Functionalization Of Fullerenes Research Articles

On the Functionalization of C60 with Vinylallenes Generated in situ by Rhodium Catalysis

AbstractThe functionalization of fullerenes is important for several reasons, primarily related to enhancing their chemical reactivity, solubility, and potential of applications in optoelectronics and biomedicine. In this study, we present a novel approach to functionalize C60 through a cascade process encompassing an unprecedented Rh‐catalyzed cycloisomerization of 1,6‐allenynes to in situ generate a vinylallene that is followed by a Diels‐Alder reaction with pristine fullerene, resulting in the formation of 6,6‐fused bicyclic fullerene derivatives. The mechanism governing this process was elucidated by DFT calculations and confirmed by deuterium labelling and control experiments, demonstrating the critical role of traces of water in the reaction medium to mediate the observed reactivity.

Subphthalocyanine metallo-organic cage as catalytic molecular photoreactor for the functionalization of fullerenes

ABSTRACT Subphthalocyanines (SubPcs) are aromatic chromophores with a bowlshaped structure and outstanding optoelectronic properties. The cavity formed by a C3-symmetry trispyridyl-SubPc, Pd(II)-metalloorganic capsule has proved an optimal, shape-complementary space for the complexation of C60. Taking advantage of the intense green light absorption of the SubPc components of the capsule, and their ability to transfer energy/electrons from the excited state, our group has recently described the unprecedented use of SubPc cages as molecular photoreactors to perform photoredox-triggered addition of diphenylamine radicals over encapsulated C60. Unfortunately, the reaction could only be performed using stoichiometric amounts of the cage due to inhibition of the SubPc cavity by the addition compound. Here, we describe the preparation of a more flexible SubPc cage built with a related C1-symmetry trispyridyl-SubPc (C1-SubPc-cage), which could facilitate the exchange between the complexed addition compound and pristine fullerene, thus allowing to use it in catalytic amounts. After assessing the ability of C1-SubPc-cage to host C60, the addition of α-aminoalkyl radicals in the presence of the cage under green light irradiation was tested. Curiously, optimisation of the reaction conditions (using catalytic amounts of C1-SubPc-cage in diluted solutions) rendered a different reaction outcome, that is, a cyclopropanated fullerene, in remarkably high yields.

Fullerene Derivatives for Tumor Treatment: Mechanisms and Application.

Fullerenes hold tremendous potential as alternatives to conventional chemotherapy or radiotherapy for tumor treatment due to their abilities to photodynamically kill tumor cells, destroy the tumor vasculature, inhibit tumor metastasis and activate anti-tumor immune responses, while protecting normal tissue through antioxidative effects. The symmetrical hollow molecular structures of fullerenes with abundant C=C bonds allow versatile chemical modification with diverse functional groups, metal clusters and biomacromolecules to synthesize a wide range of fullerene derivatives with increased water solubility, improved biocompatibility, enhanced photodynamic properties and stronger targeting abilities. This review introduces the anti-tumor mechanisms of fullerenes and summarizes the most recent works on the functionalization of fullerenes and the application of fullerene derivatives in tumor treatment. This review aims to serve as a valuable reference for further development and clinical application of anti-tumor fullerene derivatives.

Reactive Oxygen Species Scavenging Capacity of Functional Fullerenes in Solution and in Macrophage Cells

Reactive Oxygen Species Scavenging Capacity of Functional Fullerenes in Solution and in Macrophage Cells

Catalytic System-Controlled Regioselective 1,2- and 1,4-Carboannulations of [60]Fullerene.

Selective functionalization of fullerenes is an important but challenging topic in fullerene chemistry and synthetic chemistry. Here we present the first example of catalytic system-controlled regioselective 1,2- and 1,4-addition reactions for the flexible and efficient synthesis of novel 1,2- and 1,4-carbocycle-fused fullerenes via a palladium-catalyzed decarboxylative carboannulation process.

Interrupted N-Heterocyclic Carbene-Catalyzed Radical Coupling Strategy: A Versatile Platform for Alkylation and Arylation of [60]Fullerene.

An interrupted N-heterocyclic carbene-catalyzed radical coupling strategy is disclosed for efficient alkylation and arylation of [60]fullerene. This novel and general strategy bridges the gap between organocatalytic radical cross-coupling and functionalization of fullerenes. Readily available feedstocks, remarkably broad substrate scope and functional group compatibility, and convenient late-stage nanomodification of complex molecules make this strategy with incomparable diversity and practicality in the synthesis of monoalkylated and -arylated fullerenes.

