Novel synthetic method of one-dimensional conjugated polyyne so-called carbyne is presented. Synthetic strategy employed is a dehydrochlorination of stereospecifically chlorinated polyacetylene, (CHCl)x, synthesized through prolonged FeCl3-doping. In the dehydrochlorination using DBU as a strong base, usage of polar solvent such as DMSO or DMF was confirmed essential. It was elucidated from spectroscopic measurements that the dehydrochlorination proceeds via two steps of trans-elimination of HCl to yield carbyne but not cumulene, and that carbynes formed are composed of polyyne segments with various chain lengths ranging from nC≡C = 10 to 65. Electrical conductivity of the carbyne was enhanced by 107 times upon I2-doping to give a maximum value of 1.6 × 10-1 S/cm-1.
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