Donor–acceptor interaction-driven folding of linear naphthalene–glycol oligomers templated by a rigid bipyridinium rod

This paper reports the construction of folded and helical supramolecular structures through the self-assembly of a series of flexible linear donor oligomers induced by a rigid rod-like acceptor template. The donor oligomers were constructed by connecting two, four, six, and eight 1,5-dioxynaphthalene (DAN) units with polyether chains, respectively, and the acceptor template was generated by incorporating 4,4′-bipyridine moieties at the 3,6-positions of a pyridazine skeleton. 1H NMR, UV-vis, and fluorescence spectroscopy studies indicated that the formation of the folded and helical structures was mainly driven by the intermolecular donor–acceptor interactions between the electron-rich DAN units and the electron-deficient template, which was further supported by DFT calculations. It was also found that the strength of the interactions between the donor oligomers and the acceptor template remarkably increased with the elongation of the oligomers.