Synthesis and characterization of water-soluble C₆₀–peptide conjugates

• Yue Ma,
• Lorenzo Persi and
• Yoko Yamakoshi

Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71

• example, as a photosensitizer in photodynamic therapy. Keywords: biomaterial; fullerene; peptide; water-soluble; Introduction Since the seminal discovery in 1985 by Kroto, Smalley, Curl, and co-workers [1], fullerenes, specifically buckminsterfullerene C60, have intrigued the scientific community. The

• unique structure of fullerenes, characterized by a fully conjugated closed-cage structure, containing a mixture of hexagonal and pentagonal rings, have been recognized for the unique electronic [2][3][4], optical [5][6], and mechanical properties [7][8]. Despite the notable achievements in fullerene

• research and the potential applications in diverse fields, a significant obstacle remained for the use in biological studies: fullerenes are poorly soluble in polar solvents, including water and other water-miscible solvents [9]. This challenge consequently restricted the studies of fullerenes as

Enhanced reactivity of Li⁺@C₆₀ toward thermal [2 + 2] cycloaddition by encapsulated Li⁺ Lewis acid

• Hiroshi Ueno,
• Yu Yamazaki,
• Hiroshi Okada,
• Fuminori Misaizu,
• Ken Kokubo and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2024, 20, 653–660, doi:10.3762/bjoc.20.58

• the burgeoning family of ion-endohedral fullerenes, holds substantial promise for diverse applications owing to its distinctive ionic properties. Despite the high demand for precise property tuning through chemical modification, there have been only a few reports detailing synthetic protocols for the

• acid catalyst; thermal [2 + 2] cycloaddition; Introduction Chemical functionalization of fullerenes is a fascinating and extensively studied approach, playing a pivotal role in fullerene-based materials science to introduce various characteristic functionalities [1][2][3][4][5][6][7]. Significant

• progress in synthetic procedures has contributed to diversifying their properties, enabling widespread and interdisciplinary applications in various research fields, such as biomedicine, photovoltaic devices, and materials chemistry. Meanwhile, lithium ion-endohedral fullerenes (Li+@C60) [8], the first

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• upon oxidation. As expected, the preorganized rigid form presents stronger binding affinities to fullerenes than the freely rotating dithiol form [64]. Recently, similar bipyridine-based tweezers with Zn–porphyrin functional units for fullerene binding were reported, using different stimuli for

• with electronically differentiated states using the tweezers' switching and modulation of host–guest complexes' electronic properties [69][70]. Sessler also explored the host–guest properties of the cone conformation towards the complexation of fullerenes. Indeed, the large cavity of the cone

• fullerene complexation. Other halides (Br− and F−) also allowed C60 and C70 complexation while tetrabutylammonium cations inhibited the fullerenes' complexation by competing for the cavity of the calix [72]. These calixpyrrole-based tweezers provide a good example of ON/OFF molecular sensors for neutral

Enhanced host–guest interaction between [10]cycloparaphenylene ([10]CPP) and [5]CPP by cationic charges

• Eiichi Kayahara,
• Yoshiyuki Mizuhata and
• Shigeru Yamago

Beilstein J. Org. Chem. 2024, 20, 436–444, doi:10.3762/bjoc.20.38

• . Furthermore, Isobe and co-workers also showed that the carbon nanorings with the simplest structural unit of chiral CNTs, such as cyclochrysenylene [34], cyclonaphthylenes [35], and cycloanthanthrenylene [36], are also excellent hosts of fullerenes with exceptionally high binding constants. These results open

• is driven by van der Waals interactions, and no new electronic states are created by electronic perturbations between the host and the guest, except for a few examples using special fullerenes as guest molecules, i.e. [11]CPP⊃La@C82 [39], and [10]CPP⊃Li+@C60 [40], and [10]CPP⊃(C59N)2 [41], or

Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• developed by Murata, Komatsu et al. [80]. In this approach, C60 or C70 fullerenes are modified stepwise towards an open-cage derivative in order to encapsulate small molecules such as H2 [81][82]. Eventually, the chemical modifications are reversed to close the hole and give an endohedral fullerene. As

• -dihydrothiophene 1-oxides [79]. SO-extrusion as a key step in the synthesis of fullerenes (C60 and C70) encapsulating H2 molecules [80][82]. Synthesis of diepoxytetracene precursor 56 and its on-surface conversion into tetracene upon O-extrusion. Inset in the top right shows a Laplace-filtered AFM image of a

Unveiling the regioselectivity of rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions for open-cage C₇₀ production

• Cristina Castanyer,
• Anna Pla-Quintana,
• Anna Roglans,
• Albert Artigas and
• Miquel Solà

Beilstein J. Org. Chem. 2024, 20, 272–279, doi:10.3762/bjoc.20.28

• Cristina Castanyer Anna Pla-Quintana Anna Roglans Albert Artigas Miquel Sola Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona (UdG), Girona 17003 Catalunya, Spain 10.3762/bjoc.20.28 Abstract The regioselective functionalization of fullerenes

• opening. Keywords: cycloadditions; DFT calculations; [70]fullerene; open-cage fullerenes; rhodium; Introduction The discovery of C60 (buckminsterfullerene) in 1985 [1] initiated the search for possible technological applications of fullerenes. Nowadays, applications for these carbon-based molecules have

• been proposed in different fields such as medicinal chemistry [2][3][4][5][6], materials science [7][8], energy production, storage, and delivery [9][10][11][12][13], and electronics and optoelectronics [14][15][16]. Despite fullerenes having immense promise in all of these areas, their practical

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• in TCBDs and DCNQs and their optical resolutions were first realized in 2010 through their conjugation with methylated fullerenes, as shown in Figure 2 [130]. The optical resolution was realized using a chiral high-performance liquid chromatography (HPLC) system equipped with an (S,S)-WHELK-O1 column

• unequivocally demonstrated that compounds 77–83 exhibited negligible emissions upon excitation in the charge-transfer (CT) band. In contrast, compound 76 emitted radiations corresponding to fluorescence exhibited by fullerenes, with a peak wavelength of 708 nm, upon CT-band excitation. This observation confirms

Electron-beam-promoted fullerene dimerization in nanotubes: insights from DFT computations

• Laura Abella,
• Gerard Novell-Leruth,
• Josep M. Ricart,
• Josep M. Poblet and
• Antonio Rodríguez-Fortea

Beilstein J. Org. Chem. 2024, 20, 92–100, doi:10.3762/bjoc.20.10

• confinement for the reaction to proceed. The barriers for the reversible phase 1 are found to be easily surmountable at ambient temperature for both the forward and the inverse processes, especially for the dimerization of radical cation fullerenes. For the initial steps of irreversible phase 2, up to six C–C

• one electron of the highest-occupied band of the fullerene is excited to the lowest-unoccupied band of SWCNT. DFT-optimized structures of C60 dimers 1-D2h, 1-Cs and nanotubular C120-NT-D5d fullerene. Energy profiles for the dimerization of 2 C60 and C60 + C60•+ fullerenes in the gas phase. All energy

• profiles for C60 + C60+• radical and C60 + C60 neutral dimerizations computed with the standard molecular (M) approach (atomic basis functions, ADF) are represented in grey and blue, respectively. Energy profiles for the dimerization of 2 C60 (neutral) and C60 + C60•+ (radical cation) fullerenes inside the

Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water

• Lorenzo Catti,
• Shinji Aoyama and
• Michito Yoshizawa

Beilstein J. Org. Chem. 2024, 20, 32–40, doi:10.3762/bjoc.20.5

• ., graphitic carbon nitride) in the form of 10–30 nm-sized stacks is also demonstrated using the present amphiphiles. Keywords: aromatic micelle; nanocarbon; nonionic surface modification; pyridinium; water-solubilization; Introduction Nanocarbons, such as fullerenes, graphenes, and carbon nanotubes, are

