Crystal structure and magnetic property of a 3D heterometallic coordination polymer constructed by 3-cyanobenzoate and 3-(5H-tetrazol) benzoate ligands

Hydrothermal reaction of Cd(NO₃)₂, Co(NO₃)₂, Na(3-cba) and NaN₃ yielded a 3D heterometallic coordination polymer, [Cd(μ₅-3-tzba)(μ₂-3-cba)(μ₃-OH)Co(H₂O)]_n·2nH₂O 1 (3-H₂tzba = 3-(5H-tetrazol)benzoic acid and 3-Hcba = 3-cyanobenzoic acid), which was characterized by single-crystal X-ray diffraction. The in situ [2 + 3] cycloaddition reaction of nitrile and azide in presence of Cd(II) salt afforded tetrazolate-based 3-tzba^2? ligand. In 1, metal-oxo chains [Cd(μ₃-OH)Co]_n are linked by 3-tzba^2? in an unprecedented μ₅-κN1:κN2:κN3:κN4:κO1,O2 coordination mode to form 2D layers, which are further pillared by 3-cba^? to generate a 3D open framework encapsulating 1D chiral channels. Variable-temperature magnetic studies show that 1 exhibits antiferromagnetic interactions between Co(II) ions bridged by μ₃-OH group.     

Tunable photoluminescence of a dual-emissive zinc(II) coordination polymer with an in-situ generated tetrazole derivative and benzenetetracarboxyli

Hydrothermal reaction of the cyano-substituted derivative, NaN₃, ZnCl₂ and H₄PMA (H₄PMA = 1,2,4,5-benzenetetracarboxylic acid) yielded a dual-emissive coordination polymer: {[Zn₂(PMA)(tzmb)₂]∙6H₂O}_n (1) (tzmb = N-(tetrazolmethyl)-4,4′-bipyridinium). In 1, the μ₂-κN2,κN6 tzmb and μ₄-bridging PMA^4 − connect four-coordinated Zn(II) atoms to form a 2D (4,4)-connected topologic structure. The solid-state sample of 1 exhibits tunable blue-to-white-to-yellow photoluminescence (PL) upon variation of excitation wavelengths, and the PL appearance has been studied by the theoretical calculation.     

Two new d10 2D layered frameworks based on 1,2,4-triazole bridge: Syntheses,structures, and fluorescence

Two new triazole-bridging d¹⁰ 2D layered frameworks, [Cd(H₂O)₂(Httr)₂](SiF₆) (1), [Zn(ttr)(OAc)] (2) (Httr = 3-amino-1H-1,2,4-triazole), were synthesized with structures and fluorescence characterized. 1 is based on a kind of 16-membered ring with μ₂-1 κN:4 κN coordination mode of Httr and 2 is constructed from the fuse of different 6- and 16-membered rings with μ₃-1 κN:2 κN:4 κN mode of ttr⁻. The hydrogen bondings in 1 and 2 between the anions and ttr connect the 2D layers into 3D supramolecular architectures. The fluorescent studies of compounds 1 and 2 show an important difference, emission at 460 nm in 1 and a dual one at 334 and 462 nm in 2.     

The novel polymeric potassium complex with a new coordination mode of orotic acid [K(μ5-H2Or)(μ-H2O)]n: Synthesis and structural characterization

Novel polynuclear seven-coordinated potassium complex, [K(μ₅-H₂Or)(μ-H₂O)]_n(H₃Or = orotic acid), with the new coordination mode of orotic acid has been prepared and characterized by elemental analysis, FT-IR spectra, X-ray diffraction. The orotate ligand exhibits new coordination mode of μ₅-κO, O: κO′, O′: O″ for H₂Or⁻.     

Design,synthesis, structure and magnetic behavior of a high spin binuclear Fe(III) complex of N-(1-ethanol)-N,N-bis(3-tert-butyl-5-methyl-2-hydroxybenxyl) amine

The Mannich reaction of 2-aminoethanol, 2-tert-butyl-4-methylphenol, and formaldehyde at the ratio sets of 1:2:2 provided a new ligand, N-(1-ethanol)-N,N-bis(3-tert-butyl-5-methyl-2-hydroxybenxyl)amine (H₃L). In the presence of base, H₃L reacted with FeCl₃·6H₂O to form a dinuclear Fe(III) complex [Fe₂L₂] 1. The value of μ_eff at room temperature (5.95 μ_B), is much less than the expected spin-only value (8.37 μ_B) of two high spin (hs) Fe³⁺ (S = 5/2) ions [μ = g[∑ ZS(S + 1)]^1/2], indicating there were strong interactions between Fe³⁺ ions. The effective magnetic moment (μ_eff) decreased abruptly with cooling to a minimum value of 0.1 μ_B at 2 K. It was worth noting that Fe³⁺ ions of 1 exhibited thermally induced quartet ? doublet spin transitions, and these transitions were abrupt. The magnetic behaviors of 1 denoted the occurrence of intramolecular anti-ferromagnetic interactions. J (? 13.58 cm^? 1) agrees with the result from Gorun–Lippard equation, ? J (cm^? 1) = Aexp(BP(Å) = 12.9).     

