Fullerene Structures Research Articles

Reducing Interfacial Recombination in Inverted Perovskite Solar Cells With Selenophene-Substituted PCBM: Comparison With Thiophene and Furan Substitution.

Reducing the interfacial recombination and improving the charge transfer capability of charge transport layers are effective strategies to enhance the efficiency and stability of perovskite solar cells (PSCs). This study evaluates, for the first time, the effects of selenophene substitution in the chemical structure of phenyl-butyric acid methyl ester (PCBM) on the performance and stability of inverted PSCs. Selenophene substitution was compared to thiophene and furan substitutions, and the reference PCBM without chalcogenophene moiety. Additionally, this study investigates the differences between using the fullerene cages C70 and C60 in the PCBM chemical structure. The photovoltaic results demonstrate that, with an adequate control of the thickness of the electron transport layer (ETL), incorporating the selenophene moiety in the structures of fullerenes enhances the photovoltaic parameters of PSCs. This improvement results from the reduction in trap-assisted recombination, an increase in electron mobility, and the improved charge extraction processes. The use of C70, as opposed to C60, allows for the preparation of a series of ETLs with comparable thicknesses, although slightly lower efficiencies. This feature facilitates a systematic comparative analysis focused on variations in the electron properties of ETLs, thereby avoiding the inclusion of issues related to thickness and charge recombination processes.

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.

(Invited) Density Functional Theory Study on Molecular Structures of Polyhydroxy Fullerenes

Polyhydroxy fullerenes (PHF), also known as fullerenols or fullerols, are water-soluble fullerenes that are being studied for several applications. PHF is usually synthesized by acid or alkali method and is assumed to have only hydroxyl groups. These approaches use uncontrolled oxidation method and it is possible to have unintended functionalization. In fact, few studies have proposed presence of hemi-ketal and carbonyl groups based on NMR, XPS and FTIR studies. However, a complete understanding of their molecular structures is still lacking. Theoretical quantum chemical calculations based on density functional theory (DFT) are commonly used to predict and corroborate vibrational spectrum of molecules. Interestingly, in silico studies thus far have considered fullerenes with only hydroxyl groups with a big mismatch in their calculated vibrational energies and experimental FTIR spectrum.In this study, we investigated the presence of carbonyl and hemi-ketal functional groups on hydroxylated fullerenes using DFT. We also evaluated the influence of counterions on oxygen-containing functional groups. All DFT calculations were carried out on Gaussian19 with hybrid B3LYP functional and 6-31G(d,p) basis set. By bridging the gap between theoretical calculations and experimental measurements, we offer an alternative interpretation for the characteristic peaks observed in the FTIR spectrum. Furthermore, our theoretical calculations suggest a dynamic nature inherent in these oxygen-containing functional groups residing on the carbon cage of the fullerene structure.

(Invited) Predicting the Optical Spectra of Fullerenes with Vibronic Coupling

Following the mid-1980s discovery of fullerenes, their optical properties quickly drew a lot of attention as the intrinsically allowed electronic transitions did not seem to alone explain the complexities of their spectra. Even after more than three decades, there is still little knowledge of the intricate details of their absorption and emission spectra. The main issue with these carbon cages is the high density of electronic states in the energy range of interest. From an experimental standpoint, this means that high resolution spectra are needed to accurately distinguish the electronic and vibronic structure. On the other hand, such a high density of electronic states tests the limits of first-principle calculations, as the computational cost for precisely predicting electronic states quickly becomes prohibitive for systems as large as fullerenes.In this presentation, we will discuss the challenges and importance of including vibronic coupling in the Ab initio calculation of fullerenes' optical spectra. This is necessary in order to gain a reliable interpretation of their electronic spectra and make the most of spectroscopy to probe the electronic structure of fullerenes.

