Four Novel Zn (II) Coordination Polymers Based on 4′-Ferrocenyl-3,2′:6′,3′′-Terpyridine: Engineering a Switch from 1D Helical Polymer Chain to 2D Network by Coordination Anion Modulation

Four novel ZnII coordination polymers, [(ZnCl₂)₂(L)₂]n (1), [(ZnBr₂)₂(L)₂]n (2), and [(ZnI₂)₂(L)₂]n (3) and {[Zn(SCN)₂]1.5(L)₃}n (4), have been synthesized based on 4'-ferrocenyl-3,2':6',3''-terpyridine with ZnII ions and different coordination anions under similar ambient conditions. Their structures have been confirmed using single crystal X-ray diffraction analysis, showing that complexes 1-3 are one-dimensional (1D) double-stranded metal ion helical polymer chains and complex 4 is of a two-dimensional (2D) network. The structural transformations of them from a 1D polymer chain to a 2D network under the influence of the coordination anions has been systematic investigated. Furthermore, the optical band gaps have been measured by optical diffuse reflectance spectroscopy, revealing that the ligand and the complexes should have semiconductor properties.