Synthesis of highly water soluble C60 end‐capped vinyl ether oligomers with well‐defined structure

Highly water soluble 60]fullerene (C₆₀) end‐capped vinyl ether (VE) oligomers with well‐defined structure were synthesized by living cationic polymerization technique. The addition reaction between 1‐octynylfulleride anion and oligomeric cationic species of VEs with pendant acetoxyl or malonic ester functions afforded the precursor C₆₀ end‐capped oligomers. The living VE oligomers were prepared by living cationic polymerization of diethyl 2‐(vinyloxy)ethylmalonate (VOEM) and 2‐acetoxyethyl vinyl ether (AcOVE) by the CH₃CH(OR)Cl/ZnI₂ R = CH₂CH₂OCOCH₃ and CH₂CH₂CH(COOEt)₂, respectively] initiating system. The precursors were obtained as dark brown gummy solid in 33 and 72% yield for AcOVE and VOEM, respectively. UV‐vis and ¹³C NMR spectroscopy indicated the formation of 1,2‐disubstituted dihydrofullerene derivatives. Hydrolysis of the precursors proceeded quantitatively to give the water‐soluble C₆₀ end‐capped oligomers having oligo(sodium 2‐vinyloxyethylmalonate) oligo(VOEMNa)] and oligo(2‐hydroxyethyl vinyl ether) oligo(HOVE)] moieties. Solubility measurements revealed the water‐soluble C₆₀ end‐capped oligomer with oligo(VOEMNa) chain to have the excellent aqueous solubility compared to that of the water‐soluble C₆₀ derivatives thus far known; the maximum solubility in water is 96.6 mg/mL, which corresponds to 25.9 mg/mL of the C₆₀ moiety. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3578–3585, 2000