- A Trefoil Macrocycle Synthesized by 3-Fold Benzannulation
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A new trefoil-shaped molecular architecture consisting of three conjugated macrocycles was synthesized through an unprecedented 3-fold copper catalyzed [4 + 2] benzannulation. DFT calculations indicate that the most stable conformation of this trefoil macrocycle is D3-symmetric. In agreement with the calculated results, the trefoil macrocycle in single crystals exists as a pair of enantiomers with D3-symmetry and exhibits interesting honeycomb-like supramolecular structures.
- Yang, Xuejin,Yuan, Luyan,Chen, Ziyi,Liu, Zhifeng,Miao, Qian
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- Functionalization studies of C60 and synthetic approaches to endohedral metallofullerenes
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Two strategies aimed at the synthesis of endohedral metallofullerenes are presented. They have required the exploration of the surface chemistry of C60 as well as the development of efficient syntheses of highly unsaturated acetylenic cyclophanes. These studies have led to the formation of the largest orifice on the framework of C60 in the form of a cobalt(III) complex having the metal sitting on top of the opening. Further exploitation of the mechanisms involved in the formation of this cavity are discussed. In the second approach to metallofullerenes, highly unsaturated acetylenic cyclophanes have been designed to fold to fullerenes in a series of cascade reactions, either in the gas phase (mass spectroscopy, flash vacuum pyrolysis), or in solution (metal catalysis, radical-anion rearrangements). The origin of this second approach lies in the mechanism of gas-phase coalescence of polyynes during fullerene formation in the graphite evaporation method. Endohedral metal complexes of C60 are expected to have interesting and diverse properties perhaps as rich as those of C60 and other empty fullerenes.
- Rubin, Yves
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p. 118 - 126
(2007/10/03)
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- 1,3,5 / 2,4,6-Differentiated hexaalkynylbenzenes: Absorption and fluorescence properties of a D(3h)-symmetric donor-substituted system
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The synthesis of 1,3,5 / 2,4,6 differentially functionalized hexaethynylbenzene derivatives is described. Interesting solvatochromic behavior was observed for 9b in the absorption and emission spectre. A twisted intramolecular charge transfer (TICT) state in polar solvents appears to be involved.
- Anthony, John E.,Khan, Saeed I.,Rubin, Yves
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p. 3499 - 3502
(2007/10/03)
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