Alkoxo- and carboxylato-bridged hexanuclear copper(II) complex: Synthesis,structure and magnetic properties

Reaction of copper(II) nitrate trihydrate with N,N-dimethylethanolamine (dmea) and pivalic acid in methanol led to the hexanuclear copper(II) complex Cu₆(η¹:μ₂-C₄H₁₀NO)₄(η¹:η¹:μ₂-C₅H₉O₂)₄(η¹:μ₁-C₅H₉O₂)₂(μ₃-OH)₂ (1). The crystal structure of 1 indicates that hexametallic centers are bridged by the μ₃-alkoxo, dmea oxygens, and the μ₂-dicarboxylato oxygen atoms of pivalate ions. Furthermore, in the asymmetric unit, three types of copper ions have been found labeled as Cu₁, Cu₂ and Cu₃. The Cu₂ takes a distorted octahedral shape, whereas Cu₁ and Cu₃ adopt square pyramidal geometries. The complex 1 shows strong antiferromagnetic interactions through the oxo groups within the dimeric units (J = − 82.6 to − 25.8 cm^− 1) and weak antiferromagnetic couplings between the dimers (J = − 10.9 and 0.8 cm^− 1).     

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.     

Reversible water inclusion in a porous magnetic material synthesized from copper(II) incorporated metal-organic framework showing alternate ferro- and antiferromagnetic interactions

X-ray structural analysis shows that {[Cu₂(CTA) (H₂O)] · 5 H₂O}_n constitutes infinite one-dimensional parallel chains along the c-axis with water columns running down the crystallographic a-axis. The inclusion of water molecules is reversible and is confirmed by X-ray powder diffraction studies. The magnetic data (2–300 K) reveal that there are alternate ferro- (J = 0.29 cm⁻¹) and antiferromagnetic (J = −2.5 cm⁻¹) interactions.     

Synthesis and cytotoxicity of a ruthenium nitrosyl nitric oxide donor with isonicotinic acid and a cell penetrating peptide

The syntheses and properties of trans-[Ru(NH₃)₄(L)(NO)](BF₄)₃ (L = isonicotinic acid (inaH) (I) or ina-Tat48–60 (II)) are described. Tat48–60, a cell penetrating peptide fragment of the Tat regulatory protein of the HIV virus, was linked to the ruthenium nitrosyl through inaH. I and II release NO after reduction forming trans-[Ru(NH₃)₄(L)(H₂O)]^3 +. The IC₅₀ values against B16-F10 melanoma cells of I and II (21 μmol L^− 1 and 23 μmol L^− 1, respectively) are close to that of the commercially available cisplatin (33 μmol L^− 1) and smaller than similar complexes. The cytotoxicity is assigned to the NO released from I and II.     

In situ synthesis and dielectric properties of copper(II) and nickel(II) chiral Schiff base complexes

Two chiral Schiff base-containing complexes, [Cu(L¹)](ClO₄)₂·H₂O (1, L¹ = (S,S)-N1,N2-bis((1H-imidazol-4-yl)methylene)cyclohexane-1,2-diamine) and [Ni(L²)₂](ClO₄)₂ (2, L² = (S,S)-N1-((1H-imidazol-4-yl)methylene)cyclohexane-1,2-diamine) were synthesized from the reaction mixture of 1H-imidazole-4-carbaldehyde, (S,S)-1,2-diaminocyclohexane and Cu(ClO₄)₂·6H₂O or Ni(ClO₄)₂·6H₂O in methanol. Single-crystal X-ray diffraction analyses reveal that the in situ generated chiral Schiff base ligands L¹ and L² are bisubstituted and monosubstituted, respectively, corresponding to the different metal ions Cu^II and Ni^II. Variable-frequency and -temperature dielectric properties of 1 and 2 have been studied.     

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.     

One-dimensional copper(II) complex containing alternate single and double end-on azide ligands: Crystal structure and magnetic characterization

A novel one-dimensional azido-bridged coordination polymer of formula [Cu₂(L)₂(H₂O)(N₃)₄]_n (1) has been synthesized and characterized crystallographically and magnetically, where L is 5-methylpyrimidin-2-amine. Complex 1 consists of 1D chain in which the Cu(II) ions with a square pyramidal geometry are alternately bridged by asymmetric single and symmetric double end-on (EO) azido ligands. Magnetic analysis reveals that the dominating ferromagnetic interaction is mediated by the symmetric double azido bridge with the exchange parameter J = 55.17 cm⁻¹.     

