Synthesis of New Polyhydroxylated Fullerenes

Abstract

In this paper, we report on the synthesis of a new polyfunctional derivative of fullerene ë 60 containing, on average, five hydroxyalkyl groups. The synthesis was carried out by addition of an organolithium compound to fullerene ë 60 followed by transformation of ë 60 (RLi) n into poly(hydroxyalkyl)fullerene.The synthesis of hydroxyl-containing derivatives of C 60 is an area of fullerene chemistry rapidly developing since the discovery of fullerene. The interest in polyhydroxylated fullerenes is due to their potential applications in, for example, biology and medicine (water-soluble fullerenes) and in polymer chemistry, in particular, as branching reagents in the synthesis of cross-linked polymers [1].An analysis of published data on the synthesis and application of hydroxyl-containing fullerenes has shown that these derivatives can be divided into two types: type I, fullerenols, in which the hydroxyl groups are attached to the cage carbon atoms, and type II, hydroxyalkyl(aryl)fullerenes (HAFs), in which the hydroxyl groups are parts of the hydrocarbon fragments attached to the fullerene cage. Various methods for the synthesis of fullerenols have been reported [2-4]. As regards HAFs, only two representatives of this class are currently known, namely, monohydroxyalkylfullerene ë 60 (åÂ) 5 (ëç 2 ) 3 éç [5] and bis(4-hydroxyphenyl)methanofullerene ë 61 (PhOH) 2 [6].This study deals with the synthesis of previously unknown poly(hydroxyalkyl)fullerenes (PHAFs).Actually, the idea of PHAF synthesis is underlain by known reactions. It has been found [7,8] that fullerene is readily alkylated with alkyllithiums and organomagnesium compounds to give both mono-and polyalkylated fullerene derivatives even when the organometallic-tofullerene ratio is ≤ (1 : 1). It has also been found [9] that the fullerene molecule contains at least six active sites able to react with nucleophilic reagents. In particular, a fullerene molecule adds up to six polystyryllithium molecules to give (Ps) 6 C 60 Li 6 ; all six lithium atoms in the resulting compound are reactive; i.e., the adduct is able to add an equivalent number of ethylene oxide (EO) molecules [10].We prepared PHAFs via two reactions: alkylation of fullerene with excess alkyllithium and treatment of the resulting adduct with excess EO: C 60 nAlkLi Alk n C 60 Li n + A l k n C 60 CH 2 CH 2 OLi ( ) n Alk n C 60 CH 2 CH 2 OHThe alkyllithium used was sec -BuLi. For increasing the PHAF yield and attaining a full consumption of fullerene, the reaction was carried out at a sec -BuLi-tofullerene molar ratio of 16. After the addition of a benzene solution of sec -BuLi to a transparent violet solution of C 60 in toluene, the reaction mixture almost immediately became turbid and turned black. The contents of the reactor were stirred for at least 2 h, and then EO was supplied from the gas phase (the EO molar excess with respect to sec -BuLi was no less than 20%). The addition of EO to lithiumalkylfullerene was accompanied by coagulation of the reaction product to give a black precipitate. The ...

Nanocomposites based on polyurethanes and carbon nanoparticles: preparation, properties and application

“…Most of the publications report on that essential improvement of properties of PU is observed at relatively low concentrations of llers, from 0.1 wt% to a few percent, and in the some publicationseven at ultralow concentrations of CNT (from 0.001 to 0.01 wt%). 31,32,93,94 Such hopeful results at such low concentrations of modiers are of special interest since PU-CNP composites of this type show several advantages which can be commercialized.…”

“…Preparation of hydroxyl containing fullerene derivatives of the second type is described, for example, ref. 20-25. In particular, some publications 20,[23][24][25] However, some of the hydroxyl fullerene derivatives cannot be used for the formation of PU composites because of complicated synthetic procedures, instability of some composites or poor compatibility with components used in syntheses of PU.…”

“…30 The authors of ref. 31 and 32 for the rst time used two approaches to the synthesis of fullerene containing PU: (i) the use of prepared PHAF 25 as a cross-linker similarly to that reported in ref. 26 and (ii) the addition of native C 60 to the reaction mixture.…”

The Triumph of the Spin Chemistry of Fullerene C60 in the Light of Its Free Radical Copolymerization with Vinyl Monomers

“…tent being the final product of reaction (8). The second fullerenyl belongs to the metalloorganic content, and presents the monoadduct composed of the C60 coupled with butyl lithium [104][105][106][107]. Figure 7 shows the equilibrium structures of the DTs corresponding to monomers, dimers, and tetramers of these fullerenyls.…”

“…The first set corresponds to fullerenyls of the FR type, which presents a coupling of free radical AIBN • with the C 60 fullerene and belongs to the organic content being the final product of reaction (8). The second fullerenyl belongs to the metalloorganic content, and presents the monoadduct composed of the C 60 coupled with butyl lithium [104][105][106][107]. Figure 7 shows the equilibrium structures of the DTs corresponding to monomers, dimers, and tetramers of these fullerenyls.…”