Molecular Interactions Between Hexanal Schiff Bases and Boron Nanocages: A DFT Approach

This study explores the interactions between hexanal Schiff bases and a B12N12 nanocage, employing density functional theory (DFT) calculations to deepen our understanding of noncovalent bonds. Hexanal, a key component in tea, plays a vital role in prolonging the shelf-life of various plant-based products by inhibiting phospholipase-D. Our research initially focused on synthesizing Schiff bases through the condensation of hexanal with nucleobases and an amino acid. We then conducted a series of DFT calculations, including geometry optimizations, frontier molecular orbital (FMO), natural bond orbital (NBO) and noncovalent interactions (NCI) assays, using Gaussian 16 and ORCA 5.0.2 software packages. This study reveals that hexanal Schiff bases form stable complexes with the B12N12 nanocage, exhibiting notable dative coordinate bonding. The FMO analysis indicates a significant energy gap variation among the complexes, with CSB2 showing the lowest energy gap, hinting at its high reactivity. In the LED assay, CSB2 demonstrates the lowest decomposition energy, highlighting its potential stability. The AIMD simulations provide insights into the electronic motions of these complexes, underscoring their dynamic nature. Our NBO analysis offers a comprehensive view of the electron distribution within these complexes, emphasizing the significance of nitrogen and boron atoms in the bonding process. The NCI assay sheds light on the predominant van der Waals and steric interactions contributing to the stability of the complexes. This investigation provides a detailed account of the NCI between hexanal Schiff bases and the B12N12 nanocage. The findings not only contribute to the field of noncovalent bonding in inorganic-fullerene structures but also open avenues for future applications in material science and molecular engineering.

DFT investigation on the design and optimization of icosahedral and octahedral beryllium nitride (Be3N2)x fullerene analogue. A comparative study with isosymmetry carbon fullerene

In this contribution, based on density Functional Theory, we focus on studying the structural and dynamic stability of octahedral and icosahedral beryllium nitride (Be3N2)x fullerenes and their symmetry equivalent carbon molecules. The icosahedron structure of beryllium nitride and carbon-based fullerenes shows hybrid features, between a sphere and a polyhedron. Nevertheless, the cohesive energies of carbon fullerenes are slightly lower than those of beryllium nitride based on Be3N2 units. Although icosahedral Ih (1,1) and Ih (2,2) (Be3N2)30 and (Be3N2)120 are energetically slightly less favorable than their corresponding carbon fullerenes, they showed chemically stable structures. IR & Raman spectra are also simulated using a coupled-perturbed KS/HF scheme permitting their identification. Importantly, no imaginary frequency is recorded in their vibrational spectra which confirms an inherent dynamic stability. These results provide valuable insights that can be extrapolated to other noncarbon nanostructures containing pentagonal rings or pentagonal defects.

Gas-phase hydrogenation processes of cationic carbon clusters

ABSTRACT In this work, the gas-phase ion–atom collision reaction between large cationic carbon clusters and H-atoms is investigated. The carbon cluster cations (C$_{48-2*n}$$^+$, n = [0$-$8]) are produced from the photo-fragmentation processes of large PAH (dicoronylene, DC, C$_{48}$H$_{20}$) cations. The hydrogenated carbon cluster cations are efficiently formed (e.g. C$_{44/46}$H$_{9}$$^+$), and no even–odd hydrogenated mass patterns are observed. The hydrogenation behaviour and hydrogenation rate for these carbon cluster cations are the same. With theoretical calculations, the formation and bending processes of carbon cluster cations, the structure of these newly formed hydrogenated carbon cluster cations, and the bonding energies for the hydrogenation pathways are investigated. During the formation process of carbon clusters, the zigzagged edges gradually increase, and the planar configuration tends towards a bent and folded molecular configuration, i.e. from graphene to fullerene structures. The bending process with higher exothermic energies provides a reasonable explanation for the formation of the ‘magic numbers’ (e.g. C-atoms = 44) carbon clusters and their greater stability. The exothermic energy for each hydrogenation reaction pathway is relatively high; consequently, the forms and the hydrogenated states of carbon clusters are complex. The hydrogenation ability of edge carbon sites is higher than that of internal carbon sites; after bending and folding, the hydrogenation ability of these originally internal carbon sites becomes higher due to structural caged. As a result, under the co-evolution interstellar chemistry network, the (hydrogenation) states and forms of carbon compounds are complicated and diverse in the ISM.

Silvery fullerene in Ag102 nanosaucer.

