Self-Assembled PdII6 Molecular Spheroids and Their Proton Conduction Property.

A series of molecular spheroids (SP1-SP4) was synthesized using pseudolinear bisimidazole and bisbenzimidazole donors in combination with Pd(NO3)2 acceptor via coordination-driven self-assembly. They were characterized by NMR and mass spectrometry, and the solid-state structures of SP1 and SP3 were confirmed by X-ray diffraction. Crystal packing revealed the presence of molecular channels with water molecules in the channels as proton source. All the systems showed proton conductivity across a wide range of temperature and relative humidity. Furthermore, the mode of proton conduction in these molecular spheroids was explored by performing a control experiment using 2,4-dinitrophenol molecule, which indicates that the proton conductivity in the present case increases with increasing surface area of these molecular spheroids.