Fluorine-Directed Structure-Specific Carbon Nanothreads.

Abstract

Carbon nanothread (CNTh) is a sp³-bonded one-dimensional nanomaterial that was predicted to combine the extreme strength with excellent flexibility. However, the reported CNTh usually has a nonuniform intrathread structure, and the synthesis of structure-specific CNTh is still a big challenge. Here, we selected 1,2,3-trifluorobenzene (1,2,3-TFB) with strong dipole as a precursor. By compressing 1,2,3-TFB to 20.1 GPa, a CNTh with a "zipper polymer" structure is obtained. Under applied pressure, 1,2,3-TFB are anti-parallelly stacked in column, and polymerize via selective sequential [4 + 2] polymerization between H-carbon dienophile/F-carbon dienophile and F, H-carbon diene within the column, followed by the "zippered" bonding of the rest atoms. The obtained CNTh is highly hydrophobic with contact angle of 124.6°. The excellent columnar anti-parallel π···π stacking and distinct reactivities of carbon atoms introduced by the F-substitution are responsible for the high reaction selectivity, which provides new insight for the precise synthesis of atom-level ordered CNThs.