Anion–π catalysis on carbon allotropes

• M. Ángeles Gutiérrez López,
• Mei-Ling Tan,
• Giacomo Renno,
• Augustina Jozeliūnaitė,
• J. Jonathan Nué-Martinez,
• Javier Lopez-Andarias,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2023, 19, 1881–1894, doi:10.3762/bjoc.19.140

• , stands for the stabilization of anionic transition states on π-acidic aromatic surfaces. Anion–π catalysis on carbon allotropes is particularly attractive because high polarizability promises access to really strong anion–π interactions. With these expectations, anion–π catalysis on fullerenes has been

• catalysis; electromicrofluidics; enolate addition; ether cyclizations; fullerenes; Introduction Anion–π catalysis was introduced ten years ago [1]. The idea is to stabilize anionic transition states on electron-deficient, π-acidic aromatic surfaces (Figure 1A). The true beginning is arguably in 2015

• polarizability [9][10][11], the dream scaffolds for induced anion–π interactions are carbon allotropes. Anionic transition states placed on C60 fullerenes 1 will drive the 60 π electrons toward the other side, thus inducing a transient macrodipole that will stabilize the same transition state that induced its

Controlling the reactivity of La@C₈₂ by reduction: reaction of the La@C₈₂ anion with alkyl halide with high regioselectivity

• Yutaka Maeda,
• Saeka Akita,
• Mitsuaki Suzuki,
• Michio Yamada,
• Takeshi Akasaka,
• Kaoru Kobayashi and
• Shigeru Nagase

Beilstein J. Org. Chem. 2023, 19, 1858–1866, doi:10.3762/bjoc.19.138

• reaction is believed to occur via electron transfer, followed by the radical coupling of La@C2v-C82 and benzyl radicals, rather than by bimolecular nucleophilic substitution reaction of La@C2v-C82 anion with 1. Keywords: electron transfer; metallofullerene; radical; reduction; Introduction Fullerenes

• , the third carbon allotrope, have unique spherical molecular structures and exhibit high reactivity as electron-deficient polyolefins. The excellent redox properties of fullerenes are useful for their chemical derivatization and practical applications [1][2][3][4][5]. Fullerene anions can be easily

• metal atoms to the fullerene cage. Because of this intramolecular electron transfer, the characteristic properties of metallofullerenes, such as their redox potentials, are significantly different from those of empty fullerenes. For example, La@C82 has paramagnetic properties, and its formal electronic

Quinoxaline derivatives as attractive electron-transporting materials

• Zeeshan Abid,
• Liaqat Ali,
• Sughra Gulzar,
• Faiza Wahad,
• Raja Shahid Ashraf and
• Christian B. Nielsen

Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124

• and optimization, Qx polymer acceptors are expected to evolve into high-performance materials for organic electronics. Quinoxalines as NFAs Fullerene acceptors have long dominated OSCs until the emergence of NFAs; nonetheless, researchers have attempted to improve fullerenes and address their

Decarboxylative 1,3-dipolar cycloaddition of amino acids for the synthesis of heterocyclic compounds

• Xiaofeng Zhang,
• Xiaoming Ma and
• Wei Zhang

Beilstein J. Org. Chem. 2023, 19, 1677–1693, doi:10.3762/bjoc.19.123

• (such as C60/C70 fullerenes) [56][57][58]. Other than amino esters and amino acids shown in Scheme 1, cyclic amines can also react with arylaldehydes to form B1-type semi-stabilized AMYs. In this context, the Seidel group reported the reactions of pyrrolidines 5 with arylaldehydes for the formation of

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• only introduced in n-dopants in 2010, when Bao and co-workers reported the use of N-DMBI-H (1bH, Figure 1) to n-dope fullerenes [7]. Although widely used, due to their facile synthesis, structural tunability, and good air stability in the solid state, 1H derivatives are relatively limited in dopant

Polymer and small molecule mechanochemistry: closer than ever

• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1225–1235, doi:10.3762/bjoc.18.128

