The conformational behavior of multivalent tris(imidazolium)cyclophanes in the hybrids with metal (pseudo)halides or polyoxometalates

Abstract

Three 3D imidazole or benzimidazole-bearing cages (L1–L3) were synthesized as trivalent cationic templates to react with metal (pseudo)halides or molybdate to obtain seven different organic–inorganic supramolecular hybrids: {[CuBr₃]₃·(L1)₂·2(CH₃CN)} (1a), {L1·[CuI₃] (H₂O)} (1b), {L2·[PbI₅]} (2a), {(L2)₂·[Cu₂I₅]₂} (2b), {L3·Ag(SCN)₄·(CH₃CN)·2H₂O} (3a), {L3·[HgI₄]·I} (3b), and {L2·[HMo₅O₁₇](H₂O)_3.25} (4). Their structures were determined by single-crystal X-ray diffraction analyses, which showed that the cages exhibit breathing behavior of expansion and contraction. In addition, the fluorescence properties of 1b–3b in solid state were studied, which indicated that they could be employed as fluorescence sensors for detecting Fe³⁺ ions with high sensitivity and recyclability.