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Fullerene
About: Fullerene is a research topic. Over the lifetime, 12723 publications have been published within this topic receiving 359173 citations.
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TL;DR: According to variable-temperature 13C NMR spectroscopy, included C70 adopts, over a wide temperature range, an end-on orientation relative to the metalloporphyrin units, as a consequence of the site-specific bond formation onto the CC bonds located at the pole positions of C70.
Abstract: A cyclic dimer of methyliridium porphyrin 1Ir shows an extraordinary affinity toward fullerenes via a dynamic bond-forming interaction. The crystal structure of inclusion complex 1Ir⊃C60 demonstrates the bond formation between the iridium centers of 1Ir and guest C60, leading to an ellipsoidal deformation of C60. According to variable-temperature 13C NMR spectroscopy, included C70 adopts, over a wide temperature range, an end-on orientation relative to the metalloporphyrin units, as a consequence of the site-specific bond formation onto the CC bonds located at the pole positions of C70. Such a bond formation is dynamic but prevails over van der Waals interactions and gives rise to a “chemical friction” for the rotary motions of the included fullerenes. Noteworthy is a restricted rotation of included C70 along its longer axis as a consequence of thermal slipping of the iridium centers from one CC bond to the neighboring ones at the pole positions of C70. In sharp contrast, rhodium complex 1Rh as a referenc...
102 citations
TL;DR: Car-Parrinello calculations show that the transformation between C60 isomers involves barriers in excess of 5 eV, although the energetic difference between the buckyball and the next lowest isomer is only 1.6 eV.
Abstract: Car–Parrinello calculations show that the transformation between C60 isomers involves barriers in excess of 5 eV, although the energetic difference between the buckyball and the next lowest isomer is only 1.6 eV. C60 isomerization thus requires high temperatures and long annealing times.
102 citations
TL;DR: In this paper, photoexcitation of oligothiophenes (nT)/polythiophene (poly-T) to fullerenes (C60/C70) was studied by the nanosecond laser flash photolysis method, observing the transient absorption spectra in the visible and near-IR regions.
Abstract: Photoinduced electron-transfer processes from oligothiophenes (nT)/polythiophene (poly-T) to fullerenes (C60/C70) have been studied by the nanosecond laser flash photolysis method, observing the transient absorption spectra in the visible and near-IR regions. When fullerene was selectively photoexcited in polar solvents, electron transfer from nT to the excited triplet state of fullerene was confirmed. The electron-transfer rate constants increased with the number of repeating unit (n) of nT. On the other hand, the efficiency of electron transfer showed a maximal value at n = 4; for n > 4, electron-transfer efficiency of nT decreased, indicating contribution of other processes such as energy transfer. By the photoexcitation of nT in polar solvent, both electron and energy transfer processes were observed for 4T and 6T. In the case of 3T, energy transfer occurred predominantly even in polar solvent. In nonpolar solvent, energy transfer was a predominant deactivation process. Electron-transfer efficiencies ...
102 citations
Patent•
27 Nov 1991TL;DR: Fullerenes are generated by vaporizing carbon with a laser beam and maintaining the vaporized carbon at conditions selected to promote fullerene growth and formation as discussed by the authors, which may be used to form new compounds including fullerene surrounding one or more metal atoms, and fulenes wherein one ormore carbon atoms have been substituted with boron or nitrogen.
Abstract: Fullerenes are generated by vaporizing carbon with a laser beam and maintaining the vaporized carbon at conditions selected to promote fullerene growth and formation. This method of fullerene generation may be used to form new compounds including fullerenes surrounding one or more metal atoms, and fullerenes wherein one or more carbon atoms have been substituted with boron or nitrogen.
102 citations
TL;DR: Fullerenes have been used successfully in the covalent assembly of supramolecular systems that mimic some of the electron transfer steps of photosynthetic reaction centers, and these systems exhibit several differences from the superficially more biomimetic quinone electron acceptors.
Abstract: Fullerenes have been used successfully in the covalent assembly of supramolecular systems that mimic some of the electron transfer steps of photosynthetic reaction centers. In these constructs C60 is most often used as the primary electron acceptor; it is linked to cyclic tetrapyrroles or other chromophores which act as primary electron donors in photoinduced electron transfer processes. In artificial photosynthetic systems, fullerenes exhibit several differences from the superficially more biomimetic quinone electron acceptors. The lifetime of the initial charge-separated state in fullerene-based molecules is, in general, considerably longer than in comparable systems containing quinones. Moreover, photoinduced electron transfer processes take place in non-polar solvents and at low temperature in frozen glasses in a number of fullerene-based dyads and triads. These features are unusual in photosynthetic model systems that employ electron acceptors such as quinones, and are more reminiscent of electron transfer in natural reaction centers. This behavior can be attributed to a reduced sensitivity of the fullerene radical anion to solvent charge stabilization effects and small internal and solvent reorganization energies for electron transfer in the fullerene systems, relative to quinone-based systems.
101 citations