Zinc(II), Cobalt(II), and Copper(II) Complexes Based on Dibenzimidazolyl Bidentate Ligands with Oligoether Linkers: Crystal Structure and Weak Interactions

The seven metal complexes, [Zn(L1)2]n (1), [Co(L2)(LA)]n (2), [Zn(L2)(LB)]n (3), [Cu(L2)(SO4)]2 (4), [Co2(L1)2Cl4] (5), [Co(L2)(LC)2] (6), and [Zn(L2)(NO3)2] (7) (L1 = 2,2′-bis(benzimidazol-l-yl)ethylether, L2 = 1,2-bis[2′-(benzimidazol-1-yl)ethoxy]ethane, LA = succinate, LB = terephthalate, and LC = 4-aminobenzoate) have been prepared by means of self-assemblies of Zn(II), Cu(II), or Co(II) salts, dibenzimidazolyl bidentate ligands with oligoether linkers, and organic acids (succinic acid (H2LA) for 2, terephthalic acid (H2LB) for 3, and 4-aminobenzoic acid (HLC) for 6). These complexes are structurally characterized by X-ray diffraction analyses. In complexes 1–3, one-dimensional (1D) polymeric chains are formed via metal centers and ligands. In complex 4, two 15-membered metallomacrocycles are connected by two sulfate groups to form a dimer. Complex 5 contains a 24-membered metallomacrocycle formed by two ligands and two Co(II) atoms. Each of complexes 6 and 7 contains a 15-membered metallomacrocycle formed by one ligand and one metal atom. In the crystal packings of complexes 1–7, two-dimensional (2D) supramolecular layers and three-dimensional (3D) supramolecular frameworks are formed via intermolecular weak interactions, including π–π interactions, hydrogen bonds, and C–H···π contacts. Additionally, the fluorescence emission spectra and quantum yields of ligands and metal complexes are described.