Construction of a Series of Zn(II) Compounds with Different Entangle Motifs by Varying Flexible Aliphatic Dicarboxylic Acids

By employing a variety of different aliphatic dicarboxylic acids as the secondary auxiliary ligands, six novel zinc compounds, namely, {[Zn2(mal)2(bix)1.5]·3H2O}n (1), {[Zn2(male)2(bix)2]·3H2O}n (2), {[ Zn3(suc)2(bix)4]·2NO3·7H2O}n (3), {Zn(glu)(bix)]·2H2O}n (4), {Zn(fim)(bix)]·2H2O}n (5), and {Zn(sub)(bix)]·3H2O}n (6) (mal = malonic, male = maleate, suc = succinate, glu = glutaric, fim = pimelic, sub = suberate, bix = 1,4-bis(imidazol-1-ylmethyl)-benzene) have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction analyses, and further characterized by infrared spectra, elemental analyses, powder X-ray diffraction, and thermogravimetric analyses. Compound 1 exhibits an extremely rare example of 1D rotaxane-like chain. Compound 2 features a novel 4-connected {65·8} topology. Compound 3 shows an unprecedented two-level hierarchical self-penetrating system based on unusual 2D + 2D → 2D and 1D + 2D → 3D polyrotaxane array. Both compounds 4 and 5 are comprised of undulated 2D 44-sql networks. In 4, the adjacent undulated layers are parallel interpenetrated to each other to give a 2D → 3D polycatenation framework, which further constructs a 3-fold interpenetrating pcu network through extensive hydrogen bonding. In compound 5, there are only two identical undulated layers which are interpenetrated to each other to give a 2D → 2D parallel interlocked structure. Compound 6 displays a 4-connected non-interpenetrating cds network. Structural diversity of these six complexes indicates that the conformation of bix ligand and the spacer length of aliphatic dicarboxylic anions play an important role in the assembly of different frameworks. Furthermore, the solid-state luminescent properties of compounds 1–6 have also been investigated at room temperature.