Reaction-determined assemblies of 0D to 3D complexes: structural diversities and luminescence properties

Reaction-determined assemblies of 6,6′-dinitrobiphenyl-2,2′,4,4′-tetracarboxylic acid (H4nbtc), various N-donor ligands and transition metal ions produce ten complexes, namely, [Zn2(nbtc)(bpa)·H2O]n (1), [Zn2(nbtc)(bpe)·H2O]n (2), [Zn2(nbtc)(2,2′-dpy)]n (3), Zn(H3nbtc)(phen)2 (4), {(H3O)2[Cd3(nbtc)2(H2O)3]·5H2O}n (5), [Cd2(nbtc)(ndpy)·0.5H2O]n (6), [Ag2(H2nbtc)(bpp)]n (7), [Co2(nbtc)(phen)2(H2O)2]n (8), [Ni2(nbtc)(phen)2(H2O)2]n (9) and Co(H2nbtc)(phen)2·2H2O (10) (bpa = 1,2-bis(4-pyridyl)ethane, bpe = 1,2-di(4-pyridyl)ethylene, bpp = 1,3-bis(4-pyridyl)propane, 2,2′-dpy = 2,2′-dipyridyl, phen = 1,10-phenanthroline, ndpy = 2-pyridinamine). Isostructural 1 and 2 feature 3D “bilayered-pillared” frameworks constructed from Zn2(μ2-COO)2(μ1-COO)2-nbtc4− wave-bilayers and bpa/bpe pillars. Unlike 1 and 2, both 3 and 6 exhibit 3D “brick-wall” frameworks constructed from nbtc4− and various SBUs (0D Zn2(μ2-COO)3(μ1-COO)1 for 3, 1D [Cd2(μ2-COO)4]n for 6). However, 3D 5 can be viewed as a combination of 2D “brick-wall” layers and 1D [Cd3-nbtc] chains. Moreover, in comparison to neutral 3 and 6 with pensile and cosmetic terminal ligands, complex 5 without an N-donor ligand is particularly interesting, containing two hydronium ions to balance the anion unit [Cd3(nbtc)2(H2O)3]2− as well as three types of coordinated Cd(II) ions (6-, 7- and 8-). Unlike 3, complex 4 is mononuclear, despite the two complexes employing similar terminal ligands (2,2′-dpy for 3, phen for 4). In 2D layered Ag(I) 7, the 0D Ag4(μ2-COO)4 SBUs initially form Ag4(μ2-COO)4-H2nbtc2− chains before being bridged by bpp ligands. Isostructural Co(II) 8 and Ni(II) 9 exhibit 1D looped infinite chains. Structural comparisons indicate that the SBUs, the coordination modes of the H4nbtc ligand, the synthetic conditions and the nature of the N-donor ligands are crucial factors with respect to the structures of these compounds. Furthermore, the luminescence properties of 1–7 were investigated in the solid state at room temperature.