Synthesis,characterization, and magnetochemical properties of two Mn4 clusters derived from 2-pyridinecarboxaldehyde Schiff base ligands

Two tetranuclear manganese complexes, [Mn₄(L¹)₆](ClO₄)₂?2.75H₂O (1) [HL¹ = 4-methyl-2-((pyridin-2-ylmethylene)amino)phenol] and [Mn₄(L²)₄(NO₃)₃(OH)]?pz?3H₂O (2) [HL² = (1H-pyrazol-1-yl)(pyridin-2-yl)methanol, pz = pyrazole], have been synthesized and characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction, and magnetic measurements. The structural analysis revealed that the central manganese ion is linked with three apical manganese ions through six phenoxo-bridges creating a Mn₄O₆ core for 1; 2 has a cubane-like topology with the Mn(II) ions and the deprotonated oxygens from L² alternatively occupying vertices. The magnetic studies indicated a weak ferromagnetic coupling interaction (J = 0.48 ± 0.087 cm^?1, g = 2.00, θ = ?0.78 K) for 1 and a weak antiferromagnetic spin-exchange interaction (J₁ = ?0.50 ± 0.075 cm^?1, J₂ = ?0.13 ± 0.082 cm^?1, g = 1.98) between Mn(II) ions for 2. The magnetostructural correlations of the two Mn₄ clusters have been discussed tentatively.     

A new tetranuclear copper(II) complex containing decameric water clusters bridged by–OH–and pyridine-2,4, 6-tricarboxylate: synthesis and magnetic characterization

Using pyridine-2,4,6-tricarboxylic acid (H₃ptc) and 2,2-bipyridine (2,2-bipy), a tetranuclear copper(II) compound [Cu₄(2,2-bipy)₄(ptc)₂(H₂O)₂(OH)₂] · 12H₂O (1) has been isolated under hydrothermal conditions. Variable temperature magnetic susceptibility of 1 from 2–300 K indicates anti-ferromagnetic interactions. The magnetic exchange coupling constants of J = ?159.4 and J′ = ?18.66 cm^?1 for 1 can be obtained through fit of the magnetic data, corresponding to two kinds of bridges, hydroxyl anions (OH^?) and pyridine carboxylate oxygen of ptc^3?. Moreover, decameric water clusters can also be observed, which are located between these tetranuclear copper(II) entities, forming a series of intricate O-H ··· O hydrogen bonds and stabilizing the resulting three-dimensional (3-D) hydrogen-bonded framework structure.     

Synthesis,structure, and characterizations of a new antiferromagnetic manganese(II) dichloro-bridged 1-D polymer decorated by 5-amino-1-H-tetrazole

[Mn(5-ATZ)₂Cl₂]_n (1) (5-ATZ – 5-amino-1-H-tetrazole) was synthesized from the reaction of 5-ATZ and manganese(II) chloride and isolated by solution evaporation at room temperature. 1 was characterized by elemental analysis, X-ray crystallography, infrared, and EPR spectroscopy as well as magnetic measurements. In the crystal structure, [Mn(5-ATZ)₂Cl₂] units are linked by double μ₂-bridging chlorides to form 1-D chains parallel to the a-axis. The Mn sphere approximates to octahedral with the metal coordinated by four chlorides in the equatorial plane and two 5-ATZ molecules, bound through their ring nitrogens, in axial positions. The intramolecular N–H···Cl hydrogen bond between the 5-ATZ amino group and the adjacent coordinated Cl^? stabilizes the chain. N–H···N hydrogen bonds between adjacent chains form a 3-D supramolecular framework. No hyperfine coupling to the Mn nuclei (I = 5/2) is observed in the powdered EPR spectrum of 1 at 77 K. The frozen solution EPR spectrum provides evidence of the mononuclearity of 1 in methanol. The magnetic properties have been analyzed using the Hamiltonian H = –J∑S_i · S_i+1 with J = ?1.38(3) cm^?1 and g = 2.00(1). A small value of the exchange parameter is typical for 1-D six-coordinate bis(μ₂-chloro) Mn(II) polymers.     

