Guo-Cheng Liu

Self-Assembly of Organic–Inorganic Hybrid Materials Constructed from Eight-Connected Coordination Polymer Hosts with Nanotube Channels and Polyoxometalate Guests As Templates

Two polyoxometalate-templated organic-inorganic hybrid porous frameworks, namely, [Cu2(H2O)2(bpp)2Cl][PM12O40].approximately 20H2O (for 1, M = W; for 2, M = Mo; bpp = 1,3-bis(4-pyridyl)propane), were self-assembly obtained and structurally determined by elemental analyses, inductively coupled plasma analyses, infrared spectroscopy, and single-crystal X-ray diffraction analyses. Single-crystal X-ray analysis of these crystals revealed that both of the structures are constructed from eight-connected three-dimensional coordination polymer hosts [Cu2(H2O)2(bpp)2Cl]n(3n+) and ball-shaped Keggin-type guests [PM12O40]n(3n-) as templates. The polymer hosts resulted from a bcc-type framework with nanotubes, and the nanotubes can be regarded as a tetra-stranded helix structure. Furthermore, compounds 1 and 2 exhibit photoluminescent properties at ambient temperature, and the compound 2 bulk-modified carbon paste electrode ( 2-CPE) displays good electrocatalytic activity toward the reduction of nitrite.

Self-assembly of nanometre-scale metallacalix[4]arene building blocks and Keggin units to a novel (3,4)-connected 3D self-penetrating framework

A novel (3,4)-connected 3D self-penetrating metal-organic framework with a nanometre-scale cavity constructed from metallacalix[4]arene building blocks and Keggin-type polyanions has been obtained by using a 1,3-bis(1-methyl-5-mercapto-1,2,3,4-tetrazole)propane ligand.

Zn(II) coordination architectures with mixed ligands of dipyrido[3,2-d ∶ 2′,3′-f]quinoxaline/2,3-di-2-pyridylquinoxaline and benzenedicarboxylate: syntheses, crystal structures, and photoluminescence properties

Five new Zn(II) metal–organic coordination polymers, [Zn2(L1)2(Dpq)2]·H2O (1), [Zn(L2)(Dpq)(H2O)] (2), [Zn(L3)(Dpq)(H2O)]2 (3), [Zn(Dpdq)(L3)] (4) and [Zn(Dpdq)(L4)]·H2O (5) (Dpq = dipyrido[3,2-d∶2′,3′-f]quinoxaline, Dpdq = 2,3-di-2-pyridylquinoxaline, H2L1 = benzene-1,2-dicarboxylic acid, H2L2 = benzene-1,3-dicarboxylic acid, H2L3 = benzene-1,4-dicarboxylic acid, H2L4 = biphenyl-4,4′-dicarboxylic acid), have been hydrothermally synthesized and structurally characterized by elemental analyses, IR spectroscopy, and single-crystal X-ray diffraction analyses. Single-crystal X-ray analyses show that complexes 1–4 possess chain structures which are further assembled to form four three-dimensional (3-D) frameworks by π–π stacking and/or hydrogen-bonding interactions, while a similar chain of 5 has a two-dimensional (2-D) network packed by π–π stacking and hydrogen-bonding interactions. In 1–3, the Dpq ligand takes a chelating coordination mode while the other two nitrogen atoms did not coordinate to the Zn(II) ions. In 4 and 5, the Dpdq ligands have two coordination modes. The structural differences of the benzenedicarboxylate ligands and N-containing rigid/flexible chelating ligands have a great influence on the geometries of the corresponding complexes. This result also shows that intramolecular/intermolecular weak interactions play an important role in the formation of supramolecular networks, especially in linking low-dimensional entities into high-dimensional supramolecular frameworks. In addition, complexes 1 and 3–5 exhibit blue emission in the solid state at room temperature.

