Anisotropic Paramagnetic Properties of Metallofullerene Confined in a Metal–Organic Framework

Paramagnetic metallofullerenes have a spherical molecular structure and stable unpaired spin protected by a fullerene cage and have potential applications in quantum information processing, etc. For endohedral azafullerene Y₂@C₇₉N, the N atom on the cage endows the molecule with unpaired spin and is proposed to induce the molecule orientation within the MOF pore via host–guest interaction. Angular-dependent EPR spectroscopy was employed on the Y₂@C₇₉N⊂MOF-177 complex to detect the anisotropic paramagnetic properties. These results experimentally confirmed the trend of molecule orientation of Y₂@C₇₉N within MOF-177 under certain conditions, which also induces the presence of several conformers of Y₂@C₇₉N. The additional EPR splittings in Y₂@C₇₉N⊂MOF-177 are proposed to originate from partially disordered molecules as well as the N-coupling of Y₂@C₇₉N upon implanting it into the MOF-177 pore. The N-defect on the fullerene cage of Y₂@C₇₉N is expected to be utilized as an anchor to build a three-dimensional spin array within MOF matrix

Optoelectronic Properties of a Fullerene Derivative Containing Adamantane Group

A fullerene derivative linked with an adamantane cage, [6,6]-phenyl-C₆₁-butyric acid 1-adamantane methyl ester (PC₆₁BAd), has been designed and synthesized. Systematic investigations on its organic field effect performance, photovoltaic properties, and corresponding thermal stability have been made. In OFET device, the electron mobility (μ_e) of PC₆₁BAd was found to reach a value as high as 0.01 cm²/V·s with a high on-off (<i>I</i>_on/<i>I</i>_off) ratio of 4.9 × 10⁶ that is useful for logic device applications. In the organic photovoltaic devices of P3HT:PC₆₁BAd, the power conversion efficiency (PCE) was found to reach 3.31 % in the optimized device. More importantly, the active layer of P3HT:PC₆₁BAd was found to exhibit superior thermal stability over that of P3HT:PC₆₁BM. After heating at 150 °C for 20 h, the P3HT:PC₆₁BAd device still showed a PCE of 2.44 %, demonstrating the applicability of PC₆₁BAd as an acceptor material for the preparation of thermally stable organic solar cells. X-ray diffraction and atomic force microscopy were employed to probe the structure and morphology of PC₆₁BAd and to rationalize its performance as an organic electronic material

Gd@C₈₂-(ethylenediamine)₈ Nanoparticle: A New High-Efficiency Water-Soluble ROS Scavenger

It is important to maintain a reactive oxygen species (ROS) balance in organisms; thus, a valid ROS scavenger with good biocompatibility is urgently required. To prepare a high-efficiency ROS scavenger, multiple ethylenediamine (EDA) groups are bonded for the first time to a metallofullerene Gd@C₈₂ to obtain water-soluble Gd@C₈₂-(EDA)₈ nanoparticles (NPs) through a facile solid–liquid reaction. Gd@C₈₂-(EDA)₈ NPs with a relatively better conjugation possess an excellent capability to scavenge hydroxyl radicals. Moreover, Gd@C₈₂-(EDA)₈ NPs exhibited a remarkable cytoprotective effect against H₂O₂-induced injuries to human epidermal keratinocytes-adult (HEK-a) cells at a low concentration of 2.5 μM. In contrast, Gd@C₈₂-(OH)₂₆ NPs that modified with hydroxyls show an apparent protective effect at a much higher concentration of 40 μM. This outstanding cytoprotective performance of Gd@C₈₂-(EDA)₈ NPs is mainly attributed to their extremely high cellular uptake and comparably strong conjugation. Gd@C₈₂-(EDA)₈ NPs with good biocompatibility exhibit excellent ROS scavenging capability even at a significantly low concentration, which promotes its versatile applications in cosmetics and biomedicine

Protective Effect of C₇₀-Carboxyfullerene against Oxidative-Induced Stress on Postmitotic Muscle Cells