Selective adenine/cytosine cations in one-dimensional coordination polymers of manganese (II) and copper (II) 2,3-pyridinedicarboxylates

One-dimensional coordination polymer {[1H,9H-ade]₂[MnL₂]?4H₂O}_n (1) and {[1H,3H-cyt]₂[CuL₂]?6H₂O}_n (2) (ade = adenine, cyt = cytosine, L = dianion of 2,3-pyridinedicarboxylic acid) are selectively synthesized and variable-temperature magnetic susceptibility measurements revealed weak antiferromagnetic interactions within the chains of 1 and 2 (J = ? 0.29 cm^? 1 for 1 and J = ?0.03 cm^? 1 for 2, according to the ? 2J_ijS_iS_j HDvV Hamiltonian formalism).     

Two Gd2 compounds constructed by 8-hydroxyquinoline Schiff base ligands: Synthesis,structure, and magnetic refrigeration

Two new Gd₂ compounds having formulae, [Gd₂(hfac)₄(L1)₂] (1) and [Gd₂(hfac)₄(L2)₂] (2) (hfac = hexafluoroacetylacetonate, HL1 = 2-[4-methylaniline-imino]methyl]-8-hydroxyquinoline and HL2 = 2-[(3,4-dimethylaniline)-imino]methyl]-8-hydroxyquinoline), have been successfully synthesized via applying two different 8-hydroxyquinoline Schiff base ligands, and further characterized by crystallography. Structural analysis shows that both of 1 and 2 are phenoxo-O bridged dinuclear complexes. The magnetic study reveal that 1 and 2 display cryogenic magnetic refrigeration properties with maximum − ΔS_m = 17.66 J kg^− 1 K^− 1 at 2 K and 7 T for 1 and − ΔS_m = 14.81 J kg^− 1 K^− 1 at 3 K and 7 T for 2.     

Ferromagnetic interactions in zinc(II) coordination complex containing nitronyl nitroxide radicals

A novel complex Zn(NIT2-py)₃(ClO₄)₂(NIT2-py = 2-(2′-pyridyl)-4,4,5,5-tetramethyl-2-imidazoline-1-oxyl-3-oxide) (1) has been synthesized and characterized structurally and magnetically. The metal coordination sphere is fully occupied by three chelating nitroxide ligands, showing a distorted octahedral geometry. Temperature dependence of susceptibility measurements shows a weak ferromagnetic coupling between NIT2-py radicals with J = 2.13 cm⁻¹. The field dependence of the magnetization further confirms that the ground state of the compound S = 3/2 results from ferromagnetic interactions within the complex 1.     

Synthesis,crystal, luminescent properties and electronic structures of two copper(I) halide polymers based on Cu4I4 cubane tetramers

Two novel coordination polymers [Cu₄I₄(en)₂]_n 1 and [Cu₄I₄(pn)₂]_n 2 (en = 1,2-diaminoethane and pn = 1,3-diaminopropane) were prepared by hydrothermal methods and determined by single-crystal X-ray diffraction analysis. Compound 1 possesses a 3D zeolite-like architecture with infinite intersected channels, constructing from cubane Cu₄I₄ tetramers, which is simplified into a twofold interpenetrating dia network. Compound 2 with the similar Cu₄I₄ cores, features a 2D layer with parallelogram-shaped channels along the b axis, showing a uninodal sql net. Both exhibit luminescent emission bands at about 600 nm at room temperature when excited at 350 and 370 nm, respectively. Furthermore, thermogravimetric analyses, optical diffuse reflectance spectroscopy, and the theoretical calculations were discussed.     

One rare 3D unipolar pillared-layer framework with a 1D carboxyl-copper chain formed by the syn-anti-COO– group

One 3D pillared-layer coordination polymer, [Cu(ipa)(bib)_0.5(H₂O)]_∞ (I), has been prepared from a solvothermal reaction of Cu(NO₃)₂·3H₂O with isophthalic acid (H₂ipa) and 1,4-bis(imidazolyl)benzene (bib). The pyramid Cu^II node is connected by the ipa^2 − ion into a 2D simplified (4,4) layer with a 1D syn-anti-COO⁻–Cu^II chain. The 2D layer is further unilaterally pillared by the bib spoke to afford a rare 3D unipolar pillared-layer framework. The overall topology can be described as a 6-connected self-catenated mab topology with point symbol of {4⁴.6¹⁰.8} through crosslink the (4,4) sheets. The magnetic properties have been studied, and the weak AFM interaction in the 1D chain has been estimated as − 0.15 cm^− 1 by fitting the experimental data. Furthermore, the magneto-structural correlation has been well discussed.     

Synthesis,crystal structure,and magnetic property of a stepped tetranuclear copper(II) complex of 3,5-diisopropylpyrazole-1-methoxide

Reaction of copper(II) chloride dihydrate in methanol with deprotonated 3,5-diisopropylpyrazole-1-methanol (dippmOH) led to the tetranuclear copper(II) complex [(dippmO)CuCl]₄ (1). The crystal structure of 1 indicates that two copper(II) ions connect via the oxygen atoms of dippmO⁻ ligands each other in which two dimeric units are formed. Furthermore, one of the coordinated oxygen atoms in a dimer is bonded to an adjacent copper(II) ion positioned other dimer, which gives rise to a stepped tetranuclear structure. 1 shows strong antiferromagnetic interactions through the oxo groups within the dimeric units (J₁ = − 239 cm^− 1) and weak antiferromagnetic couplings between the dimers (J₂ = − 15 cm^− 1).     

