Bottom-up synthesis and structures of π-lengthened tubular macrocycles

Belt-persistent tubular cycloarylenes possessing extended sp2-networks of finite single-wall carbon nanotubes (SWNT) have been synthesised from an abundantly available pigment possessing the dibenzo[def,mno]chrysene (anthanthrene) framework. The introduction of bulky substituents allowed for the diastereoselective production of a single helical isomer as a racemate, and the extension of the π-systems in the cycloarylene unexpectedly lowered the enthalpic barrier for the rotation of the arylene unit. Crystallographic analysis of the helical finite SWNT molecules revealed alternate layers of homohelical columns.