Shuangquan Zang

Metal–organic frameworks constructed from mixed-ligand 1,2,3,4-tetra-(4-pyridyl)-butane and benzene-polycarboxylate acids: syntheses, structures and physical properties

Three novel coordination polymers, [Mn(TPB)0.5(IPA)(H2O)2]n (1), [Zn1.5(TPB)0.5(TMA)(H2O)·(H2O)]n (2), and [Co(TPB)0.5(PMA)0.5(H2O)2·(H2O)]n (3) (TPB = 1,2,3,4-tetra-(4-pyridyl)-butane; H2IPA = isophthalic acid; H3TMA = trimesic acid; and H4PMA = pyromellitic acid), have been synthesized under hydrothermal conditions and structurally characterized. Complex 1 features a 2D infinite layer framework consisting of bi-manganese clusters, which is further stacked along the [11] direction via strong interlayer π⋯π interactions to form a 3D supramolecular architecture. Complex 2 has a 3D complicated framework comprised of two kinds of infinite 1D chains. The 3D framework of complex 3 possesses three topologically nonequivalent 4-connected nodes synchronously and exhibits an unprecedented (64·102)(42·84)(4·65)2 topology. The magnetic susceptibility data of complex 1 show strong antiferromagnetic interactions in the dinuclear Mn(II) units. Complex 2 exhibits strong fluorescent emissions in the solid state at room temperature and may be suitable as a candidate of blue-fluorescent material.

Four 2D metal–organic networks incorporating Cd-cluster SUBs: hydrothermal synthesis, structures and photoluminescent properties

Hydro(solvo)thermal reactions between 1,1′-biphenyl-2,2′,3,3′-tetracarboxyl acid (H4bptc) and Cd(NO3)2·4H2O at the presence of the ‘second’ ligands of bpydo, bpe, bpp and bix (bpydo = 4,4′-bipyridine-N,N′-dioxide; bpe = 1,2-bis-(4-pyridyl)ethane; bpp = 1,3-Bis-(4-pyridyl)propane; bix = 1,4-bis(imidazol-1-yl-methyl)benzene) yield four new 2D metal–organic coordination polymers [Cd9(bptc)4(μ3-OH)2(H2O)14]·(bpydo)·2H2O (2), [Cd2(bptc)(bpe)(H2O)2]·H2O (3), [Cd4(bptc)(Hbptc)(bpp)(μ3-OH)(H2O)4] (4), [Cd2(bptc)(bix)(H2O)] (5). Compound 2 presents a 2D grid structure with heptanuclear cadmium cluster and two kinds of discrete Cd atoms secondary building units (SUBs), 3 has a 2D structure with the novel Schlafli symbol of (4.62)(43.63)(44.610.8), 4 gives a 2D grid structure with a pentanuclear cadmium cluster, binuclear cadmium cluster and discrete Cd atom SUBs, and 5 has a 2D distorted CdI2-type topology structure with the Schlafli symbol of (43)2(46.66.83). The novel achiral crown-ether-like cycles in 2, 4 and 5 are found and occupied by the single Cd atom or binuclear cadmium cluster. All compounds give strong luminescent emission and have potential application as optical materials.

Ligand-to-metal ratio controlled assembly of nanoporous metal–organic frameworks

Two bilayered metal-organic frameworks with nanoporous channels were synthesized at different ligand-to-metal ratios, which demonstrated an interesting crystal-to-crystal transformation property and a special fluorescent response to the different guest molecules included.