Synthesis,structure, magnetic properties and kinetics of formation of a cluster containing a {Cu3(μ3-OH)} core supported by a triazole-based ligand

The trinuclear copper complex, [Cu₃(μ₃-OH)(CTMB)₃(NO₃)₂(CH₃CN)₂]·5CH₃CN·H₂O (1) {CTMB = cyclohexotriazole-3-(4-methoxybenzamide)}, has been prepared by mixing Cu(NO₃)₂·2.5H₂O and CHMBH {CHMBH = N,N′-cyclohexane-1,2-diylidene-bis(4-methoxybenzoylhydrazide)} in acetonitrile under ambient conditions. Compound 1 was characterized by IR and UV–visible spectroscopies as well as elemental analyses. X-ray crystallography shows that the cluster contains a {Cu₃(μ₃-OH)} core supported by three triazole-based Schiff base ligands. Each Cu is bound to the 2-N of one triazole ring and the 1-N of another. However, the coordination sphere of each Cu is different, one is five-coordinate and the other two are six-coordinate and bridged by a NO₃ group. The six-coordinate sites are different, one has a terminal NO₃ and the other a MeCN ligand. Magnetic measurements revealed the presence of isotropic and antisymmetric exchange between the copper(II) centers. The data were analyzed using the Hamiltonian containing isotropic exchange for an isosceles triangle together with antisymmetric exchange: H = –J₁(S₁S₂ + S₂S₃)?J₂S₁S₃ + G[S₁ × S₂ + S₂ × S₃ + S₃ × S₁]. Compound 1 exhibits strong antiferromagnetic coupling with J₁ = ?180 and J₂ = ?118 cm^?1 and antisymmetric exchange with G_z = 15 cm^?1. Stopped flow spectrophotometric studies show that the formation of 1 occurs in three distinct phases and the kinetics of each phase has been determined.     

Synthesis,crystal structures,and magnetic properties of methoxido-bridged dinuclear MnIII complexes derived from tri-dentate chelating ligands

Two new doubly methoxido-bridged Mn^III dinuclear complexes, [Mn^III(mphp)(μ-OCH₃)(CH₃OH)]₂·2CH₃OH (1) and ([Mn^III(ahbz)(μ-OCH₃)(CH₃OH)]₂·2CH₃OH (2), have been synthesized by using the tridentate ligands H₂mphp (H₂mphp = 2-methyl-6-(pyrimidin-2-yl-hydrazonomethyl)-phenol) and H₂ahbz (H₂ahbz = N-(2-amino-propyl)-2-hydroxy-benzamide). The complexes have been characterized by single-crystal X-ray diffraction analysis and magnetic measurements. Complexes 1 and 2 have a similar dimeric molecular structure. Two [Mn(L)(CH₃OH)]⁺ moieties (L^2? = mphp^2? or ahbz^2?) are bridged by two μ-OCH₃^? groups in the axial-equatorial asymmetric manner. The coordination geometry of Mn^III is an axially elongated octahedron with two oxygens of a methanol ligand and a methoxido ligand situated at the axial positions. Magnetic measurements indicate that 1 and 2 exhibit antiferromagnetic behavior with the fitting parameter of J = ?1.49(3) cm^?1, D = ?1.3(1) cm^?1, g = 1.98(1) and zJ′ = ?0.18(4) cm^?1 for 1, and J = ?1.6(2) cm^?1, D = 4.5(3) cm^?1, g = 2.06(1) and zJ′ = 1.4(1) cm^?1 for 2 on the basis of the spin Hamiltonian ? = ?2J?_Mn1?_Mn2.     

Two tetranuclear Ni(II) complexes from substituted imidazole dicarboxylates: syntheses,structures, thermal and magnetic properties

Two tetranuclear nickel(II) complexes, [Ni₄ (p-BrPhHIDC)₄(py)₄(H₂O)₄]·CH₃OH (p-BrPhH₃IDC = 2-(p-bromophenyl)-1H-imidazole-4,5-dicarboxylic acid) (1) and [Ni₄(p-ClPhHIDC)₄ (CH₃CN)₄(H₂O)₄]·4H₂O (p-ClPhH₃IDC = 2-(p-chlorophenyl)-1H-imidazole-4,5-dicarboxylic acid, py = pyridine) (2), have been solvothermally synthesised and structurally characterised. Both compounds consist of similar tetranuclear Ni(II) cores, in which the imidazole dicarboxylate ligands adopt the similar coordination mode. The thermal properties of 1 and 2 have been investigated. Also, it is discovered that there exists antiferromagnetic coupling between the Ni(II) ions in 1 and 2; the best fittings to the experimental magnetic susceptibilities gave J = ? 9.89 cm^? 1 and g = 2.18 for 1, and J = ? 10.54 cm^? 1 and g = 2.14 for 2.     

