Design and synthesis of two macrocyclic dinuclear coordination polymers with binding of nitric oxide

Two new coordination polymers of Robson-type macrocycles, {[CuL¹]_n (1) and {[CuL²]_n (2), were obtained by the condensation between bapa and N,N′-bis(3-formyl-5-R-salicylimine)-1,2-propylenediimine in the presence of Cu(II). These polymers have the common feature that the 3-methylaminopyridine group in one ligand coordinates to the metal ion in the neighboring coordination unit, leading to the formation of one-dimensional infinite chain. The formation of NO complexes has been confirmed by UV/Vis spectrophotometry. The binding constants were calculated to be 8.18 × 10² M^− 1, 1.2 × 10³ M^− 1 for 1 and 2, respectively. The control experiments revealed there was non-reversible binding of NO, which can be ascribed to specially coordination environment of the central Cu(II) ions. Moreover, the interactions of the complexes with calf thymus DNA (CT-DNA) have been measured by agarose gel electrophoresis, and the results showed that they can not cleavage the CT-DNA. These two complexes can be served as potential NO scavengers.Graphical abstractTwo new coordination polymers of Robson-type macrocycles, {[CuL¹]_n (1) and {[CuL²]_n (2), were obtained by the condensation between bapa and N,N′-bis(3-formyl-5-R-salicylimine)-1,2-propylenediimine in the presence of Cu(II). The NO absorption experiments revealed a moderate binding to NO and control experiments showed the non-reversibility of the binding NO to these two macrocyclic metal Cu(II) complexes.     

Helical poly(N-propargylamide)s with functional catechol groups: Synthesis and adsorption of metal ions in aqueous solution

A novel type of helical N-propargylamide (PA) copolymer was synthesized by catalytic polymerization of monomer 1 (M1), which provided pendent functional catechol groups, and monomer 2 (M2), which endowed the expected copolymer backbones with helical structures. With [(nbd)Rh⁺B^?(C₆H₅)₄ (nbd = 2,5-norbornadiene)] as catalyst, PA copolymers could be obtained with moderate molecular weights (3800–14,000) in high yields (?96%). The functional catechol groups enhanced the hydrophilicity of the hydrophobic mono-substituted polyacetylenes and aided the helical PA copolymers in showing a considerable adsorbance toward metal ions [Fe(III), Cr(III), Ni(II), Zn(II), Cu(II) and Cu(I)] in aqueous solution. The prepared copolymer in which M1/M2 was 0.1/0.9 [mol/mol, poly(1_0.1-co-2_0.9)] showed the highest adsorption capacity among the examined helical copolymers. In particular, for Fe(III), the maximum adsorption capacity was 186 mg g^?1.     

Phosphate diester hydrolysis promoted by new Cu(II) alkoxide complexes

Three Cu(II) complexes of N3 donor pyridyl-amine ligands, bis-(2-pyridin-2-yl-ethyl)-amine (L¹), which does not have an alcohol pendant, and 2-[bis-(2-pyridin-2-yl-ethyl)-amino]-ethanol (L²) and 3-[bis-(2-pyridin-2-yl-ethyl)-amino]-propan-1-ol (L³), both containing alcohol pendants, have been synthesized and structurally characterized. The reactivities of CuL¹ (1), CuL² (2), and CuL³ (3) for promoting the hydrolysis of bis(p-nitrophenyl)phosphate (BNPP) have been investigated, showing that 3 is much more active (observed second order rate constant k = 6.1 × 10⁻¹ M⁻¹ s⁻¹ at pH 8.4, 50 °C) than 1 (k = 9.4 × 10⁻³ M⁻¹ s⁻¹ at pH 8.4, 50 °C) or 3 (observed second order rate constant k = 5.2 × 10⁻³ M⁻¹ s⁻¹ at pH 8.4, 50 °C) at promoting the hydrolysis of BNPP. The much higher reactivity of 3 compared to 2 and 1 may be explained by the higher flexibility of the alkoxide tether in 3, which may allow the nucleophilic alkoxide O-atom in 3 better access to attack a metal-bound BNPP substrate, whereas 2, which has a shorter alkoxide tether, may resort to hydrolyzing the BNPP substrate with a metal-bound hydroxide instead of utilizing its alkoxide moiety because of constraints in the ligand tether. The similar reactivities of 1 and 2 suggest that this is a possible scenario. Another possible explanation for the difference in reactivity between 3 and 2 may be attributed to the alcohol pendant in 3 being better oriented to serve as a proton acceptor from a Cu(II)-bound aqua ligand, which would facilitate its deprotonation and the subsequent nucleophilic attack of the Cu(II)-hydroxide moiety towards the substrate. The reactivities of 2 and 3 towards hydrolyzing BNPP are also compared with that of their Zn(II) analogues, showing that the Cu(II) complexes of the same ligand sets are more hydrolytically active than the corresponding Zn(II) complexes. Single crystal X-ray structures of 1, 2, and 3 are also reported, which show that complexes 2 and 3 form dimers with bridging alkoxide ligands in the solid state, while 1 forms a dimer with bridging chloride ligands in the solid state.     