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.     

A 3D pillared-layer porous framework with rare magnetic corner-sharing ∆-chain and unprecedented pentadentate 5-(4-pyridyl)tetrazolate ligand

A 3D pillared-layer porous framework, {[Co₂(H₂O)(μ₃-OH)(ptz)(nip)]·2H₂O}_n (1) (ptz = 5-(4-pyridyl)tetrazolate, nip = 5-nitroisophthalate), was in situ hydrothermally synthesized and structurally and magnetically characterized. Interestingly, the layered substructure of 1 consists of scarcely observed corner-sharing Co₂(μ₃-OH) ?-chain and unprecedented pentadentate ptz ligand. More importantly, due to the mixed triple syn,syn-carboxylate-μ₃-OH-μ₄-tetrazolyl bridges as well as the triangular Co^II arrangement, 1 behaves as a typical antiferromagnetically coupled paramagnet with a slight spin frustration, which exhibits a low-dimensional antiferromagnetic ordering below 10 K (Neel Temperature).     

Formation of a 1D water chain into the channel of a unique 3D hydrogen-bound coordination polymer {[Cd(μ-Cl)(4-pya)(H2O)]2 · 4H2O}∞ (4-pya = trans-4-pyridylacrylate)

A novel Cd(II)/4-pya coordination polymer {[Cd(μ-Cl)(4-pya)(H₂O)]₂ · 4H₂O}_∞ (1) (4-pya = trans-4-pyridylacrylate) was synthesized and structurally characterized. Single-crystal X-ray diffraction revealed that 1 consists of a 2D (4, 4) network constructed from the 4-pya bridging ligand and the dimeric [Cd(μ-Cl)]₂ cores, in which each six-coordinated Cd(II) ion adopts an octahedral coordination geometry. Each 2D layer is further stacked along the a axis through hydrogen bonding interactions to afford a 3D hydrogen-bound network. An infinite water chain is generated via hydrogen bonds into each resulting 1D channel. The luminescent properties of 1 in the solid state were investigated.     

Binuclear rhodium(III) and iridium(III) monoselenocarboxylates: Synthesis,spectroscopy and structure of an ortho-metallated iridium complex featuring an IrCCC(μ-Se) chelate ring

Monoselenocarboxylate–bridged binuclear complexes of Rh^III and Ir^III, [(Cp1MCl)₂(μ-SeCOAr)₂] (1) (M = Rh or Ir; Cp1 = pentamethylcyclopentadienyl; Ar = Ph, C₆H₄Me–4), have been isolated either by the reaction between [Cp1₂M₂(μ-Cl)₂Cl₂] with KSeCOAr in acetonitrile or by treatment of [Cp1MCl(solvent)₂][PF₆] with KSeCOAr in acetone. The novel binuclear complexes, [Cp1IrCl(μ-SeCOAr)(κ²-SeCOC₆H₃R–)IrCp1] (2) (R = H or Me-4) with ortho-metallation at one of the iridium centres have been isolated following the use of excess AgPF₆. The single crystal structure of [Cp1IrCl(μ-SeCOC₆H₅)(κ²-SeCOC₆H₄–)IrCp1] (2a) exhibits two phenylcarboselenolate moieties situated in syn fashion with respect to the “Ir₂Se₂” plane, one of which leans towards the metal centre in order to undergo ortho-metallation after iridium–chlorine bond dissociation.     

Assembly of an eight connected porous Cd(II) framework with octahedral and cubo-octahedral cages: Sorption and luminescent properties

An eight connected 3D porous coordination polymer, {[Cd(BTC)_0.66(BPz)₂] · 6H₂O}_n (1) (BTC = benzene-1,3,5-tricarboxylic acid, BPz = 3,3′,5,5′-tetramethyl-4,4′-bipyrazole) has been synthesized from hydrothermal reaction of Cd(NO₃)₂ · 4H₂O with BPz and BTC. Complex 1 is a thermally stable microporous MOF having cubo-octahedral and octahedral cages as the Supermolecular Building Block (SBB) with an eight connected reo topology. It shows moderate N₂ sorption (101 cm³ g^− 1) at 77 K with a BET surface area of 330 m² g^− 1. Complex 1 also exhibits photoluminescent property in solid state with λ_max at 397 nm.     

