Fullerenes carboxylate

Periya VK, Koike I, Kitamura Y, Iwamatsu S-I, Murata S (2004) Hydrophilic [60]fullerene carboxylic acid derivatives retaining the original 60 It electronic system. Tetrahedron Lett. 45 8311-8313. 

Tokuyama H, Yamago S, Nakamura E (1993) Photoinduced biochemical activity of fullerene carboxylic acid. J Am Chem Soc 115 7918-7919. 

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... 

Fullerene derivative 34 substituted with two long alkyl chains (solubilizing groups) and a carboxylic function was used as peripheral subunit for the constructions of the dendrons (Fig. 14). 

The PCBM methyl ester can be used for coupling amine-containing ligands after removal of the methyl group and activation of the carboxylate using a number of different reaction strategies. Hummelen et al. (1995) successfully coupled cholestanol and histamine to the fuller-ene-PCBM derivative (after acid chloride formation) for use in fabrication of photodetectors and biological studies, respectively. For specific applications of PCBM-fullerenes, see Shaheen et al. (2001), Brabec et al. (2001), Yu et al. (1995), Mecher et al. (2002), Meijer et al. (2003), van Duren et al. (2004), and Anthopoulos et al. (2004). 

Various commercial suppliers now offer fullerene derivatives with functionalities available for bioconjugation, including carboxylic and poly-hydroxylic derivatives, which are very hydrophilic and water-soluble (BuckyUSA, NanoLab, NanoNB, Nano-C, and Aldrich). 

Both type I and II mechanisms are involved in the lipidic peroxidation of erythrocytes caused by irradiation of anionic fullerene derivatives (bearing carboxylic or phosphonate residues) (Yang et al., 2007e), with a significant activity at 10pM concentration and 30 min of irradiation, or at half concentration and double exposure time. The bis-methanophosphonate fullerene is the most effective, but no structure-activity correlations were reported. 

The first demonstration of phototoxicity in cancer cells mediated by fullerenes was in 1993 when Tokuyama et al. (1993) used carboxylic acid functionalized... 

Fig. 10.3 Examples of water-soluble derivatized fullerenes with 1, 3, and 18 carboxyl groups attached (Reprinted from Bosi et al., 2003. With permission from Elsevier)...

As with fullerenes, carbon nanotubes are also hydrophobic and must be made soluble for suspension in aqueous media. Nanotubes are commonly functionalized to make them water soluble although they can also be non-covalently wrapped with polymers, polysaccharides, surfactants, and DNA to aid in solubilization (Casey et al., 2005 Kam et al., 2005 Sinani et al., 2005 Torti et al., 2007). Functionalization usually begins by formation of carboxylic acid groups on the exterior of the nanotubes by oxidative treatments such as sonication in acids, followed by secondary chemical reactions to attach functional molecules to the carboxyl groups. For example, polyethylene glycol has been attached to SWNT to aid in solubility (Zhao et al., 2005). DNA has also been added onto SWNT for efficient delivery into cells (Kam et al., 2005). 

As a complement, Shiga et al. reported on porphyrins that link to the Ti02 nanoparticles by using a fullerene bearing carboxylic acid groups (Fig. 18.7) [116]. Although the authors measured very low efficiencies of around 0.53 %, the success of their approach was demonstrated by the incident photo-to-current efficiency spectra, in which the porphyrin features, that is, the Soret band, are discernible. In addition, they reported extraordinary stabilities with values up to 3000 hours. 

Another versatile synthon for the preparation of fullerene derivatives with polar groups on the side chain is the l,2-(carboxymethano)[60]fullerene 123, which can be obtained either from the corresponding ethoxycarbonylmethyl carboxylate 124 or tert-butyl carboxylate 125, which themselves are accessible by the reaction of the corresponding diazoacetate with Cjq (Scheme 4.26) [113],... 

Even an oligopeptide has been attached to (Table 4.3, compound 130) [111]. This was achieved by a coupling reaction of the carboxylic group in the side chain of the cyclopropane ring as well. First, the tert-butylcarboxylate 129 was synthesized by the reaction of the corresponding diazomethylbenzoate with Cgg. After hydrolysis with trifluoromethanesulfonic acid, the acyl chloride was generated by treatment with oxalyl chloride. Finally, in a one-step procedure the fullerene peptide 130 was obtained by the reaction with the N-deprotected pentapeptide H-(L-Ala-Aib)2-L-Ala-OMe. 

An example of side-chain fimctionalizahon is the attachment of tetraphenyl-porphyrin carboxylic acid to a fullerene bound steroid (214) via standard EDCl coupling with the hydroxy group of the steroid (Scheme 4.36) [230]. 

However, transfer of the monolayers to solid substrates was inefficient because of the small size of the hydrophilic anchor, which imparted a hydrophobic/hydrophilic imbalance. Accordingly, increasing the size of the hydrophilic anchor facilitated the formation of stable Langmuir films that could be transferred to sohd substrates with a transfer ratio of 1 (Nierengarten et al. 2001). Bayer s research group reported a related approach in which the fullerene was modified with carboxylate-terminated dendrons and alkyl chains (Maierhofer et al. 2000). This amphiphilic fullerene derivative formed stable monolayers that could be compressed and expanded without hysteresis (Fig. 11.46d Maierhofer et al. 2000). 

In the substrates, special attention has been devoted to zeolites and fullerenes [34, 38, 39, 44], in the reactions to acid-base equilibria and the influence of hardness and softness on both sides of the equilibrium (acidity of carboxylic acids [45], alkyl [46] and halogenated alcohols [47], hydrides [48] and recently hydrofullerenes [49], basicity of amines [50, 51] and proton affinities of amino acids [52]). For reviews of these studies, see [18, 53, 54],... 

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