Two novel decavanadate salts with organic cations, (C5H12N)4[H2V10O28]·3.25H2O (I) and (C6H12N(OH)3)2[H4V10O28]·10H2O (II), have been synthesized in aqueous solution and characterized by IR, UV–Vis spectroscopies, EDX-SEM and single crystal X-Ray diffraction completed by DFT calculations. The asymmetric unit of (C5H12N)4[H2V10O28]·3.25H2O is composed of one decavanadate [H2V10O28]4−, four piperidinium cations and water molecules. The structures of (II) is based on one decavanadate cluster, two triethanolaminum cations (TEAH)+ and ten water molecules. The cohesion of the crystal packing in both compounds is provided by a complex network of Nsingle bondH ··· O, Ow-H ···O and Osingle bondH ···O hydrogen bonds involving water molecules and organic molecules as well as vander Waals interactions for the connection between the organic molecules. The IR spectra confirmed the presence of organic cations, decavanadate (V10O28)6− groups and water molecules. The UV–Vis diffuse reflectance spectrum shows that these compounds exhibit semiconducting behavior with an optical band gap of 2.22 eV and 2.13 eV, respectively for compound (I) and (II). Furthermore the Hirshfeld surface analysis shed more light on the intermolecular interactions occurring in the two crystals and the structure-properties relationships.< Leer menos