Assembly of Zn/Cd coordination polymers containing helixes or polycatenane structures tuned by the tri-pyridyl–bis-amide ligands with different spacer: syntheses, structures, photoluminescent and photocatalytic properties

Four new d10 metal–organic coordination polymers tuned by the “V”-shaped tri-pyridyl–bis-amide ligands with different spacers, namely, [Zn(L1)(BDC)]·H2O (1), [Cd(L1)(BDC)]·H2O (2), [Zn(L2)(BDC)] (3) and [Cd(L2)(BDC)] (4) (L1 = N,N′-bis(pyridine-3-yl)pyridine-2,6-dicarboxamide, L2 = N,N′-bis(pyridine-3-yl)pyridine-3,5-dicarboxamide, H2BDC = 1,4-benzenedicarboxylic acid) have been synthesized under hydrothermal conditions. In complexes 1 and 2, the metal ions are linked by L1 to form left- and right-helical Zn/Cd–L1 chains, which are further extended into two-dimensional (2D) wave-like layers by BDC anions. In 3, two L2 ligands link two ZnII ions forming the Zn2(L2)2 loops, which are connected by BDC anions to form a (2·65) topological 2D network. In addition, the large Zn2(L2)2 loops are threaded by the BDC rods from above and below 2D layers so as to form 2D → 3D polyrotaxane and polycatenane structures. In 4, the CdII ions are linked by L2 ligands to generate 1D double chain ribbons with Cd2(L2)2 loops, which are further connected by the BDC linkers to form a 3D framework. Two identical 3D frameworks interpenetrate each other in a twofold mode, giving rise to a polyrotaxane and polycatenane array, which is relative limited. The diverse structures of complexes 1–4 demonstrate that the tri-pyridyl–bis-amide ligands and the central metals have significant effect on the final structures. The thermal stability and fluorescent properties of complexes 1–4 have been investigated. In addition, the title complexes exhibit photocatalytic activity for dye methylene blue degradation under UV light.

The design and construction of a series of metal–organic coordination polymers based on two isomeric semi-rigid bis-pyridyl-bis-amide ligands and three aromatic polycarboxylates

A series of metal–organic coordination polymers, namely, {[Cu3(4-bpah)4(1,3,5-BTC)2]·8H2O}n (1), {[Cu3(4-bpah)3(1,2-BDC)3(H2O)2]·4H2O}n (2), {[Cu(4-bpah)(1,3-BDC)(H2O)]}n (3), {[Co(4-bpah)(1,3-BDC)(H2O)]}n (4), {[Ni(4-bpah)(1,3-BDC)(H2O)]}n (5), {[Zn(4-bpah)(1,3-BDC)(H2O)]}n (6), {[Cd(4-bpah)(1,3-BDC)]}n (7), {[Cd(3-bpah)(1,3-BDC)]·H2O}n (8), {[Cu2(3-bpah)(1,3-BDC)2]·H2O}n (9), where 4-bpah = N,N′-bis(4-pyridinecarboxamide)-1,2-cyclohexane, 3-bpah = N,N′-bis(3-pyridinecarboxamide)-1,2-cyclohexane, 1,3,5-H3BTC = 1,3,5-benzenetricarboxylic acid, 1,2-H2BDC = 1,2-benzenedicarboxylic acid, 1,3-H2BDC = 1,3-benzenedicarboxylic acid, have been synthesized under hydrothermal conditions. The structures of 1–9 have been determined by single crystal X-ray diffraction analyses and further characterized by infrared spectroscopy (IR), elemental analyses, powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). Complex 1 displays a 2D (42·83·10)(43·62·8)4(4)2 topological network. Complex 2 shows a 2D (3·4·5·62·7)2(3·42·52·7) topological framework that contains tri-flexural and left-hand helix chains. Complexes 3–6 reveal a similar 2D sql network with (44·62) topology. Complexes 7 and 8 show two different 2D double-layer structures with (42·6)(43·6·84·102)(4) and (42·6·86·12)(42·6)(8) topology, respectively. Complex 9 exhibits a new 3D 3-nodal topology with the Schlafli symbol (4·62)2(42·64)2(42·68·82·103). The successful construction of complexes 1–9 implies that using semi-rigid bis-pyridyl-bis-amide ligands can obtain various architectures with small voids. The effect of the isomeric semi-rigid bis-pyridyl-bis-amide ligands and the three aromatic polycarboxylates, as well as the central metal ions on the formation and structures of the title coordination polymers have been discussed. The fluorescent and photocatalytic properties of complexes 1–9 have also been investigated.

