The present tutorial review reports on the synthetic approaches for the formation of "polyoxothiometalate" compounds with special emphasis on the unique reactivity of the preformed sulfur-containing cationic building blocks {Mo(2)O(2)S(2)}(2+) and {Mo(3)S(4)}(4+) toward polyoxometalate building blocks. Such simple chemical systems, based on chemical and structural complementarities between ionic reactive moieties have led to the synthesis of a series of relevant clusters with unrivalled large nuclearity structural arrangements, such as loops, triangles, squares and boxes. Specific reaction parameters and considerations will be pointed out showing that a deliberate pure inorganic supramolecular chemistry based on weak interactions, flexibility and dynamic is possible with polyoxometalates.

The use of the [Mo(3)S(4)(Hnta)(3)](2-) complex (nta(3-) = nitrilotriacetate) as structuring agent toward the self-condensation process of the [Mo(2)O(2)S(2)(OH(2))(6)](2+) cation leads to the largest oxothiomolybdenum ring. In the solid state, X-ray diffraction analysis reveals the presence of the targeted molecular compound (noted 1a), which consists of the {Mo(18)O(18)S(18)(OH)(18)} host templated by the [Mo(3)S(4)(Hnta)(3)](2-) guest. Nevertheless, the structure shows an additional molecular moiety corresponding to a dinuclear unit {Mo(2)O(2)S(2)} coordinated to two nta(3-) ligands, mutually arranged in a cis fashion (1b). In the solid state, both entities interact through two short hydrogen bonds to give a striking supramolecular adduct, noted {1a-1b}. Synthetic procedures to prepare the individual species as pure compounds were reported. 1a was obtained as a pure mixed Cs(+)/NMe(4)(+) salt while the dinuclear unit [Mo(2)O(2)S(2)(Hnta)(2)](2-) was obtained as mixed K(+)/Na(+) crystals. X-ray diffraction study of the latter reveals a trans isomer (noted 1b'), characterized by the specific coordination of both nta(3-) ligands. All the compounds were characterized in solution (D(2)O or DMSO) by multiexperiment (1)H NMR (1D, COSY, NOESY, and DOSY). The overall results were consistent with the retention of the adduct {1a-1b} which exhibits a supramolecular reactivity. The dinuclear individual species in solution gave rise to cis-trans equilibrium, while in the presence of the oxothiomolybdenum ring 1a, the dinuclear unit is maintained as a frozen cis complex. DOSY NMR provides a definitive argument for the integrity of the supramolecular assembly. In addition, preliminary electrochemical study of 1a is also reported.

International audienceA series of bionanocomposites has been synthesized through a complex coacervation process inducing the assembly of gelatin with a wide range of inorganic polyanions (IPyAs) differing by their diameter and charge and including polyoxometalates (POMs) and a polythiomolybdate cluster. The microstructure and stoichiometry of these hybrid coacervates, which are strongly dependent on the charge matching between both components, have been studied by combining Fourier transform infrared (FT-IR) spectroscopy, solid-state nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), elemental analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) elemental mapping. The mechanical properties of these materials were deeply characterized by tensile measurements at large deformation, revealing different behaviors (i.e., elastomer and ductile), depending on the nature of the IPyA. It is noteworthy that the mechanical properties of these bionanocomposites are strongly enhanced, compared to pure gelatin hydrogels. When attempting to connect structure and properties in these bionanocomposites, we have demonstrated that the density of cross-links (gelatin triple helices and IPyA) is the key parameter to control the extensibility of these materials