Tian-Jiao Li

Unprecedented Application of Flexible Bis(pyridyl-tetrazole) Ligands To Construct Helix/Loop Subunits To Modify Polyoxometalate Anions

By introducing the unprecedented and flexible isomeric bis(pyridyl-tetrazole) ligands into a polyoxometalates (POMs) system, three POM-based compounds, {Ag2(4-bptzb)2(H2O)2[H2PMo12O40]2}·4-bptzb·5H2O (1), [Ag4(3-bptzb)2(PMo(V)Mo(VI)11O40)]·2H2O (2), and Ag3(3-bptzb)2.5(H2O)2[H3P2W18O62] (3) [4-bptzb = 1,4-bis(5-(4-pyridyl)tetrazolyl)butane and 3-bptzb =1,4-bis(5-(3-pyridyl)tetrazolyl)butane], were synthesized under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction analyses. Compound 1 exhibits a dimeric structure constructed from two Keggin [PMo12O40](3-) anions and a binuclear [Ag2(trans-4-bptzb)2](2+) subunit in which the trans-4-bptzb acts as a bidentate bridging ligand with one tetrazolyl group. In 2, the 3-bptzb acts as a tetradentate bridging ligand with the tetrazolyl and pyridyl groups linking Ag(I) ions to generate a 3D metal-organic framework (MOF), which contains charming meso-helix chains. The Keggin anions acting as bidentate inorganic ligands reside in the distorted tetragonal channels of the MOF. In compound 3, the 3-bptzb adopts versatile coordination modes linking Ag(I) ions to first construct loop connecting loop 1D chains, which are linked by {Ag[P2W18O62]}n zigzag chains to form a scarce hamburger-style 2D sheet. These adjacent sheets are further fused by 3-bptzb ligands to construct a 3D framework. The influences of isomeric bptzb ligands and POMs on the construction of Ag-bptzb subunits and the whole structures of the title compounds are discussed. The electrochemical behaviors and electrocatalytic activities of compounds 2 and 3 and their corresponding parent POMs as well as the fluorescent properties of the title compounds have been studied in detail. In addition, the photocatalytic activities of compounds 2 and 3 and their corresponding parent POMs for decomposition of methylene blue, rhodamine B, and methyl orange under UV irradiation have also been investigated.

Polyoxometalate-directed assembly and various structures of inorganic–organic hybrid compounds based on a semi-rigid bis-pyridyl-bis-amide

Through tuning different kinds of polyoxometalates (POMs), four POM-based inorganic–organic hybrid compounds with different dimensionalities, namely [(H2L)2(Mo8O26)] (1), [CuII2L6(P2W24O79)·4H2O]·7H2O (2), {CuII2L2(μ2-OH)[CrMo6(OH)6O18]·4H2O}·4H2O (3), and {CuI2CuII2L2(μ3-OH)2[CrMo6(OH)5O19]·6H2O}·4H2O (4) [L = 1,4-bis(3-pyridinecarboxamido)benzene], have been synthesized under hydrothermal conditions and characterized by IR spectroscopy, TG analysis, powder XRD and single-crystal X-ray diffraction. Single-crystal X-ray analyses reveal that compound 1 exhibits a two-dimensional (2D) supramolecular network, which is constructed from protonated L ligands and [Mo8O26]4− anions through hydrogen bonding interactions. Compound 2 is a 1D hybrid chain based on an uncommon inorganic [P2W24O79]4− chain and “Y”-shaped (CuL3)2+ subunits. Compound 3 shows a 2D network constructed from 1D inorganic Cu2–CrMo6 chains and bidentate L ligands, which is obtained at pH = 4.1. When the pH was adjusted to 4.8, compound 4 is obtained which exhibits a 4-connected {66} 3D framework. The CrMo6 anions are connected by adjacent [CuI2CuII2(μ3-OH)2(H2O)6]4+ subunits to form 1D Cu4–CrMo6 inorganic chains, which are further extended by L ligands to construct a 3D network. The effect of different types of polyanions and pH values on the assembly and various structures of the title compounds has been discussed. Furthermore, the electrochemical properties of 1 and 2, and the photocatalytic properties of 2 and 3 under different conditions have been investigated.

Influence of N-donor sites in 5-(x-pyridyl)-1H-tetrazole ligands (x = 2, 4) on assembly of polyoxometalate-based compounds modified by multinuclear metal clusters and infinite chains

