New Isolated-Pentagon-Rule Isomers of Fullerene C₉₈ Captured as Chloro Derivatives

Fullerene C₉₈ possesses 259 isomers obeying the isolated pentagon rule (IPR), from which two, nos. 116 and 248, have been confirmed earlier as chloro derivatives. High-temperature chlorination of C₉₈-containing mixtures afforded crystals of several chloro derivatives, and their structure elucidation by X-ray crystallography revealed the presence of new isomers, nos. 107, 109, and 120, in the fullerene soot. Evidence for an isomer of no. 111 is also presented. In addition, a new chloride of the known isomer 248 has been isolated and structurally studied. The chlorination patterns of the chlorides are discussed in terms of the formation of isolated CC bonds and aromatic substructures on the fullerene cages

New Giant Fullerenes Identified as Chloro Derivatives: Isolated-Pentagon-Rule C₁₀₈(1771)Cl₁₂ and C₁₀₆(1155)Cl₂₄ as well as Nonclassical C₁₀₄Cl₂₄

High temperature chlorination of HPLC fractions of higher fullerenes followed by single crystal X-ray diffraction with the use of synchrotron radiation resulted in the structure determination of IPR C₁₀₆(1155)­Cl₂₄ and IPR C₁₀₈(1771)­Cl₁₂. C₁₀₆(1155)­Cl₂₄ is cocrystallized with C₁₀₄Cl₂₄, a chloride of the nonclassical isomer of C₁₀₄. The moderately stable isomer C₁₀₆(1155) and the most stable C₁₀₈(1771) represent so far the largest pristine fullerenes with known cages

Skeletal Transformation of a Classical Fullerene C₈₈ into a Nonclassical Fullerene Chloride C₈₄Cl₃₀ Bearing Quaternary Sequentially Fused Pentagons

A classical fullerene is composed of hexagons and pentagons only, and its stability is generally determined by the Isolated-Pentagon-Rule (IPR). Herein, high-temperature chlorination of a mixture containing a classical IPR-obeying fullerene C₈₈ resulted in isolation and X-ray crystallographic characterization of non-IPR, nonclassical (<i>NC</i>) fullerene chloride C₈₄(<i>NC</i>2)­Cl₃₀ (<b>1</b>) containing two heptagons. The carbon cage in C₈₄(<i>NC</i>2)­Cl₃₀ contains 14 pentagons, 12 of which form two pairs of fused pentagons and two groups of quaternary sequentially fused pentagons, which have never been observed in reported carbon cages. All 30 Cl atoms form an unprecedented single chain of ortho attachments on the C₈₄ cage. A reconstruction of the pathway of the chlorination-promoted skeletal transformation revealed that the previously unknown IPR isomer C₈₈(3) is converted into <b>1</b> by two losses of C₂ fragments followed by two Stone–Wales rearrangements, resulting in the formation of very stable chloride with rather short C–Cl bonds

Steering the Geometry of Butterfly-Shaped Dimetal Carbide Cluster within a Carbon Cage via Trifluoromethylation of Y₂C₂@C₈₂(6)

As one of the largest sub-branches of endohedral clusterfullerenes, dimetal carbide clusterfullerene (CCF) in the form of M₂C₂@C_2<i>n</i> is quite intriguing since an alternative structure of M₂@C_2<i>n</i>+2 as conventional dimetallofullerene may exist as well. Herein, by using high-temperature trifluoromethylation followed by HPLC separation and single-crystal X-ray diffraction study, we report for the first time the unambiguous structural determination of yttrium (Y)-based CCF as its trifluoromethyl derivatives, Y₂C₂@C₈₂(6)­(CF₃)₁₆. Four isomers of Y₂C₂@C₈₂(6)­(CF₃)₁₆ with different addition patterns of 16 CF₃ groups are successfully isolated, and two Y atoms of the butterfly-shaped Y₂C₂ cluster are coordinated by two cage pentagons in each isomer. The butterfly geometry of Y₂C₂ cluster varies significantly in the four Y₂C₂@C₈₂(6)(CF₃)₁₆ isomers, with Y···Y distances ranging from 3.544 to 4.051 Å dependent on the relative positions of the two yttrium-coordinated pentagons on the carbon cage

