Functionalization Of Fullerenes Research Articles

(Invited) Synthesis and Characterization of Unprecedented D2h -Symmetrical Trans-1-(S,R,R,S-bis-pyrrolidine)-Tetra-malonate Hexakis Adducts of C60

The unique chemical and physical properties of fullerenes and their derivatives is mainly the result of their unique electron accepting abilities and their high charge transport capabilities in three dimensions. The octahedral arrangement of the addends in hexaadducts of C60 is unique in organic chemistry. However, stereo-chemically controlled functionalization of fullerenes has been scarcely addressed so far. Here we report the synthesis and characterization of unprecedented D2h -symmetrical trans-1-(S,R,R,S-bis-pyrrolidine)-tetra-malonate hexakis adducts of C60, employing the topologically controlled method introduced by Krӓutler et al., followed by a 1,3-dipolar cycloaddition reaction. Figure 1. Synthesis of D2h -symmetrical trans-1-(S,R,R,S-bis-pyrrolidine)-tetra-malonate hexakis adducts of C60. Figure 1

Fullerene-Gold Core-Shell Structures and Their Self-Assemblies

Hybrid nanomaterials consisting of functionalized fullerene and gold nanoparticle (NP) have been synthesized. Fullerene was functionalized by citric acid and used as reducing and capping agent for preparation of gold NPs. Functionalization of fullerene by use of citric acid was performed by enzymatic and thermal approaches. The core-shell structures containing gold NPs as core and fullerene as shell (gold/fullerene) were prepared. It was found that method and density of functionalization of fullerene effect final structure and therefore their physicochemical property of hybrid nanomaterial dramatically. Ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), atomic force microscopy (AFM), transmission electron microscopy (TEM) were used to analyze the structure of the synthesized hybrid nanomaterial and also study their self-assembly and physicochemical properties. Effect of the size, structure and morphology (e.g., agglomeration) of the synthesized hybrid nanomaterial on their UV-Vis absorption behavior has been also verified by theoretical modeling.

Stereodivergent‐at‐Metal Synthesis of [60]Fullerene Hybrids

AbstractChiral fullerene–metal hybrids with complete control over the four stereogenic centers, including the absolute configuration of the metal atom, have been synthesized for the first time. The stereochemistry of the four chiral centers formed during [60]fullerene functionalization is the result of both the chiral catalysts employed and the diastereoselective addition of the metal complexes used (iridium, rhodium, or ruthenium). DFT calculations underpin the observed configurational stability at the metal center, which does not undergo an epimerization process.

Stereodivergent-at-Metal Synthesis of [60]Fullerene Hybrids.

Chiral fullerene-metal hybrids with complete control over the four stereogenic centers, including the absolute configuration of the metal atom, have been synthesized for the first time. The stereochemistry of the four chiral centers formed during [60]fullerene functionalization is the result of both the chiral catalysts employed and the diastereoselective addition of the metal complexes used (iridium, rhodium, or ruthenium). DFT calculations underpin the observed configurational stability at the metal center, which does not undergo an epimerization process.

Inhibitors or toxins? Large library target-specific screening of fullerene-based nanoparticles for drug design purpose.

Fullerene-based nanoparticles have been the subject of vital interest due to their unique properties and potential application in many areas, including medicine. Here we explore their characteristics that could make them prospective leads for known disease-related proteins. High-throughput virtual screening supported by comprehensive multi-software protein-ligand docking simulation and cheminformatics approaches has been applied in investigation of interactions of 1117 proteins with a 169 fullerene nanoparticles decorated with different small molecules. Moreover, obtained docking results were confirmed by the series of unrestricted all-atom molecular dynamics (MD) simulations. Hydrophobicity of fullerene core along with hydrophilic interaction of side chains plays a key role in binding with the studied proteins. We identified a series of nanoparticles that can lead to development of robust drugs for target proteins and another series that can behave as a highly toxic agent. The structure-activity relationship analysis revealed two significant molecular properties responsible for the binding score values. The application of carefully selected computational techniques and described outcome of the study facilitate development of functional fullerene nanoparticles for drug-like and drug delivery applications.

