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

• Yue Ma Lorenzo Persi Yoko Yamakoshi Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 3, 8093 Zürich, Switzerland 10.3762/bjoc.20.71 Abstract With the aim of developing biocompatible and water-soluble C60 derivatives, three types of C60–peptide conjugates consisting

• of hydrophilic oligopeptide anchors (oligo-Lys, oligo-Glu, and oligo-Arg) were synthesized. A previously reported Prato reaction adduct of a biscarboxylic acid-substituted C60 derivative was subjected to a solid phase synthesis for amide formation with N-terminal amines of peptides on resin to

• successfully provide C60–peptide conjugates with one C60 and two peptide anchors as water-soluble moieties. Among three C60–peptide conjugates prepared, C60–oligo-Lys was soluble in water at neutral pH, and C60–oligo-Glu was soluble in buffer with a higher pH value, but C60–oligo-Arg was insoluble in water and

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

• , Graduate School of Science, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan 10.3762/bjoc.20.58 Abstract Lithium ion-endohedral fullerene (Li+@C60), a member of

• derivatization of this novel material. In this study, we report the synthesis of Li+@C60 derivatives via the thermal [2 + 2] cycloaddition reaction of styrene derivatives, achieving significantly higher yields of monofunctionalized Li+@C60 compared to previously reported reactions. Furthermore, by combining

• experimental and theoretical approaches, we clarified the range of applicable substrates for the thermal [2 + 2] cycloaddition of Li+@C60, highlighting the expanded scope of this straightforward and selective functionalization method. Keywords: electron transfer; fullerene; ion-endohedral fullerene; Lewis

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

• for C60 complexation. Bipyridine was also used in fluorescence signal transduction systems to induce a conformational change by coordination stimuli (Figure 15b) [60]. The tweezers-like system 27 is built around a tetrasubstituted cis-anti-cis-perhydroanthracene core functionalized at opposite ends

• C60 and C70 complexation, with selectivity for C70 (log KC60 = 3.3 and log KC70 = 4.7). In a follow-up of this work, they reported a similar redox-switchable biscorannulene tweezers system with a bis(arylthiol) switching unit that can be locked in the cis-conformation by forming a disulfide S–S bridge

• -conformation calix[4]pyrrole and the electron-donating nature of TTFs allow the complexation of electron-poor C60 guests [71]. A 2:1 complexation of C60 by TTF-functionalized calix[4]pyrrole 33 was observed for the Cl− bound cone conformation with each calix[4]pyrrole entrapping C60 on one side. The complex

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

• function. After our first report on the selective encapsulation of C60 by [10]CPP (the number in the brackets is the number of paraphenylene units in the CPP) (Figure 1a) [22], the concave inner surface of CPPs was found to interact with a variety of molecules with convex surfaces through π–π interactions

• 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

• applying high pressure (6 GPa) in the complexation between [9]CPP and C60 [42]. In these examples, partial charge transfer (CT) from the CPP host to the guest was observed, but the degree of CT was limited. Furthermore, no clear effects of CT on the physical properties have been reported. We have already

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

• 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

• cages. However, in other cases, some of the bonds between the C atoms of the cage are broken and the cage is opened. The first example of an open-cage fullerene was reported in 1995 by Hummelen, Prato, and Wudl [21] through the reaction of C60 with azides followed by photooxygenation. Since then, many

• open-cage C60 derivatives have been reported. These open-cage fullerenes can act as molecular containers. Of special interest is the procedure called molecular surgery designed by Murata et al. [22][23][24][25] in which a hole in the fullerene is opened, an atom or small molecule is introduced and then

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

• congestion on the surface of fullerene, with its endurance contingent upon the bulkiness of the substituent incorporated onto the fullerene core. This observation was supported by the absence of axial chirality in molecules where an additional alkyne moiety is intercalated between the C60 core and TCBD or

• DCNQ unit or where a methyl group on the C60 surface is replaced by a hydrogen atom. The C60–TCBD conjugate 57 and C60–DCNQ conjugate 58 exhibited substantial optical rotations at 589 nm, presenting +770 for (P)-57 and +5,800 for (P)-58. In concordance, robust Cotton effects related to ICT absorption

• conjugates featuring diethylamino groups and TCBD or DCNQ structures covalently linked to C60 (76 and 77) and conjugates incorporating octamethylferrocenyl (OEF) groups and TCBD or DCNQ structures bonded to C60 (78 and 79) in addition to their respective reference compounds (80–83) were reported (Figure 8

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

• have been published that record the dynamic behavior of a wide range of molecules and chemical reactions. One such process was the dimerization of C60 fullerene in a carbon nanotube peapod, i.e., hybrid structures consisting of fullerene molecules encapsulated in single-walled carbon nanotubes (SWCNT

• ) [6][7][8]. Different stages of dimerization of C60 molecules inside a peapod, a reaction confined within a one-dimensional nanoscale space, have been detected in the last decade [3][4][7][9]. Nakamura and co-workers termed ‘phase 1’ the stage with reversible bond formation and ‘phase 2’ the stage