Synthesis,structure and luminescent property of a new Zn(II) coordination polymer with isolated tetrahedral {Zn4O} clusters as building subunits

A new luminescent Zn(II) coordination polymer, namely [Zn₄(L)₂(μ₄-O)(H₂O)₂(DMF)]_n (1 H₃L = biphenyl-3,4,5-tricarboxylic acid, DMF = N,N′-dimethyl formamide) has been synthesized by combining the H₃L ligand with Zn(II) salts under solvothermal conditions. Single-crystal X-ray diffraction analysis reveals that 1 features μ₄-oxygen-bridged tetrahedral {Zn₄O} clusters as building subunits, which are further bridged by L^3 − ligands into a complicated three-dimensional (3D) architecture. Topological analysis reveals that it can be reduced into a (3, 6)-connected topological network with the schläfli symbol of {4 · 6²}₂{4² · 6⁹ · 8⁴}. In addition, the luminescent property of 1 was also investigated in the solid state at room temperature.     

One-dimensional salen-type heterospin trimetallic (3d–4f–3d′) chain-like coordination polymers: Syntheses,crystal structures and magnetic properties

Three one-dimensional (1D) heterospin trimetallic chain-like polymers [{LCu(H₂O)}Ln(MeOH)(H₂O)₂{(μ-CN)₂Fe(CN)₄}]·2H₂O (1, Ln = La; 2, Ln = Nd; 3, Ln = Gd) were prepared by substitution of the nitrato ligands in [LCuLn] complexes with [Fe(CN)₆]^3? ions (H₂L = N,N′-bis(3-methoxysalicylidene)propane-1,2-diamine). Single-crystal X-ray diffraction analysis revealed that the methyl on the salen-type ligand impeded the connection between cyanide groups and Cu(II) ions efficiently. Consequently, three novel one-dimensional (1D) trimetallic chain-like polymers were obtained with the linker [Fe(CN)₆]^3? ions interacting only with the lanthanide ions. The magnetic investigation for 3 indicated a ferrimagnetic chain may form.     

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.     

Squarato-metal(II) complexes: Part 6. Synthesis,structure and magnetic characterization of an usual squarate-based 1D copper(II) coordination polymer composed of hexanuclear entities and a trinucleating ligand scaffold

The reaction of the polynucleating ligand 1,3,5-tris[bis(2-pyridylmethyl)aminomethyl]benzene (L^TDPA) with Cu(ClO₄)₂ · 6H₂O afforded the trinuclear complex [Cu₃(T^TDPA)(H₂O)₇](ClO₄)₆ · 5H₂O (1). When the reaction was performed in the presence of the squarate dianion, C₄O₄^2-, the compound {[Cu₆(L^TDPA)₂(μ_1,3-C₄O₄)₃](ClO₄)₆ · 12H₂O}_n (2) was obtained. Both compounds have been characterized by X-ray crystallography, showing a trinuclear and a 1D polymeric structures for 1 and 2, respectively. Complex 2 is composed of unusual hexametallic building blocks. Magnetic susceptibility measurements (SQUID) reveal essentially uncoupled copper(II) ions in complex 1, whereas complex 2 shows weak antiferromagnetic coupling via the squarato bridges within magnetically isolated dicopper(II) subunits of the 1D chain.     

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).     

Spectroscopic studies on bis(1-amidino-O-alkylurea) copper(II) sulfate complexes where alkyl = methyl,ethyl, n-propyl or n-butyl: EPR evidence for binuclear complexes

Four new Cu(II) Complexes viz. [Cu(II)(1-amidino-O-methylurea)₂]SO₄·2H₂O (1), [Cu(II)(1-amidino-O-ethylurea)₂](SO₄)₂·2H₂O (2), [Cu(II)(1-amidino-O-n-propylurea)₂] SO₄·2H₂O (3), [Cu(II)(1-amidino-O-n-butylurea)₂]₂(SO₄)₂·2H₂O (4) have been synthesized and characterized. EPR spectrum of complex 4 at RT consisted of fine-structure transitions (ΔMs = ±1) with zero-field splitting (ZFS) of 0.0485 cm^?1 and a half-field signal (ΔMs = ±2) at ca. 1600 G, revealed formation of binuclear complex (S = 1). Whereas EPR spectrum of complex 2 in DMSO showed a mixture of mononuclear and binuclear complex in the ratio 0.75:1.0 with ZFS of 0.0385 cm^?1. From the temperature dependence of the EPR signal intensity, the isotropic exchange-interaction constant J was evaluated.     

