Anion-directed assembly of two fluorescent Cd(II) coordination polymers with a versatile multidentate N-donor building block 3-(2-pyridyl)-4,5-bis(4-pyridyl)-1,2,4-triazole

Assembly of Cd(II) nitrate with a novel tripyridyltriazole building block 3-(2-pyridyl)-4,5-bis(4-pyridyl)-1,2,4-triazole (L¹) and pseudohalide anion dicyanamide (dca) or azide (N₃) yields two coordination polymers {[Cd(L¹)₂(dca)₂](H₂O)₂}_n (1) and {[Cd₂(L¹)(μ_1,1-N₃)₂(μ_1,3-N₃)(N₃)](H₂O)_1.5}_n (2). Single crystal X-ray diffraction analysis indicates that the Cd(II) centers in 1 are bridged by the bidentate L¹ ligands to form 1D arrays, which are further extended to a 3D network via hydrogen bonding and aromatic stacking. Significantly, the L¹ ligands in 2 display the unusual pentadentate coordination and the azide anions take different μ_1,1-, μ_1,3-, and unidentate binding modes, interlinking the Cd(II) ions to afford a complicated 3D open framework with the inclusion of lattice water guests. Both complexes exhibit strong solid state fluorescent emissions at room temperature.     

Four coordination polymers derived from 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole and copper sulfate

The reaction of 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-bpt) with copper sulfate in EtOH/H₂O solvent yields four coordination polymers [Cu(3-bpt)(H₂O)₄](SO₄)·H₂O (1), [Cu(3-bpt)(H₂O)₄][Cu(3-bpt)(H₂O)₃(SO₄)](SO₄)·7H₂O (2), [Cu(3-bpt)(H₂O)₃(SO₄)]·2H₂O (3) and [Cu(3-bpt)(H₂O)(SO₄)] (4), showing one-dimensional undulated chain, zigzag chain and two-dimensional network. The formations of compounds 1, 2 and 3 are controlled by the EtOH/H₂O ratio. The synthesis of compound 4 may be controlled by the EtOH/H₂O ratio and the temperature because it is prepared under solvothermal condition. The thermal properties have been investigated.     

3-甲基-4-对甲苯基-5-（2-吡啶基）-1，2，4-三唑的合成和表征

1,2,4-三唑类化合物在农药、医药及化工领域有着广泛的应用,其与-些金属离子形成的配合物具有自旋转换功能。为了制备研究新的具有自旋转换功能的1,2,4-三唑配合物,以a-吡啶甲酸为原料,经多步反应合成3-甲基-4-对甲苯基-5-（2-吡啶基）-1,2,4-三唑,并用IR、MS、^1H—NMR对其结构进行了确证。     

4-氨基-3,5-二(4-吡啶)-1,2,4-三氮唑的新合成方法

4-氨基-3,5-二(4-吡啶)-1,2,4-三氮唑的合成方法已有报道,但合成条件严格,要求纯氮气保护.本文的合成方法简单易行,无须氮气保护,只需反应物直接混合加热就可得到产物.     

3-苯基-4-对甲苯基-5-（2-吡啶基）-1，2，4-三唑的合成和表征

1,2,4-三唑类化合物在农药、医药、生物、信息材料及化工领域有着广泛的应用,报道了3-苯基-4-对甲苯基-5-（2-吡啶基）-1,2,4-三唑的合成,并用红外、核磁（^1H—NNR、）及质谱对其结构进行了确证。     

Syntheses and topological networks of two azide complexes based on 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole ligands

Two new azide complexes, [Cd₂(3-abpt)(N₃)₄]_n (1) and [Cu(3-abpt)₂(N₃)₂] (2) (3-abpt = 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole), have been prepared and structurally characterized. Complex 1 displays an interesting 2D polymeric structure with rarely reported 3,7-connected (3²;4)(3⁴;4⁶;5⁶;6⁵) network in the Schafli notation. Complex 2 contains mononuclear pieces, and they are linked each other through weak CuN coordination bonds to form a 2D sheet with (4, 4) topology. The thermal stability and fluorescent property of 1 have also been investigated.     