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

The regioselective functionalization of fullerenes holds significant promise for applications in the fields of medicinal chemistry, materials science, and photovoltaics. In this study, we investigate the regioselectivity of the rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions between diynes and C70 as a novel procedure for generating C70 bis(fulleroid) derivatives. The aim is to shed light on the regioselectivity of the process through both experimental and computational approaches. In addition, the photooxidation of one of the C-C double bonds in the synthesized bis(fulleroids) affords open-cage C70 derivatives having a 12-membered ring opening.

Recent advances in supramolecular fullerene chemistry.

Fullerene chemistry has come a long way since 1990, when the first bulk production of C60 was reported. In the past decade, progress in supramolecular chemistry has opened some remarkable and previously unexpected opportunities regarding the selective (multiple) functionalization of fullerenes and their (self)assembly into larger structures and frameworks. The purpose of this review article is to provide a comprehensive overview of these recent developments. We describe how macrocycles and cages that bind strongly to C60 can be used to block undesired addition patterns and thus allow the selective preparation of single-isomer addition products. We also discuss how the emergence of highly shape-persistent macrocycles has opened opportunities for the study of photoactive fullerene dyads and triads as well as the preparation of mechanically interlocked compounds. The preparation of two- or three-dimensional fullerene materials is another research area that has seen remarkable progress over the past few years. Due to the rapidly decreasing price of C60 and C70, we believe that these achievements will translate into all fields where fullerenes have traditionally (third-generation solar cells) and more recently been applied (catalysis, spintronics).

Effect of d-block metals (M = Ti, Zr, Hf) decorated fullerenes M@C60 as sensor nanostructured materials for volatile organic compounds (VOCs): Approach from computational study

Volatile organic compounds (VOCs) are organic substances that readily evaporate into the atmosphere at room temperature, posing a regular exposure risk to humans. These compounds are associated with various environmental issues, including stratospheric ozone layer depletion, ground-level smog formation, climate change, sick building syndrome, plant decay, atmospheric toxicity, and potential carcinogenic effects on human health. In this study, we utilized ab-initio calculations based on density functional theory (DFT) at the B3LYP-GD3(BJ)/Def2-SVP method to examine how the functionalization of C60 fullerene with Ti, Hf, and Zr transition metals affects its sensing capabilities for volatile organic compounds, specifically methylcyclopentane (MCP), propanone (PPN), and benzene (BZN). The maximum adsorption energy of the transition metal decorated nanocages was recorded at 73.689 kcal/mol corresponding to PPN_Zr@C60 in tandem with the least energy gaps indicating higher conductivity of the PPN_Zr@C60 nanocage with the short bond distance of 1.929 Å for (Zr – O) interaction. The adsorption energy value proposes the adsorption of the volatile organic compound on the Ti, Hf, and Zr transition metal decorated C60 fullerene following the order BZN_Hf@C60 < BZN_Ti@C60 < PPN_Zr@C60. The studied systems possess a relatively high desorption time and they follow the increasing trend – BZN_Hf@C60 < MCP_Hf@C60 < MCP_Zr@C60 < MCP_Ti@C60 < PPN_Hf@C60 < BZN_Zr@C60 < BZN_Ti@C60 < PPN_Ti@C60 < PPN_Zr@C60. The results account that Zr@C60 possesses the highest desorption time and adsorption energy, hence more apposite for detecting the studied VOCs. It also divulges in Hf@C60 contains the least desorption time and least adsorption energy, therefore is not suitable for the detection as it basically portrays the least affinity for the adsorbed VOCs molecule. These results indicate that the VOC transition metal functionalized Ti@C60 and the Zr@C60 are excellent sensors for the effective detection and adsorption of volatile organic compounds which may be useful for environmental protection and the safeguard of human health.

Supramolecular Subphthalocyanine Cage as Catalytic Container for the Functionalization of Fullerenes in Water

AbstractHerein we report the first example of a supramolecular cage that works as a catalytic molecular reactor to perform transformations over fullerenes in aqueous medium. Taking advantage of the ability of metallo–organic Pd(II)‐subphthalocyanine (SubPc) capsules to form stable host:guest complexes with C60, we have prepared a water‐soluble cage that provides a hydrophobic environment for conducting cycloadditions over encapsulated C60, namely, Diels–Alder reactions with anthracene. Indeed, the presence of catalytic amounts of SubPc cage dissolved in water promotes co‐encapsulation of insoluble C60 and anthracene substrates, allowing the reaction to occur inside the cavity under mild conditions. The lower stability of the host:guest complex with the resulting C60 cycloadduct facilitates its displacement by pristine C60, which grants catalytic turnover. Moreover, bis‐addition compounds are regioselectively formed inside the cage when using excess anthracene.

Supramolecular Subphthalocyanine Cage as Catalytic Container for the Functionalization of Fullerenes in Water.

