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Preparation of a Cyclic Polyphenylene Array for a Zigzag-Type Carbon Nanotube Segment

Sekiguchi, Ryuta, Takahashi, Kei, Kawakami, Jun, Sakai, Atsushi, Ikeda, Hiroshi, Ishikawa, Aya, Ohta, Kazuchika, Ito, Shunji
Journal of organic chemistry 2015 v.80 no.10 pp. 5092-5110
carbon, carbon nanotubes, chemical reactions, chemical structure, ferric chloride, fluorescence, methylene chloride, organic chemistry, phase transition, solubility, thermal analysis
Preparation of cyclic polyphenylene array 2, which corresponds to a complete carbon array of a zigzag-type CNT segment with (18,0)-structure, has been established by a Diels–Alder reaction of cyclic biphenylylene–acetylene derivative 1 with tetraphenylcyclopentadienone. The reaction of 2 with excess FeCl₃ realized a presumed cyclodehydrogenation reaction and elimination of the alkyl chains that were introduced as a measure to counter the low solubility problem, but this resulted in the formation of a complicated mixture that included the mass region of a presumed zigzag-type CNT segment with (18,0)-structure. The rather efficient blue emission of cyclic compounds 1 and 2 was discussed utilizing fluorescence (FL) quantum efficiencies (ΦFL) and lifetimes (τFL) in their crystalline state along with those in dichloromethane solution. Thermal analyses of these compounds revealed their characteristic phase transition behavior. The synthesis of a novel cyclic polyphenylene array by utilizing a Diels–Alder reaction of cyclic phenylene–acetylene compounds with tetraphenylcyclopentadienone should afford an attractive pathway to a novel belt-shaped CNT segment.