Despite the discovery of a series of fullerenes and a handful of noncarbon clusters with the typical topology of I h-C60, the smallest fullerene with a large degree of curvature, C20, and its other-element counterparts are difficult to isolate experimentally. In coinage metal nanoclusters (NCs), the first all-gold fullerene, Au32, was discovered after a long-lasting pursuit, but the isolation of similar silvery fullerene structures is still challenging. Herein, we report a flying saucer-shaped 102-nuclei silver NC (Ag102) with a silvery fullerene kernel of Ag32, which is embraced by a robust cyclic anionic passivation layer of (KPO4)10. This Ag32 kernel can be viewed as a non-centered icosahedron Ag12 encaged into a dodecahedron Ag20, forming the silvery fullerene of Ag12@Ag20. The anionic layer (KPO4)10 is located at the interlayer between the Ag32 kernel and Ag70 shell, passivating the Ag32 silvery fullerene and templating the Ag70 shell. The t BuPhS- and CF3COO- ligands on the silver shell show a regioselective arrangement with the 60 t BuPhS- ligands as expanders covering the upper and lower of the flying saucer and 10 CF3COO- as terminators neatly encircling the edges of the structure. In addition, Ag102 shows excellent photothermal conversion efficiency (η) from the visible to near-infrared region (η=67.1%±0.9% at 450nm, 60.9%±0.9% at 660nm and 50.2%±0.5% at 808nm), rendering it a promising material for photothermal converters and potential application in remote laser ignition. This work not only captures silver kernels with the topology of the smallest fullerene C20, but also provides a pathway for incorporating alkali metal (M) into coinage metal NCs via M-oxoanions.

Monte Carlo study of magnetic properties of the fullerene C24 structure

ABSTRACT The fullerene C24 is one of the most active types of nanostructures and has been used as an active component in important applications. In this study, we investigated the magnetic characteristics of the mixed spins 5/2 and 3/2 of the Fullerene C24 system using Monte Carlo simulations. We start by offering a theoretical analysis of ground state phase diagrams. In fact, out of all potential configurations, we only present and analyze the stable configurations. Secondly, calculations are done to determine how the magnetic characteristics of this compound change as various physical parameters are changed. Additionally, we offer the examined magnetic behavior of the system with reduced temperature, reduced crystal field, reduced exchange-coupling interactions, and reduced external magnetic field. Finally, we looked into and talked about the critical reduced temperature of Fullerene C24. We showed and examined the hysteresis loops for various physical parameter values to end our work.

Non-covalent complexes of polycationic/polyanionic fullerene C60 derivatives with cyanine dyes: Spectral properties and superoxide generation under NIR light irradiation

Polycationic/polyanionic fullerene C60 derivatives and heptamethine cyanine dyes IR780, IR783, IR806, IR820 and piperazine-substituted derivative of IR780 dye form complexes through an electrostatic interaction in aqueous solutions. The fluorescence of the dye is strongly quenched in such complexes, and they efficiently generate superoxide anion-radical under near-infrared (NIR) irradiation due to the photoinduced electron transfer from the photoexcited dye to the fullerene core. The superoxide generation efficiency under NIR light irradiation increases 52 times for the IR783−(polycationic fullerene derivative) complex compared to the native dye. The demonstrated results show promising potential of such [cyanine dye]−fullerene structures as new NIR type I photosensitizers for the photodynamic therapy.

Machine-Learned Kohn-Sham Hamiltonian Mapping for Nonadiabatic Molecular Dynamics.

In this work, we report a simple, efficient, and scalable machine-learning (ML) approach for mapping non-self-consistent Kohn-Sham Hamiltonians constructed with one kind of density functional to the nearly self-consistent Hamiltonians constructed with another kind of density functional. This approach is designed as a fast surrogate Hamiltonian calculator for use in long nonadiabatic dynamics simulations of large atomistic systems. In this approach, the input and output features are Hamiltonian matrices computed from different levels of theory. We demonstrate that the developed ML-based Hamiltonian mapping method (1) speeds up the calculations by several orders of magnitude, (2) is conceptually simpler than alternative ML approaches, (3) is applicable to different systems and sizes and can be used for mapping Hamiltonians constructed with arbitrary density functionals, (4) requires a modest training data, learns fast, and generates molecular orbitals and their energies with the accuracy nearly matching that of conventional calculations, and (5) when applied to nonadiabatic dynamics simulation of excitation energy relaxation in large systems yields the corresponding time scales within the margin of error of the conventional calculations. Using this approach, we explore the excitation energy relaxation in C60 fullerene and Si75H64 quantum dot structures and derive qualitative and quantitative insights into dynamics in these systems.