Lanthanide coordination polymers constructed from 5-(4-pyridyl)-isophthalic acid: Synthesis,structure and photoluminescent properties

Nine lanthanide coordination polymers [Ln₂(pyip)₃(H₂O)₄·DMF·3H₂O]_n (Ln = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho) based on the pyip^2 − ligand {H₂pyip = 5-(4-pyridyl)-isophthalic acid} have been synthesized under solvothermal conditions. X-ray crystallographic studies reveal that 1–9 are isostructural and crystallize in the triclinic system, space group P2₁/c, and exhibit a 3D framework. Topological analysis reveals that the 3D framework can be simplified to a uninodal 6-connected pcu alpha-Po primitive cubic type structure. Meanwhile, the luminescent properties of these nine coordination polymers in the solid state are also investigated. Especially the Eu and Tb compounds show bright red and green luminescence with luminescence lifetimes of 0.39 and 0.80 ms, respectively.     

Three new d10 coordination polymers based on 2-(2-pyridyl)benzimidazole ligand: Synthesis,structures and properties

Three coordination polymers containing 2-(2-pyridyl)benzimidazole (PyHBIm) ligand, namely {[Zn₃(PyBIm)₃(PyHBIm)₂(tma)(H₂O)]?H₂O}_n (1), [Zn(PyHBIm)(oba)]_n (2), [Cd(PyHBIm)(oba)]_n (3), (tma = trimesate, oba = 4,4′-oxybis-(benzoate)), have been prepared through hydrothermal reaction. Compound 1 exhibits one-dimensional (1D) helical structure. However, compounds 2 and 3 display 1D meso-helical structure. These 1D structures are further assembled into three-dimensional (3D) networks through aromatic π–π stacking interactions and hydrogen bonding interactions. Moreover they all exhibit strong photoluminescence at room temperature and may be good candidates for potential luminescence materials.     

Syntheses,structures and photocatalytic properties of three copper(II) coordination polymers

Three coordination polymers [Cu₂(obtz)₂(tdc)₂]_n (1), {[Cu(obtz)₂(H₂O)₂][Cu₂(obtz)₂(sip)₂]5.5H₂O}_n (2) and [Cu(obtz)(nip)]_n(3) were synthesized by the hydrothermal reaction (obtz = 1.2-bis(1,2,4-triazol-1-ylmethyl)benzene, tdc = 2.5-thiophenedicarboxylate, sip = 5-sulfoisophthalate, nip = 5-nitroisophthalate). 1 shows a ladder-like one-dimensional chain with two side arms. 2 is comprised of two distinct and crystallographically independent polymeric motifs. The first motif in 2 is the ladder-like one-dimensional anionic chain with two side arms. The second motif in 2 is the cationic chain. 3 exhibits the intriguing 2-fold interpenetrated network based on the undulated 2D (4.4) network. 1, 2 and 3 are good photocatalysts for the degradation of methyl orange (MO) under UV irradiation.     

Two new three-dimensional (3,4)-connected lanthanide (III) coordination polymers based on 2-(3-Pyridyl)-1H-imidazole-4, 5-dicarboxylate: Structures and luminescent properties

Two new lanthanide (III) coordination polymers, namely, {[Eu₃(μ₃-HPyIDC)₄]·Cl}_n, (1) and {[Tb₂(μ₃-HPyIDC)₂(μ₂-Ox) (H₂O)₂]·4H₂O}_n (2) (H₃PyIDC = 2-(3-Pyridyl)-1H-4, 5-imidazoledicarboxylic acid; Ox = oxalate), were successfully synthesized under hydro(solvo)thermal conditions and structurally characterized. Compound 1 displays a 3D framework with new (3,4)-connected {4.8.10}₄{4.8⁴.12}₂{4².8⁴} topology built by 3-connected μ₃-HPyIDC⁻ nodes and 4-connected metal ions. Compound 2 exhibits a rare (3,4)-connected dmc topology, in which μ₃-HPyIDC⁻ anions are 3-connected nodes and metal ions are 4-connected nodes. Moreover, the thermal stabilities and luminescence of compounds 1–2 were also investigated.     

