HgII-containing MOFs constructed from bis-benzimidazole-based ligand with highly selective anion-exchange capacity

Two Hg(II)-containing metal–organic frameworks (MOFs) based on 1,1′-(1,5-pentanediyl)bis-1H-benzimidazole (pbbm), {[HgBr₂(pbbm)]?·?DMF} _n (1) and [HgI₂(pbbm)]₂ (2), have been constructed to explore new and potent ion-exchange materials. Single-crystal X-ray diffraction shows that 1 features a 1-D zigzag chain framework, while 2 presents a dimeric structure in which two Hg(II) cations are bridged by two pbbm ligands. The significant differences of these MOFs indicate that the counteranions have impact on assembling and structures of the resultant MOFs. Remarkably, coordinated Br^? in 1 can be replaced completely when the solid polymer is treated with an aqueous solution containing I^?. Confirmation of retention of structure is provided by FT-IR spectra and the XRPD pattern. The thermal stabilities of 1 and 2 have also been investigated.