Satellite muscle cells play an important role in regeneration of skeletal muscle. However, they are particularly vulnerable to oxidative stress. Herein, we address our efforts on the cytoprotective activities of carboxyfullerenes with different cage size (C₆₀ vs C₇₀) and adduct number on postmitotic muscle cell (C2C12 cell). The correlation of the structural effect on the cytoprotective capability of carboxyfullerenes was evaluated. We find that quadri-malonic acid C₇₀ fullerene (QF₇₀) exhibits higher capability on protecting cells from oxidative-induced stress among these tested carboxyfullerenes. The accumulation of intracellular superoxide dismutase (SOD) is proposed to play an important role in their diverse antioxidative ability. Moreover, the pretreatment of QF₇₀ could also obviously enhance the viability of myotubes originated from oxidative-stressed C2C12 cells, which facilitates the future application of carboxyfullerenes in tissue engineering and nanomedicine

Curdlan-Decorated Fullerenes Mitigate Immune-Mediated Hepatic Injury for Autoimmune Hepatitis Therapeutics via Reducing Macrophage Infiltration

Autoimmune hepatitis (AIH) is a severe immune-mediated inflammatory liver disease whose standard of care is immunosuppressive treatment with inevitable undesired outcomes. Macrophage is acknowledged to aggravate liver damage, providing a promising AIH therapeutic target. Accordingly, in this study, a kind of curdlan-decorated fullerene nanoparticle (Cur-F) is fabricated to alleviate immune-mediated hepatic injury for treating AIH via reducing macrophage infiltration in a concanavalin A (Con A)-induced AIH mouse model. After intravenous administration, Cur-F primarily distributes in liver tissues, efficiently eliminates the excessive reactive oxygen species, significantly attenuates oxidative stress, and subsequently suppresses the nuclear factor kappa-B-gene binding (NF-κB) signal pathway, resulting in the lowered production of pro-inflammatory cytokines and the balancing of the immune homeostasis with the prevention of macrophage infiltration in the liver. The regulation of hepatic inflammation contributes to inhibiting inflammatory cytokines-induced hepatocyte apoptosis, decreasing the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) contents and thus ameliorating immune-mediated hepatic injury. Notably, there is no detectable toxicity to the body. Our findings may open up novel avenues for AIH based on curdlan and fullerene materials

Fullerene-Induced Increase of Glycosyl Residue on Living Plant Cell Wall

In this work, we have investigated the change of cell wall for the tobacco plant cell (<i>Nicotiana tobacum</i> L. cv. Bright Yellow) under the repression of water-soluble carboxyfullerenes (C₇₀(C­(COOH)₂)_2–4). The adsorption of C₇₀(C­(COOH)₂)_2–4 on cell wall led to the disruption of cell wall and membrane, and consequently, cell growth inhibition. Results from atomic force microscopy (AFM) force measurement and confocal imaging revealed an increase of the glycosyl residue on the cell wall of carboxyfullerene-treated cells, with a time- and dose-dependent manner, and accompanied by the elevated reactive oxygen species (ROS). Moreover, the stimulation-sensitive alteration of glycosyl residue and ROS was demonstrated, which suggested a possible protection strategy for the plant cells under fullerene repression. This study provides the first direct evidence on the change of plant cell wall composition under the repression of fullerene and is the first successful application of AFM ligand-receptor binding force measurement to the living plant cell. The new information present here would help to a better understanding and assessment of the biological effect of fullerenes on plant

Steering Metallofullerene Electron Spin in Porous Metal–Organic Framework

Paramagnetic endohedral fullerenes are ideal candidates for quantum information processing and high-density data storage due to their protected spins with particularly high stability. Herein, we report a solid spin system based on a paramagnetic metallofullerene Y₂@C₇₉N through incarcerating it into the cage-shaped pores of a metal–organic framework (MOF-177). In this kind of guest and host complex, the Y₂@C₇₉N molecules inside the pores of MOF crystal show axisymmetric paramagnetic property. It was found that the pores of MOF-177 crystal play an important role in dispersing the Y₂@C₇₉N molecules as well as in steering their electron spin. The group of arranged Y₂@C₇₉N molecules and their electron spins in MOF crystals are potential quantum bits for quantum information science and data storage. Moreover, this kind of solid spin system can be used as a probe for nanoscale nuclear magnetic resonance or for motion imaging of a single biomolecule