Through tuning the N-donor site of the pyridyl group in 5-(x-pyridyl)-1H-tetrazole ligands (x = 2, 4), four new Keggin-based compounds, [Cu7(2-ptz)8(OH)2(H2O)2(HPMoVI10MoV2O40)]·4H2O (1), [Cu5(2-ptz)6(HPMoVI10MoV2O40)(H2O)4]·4H2O (2), [Ag6(4-ptz)4(H2SiMo12O40)] (3) and [Ag5(4-ptz)4(H2PMo12O40)]·5H2O (4) (2-ptzH = 5-(2-pyridyl)-1H-tetrazole, 4-ptzH = 5-(4-pyridyl)-1H-tetrazole), were successfully synthesized under hydrothermal conditions and structurally characterized. Compound 1 possesses two kinds of CuII subunits: penta-nuclear clusters and mono-nuclear subunits, which connect with each other to form a one dimensional (1D) stair-like metal–organic chain. The adjacent 1D stair-like chains are further linked by tetradentate Keggin anions to construct a 2D layer. In compound 2, the tetra-nuclear CuII clusters and mono-nuclear CuII subunits construct a 2D metal–organic layer, which is further linked by bidentate Keggin anions to build a 3D framework. In compound 3, the 4-ptz ligand links AgI ions with tetrazole groups to form 1D infinite Ag–ptz chains, which are extended by the pyridyl group of 4-ptz and the tetrazole groups of other 4-ptz molecules to construct a 2D layer. The adjacent 2D layers are further linked by 6-connected Keggin anions to build a 3D framework. In compound 4, the 4-ptz ligands are linked by AgI ions to form 1D infinite Ag–ptz belts. The Keggin anions are linked by AgI ions to construct another infinite inorganic chain, in which each Keggin anion provides six oxygen atoms to coordinate with the AgI ions from adjacent Ag–ptz belts to construct a 2D layer. The roles of the ptz ligands with different N-donor sites in the construction of multinuclear clusters and 1D chains are discussed. The electrochemical and photocatalytic properties of the title compounds were investigated as well.

Subtly tuning one N site of benzyl-1H-triazole ligands to build mono-nuclear subunits and tri-nuclear clusters to modify polyoxometalates

By using two kinds of organic ligands (1-benzyl-1H-(1,2,4)triazole (2-btz) and 1-benzyl-1H-(1,3,4)triazole (3-btz)), six polyoxometalate (POM)-based compounds were hydrothermally synthesized and structurally characterized, [Ag4(2-btz)4(HPMo2VMo10VIO40)] (1), [Ag4(2-btz)4(SiW12O40)] (2), [Ag4(2-btz)5K(SiWVW11VIO40)]·13H2O (3), [Cu4(2-btz)16(Mo8O26)2] (4), [Cu3(3-btz)8(H2O)4](PMo12O40)2·4H2O (5) and [Cu7(3-btz)16(OH)2(H2O)4(P2W18O62)2]·16H2O (6). Compounds 1 and 2 are isostructural with two sets of Ag–(2-btz) chains linked by Keggin anions to construct a “ladder”. Adjacent “ladders” are further connected by Ag1–O13 bonds to build a 3D framework. In compound 3, the anion dimers are linked by Ag5–O9 bonds to form a 1D chain. The chains are fused by Ag3 and K ions and a 3D framework of 3 is built. In compound 4, the Mo8 anions are linked by [Cu(2-btz)4]2+ subunits to construct a 3D structure. By changing 2-btz to 3-btz, we obtained a linear tri-nuclear cluster [Cu3(3-btz)8(H2O)4]6+ in compound 5. The discrete PMo12 anions combine with tri-nuclear clusters through hydrogen bonding interactions to construct a 2D supramolecular layer. Compound 6 contains a cycle tri-nuclear cluster-supporting anion [Cu3(3-btz)6(OH)(H2O)2(P2W18O62)]−, which is further connected by one [Cu(3-btz)4]2+ subunit to construct a discrete anion dimer. The title compounds show good electrocatalytic activities for reducing nitrite, hydrogen peroxide and bromate. These compounds also exhibit excellent photocatalytic activities for the degradation of methylene blue (MB, 1–6 as catalysts) and Rhodamine B (RhB, 5 and 6 as catalysts). Additionally, the magnetic properties of compounds 5 and 6 have been investigated.

Introduction of secondary pyridyl-1H-tetrazole derivatives into Keggin–Ag–(1,10-phenanthroline) system for tuning dimensionalities and architectures: assembly and properties

Abstract By introducing three pyridyl-1H-tetrazole derivatives to Keggin–Ag-(1,10-phenanthroline) system, five new polyoxometalate-based inorganic–organic hybrid compounds with different dimensionalities and structures, [Ag3(4-ptz)2Na(phen)(HPMo12O40)]·2H2O (1), [Ag4(3-ptz)2(phen)2(HPMo12O40)] (2), [Ag4(3-ptz)2(phen)2(HVW12O40)] (3), [Ag3(3-bptzb)(phen)2(PMo12O40)] (4) and [Ag3(3-bptzb)(phen)2(VW12O40)] (5) (phen = 1,10-phenanthroline, x-ptzH = 5-(x-pyridyl)-1H-tetrazole (x = 3, 4), 3-bptzb = 1,4-bis(5-(3-pyridyl)-tetrazolyl)butane), have been synthesized under hydrothermal conditions. Compound 1 is a 1-D belt architecture constructed from an Ag-4-ptz metal–organic chain and two Ag–PMo12O40–Na–phen inorganic–organic chains. When 3-ptzH was introduced as secondary ligand in 2 and 3 instead of 4-ptzH, two isostructural architectures were obtained, which contain a 1-D zigzag Ag-3-ptz chain with phen ligands hanging on both sides of the chain. The Keggin anions connect adjacent Ag-3-ptz chains to construct 2-D networks. When the flexible 3-bptzb was selected, isostructural 4 and 5 with 2-D networks were obtained, which were constructed from binuclear subunits and Keggin–Ag inorganic chains. The influence of three pyridyl-1H-tetrazole derivatives as secondary ligands on the dimensionalities and architectures of 1–5 was discussed. The electrochemical and photocatalytic properties of the compounds were investigated.

