title: Photoaddition of N-substituted piperazines to C60: an efficient approach to the synthesis of water-soluble fullerene derivatives.
abstract: An oxidative radical photoaddition of mono N-substituted piperazines to [60]fullerene was systematically investigated. Reactions of C60 with piperazines bearing bulky electron-withdrawing groups (2-pyridyl, 2-pyrimidinyl) were found to be the most selective and yielded C60(amine)4O as major products along with small amounts of C60(amine)2. In contrast, interactions of fullerene with N-methylpiperazine and N-(tert-butoxycarbonyl)piperazine were found to have low selectivity due to different side reactions. Tetraaminofullerene derivative C60(N-(2-pyridyl)piperazine)4O was found to react readily with organic and inorganic acids to yield highly water-soluble salts (solubility approximately 150 mg mL(-1)). In contrast, C60(N-(2-pyrimidinyl)piperazine)4O undergoes hydrolysis under the same conditions and results in a complex mixture of compounds with an average composition of C60(N-(2-pyrimidinyl)piperazine)2(OH)2O. Radical photoaddition of N-(2-pyridyl)piperazine to fullerene derivatives can be used as a facile route for their transformation into water-soluble compounds. Two model fullerene cycloadducts (a methanofullerene and a pyrrolidinofullerene) were easily converted into mixtures of regioisomers of A=C60(N-(2-pyridyl)piperazine)4O (A=cyclic addend) that give highly water-soluble salts under acid treatment.
authors.affiliation: Institute of Problems of Chemical Physics, Russian Academy of Sciences, Semenov Prospect 5, Chernogolovka, Moscow region, 142432 Russia. troshin@cat.icp.ac.ru
authors.forename: Olesya A
authors.initials: OA
authors.lastname: Troshina
authors.forename: Pavel A
authors.initials: PA
authors.lastname: Troshin
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Peregudov
authors.forename: Viacheslav I
authors.initials: VI
authors.lastname: Kozlovski
authors.forename: Rimma N
authors.initials: RN
authors.lastname: Lyubovskaya
mesh_terms: D000588:Amines / Q000138:chemical synthesis / Q000737:chemistry; D037741:Fullerenes / Q000737:chemistry*; D009025:Morpholines / Q000737:chemistry; D010879:Piperazines / Q000138:chemical synthesis / Q000737:chemistry*; D012995:Solubility; D021241:Spectrometry, Mass, Electrospray Ionization; D014867:Water / Q000737:chemistry
chemical_list: D000588:Amines; D037741:Fullerenes; D009025:Morpholines; D010879:Piperazines; D014867:Water; C037574:morpholine; C048073:1-methylpiperazine; C069837:fullerene C60