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.     

Six isostructural lanthanide-containing MOFs built on a semi-rigid tripodal organic ligand

By using a semi-rigid tripodal ligand 1,1′,1′′-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)tripyridinium-4-olate) (L), six isomorphous lanthanum metal-organic frameworks (MOFs), namely, [Pr(L)₂(Cl)₂]·(Cl)(DMF)_0.5·(H₂O)·(1), [Nd(L)₂(Cl)₂]·(Cl)(2), [Tb(L)₂(Cl)₂]·(Cl)·(DMF)·(H₂O)(3), [Eu(L)₂(Cl)₂]·(Cl)(DMF)·(H₂O)(4), [La(L)₂(Cl)₂]·(Cl)(5), [Sm(L)₂(Cl)₂]·(Cl) (DMF)·(H₂O) (6), were obtained and characterized by single crystal X-ray diffraction, IR and elemental analysis. Six compounds are isostructural with Ln^3 + (Ln = Pr, Nd, Tb, Eu, La, Sm) and in which the Ln^3 + is considered as a 6-connecting node and the L ligand is a 3-connecting node to afford a (3,6)-connected 2D layer with kgd topology, which further stacks into 3D supramolecular networks through C-H^…O weak interactions. Luminescent properties of these lanthanide MOFs have also been assessed at ambient temperature, in which the Pr^3 +-1 and the La^3 +-5 are slightly blue-shifted with respect to the ligand. Series of sharp peaks characteristic of the Eu^3 +-4, the Tb^3 +-3 and Sm^3 + − 6 metal-centered luminescence appear. The Nd^3 +-2 has no emission.     

An unique trinuclear triply bridged Cu(II) compound containing double acetato and single azido bridges: Synthesis,X-ray structure and magnetism of [Cu3(dpyam)2(μ1,1-N3)2(μ-CH3COO- κ-O1)2(μ-CH3COO-κ-O1,O2)2] · 2(H2O) (dpyam = di-2-pyridylamine)

The synthesis, characterization, crystal structure and magnetic properties of the unique azido-acetato bridged trinuclear triply bridged Cu(II) compound, [Cu₃(dpyam)₂(μ_1,1-N₃)₂(μ-CH₃COO-κ-O¹)₂(μ-CH₃COO-κ-O¹,O²)₂] · 2(H₂O), is reported. In the centrosymmetric compound, the central Cu atom is linked to two terminal Cu atoms by a double acetato bridge and an azido bridge, thereby providing a linear trinuclear unit. The coordination geometry around each of the terminal Cu(II) ions is distorted square pyramidal, while the geometry of the central Cu(II) ion is elongated octahedral. The magnetic susceptibility measurements, measured from 5 to 300 K revealed a weak antiferromagnetic interaction between the Cu(II) ions with a J value of −10.2 cm⁻¹. In the EPR no signals for the low-lying doublet are resolved at 77 K.     

Thermal dehydration of Y(TFA)3(H2O)3: Synthesis and molecular structures of [Y(μ,η1:η1-TFA)3(THF)(H2O)]1∞ · THF and [Y4(μ3-OH)4(μ,η1:η1-TFA)6(η1-TFA)(η2-TFA)(THF)3(DMSO)(H2O)] · 6THF (TFA = trifluoroacetate)

In order to obtain a better anhydrous precursor for various applications in materials science and catalysis, thermal dehydration reactions of Y(TFA)₃(H₂O)₃ (TFA = trifluoroacetate) (A) were investigated. Thermal treatment of A at different temperatures under vacuum (5 × 10^?2 mm) for several hours failed to give totally anhydrous yttrium trifluoroacetate (as indicated by IR). Two different complexes, a partially dehydrated [Y(μ,η¹:η¹-TFA)₃(THF)(H₂O)]_1∞·THF (1) and a partially hydrolyzed [Y₄(μ₃-OH)₄(μ,η¹:η¹-TFA)₆(η¹-TFA)(η²-TFA)(THF)₃(DMSO)(H₂O)] · 6THF (2), were obtained with good and moderate yield, respectively, by crystallization of two different thermally treated batches of A from THF (or THF + DMSO) at room temperature. More efficient dehydration of A could be achieved at 200 °C in a furnace, the obtained anhydrous yttrium tris-trifluoroacetate giving Y(TFA)₃(THF)₂ (3) on crystallization from THF. All the products were characterized by elemental analyses, FT-IR and ¹H NMR spectroscopy as well as thermo-gravimetric analysis. In addition, single crystal X-ray structures are reported for 1 and 2, which show either a terminal (η¹ and η²) or bridging (μ,η¹:η¹) bonding behavior of the TFA ligand.