Adsorption and formation energies of nucleobase–Fullerene: A first-principles simulation

A computational study was conducted using the density functional theory (DFT) method to determine the energy stability of a system composed of deoxyribonucleic acid/ribonucleic acid (DNA/RNA) nucleobase molecules on Fullerene C[Formula: see text] as a potential gene delivery system. The feasibility of the system for gene delivery and nanomedicine applications was assessed by examining the strong geometric bonds formed between Adenine, Cytosine, Guanine, Thymine, and Uracil nucleobases and C[Formula: see text]Si molecules in close proximity to Fullerene. The bonding affinities of each nucleobase with Fullerene were observed to follow the order Uracil > Guanine > Cytosine > Thymine > Adenine. Furthermore, calculations of adsorption and formation energies were performed to determine the most stable configuration within the Fullerene structure. Guanine demonstrated the highest stability, indicating its potential as an efficient carrier for the delivery of guanine-based genetic material into cells. Additionally, the Fullerene surface exhibited a high propensity for Cytosine adherence, as evidenced by the lowest adsorption energy observed for the interaction between Cytosine and Fullerene. The potential application of Si-doped Fullerene C60 as a gene delivery system was highlighted, based on the strong interactions observed with DNA/RNA nucleobase molecules. These valuable insights will contribute to the development of efficient gene delivery strategies and offer promising prospects for advancing gene therapy and nanomedicine.

Superpentagraphene C34: A two-dimensional network structure of C20 fullerene

The well-known smallest icosahedral fullerene C20 is comprising five-membered carbon-rings in all sp2 bonding states. Here we identify by ab initio calculations a new quasi two-dimensional (2D) carbon allotrope in sp2-sp3 bonding states, comprising the unusual five-membered C20 fullerene as the basic structural units, with a 34-atom hexagonal cell in P6/mmm(D6h1) symmetry, and term it as spg-C34 superpentagraphene. Total energy calculations show that it is energetically more stable than the previously reported 2D carbon forms such as pentagraphene and ph-graphene. Its structural stability has been verified by phonon mode analysis and ab initio molecular dynamics simulations. Electronic band calculations reveal that this 2D spg-C34 carbon is a semiconductor with a sizable indirect band gap of 3.31 eV. Moreover, we show that such 2D spg-C34 carbon structure has a larger layer modulus (281 N/m), a larger in-plane stiffness (524 N/m), and a smaller Poisson's ratio (0.069) than the values for graphene. These results establish a new exotic quasi-2D carbon phase and offer insights into its outstanding electronic and mechanical properties of two-dimensional carbon structure.

Study of magnetic properties of the fullerene C36 structure by Monte Carlo simulations

Study of magnetic properties of the fullerene C36 structure by Monte Carlo simulations

Transformation of fullerene-like lattices using octagonal defects

There are a number of structurally different fullerene cages with the same number of carbon atoms. For example, 1812 fullerene isomers C60 are possible. To date, many methods for changing the structure of fullerenes (i.e., transformations) have been developed. In this paper, one formal possible transformation is considered. It consists in sequential changes of local sections of the fullerene surface by moving an octagonal defect. A program to demonstrate the transformation of fullerene-like surfaces is described.

Interaction of vascular endothelial cells with hydrophilic fullerene nanoarchitectured structures in 2D and 3D environments

