Metal coordination architectures of 1,4-bis(imidazol-1-ylmethyl)naphthalene: Syntheses, crystal structures, and theoretical investigations on the coordination properties of the ligand

Eight new metal complexes of an imidazole-based ligand 1,4-bis(imidazol-1-ylmethyl)naphthalene (L), {[Ag(L)](ClO4)}(infinity) (1), {[Cd(L)(2)(H2O)(2)](NO3)(2)}(infinity) (2), {[Mn(L)(2)(H2O)(2)](Cl)(2)}(infinity) (3), {[Zn(L)(2)(H2O)(2)](NO3)(2)}(infinity) (4), {[Co(L)(2)(H2O)(2)](NO3)(2)}(infinity) (5), {[Co(L)(2)(H2O)(SO4)](H2O)(2)}(infinity) (6), {[Mn(L)(2)(SCN)(2)]}(infinity) (7), and {[Zn(L)(L-1)](H2O)(1.5)}(infinity) (8, H2L1 = fumaric acid), were synthesized and structurally characterized by elemental analyses, IR spectroscopy, and single-crystal X-ray diffraction analyses. 1 has a square-wave-like one-dimensional (1-D) chain structure, which further assembled into a two-dimensional (2-D) layer through an interchain pi center dot center dot center dot pi interaction. 2-7 possess similar (4,4) 2-D sheet structures containing one type of quadrangle grid, and the adjacent sheets are further interlinked by intersheet pi center dot center dot center dot pi stacking interaction to form a three-dimensional (3-D) supramolecular network. 8 also displays a (4,4) 2-D network structure but with two kinds of different quadrangle grids, being different from that of 2-7. The structural differences of the eight complexes mainly depend on the geometrical requirement of the different metal ions and the influence of anions, as well as the presence of auxiliary ligand (in 8). Our research also demonstrates that intra- and/or intermolecular pi center dot center dot center dot pi stacking play important roles in the formation of these coordination networks, especially in the aspect of linking the low-dimensional entities into high-dimensional supramolecular frameworks. Moreover, a brief analysis of the coordination properties of L has been carried out by density functional theory, combining experimental results.