Novel two-dimensional Co(II) and Cd(II) coordination polymers with intriguing net topologies

Three new two-dimensional coordination polymers were constructed from 2,6-bis(imidazole-1-yl)pyridine (2.6-bip), terephthalic acid (1,4-bdcH₂), and M(NO₃)∙nH₂O (M = Co, Cd). [M(2,6-bip)(1,4-bdc)] (1: M = Co; 2: M = Cd) were prepared under hydrothermal condition, whereas [Cd(2,6-bip)(1,4-bdc)∙xDMF] (3) was obtained under solvothermal condition in DMF solvent. Single-crystal X-ray analyses revealed the first example of a 2D 4-connected net of 6⁶ topology in 1 and 2 and a rare 2D 4,5-connected net of 4,5 L20 topology in 3. All these complexes were thermally robust and emissive in solid-states. This work confirmed the versatility of using hingelike 2,6-bip as a linker and the importance of solvent effect in the process of framework formation.     

A new 2D 5-connected coordination polymer based on 3,4-bis(pyridin-4-ylmethoxy)benzoic acid ligand

A new 2D 5-connected coordination polymer [Zn₃(HL²)(1,4-bdc)₃] (1) (HL² = 3,4-bis(pyridin-4-ylmethoxy)benzoic acid, 1,4-H₂bdc = 1,4-benzenedicarboxylate) has been hydrothermally constructed using HL², 1,4-bdc ligands as linear linkers and Zn₃-clusters as 5-connected nodes. In addition, powder X-ray diffraction, photoluminescent property and thermogravimetric analysis for 1 are investigated in detail.     

Two novel Cd(II)-based coordination polymers constructed from isomeric double betaine ligands: Syntheses,structures and fluorescent properties

Two novel Cd^2 + based coordination compounds based on two isomeric double betaine ligands (1,4-Bis(4-carboxylatopyridinium-1-methylene)benzene (H₂L₁Cl₂) and 1,4-Bis(3-carboxylatopyridinium-1-methylene)benzene (H₂L₂Cl₂)) were synthesized, structurally and optically characterized. Both compounds show two dimensional sheet architectures with different features depending on structural motifs that ranging from helical chain to linear chain, and the spatial arrangements of coordinated ligands as well as their unlike coordination modes. They further exhibit the way how three dimensional supramolecular isomers form via weak interactions. Meanwhile, two compounds exhibit intense fluorescence attributing to the ligands' emissions with stokes shift.     

A novel entangled coordination polymer presenting a 10-fold interpenetrating diamondoid network with unprecedented [5 + 5] mode

A novel coordination polymer [AgBF₄(bocb)₂] (1) (bocb = 1,4-bis(4-oxy-1-cyano)benzene) has been synthesized. This compound exhibits a ten-fold diamondoid framework with an unusual [5 + 5] mode of interpenetration. Its luminescent property was also investigated.     

Synthesis,luminescence, and structural characterization of Zn and Cd coordination polymers of flexible bis(imidazolyl) derivatives

Coordination polymers [Zn(imc)(L¹)] · H₂O, (1, imc = iminodiacetate, L¹ = bis(N-imidazolyl)methane) [Zn(hba)₂(L²)]₂ · EtOH · 3H₂O, (2, hba = p-hydroxybenzoate, L² = bis(N-benzimidazolyl)methane), [Cd(mal)(H₂O)(L³)](3, L³ = 1,4-bis(N-imidazolyl)butane, mal = maleate) have been prepared and structurally characterized. Complex 1 consists of hexa-coordinated central Zn ions and exhibits 2D network structure. The Zn atoms in 2 have tetrahedral coordination geometry, and are linked by bis(imidazolyl) ligands into 1D chain structure. The cadmium ions in 3 are hepta-coordinated with pentagonal bipyramidal geometry. Complex 3 displays 2D grid structure. The TGA showed that the coordination polymers are stable up to 200 °C. All the three complexes are emissive at room temperature in their solid state.     

Syntheses,structures and luminescence of two cadmium entangled coordination polymers based on bis(imidazole) and biscarboxylate ligands

Two entangled coordination polymers [Cd₂(bib)(bdc)₂]_n (1) and [Cd₂(bib)(bda)₂]_n (2) were synthesized by the hydrothermal reaction (bib = 1,4-bis(2-methyl-imidazol-1-yl)butane, bdc = 1,2-benzenedicarboxylate, bda = 1,4-benzenediacetate). 1 exhibits an unusual 6-connected self-catenated 3D network based on Cd₂(COO)₂ dimer with the point symbol of (4⁴·6¹⁰·8). 2 exhibits a 3-fold interpenetrating 3D pcu network based on Cd₂(COO)₂ dimer. The different conformations of bib ligands (the anti–anti–anti conformation in 1 and gauche–anti–gauche conformation in 2) play the key role in the construction of different structures in 1 and 2. The luminescence and thermal stability were investigated.     

