Supramolecular double-stranded Archimedean spirals and concentric toroids
Norihiko Sasaki, Mathijs F. J. Mabesoone, Jun Kikkawa, Tomoya Fukui, Nobutaka Shioya, Takafumi Shimoaka, Takeshi Hasegawa, Hideaki Takagi, Rie Haruki, Nobutaka Shimizu, Shin‐ichi Adachi, E. W. Meijer, Masayuki Takeuchi, Kazunori Sugiyasu
Abstract
Connecting molecular-level phenomena to larger scales and, ultimately, to sophisticated molecular systems that resemble living systems remains a considerable challenge in supramolecular chemistry. To this end, molecular self-assembly at higher hierarchical levels has to be understood and controlled. Here, we report unusual self-assembled structures formed from a simple porphyrin derivative. Unexpectedly, this formed a one-dimensional (1D) supramolecular polymer that coiled to give an Archimedean spiral. Our analysis of the supramolecular polymerization by using mass-balance models suggested that the Archimedean spiral is formed at high concentrations of the monomer, whereas other aggregation types might form at low concentrations. Gratifyingly, we discovered that our porphyrin-based monomer formed supramolecular concentric toroids at low concentrations. Moreover, a mechanistic insight into the self-assembly process permitted a controlled synthesis of these concentric toroids. This study both illustrates the richness of self-assembled structures at higher levels of hierarchy and demonstrates a topological effect in noncovalent synthesis.