Synthesis and characterization of new layered polyoxometallates–1,10-decanediamine intercalative nanocomposites

Hydrothermal reaction of phosphomolybdic acid (PMo₁₂) and phosphotungstic acid (PW₁₂) with the surfactant template 1,10-decanediamine (1,10-DAD) yielded two new nanocomposites, [C₁₀H₂₀(NH₂)₂]₂·H₃PMo₁₂O₄₀·(H₂O)_7.5 and [C₁₀H₂₀(NH₂)₂]₂·H₃PW₁₂O₄₀·(H₂O)_2.4. The produced needlelike crystals of the two nanocomposites have fine-layered structures. X-ray diffraction analyses indicate that change of polyoxometallates has little effect on the tilt angle of the 1,10-DAD molecules for such polyoxometallates–organic amine systems. Fourier transform infrared and Raman spectra show that in the hybrid, the PMo₁₂ forms infinite two-dimensional networks, and the PW₁₂ keeps its Keggin structure in the hybrid except distortion to some degree. The two nanocomposites show different photochromic properties; PMo₁₂–DAD hybrid can be colored under ultraviolet irradiation, whereas PW₁₂–DAD hybrid cannot.