Construction and properties of cobalt(II)/copper(II) coordination polymers based on N-donor ligands and polycarboxylates mixed ligands

Metal–organic coordination polymers (MOCPs) are well known organic–inorganic hybrids with infinite structures consisting of metal ions/clusters and organic ligands linked through coordination interactions. MOCPs can be constructed from one or more than one organic bridging ligands (mixed-ligands) and different metal ions. The previous reports prove the fact that the nature of organic ligands and metal ions dominates the final structures as well as properties of the MOCPs in a certain way. Therefore, we focus on discussing the cobalt(II)/copper(II) coordination polymers constructed from the mixed-ligands of polycarboxylates and N-donor ligands, which may possess potential applications in the fields of electrochemistry, electrocatalysis, magnetism and photocatalysis. In this review, we summarize some typical Co(II)/Cu(II) MOCPs based on the mixed bridging organic ligands, aiming to discuss their versatile synthesis methods, topologies and structural influence factors, as well as their tunable properties. All of these aspects are highlighted in this review, which seeks to guide further investigations of cobalt(II)/copper(II) coordination polymers.

Polycarboxylate-directed various Co(II) complexes based on a “V”-like bis-pyridyl-bis-amide derivative: construction, electrochemical and photocatalytic properties

A series of new Co(II) complexes based on a new semi-rigid “V”-like bis-pyridyl-bis-amide derivative, namely, [Co(3-bpha)2(2,3-HPDC)2] (1), [Co(3-bpha)(3-NPH)(H2O)2]·2H2O (2), [Co(3-bpha)(1,3-BDC)]·4H2O (3), [Co(3-bpha)(HIP)]·3H2O (4), [Co(3-bpha)(MIP)(H2O)]·H2O (5), and [Co3(3-bpha)2(1,3,5-BTC)2(H2O)4]·2H2O (6) (3-bpha = N,N′-bis(pyridin-3-yl)-5-hydroxybenzene-1,3-dicarboxamide, 2,3-H2PDC = 2,3-pyridinedicarboxylic acid, 3-H2NPH = 3-nitrophthalic acid, 1,3-H2BDC = 1,3-benzenedicarboxylic acid, H2HIP = 5-hydroxyisophthalic acid, H2MIP = 5-methylisophthalic acid, 1,3,5-H3BTC = 1,3,5-benzenetricarboxylic acid), have been hydrothermally synthesized by tuning aromatic polycarboxylate co-ligands and characterized by single-crystal X-ray diffraction, IR spectra, powder XRD and TG analysis. Complex 1 is a discrete zero-dimensional (0D) structure in which the 3-bpha ligands and the 2,3-HPDC anions act as the terminal groups simultaneously to coordinate with the CoII ions. Complex 2 is a 1D meso-helical chain in which the 3-bpha ligands show a μ2-bridging mode and the 3-NPH anions act as the terminal groups. In complexes 3 and 4, pairs of 3-bpha ligands integrate with two CoII ions to generate 28-membered Co2(3-bpha)2 rings, which connect with the 1D [Co-1,3-BDC]n or [Co-HIP]n chains to create the 2D networks. In complex 5, the CoII ions are linked to 3-bpha ligands, resulting in a single-strand [Co-3-bpha]n helix chain, which is further connected to the MIP anions to form a 2D network. Complex 6 shows a 3D framework with (3,3,4)-connected (83)4(84·102) topology, which contains [Co-(1,3,5-BTC)]n 2D grid-like sheets and 1D [Co-3-bpha]n helical chains. Finally, the 0D discrete architecture in 1, 1D chain in 2, and 2D networks in 4 and 5 are extended to 3D supramolecular frameworks through hydrogen-bonding interactions. The effect of polycarboxylate auxiliary ligands with different substitute groups and different carboxyl positions and number on the assembly and structures of the target complexes were discussed. Moreover, the thermal stabilities, electrochemical properties and photocatalytic activities of complexes 1–6 were investigated.

Assembly and property of four 2D layer-like coordination polymers with different structural features derived from bis(3-pyridylformyl)piperazine ligand and aromatic dicarboxylic acids with nitro group

