Ultrathin Supramolecular Architectures Self-Assembled from a C₃-Symmetric Synthon for Selective Metal Binding

Ultrathin supramolecular nanoarchitectures are an emerging class of two-dimensional (2D) materials with dynamic features that facilitate their on-demand functions. However, facile and efficient synthesis for multiple 2D topologies by taking advantage of spontaneous self-assembly is limited. In this work, we report the synthesis of ultrathin supramolecular nanoarchitectures from the self-assembly of a π-conjugated C₃-symmetric synthon (tribenzyloxybenzoic acid, TBBA), with the benzene-1,3,5-tricarboxamide core terminated by three carboxylic acids. Supported by the carboxylic acid-amide hydrogen-bonding and π-π/CH-π interactions, TBBA self-assembles into freestanding microsheets with the thickness of around 2 nm, demonstrating considerable integrity in different solvent systems or in the presence of carboxylic acid binders such as bipyridines. The deprotonation of the carboxylic acids endows TBBA with amphiphilicity, allowing for the formation of mixed micelles that are sensitive to transition-metal ions. Selectively, TBBA^3- shows relatively strong coordination to Cu(II), giving rise to long and thin organometallic ribbons (about 3 nm thickness) with a pronounced aging process. Kinetically insufficient coordination was probed by various characterization techniques and molecular dynamics simulation, which played a vital role in directing the formation of thin ribbons. This work provides a proof-of-concept study for a feasible and versatile construction of both flexible and rigid 2D supramolecular nanostructures with promising applications.