Diverse 1D chains supramolecular structures of N,N'-bis(3-pyridylmethyl)pyromellitic diimide and fluorescence iodide sensing.

Three diverse supramolecular compounds, {[3-pmpmd]}n(1), {H2[3-pmpmd]·2NO3−}n(2), {H2[3-pmpmd]·2tbb}n(3), (where 3-pmpmd was N,N′-bis(3-pyridylmethyl)pyromellitic diimide; tbb was tertiary butyl benzoic acid) were synthesized and characterized by elemental analyses, IR spectroscopy, thermogravimetric analyses, and X-ray single-crystal structure analysis. The co-crystal anions affect their structural diversity. Compound 1 is a 1D stairway chain structure by perpendicular π⋯π interactions of pyromellitic diimide and the neighboring pyridine rings. Compound 2 is a typical 1D ladder chain structure by hydrogen bond of nitrate arranged in a parallel array. Compound 3 is a 1D zigzag chain structure of one 3-pmpmd and two tbb by parallel π⋯π interactions and hydrogen bond interactions. Thermal stabilities and fluorescence properties of all compounds were investigated. The solution of compound 2 in DMF can fluorescence sense for iodide ions by remarkably quenching fluorescence intensity.