Synthesis and structural characterization of copper(II) coordination polymers with 1,1,2,2-tetra(pyrazol-1-yl)ethane

Reaction between 1,1,2,2-tetra(pyrazol-1-yl)ethane (Pz⁴) and copper(II) nitrate in ethanol at room temperature and in solvothermal conditions (90 °C) lead to coordination polymers of two different structures. A ribbon-like coordination polymer {Cu₂(μ₂-NO₃)₂(H₂O)₄ μ′₂-Pz⁴}_n was formed at room temperature in which nitrate ions bind the monomeric units, while Pz⁴ ligands are responsible for cross-linking of {Cu(μ-NO₃)} chains. At 90 °C linear 1D coordination polymer was formed, in which Pz⁴ ligands bridge copper ions that in addition bear two monodentate nitrate ions.     

A copper coordination polymer based on bis(imidazole) and thiophenedicarboxylate for photocatalytic degradation of organic dyes under visible light irradiation

The copper(II) coordination polymer [Cu₂(bix)(sdc)₂]_n (1) was synthesized by the hydrothermal method (bix = 1,4-bis(2-methyl-imidazol-1-ylmethyl)benzene, sdc = 2,5-thiophenedicarboxylate). The copper(II) atom of 1 shows unsaturated square-pyramidal configuration. 1 exhibits the 2-fold interpenetrating three-dimensional pcu network based on the [Cu₂(COO)₄] dimers. 1 is an efficient and universal photocatalyst for the degradation of the organic dyes methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) under visible light irradiation, and is very stable and can be reused.     

New multinuclear europium(III) complexes as phosphors applied in fabrication of near UV-based light-emitting diodes

Two new multinuclear europium(III) complexes, [Eu(AFTFBD)₃]₂(1,4-bmb) and [Eu(AFTFBD)₃]₃(tmb) were designed and synthesized, where HAFTFBD was 2-acetylfluorene-4,4,4-trifluorobutane-1,3-dione, 1,4-bmb was 1,4-bis[2-(2′-pyridyl)benzimidazolyl]benzene and tmb was 1,3,5-tris[2-(2′-pyridyl)benzimidazolyl]benzene. The complexes were characterized by IR, UV–visible, photoluminescence (PL) spectroscopy and thermogravimetric analysis (TGA). The complexes emit the characteristic red luminescence of Eu³⁺ ion due to the ⁵D₀–⁷F_J (J = 0–4) transitions under 395 nm-light excitation. Bright red light-emitting diodes were fabricated by coating the selected complex (Eu(AFTFBD)₃)₃(tmb) onto ～395 nm-emitting InGaN chips, and the LEDs show appropriate CIE chromaticity coordinates in red area. All these results suggest that the Eu(III) complexes are promising candidates as red component for application in fabrication of near UV-based white light-emitting diodes.     

Metal-directed syntheses of coordination polymers via in situ ligand reactions from the same precursor, 2-(1H-benzeimidazol-2-yl)-acetonitrile

Three new coordination polymers, [Co(HBit)₂]_n (1), [Mn(HBit)₂]_n (2) (H₂Bit = 2-((1H-tetrazol-5-yl)methyl)-1H-benzo[d]imidazole), and [CdCl(MBi)(HMBi)]_n (3), (HMBi = 2-methyl-1H-benzo-[d]imidazole), have been hydrothermally synthesized via in situ ligand reaction. Compounds 1 and 2 are isomorphous and display interesting 3D chiral supramolecular frameworks constructed from one-dimensional 4₁ helical chains. Complex 3 possesses a one-dimensional coordination chain, which is further connected to a 2D layer by intermolecular hydrogen bonds. More interestingly, both H₂Bit and HMBi ligands are in situ generated from the same precursor, 2-(1H-benzo[d]imidazol-2-yl)-acetonitrile, and the formation may depend on the kind of metal ion. Furthermore, the solid-state luminescence of complex 3 was investigated at room temperature.     

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.     

