions with the electron-deficient C₆₀ and C₇₀ fullerenes, but not with the electron-deficient olefin of tetracyanoethylene (TCNE). In situ UV–vis–NIR indicates that the ability of RC₆₀^– to undergo single-electron transfer (SET) to C₆₀ is crucial for the reaction