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.     

Two helical one-dimensional copper(II) coordination polymers based on N-(2-hydroxylbenzyl)glycine and N-(2-hydroxylbenzyl)-l-alanine: Syntheses,crystal structures and magnetic studies

Two new helical Cu(II) coordination polymers, [Cu(2,2′-bpy)(Hsgly)]Cl · 2H₂O(H₂sgly = N-(2-hydroxylbenzyl)glycine) (1) and [Cu(2,2′-bpy)(Hsala)](NO₃) · 2H₂O(H₂sala = N-(2-hydroxylbenzyl)-l-alanine) (2) were synthesized. Single crystal X-ray diffraction analysis indicated that both complexes showed helical chains arrangement of Cu(II) centers bridged by carboxyl groups. The magnetic measurements showed complex 1 exhibited ferromagnetic interaction while there was no interaction between the Cu(II) centers in complex 2.     

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.     

Synthesis,structure and characterization of 1D threefold-bridging copper(II) chain with strong ferromagnetic coupling

A 1D chain Cu(II) complex: [Cu(2-Clnic)(μ_1,1-N₃)(CH₃OH)]_n(1) (2-Clnic=2-chloronicotinate) has been synthesized and characterized by IR, elemental analysis, X-ray crystal diffraction and magnetic properties. Single-crystal structural analysis shows that complex 1 consists of 1D Cu(II) chains containing threefold bridging ligands, one μ_1,1-azido, one (syn–syn) 2-chloronicotinate and one methanol molecule. The magnetic susceptibilities of 1 has been investigated, indicating strong ferromagnetic interactions with J = 81.22 cm^?1.     

Construction of two mercury(II) coordination frameworks involving in situ tetrazole ligand synthesis

Two novel mercury(II)-organic polymeric complexes [HgCl(pzta)]_n (1) and [Hg₃Cl₂(pzta)₄(H₂O)₂]_n (2) [pzta = pyrazinyl tetrazolate] were obtained by in situ synthesis of pyrazinyl tetrazolate from the reaction of pyrazinecarbonitrile with sodium azide in the presence of mercury(II) salts. Complex 1 is a 3D coordination polymer with a 3,5-connected hms [(6³)(6⁹ · 8)] net consisting of mildly undulate (6, 3) sheets and bridging chlorine ligands; while complex 2 is also a 3D supramolecular network built from 2D layers with the 4-connected sql {4⁴ · 6²} net that are assembled via hydrogen bonds and π?π stacking interactions. Last but not least, photofluorescent properties of the two complexes have also been investigated.     

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.     

Synthesis,crystal structure of copper(II) complexes comprising 2-(biphenylazo)phenol and 1-(biphenylazo)naphthol ligands and their catalytic activity in nitroaldol reaction

New series of copper(II) complexes of the type [Cu(L)₂] (L = L₁–L₅) comprising bidentate 2-(biphenylazo)phenol (HL₁–HL₄) and 1-(biphenylazo)naphthol (HL₅) ligands have been synthesized. The composition of complexes and ligands (HL₁–HL₄) has been established by elemental analysis and spectral (FT–IR, UV–Vis, ¹H NMR and EPR) methods. Molecular structures of copper complexes [Cu(L₃)₂] (3) and [Cu(L₅)₂] (5) were established by X-ray crystallography. These Copper(II) biphenylazo complexes exhibit a very good catalytic activity towards nitroaldol reaction of various aldehydes with nitromethane.     

Electrochemical syntheses and structures of lead(II) and bismuth(III) complexes of 4-(trimethylammonio)benzenethiolate

Two main-group metal complexes of the zwitterionic ammonium thiolate complexes, [M(Tab)₃](ClO₄)_n (Tab = 4-(trimethylammonio)benzenethiolate) (1: M = Pb, n = 2; 2: M = Bi, n = 3), were prepared by electrochemical oxidation of Pb or Bi electrode in MeCN containing Tab and Et₄NClO₄. Each M atom in 1 and 2 is coordinated by three S atoms of three Tab ligands, forming a trigonal pyramidal coordination geometry. The resulting [M(Tab)₃]ⁿ⁺ cations are interconnected by secondary M⋯S interactions to form two different 1D cationic chains. The electrochemical properties of 1 and 2 were also investigated by cyclic voltammetry.     

Dicyanamido-metal(II) complexes. Part 5: First example for a unit cell containing dinuclear and 1-D polymeric Cu(II) complexes bridging by dicyanamide

The reaction of Cu(ClO₄)₂, N,N,N′,N″,N″-pentamethylethylenetriamine (pmedien) and sodium dicyanamide (Nadca) in aqueous medium led to the isolation of {[Cu(pmedien)(μ_1,5-dca)]₂(ClO₄)₂,[Cu(pmedien)(μ_1,5-dca)]_n(ClO₄)_n} (1). The complex was structurally and magnetically characterized. Single X-ray crystallography for 1 reveals the existence of two independent molecules in the unit cell: dinuclear doubly bridging complex and a 1-D polymeric chain with dca in both cases acting as a μ_1,5-bridging ligand via the terminal nitrile nitrogen atoms. Magnetic susceptibility measurements of the complex showed that the Cu(II) ions are weakly coupled with ferromagnetic interaction in the dinuclear unit (J_d = 0.9 cm^–1) and antiferromagnetic interaction in the polymeric chain (J_c = ? 0.6 cm^? 1).     

