Fullerene Adducts Research Articles

Pyrimidine ortho-quinodimethanes. Part 2: Synthesis of new [60]fullerene adducts based on substituted pyrimidine derivatives and their 1H NMR dynamic study

The Diels–Alder reaction of various pyrimidine ortho-quinodimethanes generated in situ with C 60 gives access to a variety of new fullerodihydroquinazoline derivatives. This variety is increased since substituents on the pyrimidine ring can be easily modified before or after its reaction with C 60. Variable temperature 1H NMR spectra provided thermodynamic parameters related to the boat-to-boat interconversion of the cyclohexene ring fused to the fullerene moiety. The mass spectra of the prepared cycloadducts show that the retro-Diels–Alder process takes place easily with elimination of the corresponding diene molecule.

Self-Assembling Fullerenes for Improved Bulk-Heterojunction Photovoltaic Devices

The fullerene adducts 1a and 1b, whose molecular shapes either promote or hinder the formation of 1-D stacks, have been examined for their potential to form 1-D wire-like domains in bulk-heterojunction organic solar cells. The photovoltaic efficiency of solar cells based on blends of the stacking fullerene 1a with regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) is greatly enhanced compared to nonstacking model fullerene 1b.

60]Fullerene cycloaddition across hindered acenes

The Diels–Alder cycloadditions of [60]fullerene across sterically hindered 6,13-bis(2′,6′-dialkylphenyl)pentacenes, 1 and 2, produce fullerene–acene monoadducts 3 and 4. In both cases, further [60]fullerene cycloaddition to form cis-bis[60]fullerene adducts is retarded by steric resistance between the [60]fullerene moieties and the o-dialkyl substituents. Instead, the fullerene moieties of monoadducts 3 and 4 sensitize the formation of 1O2 which subsequently cycloadds across the acene backbone to produce novel syn and anti [60]fullerene–dioxo bisadducts, 8–11.

Amphiphilic architectures based on fullerene and calixarene platforms: From buckysomes to shape-persistent micelles

Abstract The supramolecular aggregation properties of new prototypes of artificial amphiphiles consisting of fullerene or calixarene building blocks serving as platforms for the connection of hydrophobic and dendritic hydrophilic groups are reported. Very water-soluble monoadducts of C60 carrying a defined number of negative charges at a given pH were hybridized with cationic porphyrins including cyctochrome C and investigated with respect to photoinduced electron transfer. Fullerene adducts with dendritic deprotected sugar addends self-assemble to supramolecular sugar balls in water with a narrow size distribution of the micelles of around 4 nm. Various examples of cone- or T-shaped amphiphiles involving calixarene and fullerene cores self-organize to the first examples of shape-persistent micelles whose supramolecular arrangement in water has been determined with unprecedented precision based on the analysis of cryo-transmission electron microscopy (TEM) investigations.

Open-Cage Fullerene Derivatives Having 11-, 12-, and 13-Membered-Ring Orifices: Chemical Transformations of the Organic Addends on the Rim of the Orifice

A novel open-cage [60]fullerene derivative, having two sulfur atoms on the rim of its 13-membered-ring orifice, has been isolated and characterized. Extensive studies on the N-MEM group reactivity of this as well as other previously reported open-cage [60]fullerene derivatives led to several new open-cage [60]fullerene adducts.

Prolonged Charge-Separated States of Starburst Tetra(diphenylaminofluoreno)[60]fullerene Adducts upon Photoexcitation