Mono-, di-, and trinuclear phosphonate oxygen-bridged copper(II) complexes: syntheses,structures, and properties

Reactions of copper salts, zoledronic acid, and 2,2′-bipyridine/1,10-phenanthroline in aqueous ethanolic solutions afforded four phosphonate oxygen-bridged copper complexes, Cu(bipy)(H₄zdn)(HSO₄) (1), [Cu₂(bipy)₂(H₂zdn)(H₂O)(Cl)]·4H₂O (2), [Cu₂(phen)₂(H₂zdn)(H₂O)(Cl)]·2.5H₂O (3), and [Cu₃(bipy)₃(H₄zdn)(H₂zdn)(SO₄)]·5H₂O (4) (H₅zdn = zoledronic acid, bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline). The copper centers of 1–4 have square pyramidal coordination geometries. The Cu(II) ions are coordinated to bipy/phen, zoledronate, and HSO₄^?/Cl^? forming mononuclear units for 1, dinuclear for 2 and 3, and trinuclear for 4. These building units are further extended into 3-D supramolecular networks via multiple hydrogen bond interactions. Temperature-dependent magnetic properties of 2 and 4 suggest weak antiferromagnetic coupling (J = ?4.53(8) cm^?1 for 2, J = ?1.69(4) cm^?1 for 4). The antitumor activity of 2 was evaluated against the human lung cancer cell line and indicates effective time- and dose-dependent cytotoxic effects.     

Ferromagnetic copper(II)–copper(II) interaction in a single chlorido and dicyanamido bridged mixed–valence copper(I/II) 2-D polymer generated by in situ partial reduction of copper(II)

A mixed-valence 2-D Cu(I/II) complex, [{Cu(II)(dmen)(μ-Cl)(μ_1,5-dca)}{Cu(I)(μ_1,5-dca)}]_n (1) (dmen = N,N-dimethylethylenediamine, dca = dicyanamide = [N(CN)₂]^?), has been synthesized by in situ partial reduction of Cu(II) to Cu(I) using benzoin (2-hydroxy-1,2-di(phenyl)ethanone) as reductant. Complex 1 was characterized by spectroscopic techniques, single crystal X-ray diffraction, and low temperature magnetic measurements. Structural investigation reveals that 1 represents a mixed-valence 2-D coordination polymer formed by parallel 1-D [Cu(II)(dmen)(Cl)Cu(I)(μ_1,5-dca)₂]_n chains running along the b axis, where chloride bridges Cu(II) ions of adjacent polymers through long connections (2.8401(1) Å) to form a 2-D network. The metal centers have two different geometrical environments (distorted square pyramidal and distorted trigonal planar geometries for Cu(II) and Cu(I), respectively). The Cu(II) ions in [Cu(II)(dmen)(μ-Cl)(dca)]_n are interconnected through single chloride bridges while within the [Cu(I)(μ_1,5-dca)]_n units, the dca connects adjacent Cu(I) ions through μ_1,5-dca bridges. Magnetic susceptibility measurements reveal weak ferromagnetic interactions (J = +0.3 cm^?1) within the chlorido-bridged Cu(II) regular chain present in 1. Simultaneous presence of μ_1,5-dca and single chlorido bridges with ferromagnetic coupling is believed to be unique in mixed-valence Cu(I)/Cu(II) complexes.     