Absorption spectra and CT transitions of compounds containing ReI(CO)3Cl,S2+ and Se2+ as donors and o-benzoquinone diimine as acceptor

The electronic spectra of the cations [(BQDI)Se^II]²⁺ and [(BQDI)S^II]²⁺ are compared to that of [(BQDI)Re^I(CO)₃Cl] with BQDI = o-benzoquinone diimine. While these species show a BQDI-localized ππ¹ absorption between 300 and 360 nm, a longer-wavelength band extends to the visible region. This absorption is attributed to a CT transition from Re^I (λ_max = 538), Se^II (λ_max = 432) and S^II (λ_max = 360 nm) to the π¹ orbitals of BQDI. The analogy of MLCT and related CT transitions involving non-metals as CT donors is emphasized.     

Self-assembly of a novel 3D copper(I)-tetrazolate supramolecular framework via interpenetration of porous 2D double-layer motifs

The self-assembly of CuCN and 1H-TAZ ligand under hydrothermal conditions generated a novel three-dimensional hybrid supramolecular framework, namely, [Cu₆(TAZ)₄(CN)₂]_n (1) (TAZ = tetrazole). Single-crystal X-ray diffraction show that [Cu₂(TAZ)₂] binuclear subunits are linked by μ₂- and μ₃-CN groups to give a 2D double-wave-shaped network, which possesses 1D channels with four open-windows. The 2D bilayers interpenetrated each other to form the 3D supramolecular framework of 1.     

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).     

Two novel self-interpenetrating 3D iron(II) coordination frameworks: Synthesis,spectroscopic and structural characterizations with magnetic properties

Two novel self-interpenetrating 3D Fe(II) coordination frameworks namely {Fe(4,4′-bpy)[Ag₂(CN)₃]₂}_n (I) and {Fe(4,4′-bpy)[Ag(CN)₂]₂[AgCN]₂}_n (II) have been synthesized and fully characterized. The 3D architectures and degree of interpenetration of these coordination frameworks were significantly affected by silver(I) cyanide species. The crystal structure of I presents 4-fold interpenetrating 3D framework with 4,4′-bpy and [Ag₂(CN)₃]⁻ species. While, that of II constructed by 4,4′-bpy and two different silver(I) cyanide species, AgCN and [Ag(CN)₂]⁻ resulting to 2-fold interpenetrating 3D framework. The stability and rigidity of both coordination frameworks are mainly supported dominantly by Ag^I ⋯ Ag^I interactions. Their magnetic properties exhibit high spin behavior.     

Synthesis,structure and magnetic properties of a copper molybdate hybrid inorganic/organic solid with a novel 10-connected three-dimensional network topology

Hydrothermal reaction of CuCl₂, MoO₃, and 4,4′-dipyridylketone (4,4′-dpk) afforded green crystals of the mixed metal oxide phase {[Cu₂(MoO₄)₂(4,4′-dpk)(H₂O)]·H₂O}_n (1). According to single-crystal X-ray diffraction, {Cu₂O₂} dimers link into 1-D {Cu₂O₂(μ-H₂O)}_n chains via bridging aqua ligands. These chains form [Cu₂(MoO₄)₂(H₂O)]_n slabs via linkage through tetrahedral molybdate anions. In turn, the copper molybdate slabs are pillared through tethering 4,4′-dpk ligands into a 10-connected three-dimensional lattice with an unprecedented 3¹²4³⁰5²6 topology. Variable temperature magnetic data above 140 K were fit to the Curie–Weiss law, with C = 0.17 cm³ K/mol Cu and Θ = 70 K, indicating likely ferromagnetic coupling within the dinuclear kernels of 1; low temperature data points towards the possibility of interdimer antiferromagnetic interactions.     

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.     

Copper-assisted oxidative coupling of primary alcohol and hydrazone: A novel function model of galactose oxidase

Treatments of the MeOH, EtOH and PrOH solutions of 2-acetylpyridine, hydrazine and Cu^II salts (in molar ratio 2:3:2) afforded respectively the complexes, [Cu^II(HL)(Cl)](SO₃CF₃)H₂O (1), [Cu^II(MeL)(H₂O)](ClO₄)₂ (2) and [Cu^II(EtL)](Cl)](ClO₄) (3) (L = bis-(methyl, 2-pyridyl ketone hydrazonyl)methine), in which the ligands, HL, MeL and EtL are formed in situ from oxidative couplings of alcohols and hydrazones.