Construction of starburst C60(>DPAF-C9)4 pentads was coupled with the use of highly fluorescent diphenylaminofluorene-C9 (DPAF-C9) addends as donor components in conjunction with the fullerene acceptor during single-photon excitation processes. High quantum yields (PhiCS) of charge-separation processes in the range 0.83-0.90 for C60(>DPAF-C9)n (n = 1, 2, or 4) were obtained in the formation of C60*-(>DPAF*+-C9)(>DPAF-C9)n-1 transient states. The lifetime of the radical ion-pairs (tauRIP) was found to be 900 ns for starburst C60(>DPAF-C9)4 (3) samples, which is 6-fold longer than that of the linear analogue C60(>DPAF-C9) (1), with a ca. 2 times increase of the charge-separation rate (kCS) compared to that of 1. These data implied the important role of sterically hindered DPAF-C9 pendants arranged in a starburst-like environment that encapsulates the central C60 core on extending the tauRIP. We interpreted the phenomena by the occurrence of intramolecular migration or exchange of electron or positive charge among multiple DPAF-C9 pendants of C60*-(>DPAF*+-C9)(>DPAF-C9)n-1, which gives an increased rate in charge generation and delayed charge recombination.

Intracellular Uptake and Phototoxicity of 31,32‐Didehydrophytochlorin‐fullerene Hexaadducts

C(60)-fullerene derivatives are potential building blocks in modular carrier systems for selective tumor targeting. In [5:1] fullerene hexakis adducts, one position can be occupied by an addressing unit (e.g. monoclonal antibody) while the other five positions are suitable for dendrimers or spacers loaded with several drug moieties. This article reports intracellular uptake and phototoxicity of three fullerene hexakis adducts coupled with a different number of photosensitizers: a bis(3(1),3(2)-didehydrophytochlorin)-fullerene [5:1]-hexaadduct (FHP1), a fullerene [5:1]-hexaadduct with six 3(1),3(2)-didehydrophytochlorin groups (FHP6) and a fullerene [6:0]-hexaadduct that carries 12 3(1),3(2)-didehydrophytochlorin units (FHP12). The most promising complex, the hexa-3(1),3(2)-didehydrophytochlorin fullerene hexaadduct FHP6, was also compared with its fullerene-free analogous derivative P6. It was found that the extent of intracellular uptake is influenced by both nanomolecular size and asymmetry (amphiphilicity) of the fullerene complexes. The degree and mechanism of phototoxicity was found to depend on intracellular concentrations and singlet oxygen quantum yields.

Synthesis and Photophysical Properties of [60]Fullerene Adducts Carrying Oligocarbazole Dendrons.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Synthesis and Photophysical Properties of [60]Fullerene Adducts Carrying Oligocarbazole Dendrons

Abstract [60]Fullerene adducts carrying oligocarbazole moieties were successfully prepared by the Bingel reactions. Their fluorescence spectra and transient absorption spectra suggested the intramolecular electron transfer from the oligocarbazole moiety to the fullerene moiety mainly via 1C60*.

Multifunctionalised cationic fullerene adducts for gene transfer: design, synthesis and DNA complexation

Cationic poly-N,N-dimethylfulleropyrrolidinium derivatives have been designed and synthesised to complex plasmid DNA for gene delivery.

C60 Degradation Effect on Polystyrene under the Fullerene‐Polymer Interaction

Study of the content of composite polystyrene‐fullerene samples prepared from solution by the solvent evaporation method have been performed with the size exclusion chromatography, translation diffusion, viscometry and electro‐optical Kerr effect techniques. It was established that polystyrene interacts with fullerene C60 in benzene without any special treatment at room temperature just after the mixing of polymer and fullerene solutions. The product of this interaction contains initial polystyrene and low molecular fullerene adducts that appear as a result of depolymerization of a significant part (up to 40 wt.%) of polymer chains.

Novel Methodology for the Preparation of Five‐, Seven‐, and Nine‐Membered Fused Rings on C60.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

An Orthogonal Protection-Deprotection Route to Antipodal Fullerene Derivatives

The antipodal bisadduct of anthracene and [60]fullerene - itself obtained in exceptional yield and selectivity from a topochemical disproportionation of the readily available monoanthracene adduct - is among the few antipodal fullerene adducts that can be obtained efficiently and selectively in large quantities. A series of selective protection (cyclopropanation) and deprotection (retro-Diels-Alder, retro-cyclopropanation) steps translate the initial regioisomer into functionalized trans-1 bispyrrolidinofullerenes.

