ABSTRACT
Polyoxothiometalate ions (ThioPOM) are active hydrogen-evolution reaction (HER) catalysts based on modular assembly built from electrophilic clusters {MoSx } and vacant polyoxotungstates. Herein, the dumbbell-like anion [{(PW11 O39 )Mo3 S4 (H2 O)3 (OH)}2 ]8- exhibits very high light-driven HER activity, while the active cores {Mo3 S4 } do not contain any exposed disulfido ligands, which were suspected to be the origin of the HER activity. Moreover, in the catalyst architecture, the two central {Mo3 S4 } cores are sandwiched by two {PW11 O39 }7- subunits that act as oxidant-resistant protecting groups and behave as electron-collecting units. A detailed photophysical study was carried out confirming the reductive quenching mechanism of the photosensitizer [Ir(ppy)2 (dtbbpy)]+ by the sacrificial donor triethanolamine (TEOA) and highlighting the very high rate constant of the electron transfer from the reduced photosensitizer to the ThioPOM catalyst. Such results provide new insights into the field of molecular catalytic systems able to promote high HER activity.
ABSTRACT
The development of hybrid materials based on polyoxometalates constitutes a strategy for the design of multifunctional materials. The slow evaporation of an aqueous solution of [NaP5W30O110]14- in the presence of γ-Cyclodextrin (γ-CD) led to the crystallization of a K6Na8{[NaP5W30O110]â¢(C48H80O40)}â¢23H2O (NaP5W30â¢1CD) supramolecular compound, which was characterized by single-crystal X-ray diffraction, IR-spectroscopy, thermogravimetric and elemental analyses. Structural analysis revealed the formation of 1:1 {[NaP5W30O110]â¢[γ-CD]}14- adduct in the solid state. Studies in solution by cyclic voltammetry, electrochemical impedance spectroscopy, 1H NMR spectroscopy, and 31P DOSY, have demonstrated weak interactions between the inorganic anion and the macrocyclic organic molecule.
