New Horizons in Chemical Functionalization of Endohedral Metallofullerenes

Yamada, Michio; Liu, Michael T. H.; Nagase, Shigeru; Akasaka, Takeshi

doi:10.3390/molecules25163626

Cited by 18 publications

(17 citation statements)

References 79 publications

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“…X-ray crystallography of 9: Black block crystals suitable for X-ray diffraction were obtained using the liquid-liquid bilayer diffusion method with solutions of 9 in CS 2 using hexane as a poor solvent at 0 • C. Single-crystal X-ray diffraction data of 9 were collected on a Saturn70 CCD diffractometer (Rigaku Corp.) equipped with a nitrogengas flow low-temperature apparatus providing a constant temperature at 120 K. Crystal data for Sc 3 N@I h -C 80 (Dep 2 Ge) 2 CH 2 (9)•1.5(CS 2 ): C 122.5 H 54 Ge 2 Sc 3 NS 3 : M r = 1915.90, black block, 0.25 × 0.13 × 0.07 mm, λ = 0.71069 Å, monoclinic, space group P2 1 /n (no. 14), a = 19.5525 (17), b = 20.9254 (16), c = 19.6564(16) Å, β =111.0114(5) • , T = 120 K, V= 7506(11) Å 3 , Z = 4, 168,721 reflections measured, 16,520 unique (R int = 0.0572), which were used for all calculations, 2θ max = 54.20; min/max transmission=0.782/0.941 (numerical absorption correction applied); the structure was solved using a direct method using SIR2014 [48] and was refined with SHELXL [49]. The final wR(F 2 ) was 0.0927 (all data), conventional R 1 = 0.0424 computed for 16,316 reflections with I >2σ (I) using 1937 parameters with 876 restraints.…”

Section: Transient Absorption Spectroscopy Of Photoreactions Of Sc 3 ...mentioning

confidence: 99%

“…Endohedral metallofullerenes (EMFs) have been investigated extensively because of their fascinating structures based on electron transfer from encapsulated metal species to carbon cages [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Among EMFs, trimetallic nitride template endohedral metallofullerenes (TNT-EMFs) constitute a major EMF family for which extensive studies have been conducted to ascertain and apply their remarkable properties [2,9,10].…”

Section: Introductionmentioning

confidence: 99%

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Photoreactions of Sc3N@C80 with Disilirane, Silirane, and Digermirane: A Photochemical Method to Separate Ih and D5h Isomers

et al. 2022

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Under photoirradiation, Sc3N@Ih-C80 reacted readily with disilirane 1, silirane 4, and digermirane 7 to afford the corresponding 1:1 adducts, whereas Sc3N@D5h-C80 was recovered without producing those adducts. Based on these results, we described a novel method for the exclusive separation of Ih and D5h isomers of Sc3N@C80. The method includes three procedures: selective derivatization of Sc3N@Ih-C80 using 1, 4, and 7, facile HPLC separation of pristine Sc3N@D5h-C80 and Sc3N@Ih-C80 derivatives, and thermolysis of Sc3N@Ih-C80 derivatives to collect pristine Sc3N@Ih-C80. In addition, laser flash photolysis experiments were conducted to elucidate the reaction mechanism. Decay of the transient absorption of 3Sc3N@Ih-C80* was observed to be enhanced in the presence of 1, indicating the quenching process. When Sc3N@D5h-C80 was used, the transient absorption was much less intensive. Therefore, the quenching of 3Sc3N@D5h-C80* by 1 could not be confirmed. Furthermore, we applied time-dependent density functional theory (TD-DFT) calculations of the photoexcited states of Sc3N@C80 to obtain insights into the reaction mechanism.

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Section: Transient Absorption Spectroscopy Of Photoreactions Of Sc 3 ...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photoreactions of Sc3N@C80 with Disilirane, Silirane, and Digermirane: A Photochemical Method to Separate Ih and D5h Isomers

et al. 2022

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“…Is the metal really trivalent as a result of complete donation of its 5d 1 6s 2 electrons to the cage? How to understand the role played by La-4f orbitals in important aspects of EMFs such as the structural characteristics, endohedral stability, and chemical reactivity. , Finally, are the answers to the above questions dependent on the EMF type or cage size?…”

Section: Introductionmentioning

confidence: 99%

Overlooked Effects of La-4f Orbitals in Endohedral Metallofullerenes

Jin

2022

Inorg. Chem.

