Edison Castro

Fullerenes in biology and medicine

Fullerenes and related carbon based derivatives have shown a growing relevance in biology and medicine, mainly due to the unique electronic and structural properties that make them excellent candidates for multiple functionalization. This review focuses on the most recent developments of fullerene derivatives for different biological applications.

A dimeric fullerene derivative for efficient inverted planar perovskite solar cells with improved stability

Fullerene derivatives can efficiently passivate the interfacial defects of perovskite layers to improve the performance of perovskite solar cells. In this work, a new dimeric fullerene derivative (D-C60) with two [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) units was designed, synthesized and applied as the electron transporting material (ETM) in perovskite solar cells (PSCs) taking advantage of its appropriate energy levels, relatively fast electron mobility, and easy solution processability compared to the widely used PC61BM, D-C60 can efficiently passivate the trap states between the perovskite and fullerene layers, leading to improved electron extraction and overall photovoltaic performance. Devices based on D-C60 as the ETM achieved power conversion efficiencies (PCEs) of 16.6%, which is significantly higher than that observed with PC61BM (14.7%). In addition, the more hydrophobic and compact D-C60 layer resulted in higher device stability than that with PC61BM. These results show that covalently linked dimeric fullerene derivative can act as efficient electron transporting materials (ETMs) for high performance PSCs.

Fullerene Derivatives Strongly Inhibit HIV-1 Replication by Affecting Virus Maturation without Impairing Protease Activity.

ABSTRACT Three compounds (1, 2, and 3) previously reported to inhibit HIV-1 replication and/or in vitro activity of reverse transcriptase were studied, but only fullerene derivatives 1 and 2 showed strong antiviral activity on the replication of HIV-1 in human CD4+ T cells. However, these compounds did not inhibit infection by single-round infection vesicular stomatitis virus glycoprotein G (VSV-G)-pseudotyped viruses, indicating no effect on the early steps of the viral life cycle. In contrast, analysis of single-round infection VSV-G-pseudotyped HIV-1 produced in the presence of compound 1 or 2 showed a complete lack of infectivity in human CD4+ T cells, suggesting that the late stages of the HIV-1 life cycle were affected. Quantification of virion-associated viral RNA and p24 indicates that RNA packaging and viral production were unremarkable in these viruses. However, Gag and Gag-Pol processing was affected, as evidenced by immunoblot analysis with an anti-p24 antibody and the measurement of virion-associated reverse transcriptase activity, ratifying the effect of the fullerene derivatives on virion maturation of the HIV-1 life cycle. Surprisingly, fullerenes 1 and 2 did not inhibit HIV-1 protease in an in vitro assay at the doses that potently blocked viral infectivity, suggesting a protease-independent mechanism of action. Highlighting the potential therapeutic relevance of fullerene derivatives, these compounds block infection by HIV-1 resistant to protease and maturation inhibitors.

New organic dyes with high IPCE values containing two triphenylamine units as co-donors for efficient dye-sensitized solar cells

Here we report the synthetic routes as well as the structural and electronic properties of five new triphenylamine-based organic dyes and their application in dye-sensitized solar cells. In the designed dyes, two triphenylamine groups act as the electron donor units and the electron acceptor is a cyanoacrylic acid, and these units are linked by different π-conjugated spacers including thiophene, dioctylfluorene, ethylcarbazole, and benzo-dithiophene. Density functional theory was employed to study the electron distribution and the intramolecular charge transfer (HOMO–LUMO) of the dyes. Extending the π-conjugation of the dyes broaden and red-shift the bands and improves the light-harvesting ability, however, a device made with triphenylamine maximizer-based dye TPAM-1 without a π-conjugated spacer exhibited the best photovoltaic performance with a short-circuit photocurrent density (Jsc) of 11.37 mA cm−2, an open-circuit voltage (Voc) of 0.836 V, and a fill factor (FF) of 0.603, corresponding to an overall power conversion efficiency of 5.67% under AM 1.5 irradiation (100 mW cm−2).

Cove-Edge Nanoribbon Materials for Efficient Inverted Halide Perovskite Solar Cells

Two cove-edge graphene nanoribbons hPDI2-Pyr-hPDI2 (1) and hPDI3-Pyr-hPDI3 (2) are used as efficient electron-transporting materials (ETMs) in inverted planar perovskite solar cells (PSCs). Devices based on the new graphene nanoribbons exhibit maximum power-conversion efficiencies (PCEs) of 15.6 % and 16.5 % for 1 and 2, respectively, while a maximum PCE of 14.9 % is achieved with devices based on [6,6]-phenyl-C61 -butyric acid methyl ester (PC61 BM). The interfacial effects induced by these new materials are studied using photoluminescence (PL), and we find that 1 and 2 act as efficient electron-extraction materials. Additionally, compared with PC61 BM, these new materials are more hydrophobic and have slightly higher LUMO energy levels, thus providing better device performance and higher device stability.