Synthesis,structure and properties of a novel 3D pentanuclear [Zn5(OH)2]8 + cluster-based (3,4,11)-connected coordination polymer

A novel coordination polymer based on the multidentate N-donor ligand 1-((1H-1,2,4-triazol-1-yl)methyl)-3,5-bis(3-pyridyl)-1,2,4-triazole (3,3′-tmbpt) and 1,2,4,5-benzenetetracarboxylate anion (btec), namely, [Zn₅(3,3′-tmbpt)(btec)₂(OH)₂] (1), has been synthesized hydrothermally. Compound 1 displays a rare 3D (3,4,11)-connected framework based on a [Zn₅(OH)₂]^8 + cluster. The optical band gap and photoluminescent property of compound 1 have been studied.     

Hydrothermal syntheses and characterization of a series of mixed-ligand luminescent CdII frameworks with novel 2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl) acetate ligand and benzenedicarboxylate isomers

Under similar hydrothermal synthetic conditions using a novel flexible ligand 2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl)acetonitrile (PPAN), benzenedicarboxylate isomers (H₂pa = phthalate, H₂ip = isophthalate, and H₂tp = terephthalate) and Cadmium(II) acetate, three novel mixed-ligand Cd(II) coordination polymers {[Cd₂(PPAA)₂(μ-pa)(H₂O)]·2H₂O}_n (1), {[Cd₄(PPAA)₄ (μ₄-ip)₂]·2H₂O}_n (2) and {[Cd₂(PPAA)₂(μ-tp)]·2H₂O}_n (3) (PPAA⁻ = 2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl) acetate) have been isolated, in 1–3 PPAN, and are also hydrolyzed into a novel PPAA⁻ ligand. Complex 1 is a 1D coordination polymer in which the tetra-nuclear [Cd₄(PPAA)₄]^4 + structural units are extended by tri-dentate μ-pa^2 − ligands. Complex 2 contains binuclear [Cd₂(PPAA)₂]^4 + structural units, which are extended by four tetra-dentate μ₄-ip^2 − ligands to link eight neighboring binuclear [Cd₂(PPAA)₂]^4 + units ultimately forming a 2D layered framework, while complex 3 contains 1D double chain containing [Cd(PPAA)]_n cation structural units, which are further extended by tetradentate μ-tp^2 − ligands to form a new 2D layered framework. All the complexes have been investigated by elemental analysis, FT-IR, thermal analysis and fluorescence characterization. The flexible coordination modes of PPAA⁻ are also briefly analyzed. The flexible coordination modes of PPAA⁻ and benzenedicarboxylate isomers also reveal great potential in the construction of these novel mixed-ligand luminescent frameworks with diverse structural motifs and unique functional properties.     

Tuning the structural topologies of two luminescent metal-organic frameworks through altering auxiliary ligand

Two new metal-organic frameworks, [Zn₂(FA)₂(bix)₂]_n · 3nH₂O (1) and [Zn(FA)(bib)]_n (2), (H₂FA = fumaric acid, bix = 4,4′-bis(imidazol-1-ylmethyl)benzene, bib = 1,4-bis(imidazolyl)butane), have been synthesized by combining the fumaric acid and flexible imidazole-based ligands with Zn(II) salts under hydrothermal conditions. Single-crystal X-ray diffraction analysis reveals that 1 is a 4-fold interpenetrated unc topological net, and 2 is a 5-fold interpenetrated dia topological net. Moreover, the luminescent properties of the two compounds were also investigated in the solid state at room temperature.     

Structural diversity in coordination polymers with angular ditetrazole ligands

Three new coordination polymers with angular bis(1-tetrazol)diphenyl ligands as bridges, {[Ag(L¹)₂](NO₃) ? 2H₂O}_∞ [L¹ = 4,4'-bis(1-tetrazolyl)diphenyl methane], 1, [Ag(L²)₂(NO₃)]_∞ [L² = 4,4'-bis(1-tetrazolyl)diphenyl sulfone], 2, and [CuBr(L³)_0.5]_∞ [L³ = 4,4'-bis(1-tetrazolyl)diphenyl ether], 3, are reported, which show unique 2D structural types. Complex 1 forms 1D double-stranded helical chains where the cavities are threaded by linear hydrogen bondings formed by the co-crystallized water molecules and nitrate anions and complex 2 shows 2D grids involving M₄L₄ 64-membered metallocycles composed of helical chains, while complex 3 exhibits a 2D pleated net comprising 1D channels linked by the double-chain CuBr ribbons.     

