Construction of three new mixed-ligand Zn(II) coordination polymers based on nitrogen-containing heterotopic ligands and carboxylate co-ligands

Reactions of Zn(II) salts, presynthesized 5-(4-(1H-imidazol-1-yl)phenyl)-1H-tetrazolate (HIPT) and various carboxylate ligands result to three new coordination polymers (CPs), namely, [Zn₂[(IPT)₂(ox)]}_n (H₂ox = oxalic acid, 1), [Zn₂(IPT)₂(mNBDC)]_n (H₂mNBDC = 5-nitroisophthalic acid, 2), and [Zn₂(IPT)(CA)(H₂O)]_n (H₃CA = citric acid, 3). Compound 1 can be seen as constructed from 2D [Zn(IPT)]_n layers with (6,3) topology and pillared by ox^2 −. It is a 3D (3,4)-connected framework with InS topology. Compound 2 has 2D bilayer structure based on 2D [Zn(IPT)]_n single layer and mNBDC^2 − linkers. Compound 3 is a 3D pillar-layer framework built by Zn–CA bilayers and IPT⁻ pillars. The results showed that the coordination modes, configurations of IPT⁻, and the structure of carboxylate co-ligands have great influence on the structures of the final network. The choice of carboxylate can decide the result of CPs in Zn–IPT chains/net subunits plus carboxyl linkers or Zn–carboxylate chains/net subunits plus IPT⁻ linkers. The thermal stabilities and luminescent properties of selected compounds have also been studied.     

Microporous metal–organic frameworks constructed by Cu(I)/Zn(II), Tpt and 1,4-benzenedicarboxylate

Two novel metal–organic frameworks, [Cu(tpt)(bdc)_1/2]_n · nH₂O (1) and [Zn(tpt)(bdc)_1/2I]_n (2) (tpt = 2,4,6-tris(4-pyridyl)-1,3,5-triazine, H₂bdc = 1,4-benzenedicarboxylic acid), have been prepared by hydrothermal reactions. In complex 1, Cu(I) center is in a trigonal coordination environment with bidentate tpt coordinating Cu(I) atoms to form 1D zigzag chains, and bdc ligand links the zigzag chains to form a 2D layered structure. In complex 2, Zn(II) center is in a trigonal–pyramidal environment with bidentate tpt coordinating Zn(II) atoms to form zigzag chains, and bdc links the zigzag chains to form metal–organic framework which contains interesting hexagonal nano-channels.     

Constructing two new crystalline metal–organic frameworks based on a mixed-donor ligand

The self-assembly of a prominent ligand, 5-(4-(1H-tetrazolyl)phen)isophthalic acid (H₃TZPI), with Zn^2 +/Cu^2 + centres generates two new MOFs, [Zn₂(TZPI)(μ₃-OH)(H₂O)₂]·2H₂O (JUC-161) and [Cu(HTZPI)(μ₂-H₂O)_0.5(H₂O)_1.5]·5(H₂O) (JUC-162). JUC-161 exhibits fascinating three-dimensional structures containing rectangular channels with dimensions of 6.5 × 3.0 Å², and JUC-162 displays 3D supramolecular structures with 12.5 × 14.6 Å² hexagonal channels. The observed structural diversity in these frameworks is due to the two distinct coordinating moieties of the H₃TZPI ligand. The photoluminescence of JUC-161 and the magnetic properties of JUC-162 are also measured at room temperature. Photoluminescence investigations reveal that JUC-161 displays a strong main emission spectrum peak at 388 nm. JUC-162 is found to exhibit an antiferromagnetic interaction between Cu^2 + ions.     

Pillar-layered Zn–triazolate–carboxylate frameworks tuned by the bend angles of ditopic ligands

In the utilization of three ditopic ligands with different bend angles as pillars, we reported herein three pillar-layered Zn–triazolate–carboxylate frameworks, namely, [Zn₂(ATRZ)₂(BDC)]_n (1), [Zn₂(ATRZ)₂(TPDC)]_n·2nDMF (2) and [Zn₂(ATRZ)₂(ADDC)]_n (3) (ATRZ = 3-amino-1,2,4-triazole, H₂BDC = 1,4-benzenedicarboxylic acid, H₂TPDC = 2,5-thiophenedicarboxylic acid, and H₂ADDC = 1,3-adamantanedicarboxylic acid). Single crystal structural analyses demonstrate that different geometries of ditopic carboxylate pillars not only result in Zn–ATRZ layers adopting various corrugated configurations, but also give rise to 3,4-connected self-interpenetrated net of 1 and non-interpenetrated nets of 2 and 3. All these compounds exhibit high thermal stability and blue photoluminescence.     

