Palladium-mediated construction of chiral coordination polymers of binaphthyl-bis(amidopyridyl) ligands at the air–water interface

Molecular assemblies and nanoparticles of chiral coordination polymers composed of connector of K₂PdCl₄ and linkers of bisdentate binaphthyl-bis(amidopyridyl) (BNBAPy) ligands have been constructed at the air–water interface. The chiral S- and R-BNBAPy ligands showed similar surface pressure–area isotherms on the K₂PdCl₄ subphase surface, with the limited molecular area of about 1.2 nm², which suggested that the ligands were nearly parallel to the subphase surface. The X-ray photoelectron spectra for the Langmuir–Blodgett (LB) films of the coordination polymers revealed that the films were composed of Cl, C, Pd and N elements. These Pd-(R-/S-)BNBAPy coordination polymers formed round nanoparticles at the interface with average diameters of 15–20 nm. It was found that the chirarity of ligands was almost remained in the LB films of Pd-(R-/S-)BNBAPy coordination polymers, indicating there was little influence on the orientation or arrangement of the ligand chiral center after the formation of their coordination polymer LB films. The present method could provide a facile way to construct chiral molecular and nanostructural materials.