Anions behaviors for the dimensionalities of coordination polymers based on poly(imidazole) ligands

To explore the influence for the dimensionalities of coordination polymers, in presence of different anions with different behaviors, three new coordination polymers with different dimensionalities have been prepared by reacting M2+ (M = Zn or Co) with two structurally related rod-like poly(imidazole) ligands, 1,4-bis(benzoimidazol-1-yl)-phenyl (L1) and 1,4-bis(imidazol-1-yl)-phenyl (L2). Such three new coordination polymers with different architectures, [Zn(L1)(NO3)2]n (1), {[Zn(L2)2]·2BF4·2HCCl3·2H2O}n (2) and [Co(L2)(SO4)]n (3), have been determined by single-crystal X-ray diffraction analysis and characterized by elemental analysis, and IR analysis. Complex 1 is alternative linked by octahedral Zn centers and the ligand L1 to exhibit a one-dimensional (1D) chain structure. However, complexes 2 and 3 both present layered structures contain a similar -L(ligand)–M(metal)-L–M- chain motifs that found in complex 1. In complex 2, each Zn(II) ion is coordinated by four different L2 to form a undulated sheet. Complex 3 also present a undulated sheet structure, however, they were connected by the SO42- group and the L2 ligands, different from only of the L2 ligands in complex 2. The result indicates that the different anions behaviors could be the great influence on the degree of dimensionality of coordination polymers.

► Synthesis of three novel coordination polymers based on two related rod-like imidazole.
► Two kinds of -L(ligand)–M(metal)-L–M- chain motifs have been found in all three complexes.
► Anions behaviors play a key factor of influencing the dimensionality of architectures.