Diverse Structures and Luminescence Properties of Nine Novel Zn/Cd(II)-Organic Architectures Assembled by Two Different Rigid Ligands

Abstract

Nine new compounds, namely, {[Zn(2-pybim)(ip)]2·H2O}n (1), [Zn(2-pybim)2(Hip)2]n (2), {[Zn(2-pybim)2(H2tm)](H3tm)}n (3), {[Cd(2-pybim)(ip)(H2O)]2·H2O}n (4), [Cd(2-pybim)2(bz)2]n (5), {[Zn(3-pybim)2(Htm)(H2O)]·H2O}n (6), [Zn(4-pybim)2(pp)1.5]n (7), [Zn2(4-pybim)2(ip)2]n (8), and [Zn(4-pybim)(Htm)(H2O)]n (9) (H2ip = iso-phthalic acid, H2pp = p-phthalic acid, H3tm = trimesic acid, Hbz = benzoic acid, n-pybim = 2-(n-pyridyl)benzimidazle [n = 2, 3 4]), were successfully synthesized. Compounds 1, 4, 6, 7, and 9 exhibit one-dimensional chains. Compounds 2, 3, and 5 are zero-dimensional. Stacking interactions extend them into high-dimensional frameworks. Compound 8 can be simplified as a {4.82}{4.83.102}{42.6.82.10}{42.6} topology. The luminescence properties of solid compounds 1–9 were also investigated at 298 K. Remarkably, compound 9 shows excellent luminescence properties with 29.16% quantum yield (QY) and 23.85 (ns) luminescent decay lifetime, which are much higher than the QY and luminescent decay lifetime of the 4-pybim ligand (τ4-pybim = 1.02 ns, QY4-pybim = 2.42%) and the other compounds (1–8). On the basis of the results of the comparison of the crystal structures and luminescence properties of compounds 1–9, our conclusions indicate that a crystal structure with parallel-dispaced molecular packing (J-aggregation) interactions of strong π-electron conjugate systems can achieve a high luminescence efficiency.