Fabrication of chiral polydiacetylene nanotubes via supramolecular gelation of a triterpenoid-derived amphiphile

Abstract

Polydiacetylenes (PDA) can undergo a blue-to-red color transition in response to external stimuli because of the extensive delocalized π-electron networks and intrinsic conformational restrictions, which make PDA particularly attractive building blocks for stimuli-responsive materials. In this work, a blue chiral C4-MOP/PDA gel was fabricated successfully by UV irradiating a white supramolecular gel that was assembled from a triterpenoid-derived gelator (C4-MOP) and a diacetylene monomer (PCDA). This photopolymerization was completed within 5 min with the generation of the new negative Cotton effect at 657 nm in the visible blue light region, which strongly revealed the transmission, amplification and visualization of molecular chirality during this gelation and the photopolymerization process. Notably, the nanotubular microstructures of the white gel C4-MOP/PCDA that curled from twisted ribbons barely changed after polymerization into C4-MOP/PDA. In addition, because C4-MOP/PDA contained an alternating ene–acetylene conjugated structure, it exhibited multiple color transitions to external stimuli including temperature, organic solvent, and mechanical force. This work provides chiral polydiacetylene assemblies by using natural triterpenoid gelators, and may open new developments in the design of smart responsive chiral PDA materials.