Novel Methodology for the Preparation of Five-, Seven-, and Nine-Membered Fused Rings on C60

[reaction: see text] The photocycloaddition of dienyl cyclopropanes to C(60) gives a new synthetic approach to yield stereospecifically five-, seven-, and nine-membered [60]fullerene adducts. Our results suggest the formation of a biradical intermediate between the dienyl substrate and C(60). An electron transfer between the triplet excited state of C(60) and the dienyl substrate precedes the formation of the intermediate.

Synthesis of Fullerene Adducts with Terpyridyl‐ or Pyridylpyrrolidine Groups in trans‐1 Positions

Two C(60) hexakis-adducts (2 and 3) were synthesized by using a protection-deprotection strategy. The symmetric fullerene tetrakis-adduct 8 was obtained by anthracene removal from the hexakis-adduct 7. Reaction of 8 with terpyridylglycine or pyridylglycine afforded two hexakis-adducts, 2 and 3. By using the retro-cyclopropanation reaction, the four malonate addends located on the equatorial belt of the hexakis-adducts were removed to afford two trans-1 bis-adducts, 4 and 5, with terpyridyl- or pyridylpyrrolidine groups. The structures of 2 and 3 were confirmed by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, and (1)H, (13)C, and COSY NMR, and UV-visible spectroscopy. The cyclic voltammograms of fullerene multiadducts 2, 3, and 9 show irreversible reductions. Self-assembled monolayers (SAMs) of 1 and 3 were formed on gold surfaces through nitrogen adsorption. SAMs of 3 represent the first example of a fullerene hexakis-adduct formed on gold surfaces through nitrogen adsorption. Controlled potential electrolyses (CPE) were conducted to prepare trans-1 bis-adducts 4 and 5 modified with terpyridyl and pyridyl groups.

Full Determination of Zero Field Splitting Tensor of the Excited Triplet State of C60 Derivatives of Arbitrary Symmetry from High Field TREPR in Liquid Crystals

The low-lying photoexcited triplet state of a series of fullerene C(60) adducts has been studied by high-field TREPR (time-resolved EPR) spectroscopy in a partially oriented phase. The fullerenes adopt a biaxial alignment, driven by the substituents, that has allowed to fully determine the ZFS and g tensors, i.e., their principal values and the orientation of the principal axes in the molecular skeleton. This has been accomplished by combining line shape analysis and theoretical prediction of molecular order. A strong dependence of the magnetic tensors on the substitution pattern has been found.

Biradical Intermediate in the [2 + 2] Photocycloaddition of Dienes and Alkenes to [60]Fullerene

The photocycloaddition of vinylcyclopropanes to C60 yields stereospecifically a five-membered [60]fullerene adduct. These results suggest a biradical intermediate of the [2 + 2] photocycloaddition between dienes or arylalkenes and C60. An electron transfer between the triplet excited state of C60 and the unsaturated substrates precedes the formation of the intermediate.

Photoreactions between [60]Fullerene and Various Aromatic Tertiary Amines

The photoreactions of [60]fullerene with aromatic tertiary amines such as N,N-dimethylaniline and N,N-dimethyl-1-naphthylamine gave two or three types of [60]fullerene adducts. The reaction efficiency in the series of p-substituted N,N-dimethylanilines remarkably increased with increasing electron-donating properties of aromatic tertiary amines employed.

Theoretical studies of the relative stabilities and electronic properties on B endohedral and exohedral fullerenes

Possible structures of C 60B n and C 60B n n+ (n = 1–4) endohedral and exohedral fullerene complexes have been calculated using semiempirical AMI and DFT/B3LYP methods at the level 6–31 G in order to determine the most stable structures, to investigate the underlying causes of their stabilities and to predict their redox characteristics. In principle, the stabilities decrease with increasing number of the endohedral atoms. The most possible structures of the fullerene adducts investigated in this paper are determined. The correlation differential between the stable of B-doped heterofullerenes and that of fullerene adducts have been found. The chemical reactivity of all adducts were enhanced.

カルバゾール部位を有する[60]フラーレン付加体の合成と性質

カルバゾール部位を有する[60]フラーレン付加体の合成と性質