Pyrrolidine fullerenes

In addition, the use of appropriate hydrophilic constituents on the aldehyde or glycine reactants can result in excellent water solubility of the (To derivative. Two such modification arms can be added simultaneously to the pyrrolidine ring, thus providing a functional group for further conjugation and a hydrophilic arm for increased water solubility. PEG derivatives have been formed in this manner, which create highly soluble fullerene derivatives. 

Figure 15.5 A trityl-protected pyrrolidine derivative of Cgg can be prepared by the reaction of N-trityl-oxazolidinone with a fullerene. Deprotection of the trityl group using methanesulfonic acid gives the secondary amine, which can be used in further conjugation reactions.

Similar to the fullerene modifications using either glycine/formaldehyde derivatives or oxazolidinone compounds, Maggini and Scorrano (1993) found that aziridines could yield similar pyrrolidine derivatives. Heating aziridine compounds in toluene was found to result in ring... 

Figure 15.7 The reaction of aziridine derivatives with fullerenes also can give pyrrolidine derivatives useful for...

Figure 15.16 Some modification methods that are useful for fullerenes also can be used with carbon nanotubes. The reaction of an N-glycine compound with an aldehyde derivative can result in cycloaddition products, which create pyrrolidine modifications on the nanotube surface.

Maggini, M., and Scorrano, G. (1993) Addition of azomethine ylides to CM Synthesis, characterization, and functionalization of fullerene pyrrolidines./. Am. Chem. Soc. 115, 9798-9799. 

Fullerene polymers, 12 250-252 Fullerene pyrrolidine dicarboxylic acid (FDA), 17 57... 

Another important method for preparation for exohedrally functionalized fullerenes is the 1,3-dipolar cycloaddition of in s/Yw-generated azomethine ylides to C60 yielding fulleropyrrolidines (Maggini et al., 1993). Further functionalization is facilitated either by the use of adequate aldehydes for the azomethine ylide formation or quatemization of the pyrrolidine nitrogen atom. Both bisaddition (Kordatos et al.,... 

Ortiz AL, Rivera DM, Athans AJ et al (2009) Regioselective addition of N-(4-thiocyanato-phenyl)pyrrolidine addends to fullerenes. Eur J Org Chem 3396-3403 S3396/l-S3396/25... 

Gan et al. used amino acids such as piperidino acetic acid or morpholino acetic acid in photochemical reactions with C60 [231,232]. Whereas the reaction of the ester derivatives of the amino acids result in the formation of pyrrolidine-fused C6o derivatives, the reaction of the free amino acids give the 1-substituted l,2-dihydro[60]fullerenes 57a-b (Scheme 22). In a typical experiment a methanol solution of the amino acid 56a-b was added to a toluene solution of C6o and irradiated with a 250 W overhead projector lightbulb. Prolonged irradiation led to multiadducts. To avoid hydroxylation of C60 the pH of the amino acid solution should be no more than 9.0. 

The combination of the characteristics of the fullerene skeleton with the fused pyrrolidine ring is of great importance for the construction and synthesis of materials with novel properties. The most attractive feature of fulleropyrrolidines is... 

Finally, modifications of this type of addition have resulted in introducing fused heterocyclic rings other than pyrrolidine on fullerenes. Thus, the tetrahy-drofuran ring was fused via the intermediate formation of carbonyl ylides and their subsequent addition to C60 [15], while in a similar fashion, thiocarbonyl ylides have been used to fuse thiophene rings with fullerenes [16,17]. 

Some more complicated hybrid systems have also been constructed, sharing more than one donor unit. In one of them, a nonlinear triad where all the electroactive units are linked to the same functionality of a pyrrolidine group (e.g., utilized the 1,3-dipolar cycloaddition of the appropriate azomethine ylides as the critical step for connecting the donor units to the fullerene skeleton) was considered [245]. With this arrangement the formation of any bisadducts was minimized. 

Figure 1.45. Racemic mixtures of fullerene-fused pyrrolidines obtained by [3 + 2] cycloaddition of azomethine ylides to Cgo (left, the newly formed stereogenic center is marked by an asterisk) if the azomethine ylide is generated from optically pure (+)-2,3-0-isopropylidene-D-gly-ceraldehyde and A-methylglycine, the cycloaddition reaction is diastereoselective (right).

For further information on synthesis, properties, and applications of pyrro-lidinofullerenes, the chiral representatives of which were generally prepared and used as racemates, we refer to a recent review by Prato and Maggini.214 Fields in which many fullerene-fused pyrrolidines have been studied are biological and medicinal chemistry351 and, above all, advanced materials science.352,353 In the latter context, dyads and triads used for photoinduced charge separation between a fullerene acceptor moiety and electron donors like porphyrins, tetrathiafulvalenes, ferrocenes, or polyenes, are worth particular mentioning.354-356... 

Fullerene amino acid derivatives have merited special attention in relation with the biological application [275-280], The photochemical reactions of Ceo with amino acid esters have been utilized to obtain fullerene amino acid derivatives [281,282]. For example, the photochemical addition of iminodiacetic methyl ester to Ceo provides a pyrrolidine ring-fused fullerene carboxylate, C6o(MeOOCCHNHCHCOOMe) [281]. Although the mechanistic detail has yet to be elucidated, a possible sequence... 

We reported the first example of such a compound, porphyrin-fullerene dyad 23, in 1994 [134, 135]. Since that paper, a number of examples of dyads consisting of fullerenes linked to porphyrins or phthalocyanines have been prepared [136, 137-159]. Some of these, such as 24, use amide linkages related to those employed in some porphyrin-quinone systems [137, 149, 152]. In dyad 25, the moieties are linked by an extended, rigid bridge, of the type that has been shown to facilitate rapid long-range electron transfer in other systems [146, 147]. A number of dyads feature pyrrolidine-functionalized fullerenes, as in 26 and 27 [90, 139, 145, 148]. 

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