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.