Syntheses and crystal structures of 1D tubular chains and 2D polycatenanes built from the asymmetric 1-(1-imidazolyl)-4-(imidazol-1-ylmethyl) benzene ligand with metal saltsy

Reactions of a new asymmetric ligand, 1-(1-imidazolyl)-4-(imidazol-1-ylmethyl)benzene (IIMB), with various metal [Cd(II), Mn(II), Zn(II)] salts led to the formation of molecular, one- (1D) and two-dimensional (2D) architectures [Cd(IIMB)(2)(H2O)(SO4)].7.5H(2)O 1, [Cd(IIMB)(2)Cl-2].H2O 2, [Cd(IIMB)(4)(H2O)(2)](NO3)(2).5H(2)O 3, [Cd(IIMB)(OAc)(2)].H2O 4, [Mn(IIMB)(2)(O-S(4))(H2O)].8.2H(2)O 5, [Mn(IIMB)(4)(H2O)(2)]Cl-2.5H(2)O 6 and [Zn(IIMB)(2)](4)(NO3)(8).13.5H(2)O 7. All the structures were established by single-crystal X-ray diffraction analysis. Both compounds 1 and 5 with sulfate anion are 2D polycatenanes formed by the interlocking of 1D double-stranded chains, while 2 and 4 with chloride and acetate anions are 1D chains. The results provide nice examples of topologies of metal-organic frameworks controlled by the counter anions. Interestingly, 3 and 6 are discrete molecular complexes with monometallic cores and form 2D networks through strong intermolecular hydrogen bonds. Complex 7, obtained under the same conditions as 3, is a 1D tubular chain. The structural difference between 3 and 7 suggests the metal ions also have a significant effect on the construction of supramolecular architectures. Furthermore, the photoluminescence properties of these compounds were investigated in the solid state at room temperature.