Imine-Based Architectures at Surfaces and Interfaces: From Self-Assembly to Dynamic Covalent Chemistry in 2D

Within the last two decades, dynamic covalent chemistry (DCC) has emerged as an efficient and versatile strategy for the design and synthesis of complex molecular systems in solution. While early examples of supramolecularly assisted covalent synthesis at surfaces relied strongly on kinetically controlled reactions for post-assembly covalent modification, the DCC method takes advantage of the reversible nature of bond formation and allows the generation of the new covalently bonded structures under thermodynamic control. These structurally complex architectures obtained by means of DCC protocols offer a wealth of solutions and opportunities in the generation of new complex materials that possess sophisticated properties. In this focus review we examine the formation of covalently bonded imine-based discrete nanostructures as well as one-dimensional (1D) polymers and two-dimensional (2D) covalent organic frameworks (COFs) physisorbed on solid substrates under various experimental conditions, for example, under ultra-high vacuum (UHV) or at the solid-liquid interface. Scanning tunneling microscopy (STM) was used to gain insight, with a sub-nanometer resolution, into the structure and properties of those complex nanopatterns.