Polyguanamine derivatives having cyclic moieties constituted by two phenyl and two triazine rings have been synthesized, and a supramolecular organization based on their multiple hydrogen-bonding ability was investigated. The obtained polyguanamine derivatives with cyclic moieties were transparent and amorphous in the bulk state and showed excellent mechanical strength emanating from multiple hydrogen bonds, owing to the abundant amino groups present in the structure. These polyguanamine derivatives formed stable monolayers at the air/water interface. The multilayers were transferred using the Langmuir–Blodgett method, and they formed highly periodic layered structures. To evaluate the metal scavenging ability of the cyclic moieties, the metal ions, Cd2+, Nd3+, and Pd2+, were introduced in the subphase. As a result, the cyclic moieties in the polyguanamine derivatives efficiently captured Cd2+, Nd3+, and Pd2+ metal ions. After the metal was captured, the layered structure of each organized film showed higher periodicity because of rearrangement. Moreover, the annular part had a cup-like structure, and the steric size effect of the ring influenced the metal scavenging.

Metal desorption behavior of polyguanamine derivatives having cyclic moieties (c-PGs), with metal-scavenging abilities, organized into molecular films was investigated, and a recovery technique was realized. Cadmium (a toxic metal), palladium (a precious metal), and neodymium (a rare earth metal) were studied, along with sodium (a cationic metal). A monolayer of c-PGs forming on an aqueous metal solution surface effectively scavenges cations from the subphase owing to the relative basicity of the cyclic moiety. X-ray photoelectron spectroscopy revealed that cadmium and palladium (both divalent cations) were desorbed by simple 30-60 min ultrasonication of their Langmuir-Blodgett multilayers. Conversely, the desorption of neodymium, a trivalent cation, was very slow. Sodium, a monovalent cation, was difficult to collect. Its valence and monolayer condensation on the aqueous sodium buffer were remarkable, indicating that coordinated sodium ions escape during the monolayer condensation.

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