N-Donor Auxiliary Ligand Influence on the Coordination Mode Variations of V-Shaped Triazole Dicarboxylic Acid Ligand Affording Seven New Luminescent Zn(II) Compounds with Variable Structural Motifs

A 2D network of {[Zn(Hbcpt)(H2O)3]·7H2O} (1) was hydrothermally synthesized and structurally characterized. By employing different N-donor ligands into the system of 3,5-bis(4′-carboxyl-phenyl)-1,2,4-triazole (H3bcpt) and Zn(II) cations, six novel entangled coordination polymers, namely, {[Zn2(bcpt)(μ2-OH)(H2O)]·(py)·4H2O} (2), {[Zn2(Hbcpt)2(bpa)2]·2H2O} (3), {[Zn(Hbcpt)(bpp)]·[Zn(Hbcpt)(bpp)]·2.5H2O} (4), {[Zn5(bcpt)2(biimpy)2(μ2-OH)4]·5H2O} (5), {[Zn2(bcpt)(bib)(μ2-OH)]·H2O} (6), and {[Zn2(bcpt)(bix)4(μ2-OH)]·3H2O} (7) (H3bcpt = 3,5-bis(4′-carboxyl-phenyl)-1,2,4-triazole, bpa = 1,2-bis(4-pyridyl)ethane, bpp = 1,3-bi(4-pyridyl)propane, biimpy = 2,6-bis(imidazole-1-yl)pyridine, bib = 1,4-bis(N-imidazolyl)butane, bix = 1,4-bis(imidazol-1-ylmethyl)-benzene, py = pyridine), were obtained. Single-crystal X-ray diffraction analysis reveals that, with the different N-donor ligands, the resulting compounds present entangled structures with different topologies. Compound 1 shows a 2D (4, 4) network, and the adjacent sheets are extended into a 3D supramolecular framework via hydrogen-bonding interactions. Interesting, by introducing a series of ditopic N-donor ligands into the reaction system, compounds 2–7 with entangled structures were harvested. Compound 2 exhibits a 3D self-penetrating network with an 8-connected bcu topology. Compound 3 features an 8-fold dia network showing an unusual [4 + 4] mode of interpenetration. Compound 4 is comprised of two parts of undulated 2D 44-sql networks, and the adjacent undulated layers are parallel interpenetrated to each other to give a 2D → 3D polycatenated framework. Compound 5 presents an unusual 3D self-penetrating network with a novel 4,6,6-connected trinodal network with the point symbol of (32·4·52·6)(32·4·56·66}{32·56·66·7}. Compound 6 shows a 2-fold interpenetrating 3D architecture with 6-connected sxd topology. Compound 7 displays an unprecedented self-penetration derived from abnormal [3 + 2] 5-fold interpenetrating dia subnets. Structural diversity of these compounds suggests that different N-donor ligands can induce the organic ligand to present different conformations and coordination modes, and the influence on the final structures. Furthermore, the luminescent properties of compounds 1–7 have been investigated in the solid state.