New μ-oxo-bridged tetranuclear Cu(II) complex with Schiff-base ligand: Synthesis,crystal structure and magnetic properties

A new μ-oxo-bridged Cu(II) complex with cubane-like tetranuclear copper(II) complex, [Cu₄(L¹)₄] · 4H₂O (1) (H₂L¹ = 2-(3-methoxy-salicylidene-amino)-benzyl-alcohol), has been prepared, and structurally characterized by X-ray crystallography. Complex 1 crystallized in the monoclinic space group P₂₁/n and has a tetranuclear core of Cu₄O₄. The temperature dependence of magnetic susceptibility measurements shown that complex 1 exhibits a strong antiferromagnetic interaction with J = −103.4 cm⁻¹.     

Cyanide-bridged mixed-valence copper(II/I) coordination polymers: Unique 7-connected sev-type 3D network versus anionic 2D host network encapsulated with cationic complex

Reactions of CuCl₂, K₂[Ni(CN)₄]/K₃[Co(CN)₆], and 5-amino-1H-tetrazole led to cyanide-bridged mixed-valence Cu(II/I) complexes, [Cu(H₂O)₃Cu₃(CN)₅] (1) and [Cu(H₂O)₄][Cu₄(CN)₆] (2).The uncommon semi-closed {Cu₂(CN)₃} dimmers in 1 are bridged by μ₃-C,C,N cyanide ligands to afford rare 1D centipedal-like chain motifs, which are further bridged by μ₂-C,N and metalloligand “CN–Cu(4)–CN” to finish sophisticated zeolite-like 3-D structure. Topologically, 1 is the first example of uninodal 7-connected sev-like cyanide-bridged network. Compound 2 consists of two-dimensional honeycomb-related anionic layers [Cu₄(CN)₆]^2 −, within which the [Cu(H₂O)₄]^2 + cations are intercalated into alternate interlamellar space. Compound 1 shows antiferromagnetic couple arising from pure ground-state configuration of Cu(II) mediated by diamagnetic bridges –CN–Cu^I–CN −. The inclusion compound 2 shows blue photoluminescence originated from Cu(I) center to the unoccupied π* orbital of the cyanide ligand (MLCT) charge transfer.     

A fluorescent chemosensor for Zn2 + based on 3,8-bis(4-methoxyphenyl)-1,10-phenanthroline

3,8-Bis(4-methoxyphenyl)-1,10-phenanthroline (L) has been found to show high sensitivity toward Zn^2 + than other competitive metal ions, where Zn^2 +-selective chelation-enhanced fluorescence response at 461 nm is attributed to the formation of a 1:1 metal–ligand complex. In addition, two single-crystal structures of ligand L have been included with the same metal and ligand ratio of 1:1, namely one mononuclear Zn(II) complex [Zn(L)Cl₂] (1) and one 1D Cd(II) coordination polymer [Cd(L)(NO₃)₂]_n (2).     

An unprecedented (4, 8)-connected self-penetrating Cu(I)-MOF constructed from the rare [Cu4I2]2 + cationic cluster and in situ generated tetrazole ligand

The in situ hydrothermal reaction of CuI, NaN₃ and 4-(1H-imidazol-1-yl)benzonitrile leads to a new three-dimensional pillared-layer Cu(I)-MOF, [Cu₂(μ₃-I)(μ₅-IPT)]_n (1) (HIPT = 5-[4-(imidazol-1-yl)phenyl]tetrazolate). Interestingly, the structure of 1 exhibits an unprecedented binodal (4, 8)-connected three-dimensional self-penetrating framework first constructed from [Cu₄I₂]^2 + cationic clusters as 8-connected nodes and in situ generated IPT ligands as 4-connected nodes. Moreover, 1 is strongly luminescent with green emission (λ_em = 545 nm) in the solid-state.     

