Subnanometer Diameter Control in Nanotubes Self-Assembled via Consecutive Cyclization - Polymerization Processes

Tubular self-assembled architectures are highly appealing supramolecular objects that participate in diverse essential biological processes. Controlling with precision their dimensions, and in particular their pore diameter, is a key objective to develop the full applied potential of these structures. Here, using a strategy that relies on the controlled supramolecular polymerization of Watson-Crick H-bonded macrocycles, we target the assembly of 3 sets of nanotubes in which pore diameter is finely controlled from 1.8, to 3.2 and to 4.3 nm. This is simply done by elongating the oligo(phenylene-ethynylene) block placed in between guanine and cytosine nucleobases in the monomer. Moreover, this structural change leads to a gradual reduction in the chelate cooperativity of the cyclization process and, at the same time, to an enhancement in the tendency of the macrocycles to stack, which critically influences the coupling between these consecutive supramolecular processes.