Five Isolated Pentagon Rule Isomers of Higher Fullerene C₉₄ Captured as Chlorides and CF₃ Derivatives: C₉₄(34)Cl₁₄, C₉₄(61)Cl₂₀, C₉₄(133)Cl₂₂, C₉₄(42)(CF₃)₁₆, and C₉₄(43)(CF₃)₁₈

High-temperature chlorination and trifluoromethylation of C₉₄ isomeric mixtures followed by single-crystal X-ray diffraction with the use of synchrotron radiation resulted in the structure determination of C₉₄(34)­Cl₁₄, C₉₄(61)­Cl₂₀, C₉₄(133)­Cl₂₂, C₉₄(42)­(CF₃)₁₆, and C₉₄(43)­(CF₃)₁₈. Their addition patterns are stabilized by the formation of isolated CC bonds and aromatic substructures. Four cage isomers of C₉₄ (nos. 34, 42, 43, and 133) have been experimentally confirmed for the first time

Five Isolated Pentagon Rule Isomers of Higher Fullerene C₉₄ Captured as Chlorides and CF₃ Derivatives: C₉₄(34)Cl₁₄, C₉₄(61)Cl₂₀, C₉₄(133)Cl₂₂, C₉₄(42)(CF₃)₁₆, and C₉₄(43)(CF₃)₁₈

High-temperature chlorination and trifluoromethylation of C₉₄ isomeric mixtures followed by single-crystal X-ray diffraction with the use of synchrotron radiation resulted in the structure determination of C₉₄(34)­Cl₁₄, C₉₄(61)­Cl₂₀, C₉₄(133)­Cl₂₂, C₉₄(42)­(CF₃)₁₆, and C₉₄(43)­(CF₃)₁₈. Their addition patterns are stabilized by the formation of isolated CC bonds and aromatic substructures. Four cage isomers of C₉₄ (nos. 34, 42, 43, and 133) have been experimentally confirmed for the first time

Five Isolated Pentagon Rule Isomers of Higher Fullerene C₉₄ Captured as Chlorides and CF₃ Derivatives: C₉₄(34)Cl₁₄, C₉₄(61)Cl₂₀, C₉₄(133)Cl₂₂, C₉₄(42)(CF₃)₁₆, and C₉₄(43)(CF₃)₁₈

High-temperature chlorination and trifluoromethylation of C₉₄ isomeric mixtures followed by single-crystal X-ray diffraction with the use of synchrotron radiation resulted in the structure determination of C₉₄(34)­Cl₁₄, C₉₄(61)­Cl₂₀, C₉₄(133)­Cl₂₂, C₉₄(42)­(CF₃)₁₆, and C₉₄(43)­(CF₃)₁₈. Their addition patterns are stabilized by the formation of isolated CC bonds and aromatic substructures. Four cage isomers of C₉₄ (nos. 34, 42, 43, and 133) have been experimentally confirmed for the first time

Trifluoromethyl and Chloro Derivatives of a Higher Fullerene <i>D</i>₂‑C₈₀(2): C₈₀(CF₃)₁₂ and C₈₀Cl₂₈

Two derivatives of the low-abundant <i>D</i>₂-C₈₀ (isomer 2), C₈₀(CF₃)₁₂ and C₈₀Cl₂₈, have been synthesized, isolated, and structurally characterized by single-crystal X-ray crystallography. Notably, the addition pattern of C₈₀(CF₃)₁₂ is the same as that of the known C₈₀Cl₁₂. The molecule of C₈₀Cl₂₈ contains very short (1.33 Å) and very long (up to 1.62 Å) C–C bonds in its carbon cage

Imidazole-Functionalized Fullerene as a Vertically Phase-Separated Cathode Interfacial Layer of Inverted Ternary Polymer Solar Cells

