Templated fabrication, isomer recognition of series of 1,1′-(alkane-1,ω-diyl)-bis(3-methylimidazolium)-induced polyoxometalates (ω = 1–11)

•Cation-templated self-assembly of eleven polyoxometalates has been performed.•Most anions possess β-octamolybdate isomeric structure.•These geminal dications can serve as efficient candidate for β-isomer recognition.

Eleven novel polyoxometalates, namely [1,1′-(alkane-1,ω-diyl)-bis(3-methylimidazolium)]m [Mo8O26][nH3O+]·xH2O (ω = 1–11; m = 1, 1.5, 2; n = 0, 1; x = 0, 1, 2) were synthesized by the self-assembly with octamolybdate anions under hydrothermal reaction conditions. The crystal data analysis revealed that these compounds were all composed of discrete methylimidazolium cations and polyacid anions [Mo8O26]4− interacted by electrostatic interactions and hydrogen bonds. Interestingly, the anions of these compounds took on single [β-Mo8O26]4− cluster, twin [β-Mo8O26]4− clusters, a δ-[Mo8O26]4− cluster and a rare 1D 1/∞[β-Mo8O26]4− polymeric chain with the modification of lengths of alkane components.

Graphical abstractCation-templated self-assembly of eleven polyoxometalates has been performed, and most anions possess β-octamolybdate isomeric structure, which shows that these geminal dicationic ionic liquids can serve as an efficient candidate for β-isomer recognition.Figure optionsDownload full-size imageDownload as PowerPoint slide