Herein we report the first example of a supramolecular cage that works as a catalytic molecular reactor to perform transformations over fullerenes in aqueous medium. Taking advantage of the ability of metallo-organic Pd(II)-subphthalocyanine (SubPc) capsules to form stable host:guest complexes with C60, we have prepared a water-soluble cage that provides a hydrophobic environment for conducting cycloadditions over encapsulated C60, namely, Diels-Alder reactions with anthracene. Indeed, the presence of catalytic amounts of solubilized SubPc cage promotes co-encapsulation of insoluble C60 and anthracene substrates, allowing the reaction to occur inside the cavity under mild conditions. The lower stability of the host:guest complex with the C60 cycloadduct facilitates displacement by pristine C60, allowing catalytic turnover. Moreover, bis-addition compounds are regioselectively formed inside the cage when using excess anthracene.

Exploring exohedral functionalization of fullerene with automation and Neural Network Potential

Exohedral functionalized fullerenes have shown superior physicochemical properties over pristine carbon cages. The functional groups could significantly improve solubility, electron affinity, and photoelectric properties. However, their numerous distribution patterns have long been puzzling for theoretical chemists, and there are unmet needs for tools to unveil their functionalization mechanism. This work automates the traditional stepwise model as well as various analysis workflows within an open-source package AutoSteper. Besides, a Neural Network Potential (NNP) is trained, validated, and proven to have great generalization ability and transferability. Several case studies are performed with AutoSteper to explore functionalization mechanisms, such as the selectivity and the functionalization pathway of a specific isomer, and the Stone-Wales Rearrangement (SWR) in co-crystallization systems. In addition, to reasonably narrow down the screen scope for giant nanoclusters, a new variant stepwise model is proposed. Fruitful scientific discoveries demonstrate that AutoSteper is capable of providing complete, comprehensive, and cost-effective analysis. With the combination of Automation and NNP, a data-driven research paradigm is realized for fullerene chemistry.

Synthesis of [60]Fullerene‐Fused Allylbenzofurans via Palladium‐Catalyzed Migration Reaction†

Comprehensive SummaryChemical functionalization of fullerenes has been an important topic in fullerene chemistry. Herein, an unprecedented Pd‐catalyzed migration reaction of [60]fullerene with allyloxy‐tethered aryl iodides is present for the preparation of novel [60]fullerene‐fused allylbenzofurans. The use of 1,2‐bis(diphenylphosphino)benzene (DPPBz) as a ligand is crucial for the success of the transformation. The reaction shows high chemo‐ and regioselectivity, and is flexible with regard to allyl‐migration site, providing a new and efficient approach to rare [60]fullerene‐fused benzofurans. Control experiments disclose that the reaction most probably undergoes a sequential C—O bond cleavage/allyl‐migration/intermolecular cycloaddition cascade process.

Functionalization of fullerene with 4-benzo-9-crown-3 ether

Functionalization of fullerene via covalent addition of substituted 4-benzo-9-crown-3 ether diazonium salt has been described. This procedure is used for the preparation of new derivative fullerenes which is described as a phase transfer catalyst. The covalent grafting has led to a considerable increment in the solubility of fullerene in organic solvents such as, CH2Cl2, acetone and ethanol. The covalent grafting of crown ether (4-(benzo-9-crown-3)) to fullerene (Fullerene-CE) has been identified and confirmed by IR, H-NMR, 7Li-NMR and thermogravimetric analysis (TGA) methods. Fullerene-CE in solvents has been used as a phase transfer catalyst for organic reactions. The Fullerene-CE is capable to become the Li+ host.

Transition-metal-mediated benzylation of C60 with benzyl chlorides.

Benzyl bromides have been widely used for fullerene functionalization. However, the use of benzyl chlorides, a more affordable but less reactive counterpart of benzyl bromides, has been rarely reported. Herein, a new metal-mediated benzylation of C60 with benzyl chlorides is presented. In this method, with the combinatorial use of Mn powder and Cu(OAc)2, various benzyl chloride derivatives could react with C60 to afford 1,4-dibenzylated products in 12-53% yields. A mechanistic study by in situ visible near infrared (vis-NIR) spectroscopy and various control experiments suggests that, unlike the conventional anionic pathway that uses benzyl bromides, the transition-metal-mediated benzylation of C60 with benzyl chlorides proceeds via a metal-mediated iterative single electron transfer process.

Enantioselective fullerene functionalization through stereochemical information transfer from a self-assembled cage.

