Porous Layered Inorganic–Organic Hybrid Frameworks Constructed from Polyoxovanadate and Bolaamphiphiles

Porous inorganic–organic hybrid crystals were successfully constructed from polyoxometalate anions and cationic bolaamphiphiles, which are surfactants having two hydrophilic heads in one molecule. The proton-affinitive decavanadate ([V10O28]6–, V10) anion was utilized as an inorganic motif. 1,10-Decamethylenediammonium ([H3N­(CH2)10NH3]2+, DDA) and decamethonium ([(H3C)3N­(CH2)10N­(CH3)3]2+, DMT) bolaamphiphiles were employed as organic cations. Three types of DDA-V10 hybrid crystals were obtained under different crystallization conditions, and the number of proton(s) attached to each V10 anion was controllable from 0 to 2. This induced different ratios of the V10 species and DDA cations in the hybrid crystals, which enabled control of the crystal packings. The DMT cation gave a hybrid crystal comprising a diprotonated V10 species. These hybrid crystals possessed distinct layered structures derived from the presence of bolaamphiphiles, which resulted in anisotropic alignments of constituent molecules including solvents of crystallization. The solvent molecules were one-dimensionally aligned in the crystals and could be removed to form gas-accessible voids. Specifically, DDA-V10 hybrid crystals sorbed CO2 and C2H2 molecules into the hydrophobic voids, while the DMT-V10 hybrid crystal had affinity against the H2O sorbent.