Blue light-emitting diodes from 2-(10-naphthylanthracene)-spiro[fluorene-7,9′-benzofluorene] host material

A novel, spiro-type host material 2-(10-naphthylanthracene)-spiro[fluorene-7,9′-benzofluorene] was prepared by reacting 2-bromo-spiro[fluorene-7,9′-benzofluorene] with 9-(2-naphthylanthracene)-10-boronic acid via the Suzuki reaction. 2-4′-(Phenyl-4-vinylbenzeneamine)phenyl-spiro[fluorene-7,9′-benzofluorene], 4-[2-naphthyl-4′(phenyl-4-vinylbenzeneamine)]phenyl and diphenyl-[4-(2-[1,1;4,1]terphenyl-4-yl-vinyl)-phenyl]-amine were used as dopant materials. Devices with the configuration of ITO/N,N′-bis[4-(di-m-tolylamino)phenyl]-N,N′-diphenylbiphenyl-4,4′-diamine)/bis[N-(1-naphthyl)-N-phenyl]benzidine/2-(10-naphthylanthracene)-spiro[fluorene-7,9-benzofluorene]:5% dopant/aluminum tris(8-hydroxyquinoline)/Al-LiF showed a maximum power efficiency of 3.7 cd/A at 17.93 mA/cm² and a maximum luminance of 5018 cd/m² at 10 V with a turn-on voltage of 4.5 V.     

3D PbII-coordination framework based on rod-shaped Pb–O–Pb SBUs defining a new (4,5)-connected net topology

A novel 3D coordination framework [Pb₂(hfipbb)₂(bpp)]_n (1) [H₂hfipbb = 4,4′-(hexa-fluoroisopropylidene)bis(benzoic acid), bpp = 1,3-bis(4-pyridyl)propane] based on inorganic rod-shaped infinite Pb–O–Pb chain is presented, which possesses a new (4,5)-connected network topology and shows high thermal stability and strong photoluminescence at room temperature.     

Synthesis and characterization of decanuclear Ln(III) cluster of mixed calix[8]arene-phosphonate ligands (Ln = Pr,Nd)

Two novel decanuclear Ln(III) compounds (Ln = Pr for 1, Nd for 2) have been solvothermally obtained by using p-tert-butylcalix[8]arene (H₈TBC8A) and phenylphosphonate (PhPO₃H₂) as ligands. Single crystal X-ray diffraction studies reveal that both compounds are stacked by dumbbell-like Ln₁₀ clusters, which are capped by two TBC8A^8 − supports and linked by four complementary PhPO₃^2 − ligands as well as other bridging anions. In addition, the self-assembly behavior of both compounds is interesting: the cationic Ln₁₀ cluster layers are separated by the layers of H₆TBC8A^2 − ligands. Moreover, the luminescent and magnetic properties of both compounds were examined.     

Two new 3-D coordination polymers with 5-tert-butyl isophthalic acid and flexible N-donor co-ligands bearing linear trinuclear secondary building blocks

Two new 3-D coordination polymers bearing linear trinuclear secondary building blocks with mixed bridging ligands, {[Ni₃(tbip)₂(Htbip)₂(bib)₂]·4H₂O}_n (1) and {[Co₃(tbip)₂(Htbip)₂(btb)₂]·4H₂O}_n (2) (H₂tbip = 5-tert-butyl isophthalic acid, bib = 1,4-bis(imidazol-1-yl)butane, btb = 1,4-bis(1,2,4-triazol-1-yl)butane), were obtained and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, single-crystal X-ray crystallography and powder X-ray diffraction. Both complexes 1 and 2 display similar 3D 6-connected pcu networks containing the linear trinuclear [M₃(COO)₆] (M = Ni and Co) clusters as nodes.     

Syntheses,crystal structures,and magnetic studies of two cobalt(II) coordination polymers based on concurrent ligand extension

An ether bridged tetracarboxylic acid ligand, 5-(3′,4′-Dicarboxylphenoxy)-isophthalic acid (H₄L) was used to construct two Co(II) coordination polymers in presence of different nitrogen donor ligands such as 4,4′-bipyridine (4,4′-bpy) and 4,4′-bis(pyrid-4-yl)biphenyl (bpbp). The products formed under hydrothermal conditions are formulated as [Co₂L(4,4′-bpy)₂(H₂O)₃]_n (1) and {[Co(bpbp)₂(H₂L)]·H₂O}_n (2). The compounds were characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental analysis, and powder X-ray diffraction (PXRD) measurement. Compound 1 shows an intriguing (3,4,5)-connected 3D framework with a point symbol of (4² · 6² · 8²)(4² · 6⁵ · 8³)(6² · 8). Compound 2 is an unusual 3D supramolecular framework generated by the one-dimensional [Co(bpbp)(H₂L)]_n polymer chain. The magnetic properties of compounds 1 and 2 were examined, indicating antiferromagnetic interactions between the cobalt(II) ions in the temperature range of 2–300 K.