Polyguanamine Derivative-Based Supramolecular Assemblies with Multiple Hydrogen Bonding and Their Metal-Scavenging Abilities.

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.

Creation of High-Density and Low-Defect Molecular Films with a Flat-on Conformation by Interfacial Organization of Triphosphasumanene Trisulfides.

This paper focuses on the formation of high-density, low-defect monolayers of triphosphasumanene trisulfides, which are newly synthesized electronic and geometric Janus-type molecules, in a flat-on conformation. Although the molecules stack easily because of the developed π-conjugated plane, their application as a metal coating in a flat-on conformation via an interfacial molecular film enables the work function to be tuned. Surface pressure-area isotherms of the triphosphasumanene trisulfides show a two-dimensional phase transition at the air/water interface. Atomic force microscopy observations of the transferred monolayer and in- and out-of-plane X-ray diffraction patterns of the corresponding multilayers reveal that this phase transition occurs from the flat-on to the end-on conformation. The X-ray diffraction patterns obtained in the two directions completely reversed before and after the phase transition, indicating that the molecular arrangement that is generated by layers of molecular films and resultant molecular stacking is similar. The flat-on conformation of the molecules was evident from the out-of-plane X-ray diffraction and polarized infrared spectroscopy results, which indicate that a large, low-defect monomolecular film is obtained using a toluene solution with a small diffusion coefficient. The spectroscopic results reveal triphosphasumanene trisulfide aggregation in the organized molecular film, suggesting high-density molecular packing.