As an extension of our continued interest in the preparation of new inorganic-organic hybrids, we report the successful hydrothermal synthesis of {Na[Dy(PDA)(H2O)3]3[SiW12O40]}·12H2O (1) and {Na(H2O)[Pr(pydc–OH)(H2O)4]3[SiW12O40]}·12H2O (2) (in which PDA= 1,10-phenanthroline-2,9-dicarboxylic acid and pydc–OH = 4-hydroxypyridine-2,6-dicarboxylic acid or chelidamic acid). Both compounds have been characterized using elemental analysis, infrared spectroscopy and X-ray diffraction methods. Structural characterization by single-crystal X-ray diffraction reveal that these compounds consist of [SiW12O40]4– Keggin-type Polyoxometallates (POMs), where a single {W3O13} triad is decorated by a trinuclear Ln-complex. Moreover, the decorated polyanions are involved in a series of intermolecular interactions such as hydrogen bonds and anion–π interactions, resulting in 3D supramolecular compounds. Density Functional Theory (DFT) studies were conducted to support these intermolecular interactions in both 1 and 2, that have been rationalized using molecular electrostatic potential (MEP) surface calculations.

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