• nanotubular-shaped fullerene inside the peapod. Kinetic analysis with the variable-temperature (VT) SMART-TEM method for the aforementioned C60 dimerization has also been reported by these authors [9]. They concluded that the SWCNT, which accumulates energy by the interaction with the electron beam, activates

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

• )2–Y (Y = OCH3, OH, and imidazole)). The new amphiphiles quantitatively self-assemble into ≈2 nm-sized aromatic micelles in water independent of the side-chain. Importantly, efficient water-solubilization and nonionic surface modification of various nanocarbons (e.g., fullerene C60, carbon nanotubes

• of the side-chain present. Importantly, efficient water-solubilization and nonionic surface modification of nanocarbons (i.e., fullerene C60 (C60), single/multi-walled carbon nanotubes (s/m-CNT), and graphene nanoplatelets (GN)) can be achieved through noncovalent encircling with the present

• pyridinium-based amphiphiles (Figure 1c). The noncovalent modification of C60 with multiple imidazole side-chains is found to yield a pH-responsive surface charge, as evidenced by NMR and zeta-potential measurements. A nitrogen-doped nanocarbon, i.e., graphitic carbon nitride (g-C3N4), is likewise

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

• 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

• to C60 fullerenes [12]. These amines function as bases, their position next to the aromatic surface is essential to turn on anion–π interactions as soon as substrate 4 is deprotonated. Fullerene derivatization with the Bingel reaction installs a cyclopropane that continues with one or two acid

• electrons rushing toward one side of a C60 fullerene 1 to create a large macrodipole in response to an anionic transition state, the number of electrons available to maximize polarizability already in SWCNTs 2 is much higher (Figure 1D) [9][10][11]. Continuing in this series to increase polarizability with

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

• absorption intensity ratio at 330 nm. On the other hand, no consumption of La@C2v-C82 was observed in the reaction of La@ C2v-C82 with 1a (Figure 2b). The reaction of the La@C2v-C82 anion toward 2a–5a requires heating, therefore the reactivity of La@C2vC82 anion is lower than that of the C602− and C60 anion

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

• limitations, as demonstrated by Elavarasan and colleagues. Their team synthesized TQT-C60 and anchored it to fullerene molecules (Figure 3) to prevent aggregation during thermal aging. The researchers found that TQT-C60 demonstrated enhanced morphological stability and thermal resistance compared to the

• phenyl-C61-butyric acid methyl ester (PCBM) acceptor when used in bulk heterojunction polymer solar cell devices with poly(3-hexylthiophene) (P3HT) as the donor material. This improvement was attributed to the anchoring effect of the bulkier groups present in TQT-C60, which hindered the movement and

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

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• -induced applications. Similar to porphyrins, fullerene C60 also possesses superior acceptor properties, low reduction potential and low reorganization energy [48][49]. Thus, keeping the diverse properties of fullerene in mind, de Miguel et al. [50] successfully prepared and characterized the triazole

• conjugates (99a–d, 103a,b) were utilized for the preparation of porphyrin-fullerene dyads 100a–d and 104a,b in 30–70% yield by the reaction with C60 and sarcosine in toluene under microwave conditions. The photophysical and computational studies of these ZnP-Tri-C60 conjugates revealed that the 1,2,3

• -triazole linker significantly influences the charge separation, charge recombination, and photoinduced electron transfer processes. Since, the through-bond distance is approximately the same for all the synthesized ZnP-Tri-C60 conjugates, therefore, the variation in charge separation and charge

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

[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

• ]PCBM; diazo compounds; mechanisms and optimal conditions of cyclopropanation; methanofullerenes C60; Introduction Taking into consideration that all life on Earth is of organic origin. with carbon as its basic element (20% by weight of every living organism, and the fourth most abundant element in the

• universe), the discovery in 1985 of its new allotropic modification, fullerene, has resulted in an avalanche-like expansion of studies in this area [1]. The exceptional physicochemical properties of the fullerene family and, above all, its main representative, C60, predetermine the broad practical interest

• of socially significant diseases, is fruitful. The design of biologically active compounds based on C60 is determined, on the one hand, by the ability of its shell to serve as a transportation unit for pharmacophore groups, and on the other by the need to identify the capability of the fullerene core

Using multiple self-sorting for switching functions in discrete multicomponent systems

• Amit Ghosh and
• Michael Schmittel

Beilstein J. Org. Chem. 2020, 16, 2831–2853, doi:10.3762/bjoc.16.233

• (isocytosine) moiety, furnished the very stable tetrameric cyclic aggregates by a cooperative 3H- and 4H‐bonding [50]. The addition of C60 to the mixture resulted in an incomplete self-sorting (Figure 4d) showing the complex [(5)4(C60)] and free (6)4 as the major species together with some mixed aggregates

• . Interestingly, the fullerene C60 was not taken up as a guest by the tetramer (6)4 in chlorinated solvents. For a more defined self-sorting, the authors switched the solvent from CDCl3 to [d8]-toluene. Now, a 2-fold completive self-sorting delivered the homoleptic inclusion complexes [(5)4(C60)] and [(6)4(C60