• the covalent capsule 5 (made from resorcinarene caps connected by four dihydrazone units of ʟ-cysteine) with C60 and C70 fullerenes upon neat ball milling in a planetary ball mill (Figure 6). The mechanochemical complexation is remarkable since the porous capsule does not possess large enough openings

• for the fullerenes to pass through. However, the capsule 5 is sensitive to mechanochemical stress due to the porosity, conformational rigidity, and due to the presence of hydrazone and/or disulfide moieties that act as mechanophores. Therefore, during ball milling, 5 gets partially disintegrated at

• the weakest covalent connections, enabling the access of fullerenes. As a result, besides polymeric matrices, also porous, semirigid molecules [65] and molecular anvils [66] could eventually become effective transducers of mechanical forces to mechanophores. Simpler strategies to circumvent the need

Design, synthesis and photophysical properties of novel star-shaped truxene-based heterocycles utilizing ring-closing metathesis, Clauson–Kaas, Van Leusen and Ullmann-type reactions as key tools

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2021, 17, 1374–1384, doi:10.3762/bjoc.17.96

• hint for its utility as novel building block for the development of a range of advanced functional materials for innumerable applications [8][9][10][11][12][13][14][15][16]. Moreover, truxene has also been vividly used for the construction of fullerenes and their bowl-shaped fragments besides their

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• ], have already been discovered among functionalized fullerenes. Bearing in mind the fact that numerous fullerene derivatives with a wide range of biological activity have been synthesized to date, the idea of using functionalized fullerenes in the field of medical chemistry, especially for the treatment

• reactions with compounds containing activated C–H bonds [54]. An ample body of data on the chemistry of fullerenes has been accumulated to date. It is covered in a number of monographs [55][56][57][58] and reviews [59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75]. This review, in which we

• reactivity. According to the theory, monosubstituted fullerenes can exist as the four isomers shown in Figure 1: [5,6]-closed, [5,6]-open, [6,6]-closed, and [6,6]-open. Only [5,6]-open and [6,6]-closed have been isolated experimentally. This is explained by the preservation of energy-favorable levels in

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

• Si-Yuan Liu,
• Xin-Rui Wang,
• Man-Ping Li,
• Wen-Rong Xu and
• Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

• : fullerenes; host–guest systems; microspheres; supramolecular chemistry; tribenzotriquinacene; Introduction In the field of supramolecular chemistry, host–guest association through noncovalent interactions is an interesting and exciting topic, especially for the encapsulation of various fullerenes, such as

• C60 and C70 [1][2][3][4][5]. It is generally accepted that good complexation of fullerenes requires host molecules with bowl or basket-like shapes, such as calixarenes [6], corannulenes [7][8][9][10], cyclodextrins [11][12][13], cyclotriveratrylenes [14][15][16], and similar macrocycles [17][18][19

• shallow cavity of the parent TBTQ hydrocarbons, thus allowing for the inclusion of large guest molecules, such as the fullerenes. Several TBTQ derivatives with extended cavities have been developed by us and other groups. Volkmer et al. designed a series of novel TBTQ-based receptors, 1–3, and studied

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• the bowl structure itself, e.g., in hemifullerene or by the introduction of substituents (e.g., trimethylsumanene) or heteroatoms (e.g., triazasumanene) into the achiral bowls but also as they are partial structures of carbon nanotubes (CNTs) and fullerenes having bowl inversion activities as well as

One-pot synthesis of dicyclopenta-fused peropyrene via a fourfold alkyne annulation

• Ji Ma,
• Yubin Fu,
• Junzhi Liu and
• Xinliang Feng

Beilstein J. Org. Chem. 2020, 16, 791–797, doi:10.3762/bjoc.16.72

• nonalternant cyclopenta-fused polycyclic aromatic hydrocarbons (CP-PAHs), which represent the topological subunits of fullerenes and exhibit high chemical, physical and biological activities [1][2][3][4][5][6][7][8][9][10]. Thanks to development in organic synthetic methodology, CP-PAHs with peripheral