Convenient syntheses of fullerynes for ‘clicking’ into fullerene polymers

Alkyne-functionalized fullerenes (fullerynes) were designed and conveniently synthesized via Bingel reaction in one step with high yields. They were used to react with azido-functionalized polystyrene (PS) via Huisgen [3 + 2] cycloaddition ‘click’ chemistry to form two fullerene polymers: one with C60 tethered to the end of a PS chain (C60-1PS) and the other with C60 tethered at the junction point of two PS chains of identical molecular weight (C60-2PS). The fullerene polymers were characterized by 1H NMR, 13C NMR, FT-IR, MALDI-TOF mass spectrometry and SEC. The results showed that the fullerene polymers are well-defined with narrow polydispersity and high fullerene functionality. Besides, aggregation of C60 in THF was observed in the SEC traces. The optical properties of the fullerene polymers were studied by UV–Vis absorption spectroscopy, and the results suggested that the PS chain(s) on the fullerene core has no remarkable effect on the optic property of C60. The thermal properties of the fullerene polymers were studied by TGA and DSC, and the results indicated that the two fullerene polymers with different C60 content and distinct molecular topology may have different self-assemble architectures in the solid state. The well-defined fullerene polymers can be used as model compounds to study the self-assemble architecture of shape amphiphiles based on polymer-tethered molecular nanoparticles.

A DFT study on the functionalization of C60 fullerene with 1,2-benzoquinone

We investigated the capability of 1,2-benzoquinone as an abundant molecule in natural and biological systems to functionalize C60 fullerene. DFT calculations indicate that C60 acts as a dienophile in inverse electron-demand Diels-Alder cycloaddition reaction with 1,2-benzoquinone. Moreover, different functional groups were employed to manipulate the geometric and electronic properties of the complex. The adsorption energies increase by rising the electron withdrawing ability of functional groups as followed: -NO2>-CN>-COOH>-CHO>-H>-F>-CH3>-OH>-NH2. While all groups change the HOMO-LUMO energy gap of C60 slightly, –NH2 decreases it about 23%.

Synthesis and metal complexation of a functional fullerene containing amine, phosphine, and pyridine coordinate groups

Treating C60 with o-(diphenylphosphino)benzaldehyde and o-aminomethylpyridine in refluxing o-dichlorobenzene affords a new fullerene derivative syn-PPh2(o-C6H4)(o-C5H4N)(C2H3NC60) (1) in moderate yield. Compound 1 displays versatile coordination modes. Such that, reactions of 1 with Os3(CO)11(NCMe), W(CO)4(NCMe)2, and Ru3(CO)12 produce Os3(CO)11(η1-PPh2(o-C6H4)(o-C5H4N)(C2H3NC60)) (2), W(CO)4(η2-PPh2(o-C6H4)(o-C5H4N)(C2H3NC60)) (3), and Ru(CO)3(η3-PPh2(o-C6H4)(o-C5H4N)(C2H3NC60)) (4), respectively. Interestingly, heating 4 with Ru3(CO)12 leads to transfer of the fullerene addend to give C60 and a tetraruthenium cluster complex (μ-H)Ru4(CO)11(μ4,η4-PPh2(o-C6H4)CH2NC(o-C5H4N)) (5). The structures of 1 and 5 have been determined by an X-ray diffraction study.

A theoretical study on the reaction of diazocompounds with C70 fullerene

Using density functional theory calculations, we investigated the chemical functionalization of a C70 fullerene with diazocompounds which has been reported experimentally. The results indicate that the [5,6]-bond of the apex of C70 is more reactive than the equatorial bonds toward the cycloaddition of the diazocompounds. The energetic stability of phenyl C71 butyric acid methyl ester (PCBM)-type [5,6]-fulleroids (products) shows the same trend (1>2>3>4) to that observed experimentally. The reaction energy for different isomers of [5,6]-fulleroids is in the range of −23.3 to −37.7kcal/mol. Our frontier molecular orbital analysis explains the experimentally observed UV–vis spectrums and confirmed the formation of [5,6]-fulleroids rather than [6,6]-methanofullerenes. The electron–hole pair binding energy for C70 is calculated to be about 0.6 to 0.9eV. Theoretical 1H-nuclear magnetic resonance (NMR), in good agreement with the corresponding experimental data, was used to more investigate the structure of the most stable complex.

ChemInform Abstract: Metal—Organic Hybrid Architectures Built from Functionalized Fullerenes and Metal Ions or Clusters

AbstractReview: 71 refs.

