Hydrogenation of cage-opened C<sub>60</sub> derivatives mediated by frustrated Lewis pairs

Hashikawa, Yoshifumi; Murata, Yasujiro

doi:10.1039/d1ob02316k

Cited by 5 publications

(3 citation statements)

References 41 publications

(30 reference statements)

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“…In 2018, we demonstrated a high‐yielding triple reduction via the Luche conditions employing NaBH 4 with CeCl 3 [9] . We also found that even weak/mild reductants, such as BH 3 ⋅THF [10] and Frustrated Lewis pairs using B(C 6 F 5 ) 3 and HSiPh 3 , [11] work for reducing a carbonyl group on the C 60 orifice to generate a hydroxy stopper.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of an Open‐Cage C₆₀ Derivative with a Double Stopper

Huang,

Hashikawa,

Murata

2023

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The construction of a suitable stopper on a C60 orifice is of importance to prevent the release of once‐encapsulated chemical species. However, a single stopper on a large orifice is in usual not sufficient to retain a small molecule within the C60 cavity. In this work, we introduced a double stopper, constituted of two hydroxy groups, on a huge orifice with a ring‐atom count of 18 by a reduction using BH3⋅THF. The resulting double stopper was demonstrated to effectively isolate an argon atom inside the cavity so that the argon was retained even under mass spectrometric conditions at 200 °C. The structure of the open‐cage C60 derivative with the double stopper was confirmed by X‐ray diffraction analysis, showing a dimeric configuration via intermolecular hydrogen‐bondings. The dimerization behavior was also studied in solution.

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Section: Introductionmentioning

confidence: 99%

Synthesis of an Open‐Cage C₆₀ Derivative with a Double Stopper

Huang,

Hashikawa,

Murata

2023

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“…The ratio of the two signals were determined to be 99.67:0.33 which is in accordance with the natural abundance of 14 N (I = 1) and 15 N (I = 1/2). 16 Thus, the former signal broadening is caused by the rapid quadrupolar relaxation of 14 NH 3 while it is absent in the 15 N isotopologue showing a coupling constant of J NH = 60.1 Hz. 17 From full width at half-maximum ν 1/2 of the proton resonance, the transverse relaxation time of 14 NH 3 was estimated to be T 2 = 7.8 ms which is rather shorter than that of H 2 16 O (0.27 s) where the protons relax with a spin− rotation mechanism.…”

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“…The enol form of B then underwent hydrolysis to give quinone and NH 3 together with C which changes into D and 4 via disproportionation. 10,14 Notably, phenanthrenequinone is known to undergo a unique self-condensation reaction to give an isoimide derivative in the presence of ammonium acetate. 15 Thus, we anticipated that the formation of quinone and NH 3 is a driving force to afford imidazole-containing πextended fullerenes 3 (Figure 2c).…”

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π-Extended Fullerenes with a Reactant Inside

2022

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Fullerene–graphene hybrids potentially exhibit unprecedented properties owing to interactive communication between the two units through a linkage. However, most of their discrete molecular structures have been still undisclosed thus far. With the recent rise in the awareness of facile access to molecular nanocarbon hybrids, we showcase novel π-extended fullerenes with a fused pyrazine or imidazole. Owing to the effective planar–curved π-conjugation, their absorption coefficients significantly increased in the visible region. Curiously enough, during the formation of π-extended fullerenes, an in situ generated NH3 molecule was spontaneously encapsulated inside the fullerene cavity. The NH3 molecule then underwent a timed orifice-expansion triggered by its sustained release. This is the first demonstration that fullerene captures a reactant inside, suggesting their potential usage for a sustained dosing and/or material delivery toward postfunctionalization of fullerene–graphene hybrids.

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Aniline‐Mediated Imination and Reduction of a Cage‐Opened C₆₀ Derivative

Hashikawa

Murata

2022

Asian J Org Chem

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The imination of a cage‐opened fullerene C60 derivative was examined using N,N‐dimethyl‐1,4‐phenylenediamine. The desired imine derivative showed a remarkably intense near‐infrared (NIR) absorption band (λedge=1050 nm). According to theoretical calculations, the longest wavelength absorption is assignable to the HOMO→LUMO transition with a strong charge‐transfer character, in which the HOMO localizes on the introduced imine moiety while the high LUMO coefficients can be seen over the entire C60 skeleton. It should be noted that the two reduced compounds bearing an amine or methylene group were also formed in the reaction producing the imine derivative, the former of which again showed NIR absorption tailing to 1200 nm. In this reduction, the hydride source is considered to be α‐hydrogen of the diamine so that the use of N,N,N’,N’‐tetramethyl‐1,4‐phenylenediamine increased the yield of the methylene derivative up to 20%.

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Hydrogenation of cage-opened C₆₀ derivatives mediated by frustrated Lewis pairs

Abstract: Multiply-carbonylated fullerene derivatives were found to work as one component in frustrated Lewis pairs which caused an Si–H bond activation in the presence of B(C6F5)3, leading to the carbonyl hydrogenation in up to 99% yield.

Cited by 5 publications

References 41 publications

Synthesis of an Open‐Cage C₆₀ Derivative with a Double Stopper

Synthesis of an Open‐Cage C₆₀ Derivative with a Double Stopper

π-Extended Fullerenes with a Reactant Inside

Aniline‐Mediated Imination and Reduction of a Cage‐Opened C₆₀ Derivative

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Hydrogenation of cage-opened C60 derivatives mediated by frustrated Lewis pairs

Abstract: Multiply-carbonylated fullerene derivatives were found to work as one component in frustrated Lewis pairs which caused an Si–H bond activation in the presence of B(C6F5)3, leading to the carbonyl hydrogenation in up to 99% yield.

Cited by 5 publications

References 41 publications

Synthesis of an Open‐Cage C60 Derivative with a Double Stopper

Synthesis of an Open‐Cage C60 Derivative with a Double Stopper

π-Extended Fullerenes with a Reactant Inside

Aniline‐Mediated Imination and Reduction of a Cage‐Opened C60 Derivative

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Product

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Hydrogenation of cage-opened C₆₀ derivatives mediated by frustrated Lewis pairs

Synthesis of an Open‐Cage C₆₀ Derivative with a Double Stopper

Synthesis of an Open‐Cage C₆₀ Derivative with a Double Stopper

Aniline‐Mediated Imination and Reduction of a Cage‐Opened C₆₀ Derivative