The regioselective functionalization of C60 remains challenging, while the enantioselective functionalization of C60 is difficult to explore due to the need for complex chiral tethers or arduous chromatography. Metal-organic cages have served as masks to effect the regioselective functionalization of C60. However, it is difficult to control the stereochemistry of the resulting fullerene adducts through this method. Here we report a means of defining up to six stereocentres on C60, achieving enantioselective fullerene functionalization. This method involves the use of a metal-organic cage built from a chiral formylpyridine. Fullerenes hosted within the cavity of the cage can be converted into a series of C60 adducts through chemo-, regio- and stereo-selective Diels-Alder reactions with the edges of the cage. The chiral formylpyridine ultimately dictates the stereochemistry of these chiral fullerene adducts without being incorporated into them. Such chiral fullerene adducts may become useful in devices requiring circularly polarized light manipulation.

Chlorofullerene C60Cl6 Enables Efficient and Stable Tin‐Based Perovskite Solar Cells

Tin‐based perovskite solar cells (TPSCs) have received great attention due to their eco‐friendly properties and high theoretical efficiencies. However, the fast crystallization feature of tin‐based perovskites leads to poor film quality and limits the corresponding device performance. Herein, a chlorofullerene, C60Cl6, with six chlorine attached to the C60 cage, is applied to modulate the crystallization process and passivate grain boundary defects of the perovskite film. The chemical interactions between C60Cl6 and perovskite components retard the transforming process of precursors to perovskite crystals and obtain a high‐quality tin‐based perovskite film. It is also revealed that the C60Cl6 located at the surfaces and grain boundaries can not only passivate the defects but also offer a role in suturing grain boundaries to suppress the detrimental effects of water and oxygen on perovskite films, especially the oxidation of Sn2+ to Sn4+. As a result, the C60Cl6‐based device yields a remarkably improved device efficiency from 10.03% to 13.30% with enhanced stability. This work provides a new strategy to regulate the film quality and stability of TPSCs using functional fullerene materials.

Application of Fullerenes as Photosensitizers for Antimicrobial Photodynamic Inactivation: A Review.

Antimicrobial photodynamic inactivation (aPDI) is a newly emerged treatment approach that can effectively address the issue of multidrug resistance resulting from the overuse of antibiotics. Fullerenes can be used as promising photosensitizers (PSs) for aPDI due to the advantages of high triplet state yields, good photostability, wide antibacterial spectrum, and permissibility of versatile functionalization. This review introduces the photodynamic activities of fullerenes and the up-to-date understanding of the antibacterial mechanisms of fullerene-based aPDI. The most recent works on the functionalization of fullerenes and the application of fullerene derivatives as PSs for aPDI are also summarized. Finally, certain remaining challenges are emphasized to provide guidance on future research directions for achieving clinical application of fullerene-based aPDI.

(Invited, Digital Presentation) Aggregation Switchable Fullerene-Peptides Conjugates

Intensive research has been applied on chemical functionalization of fullerenes over the past decades, aiming at utilizing their broad availabilities in chemical biology field. Chemical moieties was induced to improve their water solubility and thus enhance their properties or interaction with biomolecules. In our previous study, we reported the synthesis of fullerene-PEG conjugates and demonstrated their ability for photoinduced DNA damage and ROS generation under visible light irradiation.In this work, we report a water-soluble fullerene derivative by constructing a fullerene-peptide conjugates. The aggregation behavior as well as bio properties has been systematically studied for this series of fullerene-peptide conjugates (Figure 1a). By altering the attached peptides, fullerenes could exist as monomer or micelle in aqueous phase (Figure 1b). Figure 1

Controlled Decoration of [60]Fullerene with Polymannan Analogues and Amino Acid Derivatives through Malondiamide-Based Linkers.

In the last few years, nanomaterials based on fullerene have begun to be considered promising tools in the development of efficient adjuvant/delivery systems for vaccination, thanks to their several advantages such as biocompatibility, size, and easy preparation and modification. In this work we reported the chemoenzymatic synthesis of natural polymannan analogues (di- and tri-mannan oligosaccharides characterized by α1,6man and/or α1,2man motifs) endowed with an anomeric propargyl group. These sugar derivatives were submitted to 1,3 Huisgen dipolar cycloaddition with a malondiamide-based chain equipped with two azido terminal groups. The obtained sugar-modified malondiamide derivatives were used to functionalize the surface of Buckminster fullerene (C60) in a highly controlled fashion, and yields (11–41%) higher than those so far reported by employing analogue linkers. The same strategy has been exploited to obtain C60 endowed with natural and unnatural amino acid derivatives. Finally, the first double functionalization of fullerene with both sugar- and amino acid-modified malondiamide chains was successfully performed, paving the way to the possible derivatization of fullerenes with immunogenic sugars and more complex antigenic peptides.