Synthesis of covalent organic pillars as molecular nanotubes with precise length, diameter and chirality

Abstract The construction of nanotubes with well-defined structures, although synthetically challenging, offers the prospect studying novel chemical reactions and transportation within confined spaces, as well fabricating molecular devices nanoporous materials. Here we report a discrete nanotube, namely covalent organic pillar COP-1 , synthesized through [2 + 5] imine condensation reaction involving two penta-aldehyde macrocycles five phenylenediamine linkers. A pair enantiomeric nanotubes, obtained in quantitative diastereoselective manner, were characterized resolved readily. NMR spectroscopy, isothermal titration calorimetric X-ray crystallographic studies revealed that 2-nm-long 4.7-Å-wide one-dimensional channel inside can accommodate α ω -disubstituted n -alkyl chains complementary lengths electron density distributions. Furthermore, length-mismatched host–guest pair, found nonamethylene dibromide thread not only displays diminished binding constant solution, but adapts an energetically unfavoured gauche conformation solid state.