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For endohedral metallofullerenes (EMFs), a central issue is how to correctly describe the intracluster and metal−cage interactions, which are critical for understanding their structures, stabilities, and various properties. In this work, density functional theory calculations were carried out for 13 La-based EMFs covering all four reported types and a rather wide cage size range (C 32 −C 104 ). The results reveal that the usually core-like lanthanide 4f subshell may play a critical role in the structural characteristics, energetic stabilities, frontier orbital energy levels, metal charges, and chemical reactivities of these endofullerenes. Regardless of the encapsulated forms, the La-4f contributions to the chemical bonding and structural stability increase with the reduced cage sizes because of the gradually enhanced cage confinement. The combination of metal-tononmetal charge transfer and compression of the cage cavity exposes and effectively activates the otherwise chemically inert 4f orbitals. By disclosing the important role of long-neglected metal orbitals inside fullerenes, the current work not only deepens our understanding of EMFs, but also provides new insights into the chemical bondings in general confined spaces at the subnanometer scale.

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“…As exemplified above, the development of efficient ring-opening reactions on the fullerene sphere is still a great topic of interest and some of methods have been demonstrated to show the applicability even for metallofullerenes [17] in which electronic structures are entirely different from those for empty cages such as C 60 and C 70 . [18] To the best of our knowledge, however, computational studies on the mechanism regarding the reaction of C 60 and azine derivatives have not yet been carried out, being in sharp contrast to the simple Diels-Alder reactions of C 60 . [19] For developing the more practical way to gain cage-opened bisfulleroids, herein, we examined the effect of benzoannulation to 3,6-di(6-tert-butylpyridin-2-yl)pyridazine on the reaction with C 60 both experimentally and computationally.…”

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Reactions of C₆₀ with Pyridazine and Phthalazine

Hashikawa

Murata

2021

Chemistry A European J

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Cage-opened bisfulleroids are one of suitable building blocks for making a large hole on fullerenes. This work focuses on the Diels-Alder reaction of C 60 with azines, among synthetic methods developed thus far, to provide bisfulleroids. Surprisingly, the computational study predicted that the reaction proceeds with normal electron demand in contrast to hitherto considered inverse-electrondemand pathway. The benzoannulation to the pyridazine ring, i. e., phthalazine, resulted in the remarkably shortened reaction time due to the better interaction between the HOMO of phthalazine and the LUMO of C 60 as well as stronger 2,3-diaza-1,3-butadiene character in the phthalazine as confirmed crystallographically. Contrary to expectations, the benzobisfulleroid was converted into corresponding orifice-enlarged derivative via the photooxygenation slightly faster than the fulleroid derived from pyridazine.The construction of openings on fullerene C 60 had received great attention in 1990s for the organic synthesis targeting endohedral fullerenes, i. e., molecular containers [1] as well as for exploring potential performance as electron acceptors in solar cells. [2] Currently, several methods are available for making holes on the fullerene surface, such as photooxygenation of azafulleroids [3] or 1,6-disubstituted derivatives, [4] oxidation of vicinal diol, [5] and sequential pericyclic reactions. [6] The first cage-opened derivative was reported by Wudl and co-workers in 1995. [3] They performed a 1,3-dipolar cycloaddition of C 60 using methoxyethoxymethyl azide, giving an azafulleroid derivative which was further transformed into a compound bearing an 11-membered-ring opening. Using the similar strategy, the research group of Rubin, Houk, Saunders, and Cross demonstrated that a two-fold addition of azide followed by photooxygenation provides a corresponding cage-opened derivative which can encapsulate an He atom and H 2 molecule. [7] Among reported methods, ring-opening reactions of cyclohexadiene-fused C 60 derivatives via sequential [4 + 4] and retro [2 + 2 + 2] rearrangements are one of well-established methods to provide cage-opened bisfulleroids having an eight-mem-

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New Horizons in Chemical Functionalization of Endohedral Metallofullerenes

Cited by 18 publications

References 79 publications

Photoreactions of Sc3N@C80 with Disilirane, Silirane, and Digermirane: A Photochemical Method to Separate Ih and D5h Isomers

Photoreactions of Sc3N@C80 with Disilirane, Silirane, and Digermirane: A Photochemical Method to Separate Ih and D5h Isomers

Overlooked Effects of La-4f Orbitals in Endohedral Metallofullerenes

Reactions of C₆₀ with Pyridazine and Phthalazine

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New Horizons in Chemical Functionalization of Endohedral Metallofullerenes

Cited by 18 publications

References 79 publications

Photoreactions of Sc3N@C80 with Disilirane, Silirane, and Digermirane: A Photochemical Method to Separate Ih and D5h Isomers

Photoreactions of Sc3N@C80 with Disilirane, Silirane, and Digermirane: A Photochemical Method to Separate Ih and D5h Isomers

Overlooked Effects of La-4f Orbitals in Endohedral Metallofullerenes

Reactions of C60 with Pyridazine and Phthalazine

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Reactions of C₆₀ with Pyridazine and Phthalazine