Structural characterization of ferromagnetic bridged-acetato and -dichlorido copper(II) complexes based on bicompartmental 4-t-butylphenol

The reaction of Cu(II) salts with 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-t-butylphenol (L^t-Bu-OH) afforded two bridged-phenoxido/hydroxido complexes. The dinuclear bridged acetate species [Cu₂(μ-L^t-Bu-O)(μ-CH₃COO)](PF₆)₂ (1) and the 1D polymeric doubly-bridged-chlorido {[Cu₂(μ-L^t-Bu-OH)(μ-Cl)₂](ClO₄)₂·4H₂O}_n (2). The two complexes were structurally characterized. Both complexes revealed ferromagnetic interactions; moderate in complex 1 (J = + 30.8 cm^− 1) and very weak (J = + 2.25 cm⁻¹) in 2.     

Dicyanamido–metal(II) complexes. Part 3: Hydrolysis of the dicyanamide into amidocyanamide during its interaction with Cu(II) perchlorate and 2-pyridylcarbonyl-N,N-bis(2-pyridylmethyl)amine

The reaction of Cu(ClO₄)₂, 2-pyridylcarbonyl-N,N-bis(2-pyridylmethyl)amine (DPA-CO-py) and sodium dicyanamide (Nadca) in aqueous medium led to the isolation of three complexes: {[Cu(DPA)(μ_1,5-dca)]ClO₄}_n (1), [Cu₂(pic)₂(μ_1,3-H₂NCO–N–CN)₂(H₂O)₂] · 2H₂O (2) and Cu(pic)₂ · H₂O (3). The Cu²⁺ ion, during its complex formation with DPA-CO-py and dca not only assisted the hydrolysis of DPA-CO-py to the corresponding di(2-methylpyridyl)amine (DPA) and picolinic acid (Hpic) but also resulted in partial hydrolysis of one of the two nitrile groups of the dicyanamide, NC–N–CN^? (dca) to amidocynamide, H₂NCO–NH–CN. The complexes were structurally characterized and the single X-ray structures for 1 and 2 reveal their identity. Complex 1 forms a 1D polymeric chain with the dca acting as a μ_1,5-bridging ligand via the terminal nitrile nitrogen atoms. A distorted SP geometry around the Cu²⁺ centers was achieved by the three N-atoms of the DPA and by the two nitrile groups of the bridging dca ligands. Complex 2 consists of a dimeric unit with CuN₃O₂ chromophore in coordination polyhedron that has a distorted SP geometry. The amidocyanamide ion, H₂NCO–N–CN^? acts as bis(monodentate) μ_1,3-bridging ligand via the central amido and terminal nitrile nitrogen atoms whereas the picolinate anion forms a six-membered chelate ring through its pyridyl nitrogen and an oxygen atom of the carboxylate group, and the aqua water occupies the apical position of the structure. Complex 1 exhibits very weak antiferromagnetic coupling (J = ?0.31 cm^?1) whereas 2 shows a significant antiferromagnetic interaction between the two copper centers (J = ?13.6 cm^?1).     

Copper(II) azide complexes of [Cu(acac)(N3)(dpyam)] and [Cu(μ-N3-κN1)(C2N3-κN1)(dpyam)]2: Synthesis,crystal structure and magnetism

Two new compounds, [Cu(acac)(N₃)(dpyam)] (1), (acac = acetylacetonate; dpyam = di-2-pyridylamine) and [Cu(μ-N₃-κ^N1)(C₂N₃- κ^N1) (dpyam)]₂ (2), have been synthesized and characterized by single-crystal X-ray diffraction and magnetic analyses. Compound 1 is a mononuclear compound in which each of two independent Cu(II) ions is penta-coordinated with a distorted square pyramidal geometry with distortion parameters τ = 0.21 and 0.16. In contrast, compound 2 is an azido-bridged dinuclear compound with monodentate dicyanamide anions and the Cu(II) ions display a distorted trigonal bipyramidal geometry with τ = 0.73 and end-on azido bridges providing an equatorial–axial position between the metal ions. The EPR spectra of powdered samples for 1 and 2 have also been investigated. Magnetic susceptibility measurements of compound 2 reveal a very weak ferromagnetic interaction between the Cu(II) ions with a J value of +5.8 cm⁻¹.     

