Supramolecular Polymers Based on Planar Organoboranes

Supramolecular polymers, which are chain-like aggregates of monomers connected by noncovalent interactions, possess some unique chemical and physical properties and functions. In the past thirty years, great achievements have been made in the field of supramolecular polymers. So far, there are some critical issues in this research field, including the development of the driving forces and design strategies for supramolecular polymerization, and supramolecular building blocks and functions of supramolecular polymers. Recently, for the first time, Meijer et al in Eindhoven University of Technology and Yamaguchi et al in Nagoya University incorporated the frustrated Lewis pair (FLP) into the design of supramolecular polymers. By developing FLP building blocks based on planar triarylborane and triarylamine, the supramolecular polymers were constructed based on noncovalent interactions of B−N coordination, and these polymers exhibited the unique fluorescence properties with the long lifetime and circularly polarized nature. Furthermore, Yamaguchi et al disclosed a novel supramolecular polymerization method through the design of the double-trap metastable state enabled by intramolecular hydrogen bonds and intermolecular B−N coordination, achieving dynamic and controllable supramolecular polymerization. These studies thus developed new driving forces and building blocks for supramolecular polymerization, and also provided novel design strategies for supramolecular polymerization and new functions of supramolecular polymers.