Two novel supramolecular isomers based on 2,2′-biimidazole derivative and zinc ions: Syntheses, structures and luminescent properties

Two Zn(II)-2,2′-biimidazole derivative supramolecular isomers 1 and 2 formulated as [Zn(L)] · 2H2O (H2L = 4,4′-(1H,1′H-2,2′-biimidazole-1,1′-diylbis(methylene))dibenzoic acid) have been synthesized, and structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray crystallography. Complex 1 exhibits a 2D four-connected network with (43.63) topology when the zinc center and the L2− ligand act as four-connected nodes (or a distorted (4,4) grid if the [Zn2(imidazole)4] units are considered as four-connected nodes). Complex 2 shows a novel four-connected twofold interpenetrated net with (42.62.82) topology when the zinc center and the L2− ligand act as four-connected nodes (or a twofold interpenetrated α-Po topology when [Zn2(imidazole)4] units are identified as six-connected nodes). Moreover, complexes 1 and 2 both exhibit strong luminescent properties at room temperature.