Supramolecular Bonding Competition Enabled Nanostructure Evolution and Mechanical Reinforcement

In this work, competition between different supramolecular interactions is investigated based on a fibrous crystal composed of hydrogen-bonded cyanuric acid (CA) and amidinothiourea (ADT). Melamine (M) is found to prevail over ADT and bond to CA due to its stronger triple H-bonding affiliation, forming hollow microtubes assembled by oriented CAM crystalline arrays, as guided by the directionality of peripheral hydrogen bonds. Furthermore, competitive interaction between hydrogen bonding and ionic/covalent bonding is demonstrated by mixing Ag+ ions with the CA-ADT fibers, where sulfur atoms are abstracted from ADT molecules to produce Ag2S ligaments. The in situ-formed Ag2S serves as a binding glue to generate CA-ADT/Ag2S composites with significantly enhanced mechanical strength compared to the pristine CA-ADT fiber pellet. [GRAPHICS] .