Three coordination polymers with helical chains based on methylenediisophthalic acid (H4MDIP)

Based on methylenediisophthalic acid (H4MDIP), three novel coordination polymers {[Mn2(MDIP)(bime)(H2O)2]2·2H2O}n (1) [bime = 1,2-ethanediylbis(imidazole)], {[Mn3(HMDIP)2(H2O)4]·4,4′-bipy·3H2O}n (2) [4,4′-bipy = 4,4′-bipyridine], and {[Co5(MDIP)2(H2O)6(μ-OH)2]·7H2O}n (3) have been synthesized and characterized by IR spectra, single-crystal X-ray diffraction analyses and thermal stability studies. The introduction of the bime and 4,4′-bipy ligands into Mn(CH3COO)2·4H2O and H4MDIP system leads to the formation of complexes 1 and 2, and the absence of the second ligand in the Co(NO3)2·6H2O and H4MDIP system leads to shape complex 3. Complex 1 is a 3D architecture with [Mn(–OCO–)]∞ helical chain. Coordination polymer2 is a 2D sheet structure with trinuclear unit, in which two kinds of 21 helical chains ([Mn(IP)]∞ (IP = isophthalic acid) and [Mn(MDIP)]∞) are included. Complex 3 exhibits the 3D porous structure with a pentanuclear cobalt unit in which a 1D shallow helical chain of hydrogen-bonded water molecules is shaped. From the topology point of view, complex 1 exhibits a (4,6)-connected network with the Schlafli symbol (42.63.8)2(44.62.74.84.9), complex 2 displays a (3,6)-connected network with CdI2 topology, and complex 3 displays a (4, 8)-connected network with Schlafli symbol (44.62)2(416.612) which is a decorated scu net.

Observation of magnetic bistability in polymorphs of the [Ni(dmit)(2)](-) complexes.

Four ion-pair complexes of [Ni(dmit)(2)](-) with [NO(2)bzql](+) have been obtained, which belong to two kinds of polymorph forms, [NO(2)bzql][Ni(dmit)(2)] (1alpha and 1beta) and [NO(2)bzql][Ni(dmit)(2)].CH(3)COCH(3) (2alpha and 2beta) (where dmit = 2-thioxo-1,3-dithiole-4,5-dithiolate and [NO(2)bzql](+) = 1-(4-nitrobenzyl)quinolinium). Though 1alpha, 2alpha, and 2beta all show anionic dimerization structures at room temperature, they have different anionic and cationic arrangement fashions, which give rise to different magnetic behaviors for these polymorphs or pseudo-polymorphs. Compounds 1alpha, 1beta, and 2alpha exhibit magnetic bistabilities. In particular, 1alpha has a hysteretic loop at approximately 55 K, while 2beta does not display a spin transition in the 2-300 K range. On the basis of the crystal structure data of 2alpha in high- and low-temperature phases, the magnetic coupling feature within the [Ni(dmit)(2)](-) spin dimer was explored with the broken-symmetry approach at the UBPW91/LANL2DZ level; combined with the experimental data and theoretical analyses, the relationship between the magnetic coupling nature and the stacking pattern of [Ni(dmit)(2)](-) anions as well as the origin of the phase interconversion are discussed.

Syntheses and solid state structures of hybrid d10 metal–organic frameworks based on methylenediisophthalic acid (H4MDIP)

Four novel hybrid d10 metal complexes [Zn(H2MDIP)(4,4′-bpy)0.5]n1 (4,4′-bpy = 4,4′-bipyridine, H4MDIP = methylenediisophthalic acid), [Zn2(MDIP)(bix)·H2O]n2 [bix = 1,4-bis(imidazol-1-ylmethyl)-benzene], {[Cd(H2MDIP)(H2O)]2·H2O}n3, {[Cd2(MDIP)(H2O)2(en)2]·2H2O}n4 (en = ethylenediamine) based on tetracarboxylate acid were synthesized and their structures were determined by X-ray single-crystal diffraction. Complexes 1–2 are 2D grid and undulated structures with four-coordinated Zn2+ ions, respectively; 3–4 are 2D grid and double-sheet structures with six-coordinated Cd2+ ions, respectively. MDIP in complexes 1 and 3 act as V-shaped and Y-shaped ligands, respectively, yet in 2 and 4 MDIP act as similar X-shaped ligands. Diverse topologies, thermal and luminescent properties of complexes 1–4 have also been investigated.