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.     

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.     

Palladium(II) complexes bearing the new pincer ligand 3,5-bis(indazol-2-ylmethyl)toluene; synthesis and catalytic properties

The reaction of 3,5-bis(bromomethyl)toluene with 1H-indazole in toluene, in the presence of triethylamine, yields the ligand 3,5-bis(indazol-2-ylmethyl)toluene (1). Compound 1 reacts with Pd(OAc)₂ in refluxing acetic acid, followed by a metathetic reaction with lithium chloride and with [PdCl₂(cod)] (cod = 1,5-cyclooctadiene) in refluxing acetonitrile to give the complexes [PdCl{3,5-bis(indazol-2-ylmethyl)tolyl-N,C,N}] (2) and [PdCl₂{3,5-bis(indazol-2-ylmethyl)toluene-N,N}] (3), respectively. Compounds 1–3 were characterized by elemental analyses, mass spectra and IR and NMR (¹H, ¹³C) spectroscopies. The molecular structure of 1 was also determined by single-crystal X-ray diffraction. The palladium(II) complexes (2,3) were tested as catalysts in ethylene polymerization and in C–C coupling reactions involving aryl halides substrates.     

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.     

Design and syntheses of blue luminescent Cu(II) and Zn(II) polymeric complexes with 2-(2′-pyridyl)benzimidazole derivative ligand

The polymeric complexes of 4,4′-bis[2-(2′-pyridyl)benzimidazolyl]biphenyl (Bmbp) with Cu(II) (1), Zn(II) (2) and 1,3,5-tris[2-(2′-pyridyl)benzimidazolyl]benzene (Tmb) with Cu(II) (3), Zn(II) (4) were successfully synthesized and characterized by IR spectroscopy, elemental analysis, thermal analysis and conductivity measurements. The results indicate that the stoichiometry of these metal complexes is metal: Bmbp (or Tmb) = 1:1 for 1 and 2 (2:1 for 3 and 4). Ligands coordinated with metal ions to get a five-membered chelate ring and formed polymeric complexes with metal ion. Their luminescence properties were also studied by UV–vis and fluorescence spectra. At room temperature, complexes 1–4 emit blue luminescence from 419 to 483 nm in the solid state and purple/blue luminescence from 385 to 437 nm in DMF solution. Thermal properties measurement and analysis shows that they have good thermal stabilities.     

Three-dimensional fourfold interpenetrated (10, 3)-b nickel(II) framework with 5-(isonicotinamido)isophthalate

A new three-dimensional nickel(II) metal-organic framework [Ni(INAIP)(H₂O)₂]_n · nH₂O (1) [H₂INAIP = 5-(isonicotinamido)isophthalic acid] was synthesized under hydrothermal conditions, and characterized by single-crystal X-ray structure determination, thermogravimetric analysis, X-ray powder diffraction, IR and magnetic studies. The compound 1 has (10, 3)-b topology with not well known fourfold interpenetration, in which both Ni(II) atoms and INAIP^2? ligands act as three-connected nodes.     

Pseudo-isomeric zinc/copper coordination polymers based on 3-(2-pyridyl)pyrazole-5-carboxylic acid

Reaction of 3-(2-pyridyl)pyrazole-5-carboxylic acid (H₂L) with Zn(II) or Cu(II) perchlorate yielded [ZnL]_n (1) and [CuL]_n (2) with similar composition. The ligand L^2 − adopts the same μ₃κ⁵ coordination mode. The Zn(II) and Cu(II) atom takes square pyramid coordination polyhedron with some discrepancy. Bigger difference in the dimeric secondary building blocks leads to distinct two-dimensional metal–organic frameworks. The Zn(II) complex fluoresces stronger than the free ligand. The Cu(II) polymer displays strong antiferromagnetic intra-dimer exchange and ferromagnetic inter-dimer exchange.     

Decomposition of allantoin in the presence of Cu(II) ions resulting in the formation of a coordination polymer containing oxalate species

A novel Cu(II) coordination polymer, [Cu(ox)(DMSO)₂]_n (1) (ox-oxalate dianion, DMSO-dimethyl sulphoxide) has been prepared in the reaction of copper nitrate dihydrate and allantoin (5-ureidohydantoin) in DMSO/water solution. Compound (1) crystallizes in the monoclinic, space group P121/c1 with a = 5.1785(7), b = 13.6311(18), c = 8.5386(12) Å, β = 107.524(12)°, V = 574,76(14) Å³, Z = 4, D_cal = 1779 mg/m³, R₁ = 0.0449. The metal ion coordinates through four oxygen atoms belonging to two bidentate bridging oxalate ligands, and two oxygen atoms from two DMSO ligands forming an elongated octahedron. The crystal structure was confirmed by FT-IR and Uv–vis spectroscopic data.