Progress in fullerene-based hybrid perovskite solar cells

In this review, we summarize recent advances that have resulted in fullerene-based high-efficiency perovskite solar cells (PSCs) by new processing methods of the perovskite films, by adding fullerenes as interfacial selective electron extraction layers and improving device stability or by incorporating fullerene derivatives to eliminate hysteretic behavior of both regular and inverted PSC structures. Finally, we outline some perspectives for further advancing PSCs for large-scale and commercial applications.

A Copper-based Supramolecular Nanocapsule that Enables Straightforward Purification of Sc3N-based Endohedral Metallofullerene Soots

A self-assembled CuII -based nanocapsule enables efficient and straightforward isolation of Sc3 N@C80 from arc-processed raw soot. The newly designed CuII -based supramolecular nanocapsule 5⋅(OTf)8 was used to effectively entrap fullerenes and endohedral metallofullerenes (EMFs) with different affinities depending on their size and shape. Moreover, we took advantage of the sharply different entrapment abilities of the 5⋅(OTf)8 cage in the solid state versus in solution to encapsulate all the species with the exception of Sc3 N@C80 (both Ih and D5h isomers), which remains pure in solution. HPLC quantification determined that up to 85 % of the total Sc3 N@C80 content in the initial mixture was recovered in very high purity (>99.5 %). The complete release of the encapsulated species with an orthogonal solvent-washing strategy regenerates 5⋅(OTf)8 ready to be re-used. This approach opens new opportunities for EMFs purification.

Fullerene derivative with a branched alkyl chain exhibits enhanced charge extraction and stability in inverted planar perovskite solar cells

Fullerene derivatives are known for their excellent electron transport properties, which can effectively serve as electron transport layers (ETLs) deposited from solution at low temperatures in perovskite solar cells (PSCs). However, it remains unclear how functional groups attached to the fullerene derivatives influence device performances. Herein, the performance of an ETL based on [6,6]-phenyl-C61 butyric acid 2-ethylhexyl ester (PC61BEH) was investigated. It was demonstrated that the branched alkyl chain of the fullerene derivative can highly influence the solubility, film morphology, passivation ability, ETL-perovskite contact, and electron extraction ability of the fullerene derivative. Overall device performance and stability are dependent on these characteristics. The results suggest that further design and improvement of fullerene-based PSCs performance may be possible through optimization of the addend structure and functionality.

Transformation of doped graphite into cluster-encapsulated fullerene cages

An ultimate goal in carbon nanoscience is to decipher formation mechanisms of highly ordered systems. Here, we disclose chemical processes that result in formation of high-symmetry clusterfullerenes, which attract interest for use in applications that span biomedicine to molecular electronics. The conversion of doped graphite into a C80 cage is shown to occur through bottom-up self-assembly reactions. Unlike conventional forms of fullerene, the iconic Buckminsterfullerene cage, Ih-C60, is entirely avoided in the bottom-up formation mechanism to afford synthesis of group 3-based metallic nitride clusterfullerenes. The effects of structural motifs and cluster–cage interactions on formation of compounds in the solvent-extractable C70–C100 region are determined by in situ studies of defined clusterfullerenes under typical synthetic conditions. This work establishes the molecular origin and mechanism that underlie formation of unique carbon cage materials, which may be used as a benchmark to guide future nanocarbon explorations.An understanding of how caged carbon materials self-assemble from doped graphite is a long-standing challenge. Here, the authors show that distinct bottom-up processes lead to the synthesis of high-symmetry clusterfullerenes.

Atomically Precise Au25(SG)18 Nanoclusters: Rapid Single-Step Synthesis and Application in Photothermal Therapy

Remarkable recent advances on Au25(SR)18 nanoclusters have led to significant applications in catalysis, sensing, and magnetism. However, the existing synthetic routes are complicated, particularly for the water-soluble Au25(SG)18 nanoclusters. Here, we report a single-step concentration and temperature-controlled method for rapid synthesis of the Au25(SG)18 nanoclusters in as little as 2 h without the need for low-temperature reaction or even stirring. A systematic time-based investigation was carried out to study the effects of volume, concentration, and temperature on the synthesis of these nanoclusters. Further, we discovered for the first time that the Au25(SG)18 nanoclusters exhibit excellent photothermal activities in achieving 100% cell death for MDA-MB-231 breast cancer cells at a power of 10 W/cm2 using an 808 nm laser source, demonstrating applications toward photothermal therapy.