Synthesis of C₇₀-fragment buckybowls bearing alkoxy substituents

• Yumi Yakiyama,
• Shota Hishikawa and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2020, 16, 681–690, doi:10.3762/bjoc.16.66

• equilibrium between the Pd(IV) intermediates through C–H bond activation. Keywords: buckybowl; C70; rearrangement through C–H bond activation; Introduction The study of buckybowls, the bowl-shaped π-conjugated aromatic hydrocarbons corresponding to the fragments of fullerenes, pioneered by the works on

Easy, efficient and versatile one-pot synthesis of Janus-type-substituted fullerenols

• Marius Kunkel and
• Sebastian Polarz

Beilstein J. Org. Chem. 2019, 15, 901–905, doi:10.3762/bjoc.15.87

• steps involved. Fullerene derivatives are of great interest in numerous research areas such as biological sciences and materials sciences [4][5][6][7][8][9]. A vast amount of synthetic protocols have been developed over the years to modify fullerenes [10][11][12][13]. A particular task was to provide

• fullerenes with solubility in water. Thus, one important class of fullerene derivatives are the hydroxylated and polyhydroxylated compounds, so called fullerenols (C60(OH)n) [14]. The degree of hydroxylation and with that the solubility of these compounds can be tuned by using different synthetic approaches

Fabrication of supramolecular cyclodextrin–fullerene nonwovens by electrospinning

• Hiroaki Yoshida,
• Ken Kikuta and
• Toshiyuki Kida

Beilstein J. Org. Chem. 2019, 15, 89–95, doi:10.3762/bjoc.15.10

• supramolecular fiber materials composed of cyclodextrin (CD)–fullerene inclusion complexes by electrospinning. Similar to the molecular state of fullerenes in solution, the resulting fibers include molecularly-dispersed fullerenes. We believe such a concept could be expanded to diverse host–guest complexes

• promising as an approach for fiber functionalization, the scope is limited to cases with 1:1 inclusion complexes and chemically modified CD. Fullerenes have been widely studied in the fields of chemistry and materials science because they have attractive chemical structures and good electron acceptor

• abilities for free radical scavengers and solar cell applications [18][19][20]. A serious issue for practical applications of fullerenes is the poor solubility in most solvents. Various methods to improve the solubility have been demonstrated by coating the surface with surfactants or host molecules and

Calixazulenes: azulene-based calixarene analogues – an overview and recent supramolecular complexation studies

• Paris E. Georghiou,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Hidetaka Nishimura,
• Jaehyun Lee,
• Atsushi Wakamiya and
• Lawrence T. Scott

Beilstein J. Org. Chem. 2018, 14, 2488–2494, doi:10.3762/bjoc.14.225

•  1) and on its mechanochemically-generated solid-state complex of C60-fullerene [17]. This all-hydrocarbon, wide-rim octaphenyl-functionalized calix[4]azulene was designed to evaluate its potential for encapsulating C60 or C70 fullerenes. The lack of sufficient solubility of 5 in common organic

• solvents prevented a fuller examination of its potential supramolecular properties with fullerenes, a topic of particular interest to us [18]. Therefore, the solid state supramolecular complexation properties of 5 were experimentally studied using solid state NMR and XRD experiments, and also theoretically

A conformationally adaptive macrocycle: conformational complexity and host–guest chemistry of zorb[4]arene

• Liu-Pan Yang,
• Song-Bo Lu,
• Arto Valkonen,
• Fangfang Pan,
• Kari Rissanen and
• Wei Jiang

Beilstein J. Org. Chem. 2018, 14, 1570–1577, doi:10.3762/bjoc.14.134

• in plots of ΔH versus temperature from 283 to 313 K (Figure 5). The release of solvent molecules upon complex formation may account for the negative heat capacity change and similar heat capacity changes were also reported for the fullerenes recognition [40]. Meanwhile, the changes of ΔG for the