Solvent directed assembly of two zinc(II)-2-(4-pyridyl)-4,5-imidazoledicarboxylate frameworks

Two zinc(II)-2-(4-pyridyl)-4,5-imidazoledicarboxylate frameworks, formulated as {[Zn₃(HPIDC)₃(DMF)₂](DMF)₂(H₂O)₂}_n (1) and {[Zn₄(HPIDC)₄(DMF)₄](DMF)₂(FMA)₂(H₂O)}_n (2) (H₃PIDC = 2-(4-pyridyl)-1H-4,5-imidazoledicarboxylic acid, DMF = N,N′-dimethylformamide, FMA = formamide) have been solvothermally synthesized depending on whatever solvents are used. In both structures, the HPIDC^2 − anions act as tripodal connectors to chelating with three zinc(II) cations while the zinc(II) cations coordinate with three HPIDC^2 − anions, to form the T-shape molecular building blocks [Zn_n(HPIDC)_n], which further connect in interdigitating or alternating fashion to result in the assembly of two different 3,3-connected networks. The luminescence behaviors and solvent effect were also discussed.     

Syntheses,structures and luminescence of three copper(I) cyanide coordination polymers incorporating flexible N-donor ligands

Three copper(I) cyanide coordination polymers, namely [Cu₈(CN)₈(btmb)₂]_n (1), [Cu(CN)(btmb)_0.5]_n (2) and [Cu₂(CN)₂(dpa)]_n (3) (btmb = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene, dpa = di(4-pyridyl)amine), were synthesized under hydrothermal conditions and characterized by elemental analyses, IR spectra, PXRD and thermogravimetric analyses. Single-crystal X-ray diffraction analyses reveal that complex 1 is an interesting 2D double-layered network constructing from eight distinct Cu(I) centers, eight μ₂-cyanides and two tetradentate cis-btmb ligands. Complex 2 is a ladder-like coordination polymer assembled by CuCN linear chain and bidentate trans-btmb linker. Complex 3 has a 2D wave-like network constructing from CuCN zigzag chain and V-shape dpa spacer. These coordination polymers are thermally stable up to 270–300 °C. They emit blue luminescence originating from ligand-centered emission.     

A new 2D HgII coordination polymer containing novel coordination mode of 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (bpo) ligand, [Hg(μ-bpo)2(N3)2]n: Spectroscopic,thermal, fluorescence and structural studies

A new two-dimensional Hg^II coordination polymer containing 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (bpo) and azide anions, [Hg(μ-bpo)₂(N₃)₂]_n, has been synthesized and characterized by elemental analysis, IR-, ¹H NMR-, ¹³C NMR spectroscopy and structurally determined by X-ray single-crystal diffraction. The thermal stability of compound [Hg(μ-bpo)₂(N₃)₂]_n was studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The single-crystal X-ray data shows that ligand bpo is bridged via one pyridyl nitrogen and one oxadiazole nitrogen atom, as a novel coordination mode of the ligand bpo. Furthermore, the ligand and complex are luminescent in the solid state, with emission maxima in the visible light region (λ_max = 470 nm for both bpo and [Hg(μ-bpo)₂(N₃)₂]_n).     

Construction and photoluminescence properties of two novel zinc(II) and cadmium(II) benzyl-tetrazole coordination polymers

Two new d¹⁰ coordination polymers, Zn(Beta)₂ (1) and Cd₂(Beta)₃Cl(H₂O) (2) (Hbeta = 5-benzyl-tetrazole) have been synthesized by the in situ [3 + 2] cycloaddition reaction of 5-benzylacetonitrile, sodium azide and MCl₂ [M = Zn (1); M = Cd (2)] under hydrothermal condition. Complex 1 is a coordination polymer comprised of numerous mildly undulated two-dimensional (2D) layers with a (4, 4) topological network; while complex 2 is a 3D coordination framework constructed from the interconnection of various helical chains through cadmium–chlorine bridges. Furthermore, the luminescence properties of two complexes have been investigated.     