Syntheses,structural characterizations and microbial activities of Ni(II) and Zn(II) 5-aminoisophthalate coordination polymers

Two coordination polymers with 5-aminoisophthalic acid (H₂aip), [Ni(μ-aip)(H₂O)₂(tmeda)]_n (1) and {H₂dap[Zn₂(μ-aip)(μ₃-aip)₂]?9H₂O}_n (2) (H₂aip = 5-aminoisophthalic acid, tmeda = N,N,N′-N′-tetramethylethylenediamine, dap = 1,3-diaminopropane) have been synthesized. Elemental and thermal analyses, magnetic susceptibilities, IR, AAS, mass and UV–vis spectroscopic studies have been performed to characterize the compounds. Nickel(II) has octahedral geometry by two oxygens of different carboxylates, bidentate, tmeda as bidentate chelating and two water ligands. Zn(II) has tetrahedral geometry by three oxygens of different carboxylate groups and one nitrogen by amine of aip. 1 crystallizes in the orthorhombic crystal system with space group Pccn and 2 in monoclinic crystal system with space group P2₁/c. Complex 2 exhibits photoluminescence properties in the solid state at room temperature. This study determined the susceptibility patterns of 1 and 2 against bacterial, yeast and mold micro-organisms. Antimicrobial activities were done on 12 different micro-organisms using the micro-dilution method. Tested microbial species were inhibited by 1 with a Minimum inhibitory concentrations (MIC) of 375–3000 μg mL^?1. Compound 2 showed antimicrobial activities against tested micro-organisms with a MIC of 188–1500 μg mL^?1. Compound 2 showed antibacterial activity against Legionella pneumophila sg1 375 μg mL^?1 (MIC value).     

Structural diversity for three Zn(II) coordination polymers from 4-nitrobenzene-1,2-dicarboxylate and bispyridyl ligand

Three Zn(II) complexes, [Zn₂(bpp)₂(FNA)₂]·H₂O (1), [Zn(bpp)(FNA)]·H₂O (2), and Zn₂(bpp)₂(FNA)₂ (3) (bpp = 1,3-bi(4-pyridyl)propane, H₂FNA = 4-nitrobenzene-1,2-dicarboxylic acid), were synthesized and characterized by single-crystal and powder X-ray diffraction methods, IR spectroscopy, TG analyses, elemental analyses, and fluorescent analysis. In 1, the Zn(II) ions are linked by FNA anions and bpp into 2-D layers. The Zn(II) ions in 2 are bridged by FNA anions into chiral chains, which are interlinked by bpp into 3-D metal–organic framework with (6⁵·8) CdS topology. Complex 3 features 1-D zigzag chains, which are interconnected by bpp ligands to give a 3-D framework with (6·7⁴·8)(6⁴·7·8) topology. Complexes 2 and 3 exhibit significant ferroelectric behavior (for 2 remnant polarization Pr = 0.050 μC cm^?2, coercive field Ec = 1.13 kV cm^?1, saturation of the spontaneous polarization Ps = 0.239 μC cm^?2; for 3 Pr = 0.192 μC cm^?2, Ec = 4.64 kV cm^?1, Ps = 0.298 μC cm^?2).     

A 1-D alternating copper(II) chain based on three acetate-bridging modes: synthesis,crystal structure,DNA binding and magnetic properties

A new 1-D alternating copper(II) polymer, [Cu₂(L)(OAc)₄]_n (1) (L = 5-chloro-2-(pyridine-2-yl)benzo[d]thiazole), has been isolated and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, and magnetic susceptibility. The complex crystallized in the triclinic space group P-1, a = 8.2277(16) Å, b = 9.4233(19) Å, c = 15.831(3) Å, α = 103.38(3)°, β = 99.95(3)°, γ = 92.70(3)°, V = 1171.3(4) Å³, and comprises a 1-D polymer linked by three kinds of acetate-bridging modes in an alternating manner. UV–visible and fluorescence spectra revealed that 1 is bound to CT-DNA in a partial intercalation mode. Through gel electrophoresis assays, 1 displayed an efficient oxidative cleavage activity on supercoiled plasmid DNA (pUC19) in the presence of H₂O₂. Magnetic measurements were performed from 2 to 300 K, and the experimental results were satisfactorily reproduced with J₁ = –160 ± 20 cm^?1, J₂ = 5.8 ± 0.2 cm^?1, zJ′ = 0.381 ± 0.005 cm^?1 and g = 2.1, showing antiferromagnetic coupling between Cu1 and Cu1i, ferromagnetic exchange between Cu2 and Cu2ii, and a weak ferromagnetic molecular field correction accounting for all interspecies interactions.     