Using the mixed ligands bis(3-pyridylformyl)piperazine (3-bpfp) and 5-nitroisophthalic acid (H2NIPH) or 3-nitrophthalic acid (H2NPH), four two dimensional (2D) copper or cadmium coordination polymers with different structural features formulated as [Cu(3-bpfp)(NIPH)(H2O)] (1), [Cu(3-bpfp)0.5(NPH)(H2O)2] (2), [Cd(3-bpfp)0.5(NIPH)] (3), and [Cd(3-bpfp)(NPH)(H2O)]·H2O (4) have been hydrothermally synthesized and structurally characterized. Single-crystal X-ray diffraction analyses indicate that complex 1 displays a new contorted 2D layer consisting of two kinds of tetranuclear cycles with different dimensions: A-cycle of 20.53 × 9.57 A and B-cycle of 19.17 × 12.07 A, in which CuII ions are knitted by the 3-bpfp ligands with μ2-bridging coordination mode (via ligation of nitrogen atoms in pyridyl rings) and NIPH. In complex 2, CuII centers are connected by the ligands NPH to form one dimensional (1D) CuII-NPH left- and right-handed helical chains, and these chains are extended into 2D layer network by the 3-bpfp ligands with μ2-bridging coordination mode. Only one hexanuclear cycle with dimension of 16.86 × 11.10 A was included in the 2D structure of 2. Complex 3 contains two types of 1D ladder-like chains composed of CdII ion, the 3-bpfp ligand with μ4-bridging coordination mode (via ligation of nitrogen atoms in pyridyl rings and oxygen atoms in carbonyl groups) and bridging NIPH ligand with two coordination modes (chelate-monodentate mode and chelate mode), forming a double layer 2D network with the (42·6)(42·84)(47·63) topology. Complex 4 possesses 2D sheet based on the 1D right-handed helical chains constructed from the CdII ions and the NPH ligands with bis-chelating coordination mode, and the 3-bpfp ligands with μ2-bridging coordination mode. Moreover, the 2D structures of complexes 1–4 are ultimately packed into three dimensional (3D) supramolecular frameworks through the hydrogen bonding or the π–π stacking interactions. In addition, the fluorescent properties of the title complexes and the electrochemical behaviors of 1–2 at room temperature have been investigated.

A 3D organopolymolybdate polymer with unusual topology functionalized by 1,4-bis(1,2,4-triazol-1-yl)butane through Mo–N bond

An unusual (4,6,6)-connected high dimensional organopolymolybdate polymer by 1,4-bis(1,2,4-triazol-1-yl)butane coordinating directly to a molybdenum atom has been obtained under hydrothermal condition, which exhibits a self-penetrating framework with (44·5·6)(45·54·66)(48·52·65) topology assembled from 2D self-threading skeleton.

Polyoxometalate-directed assembly of various multinuclear metal–organic complexes with 4-amino-1,2,4-triazole and selective photocatalysis for organic dye degradation

A series of polyoxometalate (POM)-based metal–organic complexes containing multinuclear Cu(II) clusters with a 4-amino-1,2,4-triazole (4-atrz) ligand, namely, [Cu3(4-atrz)8(PMo12O40)2(H2O)2]·2H2O (1), [Cu2(4-atrz)6(SiW12O40)(H2O)]·6H2O (2), [Cu2(4-atrz)4(μ2-OH)(CrMo6(OH)6O18)]·3H2O (3), [Cu3(4-atrz)3(Mo8O27)(H2O)4]·6H2O (4) and [Cu3(4-atrz)3(V10O30)0.5(μ3-OH)(H2O)]·H2O (5) have been synthesized by selectively adding additional citric acid or boric acid under hydrothermal conditions and have been structurally characterized by single-crystal X-ray diffraction and powder X-ray diffraction. Compound 1 has a zero-dimensional (0D) architecture, which is constructed from a linear trinuclear cluster [Cu3(4-atrz)8(H2O)2]6+ and two Keggin PMo12O403− anions. Compound 2 shows a 1D zigzag chain, in which the binuclear [Cu2(4-atrz)6(H2O)]4+ clusters and Keggin SiW12O404− anions connect to each other. Compound 3 is a 1D linear chain based on linear [Cu3(4-atrz)6]6+ clusters; the [CrMo6(OH)6O18]3− anions hang on two sides of the 1D chain. Compound 4 has a 2D layer constructed from trigonal [Cu3(4-atrz)3(H2O)4]6+ clusters and rare infinite [Mo8O27]n6n− chains. The [Mo8O27]6− anion is transformed from the Anderson-type [CoMo6(OH)6O18]3− anion, which is also rare in the POM-based reaction system. Compound 5 has a 3D framework constructed from trigonal trinuclear [Cu3(4-atrz)3(OH)]5+ clusters and rare [V10O30]10− polyanions, which represents the first example of a V10O30-based 3D metal–organic complex. Structural analyses indicate that different POMs show great effect on the various structures of 1–5 and the additional acids play an important role in the formation of 1–5. Photocatalytic experiments of 1–5 on degradation of three organic dyes (methylene blue, Rhodamine B and methyl orange) manifest that compounds 1–3 are good candidates for the photocatalytic degradation of methylene blue, and compound 1 is a good photocatalyst for the degradation of Rhodamine B.