An unusual emissive and colorimetric copper (II) detection by a selective probe based on a pseudo-crown cysteine dye: Solution and gas phase studies

An off-on-off emissive and colorimetric probe L, based on a Pseudo-Crown cysteine dye was designed for Copper (II). Compound L was studied in solution and in gas-phase (MALDI-MS) over alkaline, alkaline, earth-alkaline and transition metal ions (Li⁺, Na⁺, K⁺, Ca^2 +, Mg^2 +, Zn^2 +, Cu^2 +, Co^2 +, Ni^2 +, Pb^2 +, and Hg^2 +) in organic media. The recognition of Cu^2 + by L lead to red/dark red colored complexes, one emissive L₂Cu and another LCu, less emissive. In regards to fluorescent quantum yield in both cases an increase respective to L was visualized (2 fold for LCu and 7 fold for L₂Cu). The paramagnetic nature of both complexes was proved by the synthesis of both complex species, as well as, through ¹H NMR and FTIR. Compound L demonstrate to be able to detect and quantify the minimal amounts of 1.3 μM/3.3 μM of Cu^2 +.     

ESR,solid-state 31P MAS NMR,and UV–vis–NIR studies on linear CuI CuII CuI trinuclear species: Crystal structure of bis-μ-salicylato (2−)-1:2 κ4O; 2:3 κ4O-tetrakis (triphenylphosphine-1κ2P, 3κ2P)-tricopper(I,II, I), [(PPh3)2Cu]2(μ-o-OC6H4COO)2Cu

A novel neutral mixed-valence Cu(I)Cu(II)Cu(I) linear trinuclear copper metallomacrocycle [(PPh₃)₂Cu]₂[μ-o-OC₆H₄COO]₂Cu (3) has been synthesized and characterized. Compound 3 consists of two Cu(I) ions and one Cu(II) ion which are bridged by two salicylate (2^?) ligands, and the external copper(I) atoms are coordinated by four terminal triphenylphosphines. The essentially localized mixed-valence [Cu(I)Cu(II)Cu(I)] formulation for 3 was determined on the basis of X-ray crystallography, solid-state ³¹P MAS NMR, and ESR spectroscopy. The solid-state ³¹P MAS NMR spectra of 3 is reported, affording δ[P(2)] = ?1.7 ppm with ¹J[Cu(I), P] = 1330 Hz and δ[P(1)] = ?3.4 ppm with ¹J[Cu(I), P] = 1600 Hz. UV–vis–NIR spectral measurement demonstrates the Robin–Day class II behavior of the mixed-valence compound 3 with a weak copper–copper interaction.     

A tetranuclear pyrophosphate-bridged Cu(II) complex with 4,4′-bipyridine and 1,10-phenanthroline: Synthesis,structural, and magnetic properties

A new tetranuclear pyrophosphate-bridged Cu(II) complex with 4,4′-bipyridine and 1,10-phenanthroline [Cu₄(phen)₄(bpy)₂(P₂O₇)₂]·10H₂O (1) has been hydrothermal synthesized and characterized by single-crystal X-ray analysis, element analysis, IR spectroscopy, TG analysis, and UV–vis spectra. Variable-temperature magnetic susceptibility measurements show the occurrence of antiferromagnetic interactions between the neighbor Cu(II) centers in 1. The analysis of the magnetic data in the whole temperature range allows the determination of the value of the intramolecular magnetic coupling (J = − 13.16 cm^− 1).     

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.     