Reducible fabrication cost for P3HT-based organic solar cells by using one-step synthesized novel fullerene derivative

The cyclohexanone-containing fullerene mono-adduct, abbreviated as CHOC60, was efficiently prepared through single-step Diels-Alder reaction with 2-(trimethylsilyloxy)-l,3-butadiene and fullerenes. After reduction and esterification, CHOC60 was further converted into cyclohexyl acetate functional fullerene mono-adduct, named as CHAC60, which showed excellent solubility in common organic solvents. P3HT-based bulk heterojunction organic solar cells (OSCs) were fabricated through a typical structure of ITO/PEDOT:PSS/P3HT:(CHOC60 or CHAC60)/Ca/Al. The composite ratios of P3HT and the fullerene derivatives were modified such as 1:0.5, 1:1 and 1:1.5 (w/w). The devices fabricated using CHOC60 or CHAC60 as acceptors achieved the power conversion efficiencies (PCEs) of 2.97% and 3.15%, respectively, which exhibited comparative photovoltaic performances with commercial PC61BM. Moreover, CHOC60-based devices significantly reduced the manufacturing cost by the simplified synthesis of CHOC60 with high yield and low fullerene consumption. The non-aromatic side chain radical CHOC60 and CHAC60 provide a new idea for the design of fullerene derivative acceptors.

Fullerene Derivatives for the Applications as Acceptor and Cathode Buffer Layer Materials for Organic and Perovskite Solar Cells

Organic solar cells (OSCs) and organic‐inorganic metal halide perovskite solar cells (pero‐SCs) have been regarded as two promising photovoltaic technologies. The recent advances with power conversion efficiency over 10% and 20% have been realized in OSCs and pero‐SCs, respectively. The fullerene derivatives play important role as acceptor materials in OSCs and cathode buffer layer (CBL) materials in OSCs and pero‐SCs. Here, we provide a comprehensive overview of recent progresses and perspectives of the functional fullerene derivatives as acceptor materials and CBLs for OSCs and pero‐SCs.

Counter anion in Li+‐encapsulated C60 can further enhance the rate of Diels–Alder reaction: A DFT study

AbstractDensity functional theory calculations were carried out to investigate the Diels–Alder cycloaddition between cyclopentadiene and C60 after the encapsulation of Li+ ion with transition states identified and confirmed by intrinsic reaction coordinate calculations. Our results showed that the Li+‐encapsulation results in a lower energy barrier and the presence of counter anion can further reduce the energy barrier, making the trend in agreement with the experimental results. In addition, the influencing factors on the reactivity of Li+‐encapsulated fullerenes such as counter anion and the position of Li+ in C60 were discussed. This study aims to provide a better understanding of Diels–Alder reaction with Endohedral Metallofullerenes to allow more efficient functionalization of fullerenes.

Functionalized fullerene embedded in Nafion matrix: A modified composite membrane electrolyte for direct methanol fuel cells

Methanol permeability is a major concern for Nafion® membranes used as polymer electrolyte in direct methanol fuel cells (DMFCs). In the present study, composite membranes are formed by incorporation of functionalized fullerene (FF) in Nafion® ionomer for its use as electrolytes in direct methanol fuel cells at various methanol concentrations. Fullerene was functionalized by 4-benzene diazonium sulfonic acid precursor formed via diazotization reaction of sulfanilic acid. Surface functionalization and sulfonation of fullerene is confirmed by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and elemental analysis. Structural changes in fullerene are determined by transmission electron microscopy (TEM) analysis. The composite membranes of Nafion®-FF are prepared by solvent casting technique and characterized for their physico-chemical properties in terms of water uptake, proton conductivity and methanol permeability. The morphological changes are observed by field emission scanning electron microscopy (FE-SEM) suggesting the FF distribution in Nafion® and atomic force microscopy (AFM) explaining the presence of FF in the ionic clusters of Nafion® thereby increasing the surface roughness. Nafion®-FF composite membranes show improved proton conductivity due to the presence of surface functional –SO3H groups. Composite membranes exhibit better electrochemical selectivity and as a result enhanced DMFC power output in comparison to recast Nafion®. In addition, methanol permeability and DMFC polarization for the optimized composite membrane are carried out at different methanol concentration. The peak power density of 146mWcm−2 in DMFC is obtained for Nafion®-FF (1wt.%) at 2M methanol which is higher than the performance observed for Nafion-117. Open circuit voltage change is minimal with respect to time for Nafion®-FF (1wt.%) confirming its better stability in comparison with recast Nafion® and on par with Nafion-117.

Reductive Hydrogenation of Cs -C70 (CF3 )8 and C1 -C70 (CF3 )10.

CF3 -derivatized fullerenes prove once again to be promising scaffolds for regioselective fullerene functionalization: now with the smallest possible addends-hydrogen atoms. Hydrogenation of Cs -C70 (CF3 )8 and C1 -C70 (CF3 )10 by means of reduction with Zn/Cu couple in the presence of water proceeds regioselectively, yielding only one major isomer of C70 (CF3 )8 H2 and only two for C70 (CF3 )10 H2 , whose addition patterns are combined in the only abundant isomer of C70 (CF3 )10 H4 . The observed selectivity is governed by the electronic structure of trifluoromethylated substrates. Interestingly, we discovered that Clar's theory can be utilized to predict the regiochemistry of functionalization, and we look forward to testing it on forthcoming cases of derivatization of pre-functionalized fullerene building blocks.