By using a facile one-pot nucleophilic addition reaction, we synthesized a novel imidazole (IMZ)-functionalized fullerene (C₆₀-IMZ), and applied it as a third component of inverted ternary polymer solar cells (PSCs), leading to dramatic efficiency enhancement. According to FT-IR, XPS spectroscopic characterizations, and elemental analysis, the chemical structure of C₆₀-IMZ was determined with the average IMZ addition number estimated to be six. The lowest unoccupied molecular orbital (LUMO) level of C₆₀-IMZ measured by cyclic voltammetry was −3.63 eV, which is up-shifted relative to that of 6,6-phenyl C₆₁-butyric acid methyl ester (PC₆₁BM). Upon doping C₆₀-IMZ as a third component into an active layer blend of poly­(3-hexylthiophene) (P3HT) and PC₆₁BM, the power conversion efficiency (PCE) of the inverted ternary PSCs was 3.4% under the optimized doping ratio of 10 wt %, dramatically higher than that of the control device ITO/P3HT:PC₆₁BM/MoO₃/Ag based on the binary P3HT:PC₆₁BM blend (1.3%). The incorporation of C₆₀-IMZ results in enhancement of the absorption of P3HT:PC₆₁BM blend film, increase of the electron mobility of the device, and rougher film surface of the P3HT:PC₆₁BM active layer beneficial for interfacial contact with the Ag anode. Furthermore, C₆₀-IMZ doped in P3HT:PC₆₁BM blend may migrate to the surface of ITO cathode via vertical phase separation as revealed by XPS depth analysis, consequently forming a cathode interfacial layer (CIL), which can lower the work function (WF) of ITO cathode. Thus, the interfacial contact between the active layer and ITO cathode is improved, facilitating electron transport from the active layer to ITO cathode. The effectiveness of C₆₀-IMZ as a vertically phase-separated CIL on efficiency enhancement of inverted ternary PSCs is further verified by doping it into another active layer system comprised of a low-bandgap conjugated polymer, poly­(thieno­[3,4-<i>b</i>]-thiophene/benzodithiophene) (PTB7), blended with [6,6]-phenyl C₇₁-butyric acid methyl ester (PC₇₁BM). Under the optimized C₆₀-IMZ doping ratio of 10 wt %, the PCE of the PTB7:PC₇₁BM-based inverted ternary PSC device reaches 5.3%, which is about 2 times higher than that of the control binary device (2.6%)

Noncovalent Functionalization of Graphene Attaching [6,6]-Phenyl-C61-butyric Acid Methyl Ester (PCBM) and Application as Electron Extraction Layer of Polymer Solar Cells

A new graphene–fullerene composite (<b>rGO-pyrene-PCBM</b>), in which [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) was attached onto reduced graphene oxide (rGO) <i>via</i> the noncovalent functionalization approach, was reported. The <b>pyrene-PCBM</b> moiety was synthesized <i>via</i> a facile esterification reaction, and pyrene was used as an anchoring bridge to link rGO and PCBM components. FTIR, UV–vis, and XPS spectroscopic characterizations were carried out to confirm the hybrid structure of <b>rGO-pyrene-PCBM</b>, and the composite formation is found to improve greatly the dispersity of rGO in DMF. The geometric configuration of <b>rGO-pyrene-PCBM</b> was studied by Raman, SEM, and AFM analyses, suggesting that the C₆₀ moiety is far from the graphene sheet and is bridged with the graphene sheet <i>via</i> the pyrene anchor. Finally <b>rGO-pyrene-PCBM</b> was successfully applied as electron extraction layer for P3HT:PCBM bulk heterojunction polymer solar cell (BHJ-PSC) devices, affording a PCE of 3.89%, which is enhanced by <i>ca.</i> 15% compared to that of the reference device without electron extraction layer (3.39%). Contrarily, the comparative devices incorporating the rGO or <b>pyrene-PCBM</b> component as electron extraction layer showed dramatically decreased PCE, indicating the importance of composite formation between rGO and <b>pyrene-PCBM</b> components for its electron extraction property