Quan-Quan Li

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.

Reaction-controlled assemblies and structural diversities of seven Co(II)/Cu(II) complexes based on a bipyridine-dicarboxylate N-oxide ligand

Seven complexes, namely, {[Co2[(R,S)-bpdado]2(CH3CN)2(H2O)2]·2H2O}n1, {Cu[(R,S)-bpdado](H2O)}n2, {[Cu2[(R,S)-bpdado]2(H2O)2]·H2O}n2′, {[Cu(R,S)-bpdado]·EtOH}n2′′, {Cu[(R,S)-bpdado](phen)}2 (phen = 1,10-phenanthroline) 3, {Cu[(R,S)-bpdado](phen)(H2O)}2·8H2O 4 and {Cu[(R,S)-bpdado](dpy)(H2O)}2·4H2O (dpy = 2,2′-pyridine) 5, have been obtained via solvothermal or layered diffusional reaction based on an axially chiral ligand, (R,S)-2,2′-bipyridyl-3,3′-dicarboxylic acid-1,1′-dioxide ((R,S)-H2bpdado). These complexes tend to form under thermodynamic control in the crystallization process of complexes. Among them, 2′ and 2′′ were reported and obtained along with the preparation of 2. Five new complexes, 1–5, are characterized by single-crystal X-ray diffraction, elemental analyses, X-ray powder diffraction, and IR and thermogravimetric analyses. Four different structural complexes, 2D achiral layers 1, 2 and 2′′ and 1D nanotubular structure 2′, are constructed by the M3[(R,S)-bpdado] tecton (M = Co(II) or Cu(II)) in different arrangement modes. When various N-donor ligands are used, different binuclear complexes, 3–5, are assembled by the Cu2[(R,S)-bpdado] tecton in the same arrangement mode. Apart from the arrangement modes of the tecton, some other elements are also discussed, which influence the final structures, such as the coordination modes and conformations of (R,S)-bpdado, the different metal ions, the reaction temperature, the N-donor ligand and the solvent system.