ABSTRACT The interaction between diverse nanoarchitectured fullerenes and cells is crucial for biomedical applications. Here, we detailed the preparation of hydrophilic self-assembled fullerenes by the liquid-liquid interfacial precipitation (LLIP) method and hydrophilic coating of the materials as a possible vascularization strategy. The interactions of vascular endothelial cells (ECs) with hydrophilic fullerene nanotubes (FNT-P) and hydrophilic fullerene nanowhiskers (FNW-P) were investigated. The average length and diameter of FNT-P were 16 ± 2 μm and 3.4 ± 0.4 μm (i.e. aspect ratios of 4.6), respectively. The average length and diameter of FNW-P were 65 ± 8 μm and 1.2 ± 0.2 μm (i.e. aspect ratios of 53.9), respectively. For two-dimensional (2D) culture after 7 days, the ECs remained viable and proliferated up to ~ 420% and ~ 400% with FNT-P and FNW-P of 50 μg/mL, respectively. Furthermore, an optimized chitosan-based self-healing hydrogel with a modulus of ~400 Pa was developed and used to incorporate self-assembled fullerenes as in vitro three-dimensional (3D) platforms to investigate the impact of FNT-P and FNW-P on ECs within a 3D environment. The addition of FNW-P or FNT-P (50 μg/mL) in the hydrogel system led to proliferation rates of ECs up to ~323% and ~280%, respectively, after 7 days of culture. The ECs in FNW-P hydrogel displayed an elongated shape with aligned morphology, while those in FNT-P hydrogel exhibited a rounded and clustered distribution. Vascular-related gene expressions of ECs were significantly upregulated through interactions with these fullerenes. Thus, the combined use of different nanoarchitectured self-assembled fullerenes and self-healing hydrogels may offer environmental cues influencing EC development in a 3D biomimetic microenvironment, holding promise for advancing vascularization strategy in tissue engineering.

Noncoplanar and chiral spin states on the way towards Néel ordering in fullerene Heisenberg models

Using a high-accuracy variational Monte Carlo approach based on group-convolutional neural networks, we obtain the symmetry-resolved low-energy spectrum of the spin-1/2 Heisenberg model on several highly symmetric fullerene geometries, including the famous C60 buckminsterfullerene. We argue that as the degree of frustration is lowered in large fullerenes, they display characteristic features of incipient magnetic ordering: Correlation functions show high-intensity Bragg peaks consistent with Néel-like ordering, while the low-energy spectrum is organized into a tower of states. Competition with frustration, however, turns the simple Néel order into a noncoplanar one. Remarkably, we find and predict chiral incipient ordering in a large number of fullerene structures. Published by the American Physical Society 2024

Enhanced Chemical Insights into Fullerene Structures via Modified Polynomials

Enhanced Chemical Insights into Fullerene Structures via Modified Polynomials

Open-cage fullerenes as ligands for metals.

The remarkable structures of open-cage fullerenes with functionalization on the outer surface and an accessible inner void make them interesting ligands for reactions with metal complexes. The behaviors of open-cage fullerenes in reactions with various metal complexes are examined and compared to the corresponding reactions with intact fullerenes. The structural results from X-ray diffraction are emphasized. Open-cage fullerenes frequently undergo unanticipated structural changes such as carbon-carbon bond cleavage upon reactions with metal complexes. Much more remains to be learned about the possibility of inserting metal ions larger than Li+ into the interior void of these open-cage fullerenes and about the effects of redox reactions on metal complexes of open-cage fullerenes.

Formation of the icosahedral C60 fullerene via migration of single sp atoms and annihilation of sp-atom pairs.

The disappearance of sp2 structural defects during abundant fullerene isomer formation is considered within the framework of the atomistic mechanism with participation of carbon atoms with sp hybridization. The study is carried out using the example of the icosahedral C60-Ih fullerene formation from the appropriate C58-C2v fullerene with a 7-ring. In this case the studied atomistic mechanism includes the following stages: (1) insertion of single carbon atoms into the fullerene from carbon vapor as an sp-atom instead of or above a bond, (2) directional migration of the sp-atom positions towards the 7-ring with decrease of energy, and (3) meeting of two sp atoms near the 7-ring with annihilation of the sp-atom pair and formation of the sp2 structure of the C60-Ih fullerene. The probabilities of all possible sp-atom positions on the appropriate C58-C2v fullerene shell are estimated as a function of temperature using the total energies of these positions obtained by spin-polarized density functional theory calculations using the PBE functional. Based on these estimations, it is shown that formation of the C60-Ih isomer is the most probable within the framework of the considered mechanism relative to other C60 isomers. The energetics of sp-atom pair annihilation in the formation of the C60-Ih isomer is also studied via DFT calculations. The advantages of the considered atomistic mechanism of the abundant fullerene isomer formation are discussed.