Inorganic-organic crystalline synthetic bilayers consisting of polyoxomolybdate and double-chained surfactants

Synthetic bilayers of double-chained surfactants were successfully constructed by using polyoxomolybdates as inorganic–organic hybrid crystals. Dialkyldimethylammonium ([(CnH2n+1)2N(CH3)2]+, (Cn)2; n = 10, 12, 14, 16) cations were employed to hybridize with octamoybdate ([Mo8O26]4–, Mo8) anion. The obtained crystals were homologues which possessed distinct layered structures composed from alternate stacking of Mo8 monolayers and (Cn)2 bilayers. The layered distances were controllable with an increase in the alkyl chain length of the (Cn)2 cation. Each alkyl chain of (Cn)2 was interdigitated to result in rather unique conformations for the (Cn)2 cations packed in the solid states. Inside the inorganic monolayers, the Mo8 anions were associated with sodium ions to form two-dimensional network, which could be promising for sodium-ion conductive materials.