The rigid isomeric 5-(x-pyridyl)-1H-tetrazole ligands-directed various isopolymolybdate-based compounds: assembly, structures, and properties

Abstract Two new isopolymolybdate-based metal–organic complexes, [Cu2(2-ptz)2(Mo4O14)0.5] (1) and [Cu3(OH)2(3-ptz)4(γ-H4Mo8O26)(H2O)4]·10H2O (2) (2-ptzH = 5-(2-pyridyl)-1H-tetrazole, 3-ptzH = 5-(3-pyridyl)-1H-tetrazole), constructed from isomeric ligands with different N-donor sites were synthesized under hydrothermal conditions. In 1, each [Mo4O14]4− cluster connected with six neighboring [Mo4O14]4− clusters through six binuclear [Cu2(2-ptz)2]2+ subunits to yield a 2-D layer. In 2, bidentate inorganic [Mo8O26]4− anions link the trinuclear [Cu3(OH)2(3-ptz)4] clusters to construct a 1-D chain. Adjacent chains connect through Mo–N bonds between the [Mo8O26]4− anions and pyridyl groups from the trinuclear clusters to form a 2-D layer. The effect of the N-donor sites of the rigid isomeric ligands on the structures of 1 and 2 was discussed. The electrochemical properties and photocatalytic activities of 1 and 2 have also been studied.

A series of polyoxometalate-based compounds including infinite Ag belts and circles constructed by two tolyl-1H-tetrazole isomers

In this paper, three new polyoxometalate (POM)-based metal–organic compounds containing silver cycles/belts, namely, [K2Ag15(L1)10(H2O)2][H(PMo11VIMoVO40)2] (1), [Ag7(L1)4][PW12O40]·2H2O (2) and [Ag10(L2)8(H2O)][PW12O40] (3) (L1 = 5-o-tolyl-1H-tetrazole, L2 = 5-m-tolyl-1H-tetrazole), have been obtained under hydrothermal conditions and characterized by single-crystal X-ray diffraction, IR spectra and powder X-ray diffraction (PXRD). The organic molecules L1 and L2 are isomeric. In compound 1, there exist two dimensional (2D) Ag-L1 layers including Ag belts, which are further linked by Ag5 to form a 3D metal–organic framework (MOF). The inorganic chain in 1 with Keggin anions linked by Ag1 ions insert into the channels of this 3D MOF. In compound 2, the Ag-L1 belts are connected by Keggin anions to construct a 2D layer. Adjacent layers link with each other through Ag–O bonds and the 3D framework of 2 is thus built. In compound 3, the 2D Ag-L2 layer possesses Ag cycles. Adjacent layers are linked by Ag–N bonds and Keggin anions to form the 3D structure of 3. The influence of the types of POM anions and organic ligands on the final structures was discussed. Furthermore, the electrochemical, photocatalytic and fluorescent properties of compounds 1–3 were investigated.

Three β-octamolybdate-based supramolecular hybrids constructed from a bis-imidazolyl-bis-amide ligand: fast and selective adsorption activities of organic dyes

Three β-octamolybdate-based supramolecular hybrids assembled from a semi-rigid bis-imidazolyl-bis-amide ligand, [ML(β-Mo8O26)0.5(H2O)]·H2O [M = Co (1) and Zn (2)] and [Cu2L2(H2O)](β-Mo8O26)·4H2O (3) [L = 1,2-bis(1H-imidazole-4-carboxamido)hexamethylene], have been hydrothermally synthesized, and characterized by FT-IR spectrometry, powder X-ray diffraction (PXRD), thermogravimetric (TG) analyses, and single-crystal X-ray diffraction. Compounds 1 and 2 are isostructural, in which the circular units [M2L2]4+ are linked by [β-Mo8O26]4− polyoxoanions to give a 1D chain, which is further extended into a 3D supramolecular structure through hydrogen bonds. A kind of 1D wave-like chain [Cu2L2(H2O)]4+ is linked by [β-Mo8O26]4− polyoxoanions via hydrogen bonds, constructing a 3D supramolecular structure in compound 3. The adsorption behaviours of compounds 2 and 3 for organic dyes were investigated in detail. The results indicate that 2 and 3 show fast and selective adsorption and desorption activities for Congo red, as well as excellent stability and recyclability after ten cycles.