Helix Sense-Selective Supramolecular Polymerization Seeded by a One-Handed Helical Polymeric Assembly

Abstract

Helix sense-selective supramolecular polymerization was achieved using a one-handed helical nanotubular polymeric assembly as a seed. First, bipyridine (BPY)-appended achiral hexabenzocoronene (^BPYHBC) was copolymerized noncovalently with chiral ^BPYHBC_<i>S</i> (or ^BPYHBC_<i>R</i>) at a molar ratio of 9:1, which, via the sergeants-and-soldiers effect, afforded a <i>P</i>-helical (or <i>M</i>-helical) nanotube, which was then treated with Cu²⁺ to transform into structurally robust ^(BPY)CuNT_(<i>P</i>) (or ^(BPY)CuNT_(<i>M</i>)) with a Cu²⁺/BPY coordination polymer shell. Helical seeds ^(BPY)CuNT_(<i>P</i>) and ^(BPY)CuNT_(<i>M</i>) brought about the controlled assembly of fluorinated chiral FHBC_<i>S</i> and FHBC_<i>R</i> as well as achiral FHBC to yield one-handed helical nanotubular supramolecular block copolymers, in which the helical senses of the newly formed block segments were solely determined by those of the helical seeds employed. Noteworthy, FHBC_<i>S</i> and FHBC_<i>R</i> alone without the helical seeds form ill-defined agglomerates. Attempted supramolecular polymerization of a racemic mixture of FHBC_<i>S</i> and FHBC_<i>R</i> from ^(BPY)CuNT_(<i>P</i>) (or ^(BPY)CuNT_(<i>M</i>)) resulted in its chiral separation, affording <i>P</i>-helical (or <i>M</i>-helical) diastereomeric block segments composed of FHBC_<i>S</i> and FHBC_<i>R</i> with different thermodynamic properties