Structures and photoluminescence of coordination polymers assembled from bifunctional ligand containing both tetrazole and imidazole groups

Three new coordination polymers, namely, {[Cu₂(IPT)(SO₄)(OH)(H₂O)]·H₂O}_n (HIPT = 5-(4-(1H-imidazol-1-yl)phenyl)- 1H-tetrazolate, 1), {[Cd₂(IPT)(NPA)(OH)]·H₂O}_n (H₂NPA = 5-nitroisophthalic acid, 2), and {[Zn₂(IPT)(IDC)(H₂O)]·3H₂O}_n (H₃IDC = 1H-imidazole-4,5-dicarboxylic acid, 3), were assembled from a bifunctional organic ligand containing both tetrazole and imidazole groups with/without the aid of carboxylate coligands. Compound 1 possesses 2D structure built by 1D [Cu₂(IPT)(SO₄)(OH)]_n secondary building blocks and IPT⁻ linkers. The 2D networks are linked into 3D supramolecular framework via water chains in helical conformation. Compound 2 displays 3D pillar-layer framework with 2D layers based on tetranuclear Cd(II) SBUs and NPA^2 − pillars. Compound 3 exhibits a 3D framework constructed from the interconnection of 1D [Zn-IDC]_n chains and binuclear Zn₂(IPT)₂ rings. The thermal stabilities of porous compound 3 and luminescent properties of compounds 2 and 3 have also been studied in detail. They exhibit intense solid-state fluorescent emissions 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.     

Syntheses,structures and properties of two copper-2-picolinic-acid germanomolybdate hybrids with mixed organic components

Two inorganic–organic hybrids based on saturated α-Keggin-type germanomolybdates with mixed organic components [H₂DAP]₂[Cu(PA)₂][α-GeMo₁₂O₄₀]·8H₂O (1) and [NH₄]₂[H₈L] [Cu(PA)₂][α-GeMo₁₂O₄₀]·8H₂O (2) (DAP = 1.2-diaminopropane, HPA = 2-picolinic acid, H₆L = 1,3-bis[tris(hydroxymethyl)methylamino]propane) have been obtained via the conventional aqueous solution method and structurally characterized by elemental analysis, IR spectra, thermogravimetric (TG) analysis and single-crystal X-ray diffraction. 1 stands for an one-dimensional linear organic–inorganic hybrid germanomolybdate chain constructed from classical Keggin [α-GeMo₁₂O₄₀]^4 − units supported by [Cu(PA)₂] linkers, whereas 2 represents the first hybrid germanomolybdate containing the H₆L component and consists of a saturated α-Keggin polyanion [α-GeMo₁₂O₄₀]^4 −, a diprotonated [H₈L]^2 + cation, a copper coordination complex [Cu(PA)₂], two ammonium cations [NH₄]⁺ and eight lattice water molecules. Furthermore, the electrochemical and electrocatalytic properties of 1 and 2 have also been investigated in detail.     

A new stable Cd(II)-framework for sensitive and selective detection of Cu2 + ions

A new water-stable 3D metal–organic framework (MOF), [Cd₂L₂]·NMP·MeOH (1, H₂L = 2-(3,5-dimethyl-1H-pyrazol-4-yl)-1,3-dioxoisoindoline-5,6-dicarboxylic acid, NMP = 1-methyl-2-pyrrolidinone) has been solvothermally synthesized and structurally characterized. 1 exhibits a 3D open-framework with a 2D metallic plane pillared by L^2 − fragments. Meanwhile, luminescent studies indicate that the luminescence intensity of 1 was strongly dependent on different metal ions. Most interestingly, 1 exhibited significantly quenching effect toward Cu^2 +, which implies that it may be used as a luminescent probe for the detection of Cu^2 +.     

A 3D Cu(II) coordination polymer constructed from BIBP (BIBP = 5,5′-bis(1H-imidazol-1-yl)-2,2′-bithiophene) ligand with semiconductive property

Hydrothermal reaction of Cu(NO₃)₂·3H₂O with BIBP and H₂hfipbb at 105 °C yielded a novel 3D Cu(II) coordination polymer, {[Cu₂(BIBP)_0.5(hfipbb)₂(CH₃CN)]·5H₂O}_n (1) [BIBP = 5,5′-bis(1H-imidazol-1-yl)-2,2′-bithiophene, H₂hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid)]. Compound 1 displays a 3D 2-fold interpenetrating framework with {4⁴.6⁶} sqp topology, containing interesting ⋯LRLR⋯ double helical chains. The compound 1 was characterized by IR spectra, elemental analysis, thermal analysis and single crystal X-ray diffraction. In addition, solid-state UV–vis spectra experiment shows that compound 1 exhibits semiconductive property with a band gap of 2.46 eV.