• hydrogen-bonded octameric and tetrameric tubes. (c) A representation of the complex mixture after combining the monomers 5 and 6 in CDCl3. (d) The partial separation of the mixture upon the selective C60 complexation by monomer 5. The guest-induced rearrangement results in an incomplete self-sorted mixture

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

• Department of Chemistry, Center for Molecular Materials (CM2), Bielefeld University, 33615 Bielefeld, Germany 10.3762/bjoc.16.207 Abstract A sugar-functionalized water-soluble tribenzotriquinacene derivative bearing six glucose residues, TBTQ-(OG)6, was synthesized and its interaction with C60 and C70

• -fullerene in co-organic solvents and aqueous solution was investigated by fluorescence spectroscopy and ultraviolet-visible spectroscopy. The association stoichiometry of the complexes TBTQ-(OG)6 with C60 and TBTQ-(OG)6 with C70 was found to be 1:1 with binding constants of Ka = (1.50 ± 0.10) × 105 M−1 and

• Ka = (2.20 ± 0.16) × 105 M−1, respectively. The binding affinity between TBTQ-(OG)6 and C60 was further verified by Raman spectroscopy. The geometry of the complex of TBTQ-(OG)6 with C60 deduced from DFT calculations indicates that the driving force of the complexation is mainly due to the

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

• twentieth century when for the first time corannulene was reported by Barth et al. [10] at the University of Michigan (USA) in 1966 (crystal structure 1971) [11]. On the other hand, since the discovery of fullerene (C60) in 1985 [12] by Sir Harry Kroto and the first synthesis of sumanene in 2003 by Sakurai

• convex faces. Therefore, in recent years, the coordination of bowl-shaped molecules with the transition metals is of fundamental interest in the area of π-bowls chemistry since the first details of the metal complex of C60. In this context, Hirao’s group has reported the first example of Fe(η6-sumanene

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

• that with C60 fragment because most of them consists of acene and/or pyrene units, which might give unique photochemical and electrochemical properties. Recently, we synthesized a buckybowl C28H14 1, which is corresponding to a 40% fragment of C70, from C60-fragment sumanene (2) in three steps via ring

Selective detection of DABCO using a supramolecular interconversion as fluorescence reporter

• Indrajit Paul,
• Debabrata Samanta,
• Sudhakar Gaikwad and
• Michael Schmittel

Beilstein J. Org. Chem. 2019, 15, 1371–1378, doi:10.3762/bjoc.15.137

• porphyrin edge capsules to cone-shaped inclusion complexes depending on the presence of C60/C70, however, a process that was not selective for one of the guests [24]. A spectacular case of guest sensing, but not guest-induced recognition, was demonstrated by Clever in a supramolecular cage-to-cage

Mechanochemical Friedel–Crafts acylations

• Mateja Đud,
• Anamarija Briš,
• Iva Jušinski,
• Davor Gracin and
• Davor Margetić

Beilstein J. Org. Chem. 2019, 15, 1313–1320, doi:10.3762/bjoc.15.130

• anthracene in 95% yield. This [4π + 4π] cycloreversion in mechanochemical conditions is analogous to previously described dissociation of labile anthracene/C60 cycloadduct [52]. When the reaction of 19 with 20 was carried out in solution (DCM, overnight), 60% of dimer was converted to anthracene, and traces

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

• there are not many spherical molecules known. Examples are the giant polyoxometalates reported by Müller et al. [3] and, more importantly for the current paper, fullerene C60. Because of the high symmetry of those compounds asymmetric modification is tedious with multiple synthesis and purification

• 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

• making it possible to obtain water soluble fullerenols as well as fullerenols that are still soluble in organic solvents [15][16][17][18][19]. The maximum number of OH groups, which could be attached to C60 is n = 44 [17]. Further derivatizations, where all hydroxy moieties of the compound have been

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• by NMR as well as other spectroscopic techniques. Georghiou et al. demonstrated the mechanochemical formation of a 1:1 supramolecular complex C60–tert-butylcalix[4]azulene 41 (Figure 23). The host–guest complexation was achieved by simple grinding the individual compounds in a mortar and pestle [95

• reaction through solid-state grinding. Hydrogen-bond donors are a) resorcinol and b) 1,8-dipyridylnaphthalene, respectively. Formation of the cage and encapsulation of [2.2]paracyclophane guest molecule in the cage was done simultaneously under mechanochemical conditions. Formation of the 1:1 complex C60

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

• introducing functional groups into the molecule directly. Among them, the formation of a 2:1 inclusion complex of γ-CD and C60 has been evaluated in various solvents such as water [21], toluene/water [22], DMSO [23], and DMF/water [24]. Although an impressive report that a 2:1 complex in water can be utilized

• as a homogeneous catalyst for nitrogen reduction under ambient conditions was published, the concentration of the complex in water is very low [25]. Thus, the development of γ-CD–C60 nonwovens by electrospinning might be useful as a novel inhomogeneous solid catalyst containing more C60. In this

• , isolation of fullerene by γ-CD motivated us to fabricate CD–fullerene inclusion complex fiber materials with molecularly dispersed fullerenes (Figure 1). Results and Discussion A representative example of a CD–fullerene inclusion complex is the combination of γ-CD and C60 [21][22][23][24]. Although the