Anion-templated assembly of three indium–organic frameworks with diverse topologies

Abstract

[In(bpydc)(NO₃)(DMA)_0.5]·(DMA)(H₂O)_4.5 (JLU-Liu8), [In(bpydc)(HCOO)H₂O]·(DMF)₂(H₂O)₃ (JLU-Liu9) and [In(bpydc)Cl]·(DMF)₂(H₂O)₃ (JLU-Liu10), three novel 3D monoatomic indium–organic frameworks, have been synthesized from the 2,2′-bipyridine-5,5′-dicarboxylic acid (H₂bpydc) ligand under solvothermal conditions. These three compounds are constructed from the same ligand, but templated using three different anions (NO₃⁻, HCOO⁻ and Cl⁻), and they exhibit three different 4-connected ung, crb and cbo network topologies. JLU-Liu8 exhibits two types of single-helical chains with opposite helical directions (left-handed and right-handed), all of the left-handed and right-handed helical chains alternate together. In the structure of JLU-Liu9, there are two types of metal–ligand channels: the smaller square channels with dimensions 3.45 Å × 4.03 Å and the bigger square channels with dimensions of 11.5 Å × 11.5 Å. JLU-Liu10 displays an interesting feature of double-helical chains: both helical chains are interconnected with each other by sharing indium ions which entangle one spiral shaft. Furthermore, the role of anions in assisting the formation of distinct structures has been discussed. These three compounds display strong luminescence in the solid state at room temperature.