Static Scanning Tunneling Microscopy Images Reveal the Mechanism of Supramolecular Polymerization of an Oligopyridine on Graphite

Supramolecular polymerization of a donor-acceptor bisterpyridine (BTP) equipped with an electron-rich carbazole unit is observed by scanning tunneling microscopy (STM) at the highly oriented pyrolytic graphite (HOPG)|solution interface. It is shown that two-dimensional crystals of supramolecular (co)polymers are formed by chain growth polymerization, which in turn can be described by copolymerization statistics. From concentration-dependent measurements, derived copolymerization parameters and DFT calculations, a mechanism for self-assembly is developed that suggests a kinetically driven polymerization process in combination with thermodynamically controlled crystallization.

Automated summary

Supramolecular polymerization of a donor-acceptor bisterpyridine (BTP) equipped with an electron-rich carbazole unit is observed at the HOPG|solution interface. Two-dimensional crystals of supramolecular (co)polymers are formed by chain growth polymerization, which can be described by copolymerization statistics. A mechanism for self-assembly is developed based on concentration-dependent measurements and DFT calculations, suggesting a kinetically driven polymerization process combined with thermodynamically controlled crystallization.