Visible-Light Photoexcited Electron Dynamics of Scandium Endohedral Metallofullerenes: The Cage Symmetry and Substituent Effects

Endohedral metallofullerenes (EMFs) have become an important class of molecular materials for optoelectronic applications. The performance of EMFs is known to be dependent on their symmetries and characters of the substituents, but the underlying electron dynamics remain unclear. Here we report a systematic study on several scandium EMFs and representative derivatives to examine the cage symmetry and substituent effects on their photoexcited electron dynamics using ultrafast transient absorption spectroscopy. Our attention is focused on the visible-light (530 nm as a demonstration) photoexcited electron dynamics, which is of broad interest to visible-light solar energy harvesting but is considered to be quite complicated as the visible-light photons would promote the system to a high-lying energy region where dense manifolds of electronic states locate. Our ultrafast spectroscopy study enables a full mapping of the photoinduced deactivation channels involved and reveals that the long-lived triplet exciton plays a decisive role in controlling the photoexcited electron dynamics under certain conditions. More importantly, it is found that the opening of the triplet channels is highly correlated to the fullerene cage symmetry as well as the electronic character of the substituents

Theoretical and experimental studies on the electronic, optical, and structural properties of poly-pyrrole-2-carboxylic acid films

A theoretical approach is used here to explain experimental results obtained from the electrosynthesis of polypyrrole-2-carboxylic acid (PPY-2-COOH) films in nonaqueous medium. An analysis of the Fukui function (reactivity index) indicates that the monomer (pyrrole-2-carboxylic acid, PY-2-COOH), and dimers and trimers are oxidized in the C4 or C5 positions of the heterocyclic ring of the PY-2-COOH structure. After calculating the heat of formation using semiempirical Austin Model 1 post-Hartree-Fock parameterization for dimer species, both C4 and C5 positions adjacent to the aromatic rings of PPY-2-COOH were considered the most susceptible ones to oxidative coupling reactions. The ZINDO-S/CI semiempirical method was used to simulate the electronic transitions typically seen in the UV-VIS-NIR range in monomer and oligomers with different conjugation lengths. The use of an electrochemical quartz crystal microbalance provides sufficient information to propose a polymerization mechanism of PY-2-COOH based on molecular modeling and experimental results.FAPESPFAPEMIGCNPqCAPESInstituto Nacional de Ciência e Tecnologia em Eletrônica Orgânica (INEO)Instituto Nacional de Ciência e Tecnologia de Nanomateriais de Carbono (INCT - Nanomateriais de Carbono

Biocompatible [60]/[70] Fullerenols: Potent Defense against Oxidative Injury Induced by Reduplicative Chemotherapy

Chemotherapy as a conventional cancer treatment suffers from critical systemic side effects, which is generally considered as the consequence of reactive oxygen species (ROS). Fullerenes have been widely studied for their excellent performance in radicals scavenging. In the present study, we report a solid–liquid reaction to synthesize fullerenols and their application as ROS scavengers in chemotherapy protection. The solid–liquid reaction is carried out without catalyst and suitable for mass production. The novel [60]/[70] fullerenols show a high stability in water, and the [70] fullerenols (C₇₀–OH) exhibit radical scavenging capability superior to that of [60] fullerenols (C₆₀–OH) in chemotherapy protection. The mouse model for single and reduplicative chemotherapy-induced liver injury demonstrates their protective effects in the chemotherapeutic process, which is confirmed by histopathological examinations and hematological index. The increase of the hepatic l-glutathione (GSH) level and downregulated expression of the cytochrome P-450 2E1 (CYP2E1) give the possible mechanism associated with the impact of fullerenols on the metabolism of doxorubicin. The novel fullerenols may be promising protective agents to satisfy the demand for future clinical chemotherapy