Inorganic-organic hybrid materials based on keggin type polyoxometalates and organic polyammonium cations

Co-crystallization of a tri-ammonium cation with short and somewhat flexible 'arms', [N,N,N-tris[2-(dimethylamino)ethyl]-1,3,5-benzenetricarboxamide]³⁺, with a polyoxometalate trianion, PW₁₂O₄₀^3-, yielded an insoluble channeled or microporous structure. The polyoxometalate clusters are arranged in a layered and zig-zag fashion along the xy plane. Looking along the x-axis, channels of a dimension of ∼3.5 × ∼6.5 Å are observed. It was found that C-H⋯O bonds aided in determining the crystal packing by providing directionality to the anion-cation interaction. On the other hand the co-crystallization of a tetraammonium cation with an extended and rigid tetrahedral configuration, 1,3,5,7-tetrakis{4-[(E)-2(N-methylpyridinium-4-yl)vinyl]phenyl adamantane tetraiodide, with a polyoxometalate tetracation, SiW₁₂O ₄₀^4-, yielded a lamellar structure with alternating layers with spacing of 16.6 Å of the inorganic-organic hybrid material.