Investigation of the possibility of functionalization of C20 fullerene by benzene via Diels–Alder reaction

C20 fullerene, this novel species with all its pentagonal faces has displayed some unique operations in making fast pericyclic reactions. As an example, the high dienophile character of the C20 fullerene and the ability of this species in making an ultra-fast Diels–Alder reaction with 1,3-butadiene, has been recently reported. Moreover, new experimental reports claim that the C60 fullerene, one of the fullerene family, could make a Diels–Alder reaction with the central ring of anthracene and make the ring non-aromatic. These reports may encourage researchers to do more studies on the properties of this small carbon cage.To address this question, the present research has discussed all the reaction channels of the Diels–Alder cycloaddition of benzene molecule as a 1,3-diene with the C20 fullerene in order to answer this question: “Is C20fullerene able to make a Diels–Alder reaction with this molecule?”.

Functionalization of fullerene via the Bingel reaction with α-chlorocarbanions: an ONIOM approach.

Two-layer ONIOM method at the ONIOM(B3LYP/6-31G(d):PM6) level of theory was applied to study the cycloaddition reaction of α-chlorocarbanions (CR2Cl(─), where R is H, Cl, CH3 CN, and NO2) and fullerene. The results show that the reaction pathways depend on the electron withdrawing functional groups or the electron donating functional groups contained in the α-chlorocarbanions. The energy profile analysis reveals that functionalization of fullerene by CCl3 (─), C(CH3)2Cl(─), and CH2Cl(─) is more favorable than by C(CN)2Cl(─) and C(NO2)2Cl(─) in terms of the thermodynamic point of view.

Synthesis of [60]Fullerene‐Fused Tetralones via Palladium‐ Catalyzed Ketone‐Directed sp2 CH Activation and sp3 CH Functionalization

AbstractThe palladium‐catalyzed ketone‐directed dual sp2 CH activation and sp3 CH functionalization has been applied for fullerene functionalization for the first time. The sec‐alkyl aryl ketones have been exploited to react with [60]fullerene (C60) to provide the novel and scarce C60‐fused tetralones. The combined use of a highly active cationic palladium(II) catalyst and trifluoromethanesulfonic acid is crucial for the improvement of the reaction yield. A plausible reaction mechanism leading to the observed products has been proposed, and the electrochemistry of the fullerene products has also been investigated.magnified image

(Invited) New Endohedral Fullerene Compounds and Derivatives

We continue to work with uranium-based endohedral fullerenes and have identified several different families of compounds; some incorporate single uranium atoms encapsulated in different sized carbon cages, others incorporate two uranium atoms in variable sized cages and still other families contain odd numbers of carbons atoms, indicative of possible uranium carbides. Several of these new coompounds are being isolated and characterized and the most recent results will be presented. We are also working with mixed metallic sulfides, including Dy as one of the encapsulated metals, and have managed to purify some of these. The most recent results at the time of the symposium will be presented and discussed. Finally, functionalization of endohedral fullerenes continues to be a major component of our research efforts, mainly focused on bis-functionalization, and especially interested in the interplay between endohedral cluster nature and structure and exohedral derivatization. We are also exploring tris-functionalization and will present the most recent results at the symposium.

(Invited) Supramolecular-Driven Formation of an Elusive Phthalocyanine-C60 Fullerene Bisadduct Triad

Phthalocyanines (Pcs) are planar, two-dimensional aromatic macrocycles which possess outstanding electrical and optical properties that make them perfect building blocks for their incorporation into multifunctional materials. Similarly, the excellent electron-accepting property of C60 fullerene renders this carbon nanostructure an ideal molecular partner for photo- and electroactive molecular systems such as Pcs. Although several reports have appeared on the preparation of Pc-based, mono-functionalized fullerenes, not many examples have been reported concerning the double functionalization of C60 fullerene by Pcs, which remains problematic due to the formation of a large number of regio- and/or stereoisomers. Here, we report a novel example of controlled bisaddition over C60 fullerene in which the occurrence of π-π supramolecular interactions between structurally-rigid, Pcs addends in solution led to the formation of a Pc2-C60 bisadduct triad in a regio- and stereocontrolled fashion. In the Pc2-C60 triad, the two Pc units are interacting through intramolecular π-stacking interactions, as demonstrated by several techniques (i.e., DABCO titration experiments, ground- and excited state photophysical studies, HPLC analysis, electrochemical studies, etc.).