A Parallel Library of all Seven A2+B2+C2Th Regioisomeric Hexakisadducts of Fullerene C60: Inspiration from Werner's Octahedral Stereoisomerism

Sequential Tether-Directed Synthesis of New [3 : 2 : 1] Hexakis-Adducts of C60 with a Mixed Octahedral Addition Pattern

A new concept for the regioselective synthesis of [3 : 2 : 1] hexakis-adducts of fullerene C₆₀ was developed. Based on sequential tether-directed remote functionalizations, chiral [3 : 2] pentakis-adducts with an incomplete octahedral addition pattern were synthesized via stepwise cyclopropanation of C₆₀ with suitable macrocyclic tri- and bifunctional cyclomalonate tethers. The four resulting stereoisomers were isolated using chiral HPLC. The corresponding pairs of enantiomers show mirror image behavior in their CD-spectra. The pentakis-adducts served as suitable building blocks for the spatially controlled synthesis of mixed hexakis-adducts. Implementation of functional group-bearing monomalonates afforded octahedral [3 : 2 : 1] hexakis-adducts suitable for the construction of larger molecular and supramolecular fullerene architectures in excellent yield.

Synthesis of Fullerene Adducts with Terpyridyl- or Pyridylpyrrolidine Groups intrans-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.

Efficient preparation of monoadducts of [60] fullerene and anthracenes by solution chemistry and their thermolytic decomposition in the solid state

The efficient preparation of monoadducts of [60]fullerene and seven anthracenes (anthracene, 1-methylanthracene, 2-methylanthracene, 9-methylanthracene, 9,10-dimethylanthracene, 2,3,6,7-tetramethylanthracene, and 2,6-di-tert-butylanthracene) by cycloaddition in solution is described. The seven mono-adducts of [60]fullerene and the anthracenes were characterized spectroscopically and were obtained in good yields as crystalline solids. The monoadducts of [60]fullerene and anthracene, 1-methylanthracene, 2-methylanthracene and 9,10-dimethylanthracene crystallized directly from the reaction mixture. The thermolytic decomposition at 180 degrees C of the crystalline monoadducts of [60]fullerene and anthracene, 1-methylanthracene, 9-methylanthracene and 9,10-dimethylanthracene all gave rise to the specific formation of a roughly 1:1 mixture of [60]fullerene and the corresponding antipodal bisadducts ("trans-1"-bisadducts) of [60]fullerene and the anthracenes. In contrast, the crystalline monoadducts of [60]fullerene and the anthracene derivatives 2-methylanthracene, 2,3,6,7-tetramethylanthracene and 2,6-di-tert-butylanthracene all decomposed to [60]fullerene and anthracenes (without detectable formation of bisadducts) upon heating in the solid state to temperatures of 180 to 240 degrees C. The formation of the antipodal bisadducts from thermolytic decomposition of crystalline samples of the monoadducts was rationalized by topochemical control.