Novel chemosensory materials based on polyfluorenes with 2-(2′-pyridyl)-benzimidazole and 5-methyl-3-(pyridin-2-yl)-1,2,4-triazole groups in the side chain

Polyfluorenes with 2-(2′-pyridyl)-benzimidazole (P1, P2 and P4) and 5-methyl-3-(pyridin-2-yl)-1,2,4-triazole (P3) groups in the side chain were synthesized by Suzuki polycondensation. The responsive properties of polymers on metal ions and H⁺ were investigated by absorption and emission spectra. The fluorescences of polymers (P1-P4) were completely quenched upon the transition metal ions such as Co²⁺, Ni²⁺, Fe³⁺ and Ag⁺ due to the enhanced electronic communication properties of conjugated polymers. The obvious differences to Ni²⁺ ion responsive sensitivity were observed between P1 and P4 polymers. The fluorescences of P1 and P4 were quenched to 50 (I₀/I) and to 22 (I₀/I) upon the addition of a Ni²⁺ solution of 3.2 × 10⁻⁶ M, as well as 5.0 × 10⁻⁶ M, respectively, owing to the different conjugated backbone. The fluorescences of P2 and P3 were completely and hardly quenched upon the addition of a Al³⁺ solution of 1.0 × 10⁻⁴ M, respectively, owing to the different receptors in the side chain. P2 showed good selectivity to Ni²⁺ ion in the range of quencher concentration as low as 5 ppm, owing to the different chelating abilities of receptor with ions. Cu²⁺ and Mn²⁺ ions hardly quenched the fluorescences of polymers (P1-P4), which were different from the oligopyridyl-functionalized conjugated polymers. The results further opened the opportunities to develop the tailored sensory materials through the appropriate alteration of receptors in the side chain and the conjugated backbone.     

Structural Transitions and Thermochromism of Linear Polynuclear Cobalt(II)-4-Octadecyl-1,2,4-triazole Complexes

Combination of methanolic solutions of cobalt(II) chloride hexahydrate and 4-octadecyl-1,2,4-triazole (C₁₈trz) leads to precipitation of a linear polynuclear complex (“coordination polymer”) established by Co²⁺ centers bridged by two C₁₈trz molecules. The compound exists in a blue and a pink form in the solid, gel and dissolved state. The blue form represents tetrahedrally coordinated [Co(C₁₈trz)₂]²⁺ repeat units and the pink form octahedrally coordinated [Co(C₁₈trz)₂(H₂O)₂]²⁺ repeat units, therewith reflecting the affinity of Co²⁺ for both tetrahedral and octahedral coordination geometry. The blue and the pink form can be reversibly transformed into each other by humidification or, respectively, drying of the material. Thermochromism is observed in the dissolved state, where the pink form is reversibly transformed to the blue form upon increase in temperature. The results differ in some aspects from assumptions in previous reports on this subject.     

Synthesis,crystal structures,and luminescence properties of two new coordination compounds [Zn(pytza)2(H2O)2] and [CdCl(pytza)]n (Hpytza = 5-(2-pyridyl)tetrazole-2-acetic acid)

Reactions of Hpytza (Hpytza = 5-(2-pyridyl)tetrazole-2-acetic acid) with ZnCl₂ or CdCl₂ under hydrothermal conditions, produced two new compounds, [Zn(pytza)₂(H₂O)₂] (1) and [CdCl(pytza)]_n (2). Both compounds were structurally characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Compound 1 is mononuclear while compound 2 shows a two-dimensional network. Furthermore, the luminescence properties of 1 and 2 were investigated at room temperature in the solid state.     

Two Pb(II) coordination polymers constructed from dicarboxamido-(2-pyridyl)-pyridine by varying ratios of mixed solvents

Through varying the volume ratio of mixed solvent, we obtained two distinct polymers {[Pb₆(2,6-pda)₆] · H₂O}_n (1) (2,6-pda = 2,6-pyridyldicarboxylate) and [Pb(mpcp)(OAc)]_n (2) (mpcp = methyl-6-(pyridin-2-ylcarbamoyl)picolinate) by reaction of Pb(OAc)₂ · 3H₂O and 2,6-dicarboxamido-(2-pyridyl)-pyridine (H₂dcapp) decomposed through lead-induced hydrolysis. Photoluminescence investigations reveal that both polymers display enhanced emissions in contrast to the free ligand, respectively.