2-D coordination polymers of copper and cobalt with 3,4-pyridinedicarboxylic acid: synthesis,characterization, and crystal structures

Two new complexes involving 3,4-pyridinedicarboxylic acid (3,4-H₂pdc), copper(II) and cobalt(II) complexes, {[Cu(3,4-Hpdc)₂(H₂O)₂]·2dmso}_n (1) and {[Co(3,4-Hpdc)₂(H₂O)₂]·2H₂O·2dmso}_n (2) (dmso = dimethylsulfoxide), have been synthesized by the diffusion method and characterized by elemental analysis, IR spectroscopy, thermal analysis, powder and single-crystal X-ray diffraction analysis, and electron paramagnetic resonance (EPR). In both compounds, the metal coordination sphere is composed of a trans-MO₄N₂ core and adopts a distorted octahedral geometry in accordance with X-ray diffraction and EPR results. 3,4-Hpdc^? ligands bridge the metal centers giving two-dimensional (2-D) coordination polymers with four-connected uninodal nets of (4,4) topology.     

A new end-on azido-bridged dicopper(II) complex; syntheses,structure, solvatochromism,magnetic properties,and DFT study

Abstract

A new asymmetric azido-bridged dinuclear copper(II) complex with formula [L(N₃)Cu(μ_N,N-N₃)]₂, L = N,N-dimethyl-N′-benzyl-ethylenediamine, has been synthesized and characterized structurally and magnetically. Single-crystal structural analysis reveals the Cu(II) ions are linked by two end-on azido nitrogen atoms. The copper(II) ions adopt s penta-coordinated geometry that is intermediate between square pyramidal and trigonal bipyramidal (τ = 0.528). Variable temperature magnetic susceptibility data were collected and fitted to the appropriate equations derived from the Hamiltonian H = ?JS₁S₂ that show antiferromagnetic intradimer interactions with J = ?1.0 cm^?1 through the end-on azido bridges between the metal centers. To rationalize the magnetic behavior, a DFT calculation has been performed within the broken symmetry framework. The analyses of the magnetic orbital interaction and spin distribution indicate the nature of the magnetic properties of the complex. The complex is solvatochromic and its solvatochromism was investigated by visible spectroscopy. To explore the mechanism of interaction between the solvent molecules and the complex, different solvent parameters were utilized and analyzed by a statistical method using the multiple linear regression (MLR) method. It was found that the hydrogen bond donation (β) and polarity/polarizability (π*) parameters of the solvents lead to the solvatochromism property.     

A new oxamido-bridged dinuclear copper(II) complex with large antiferromagnetic exchange interactions

A new oxamido-bridged dinuclear compound [Cu₂(µ-pmox)(DMF)₄]?·?2ClO₄ (1) (H₂pmox?=?N,N′-bis-(2-methylpyridyl)oxalamide, DMF?=?dimethylformamide) was synthesized and structurally characterized. The five-coordinate Cu(II) is bridged by oxamido groups and further cross-linked by C–H···O hydrogen bonds between the uncoordinated oxygen of perchlorate and methyl of DMF. The complex was also characterized by infrared spectroscopy and magnetic measurement. The copper complex exhibits strong antiferromagnetic interactions via the trans oxamido bridge with J of ?414?cm^?1, where J is the exchange parameter in the isotropic Hamiltonian H?=??JS₁S₂.     

Synthesis,spectroscopic, and crystallographic characterizations of an antiferromagnetically coupled,oxobridged trinuclear manganese(IV) cluster [Mn3O4(H2O)2(phen)4](NO3)4 · 3H2O [phen = 1,10-phenanthroline]

Design and synthesis of a triangular manganese compound, [Mn₃O₄(H₂O)₂(phen)₄](NO₃)_4?·?3H₂O (1) with mono-µ-oxo and di-µ-oxo, is described. The complex has been characterized by elemental analysis, spectroscopy, single crystal and powder diffraction measurements, thermogravimetric analysis, etc. Bond Valence Sum calculations and X-ray photoelectron spectroscopy reveal that each manganese at each vertex of the triangle is +IV oxidation state. Variable temperature magnetic measurements show strong antiferromagnetic coupling between metal ions with the following set of parameters: g?=?1.99, J ₁?=??50.0?cm^?1, and J ₂?=??90.2?cm^?1 (where J ₁ describes the interaction across the two mono-µ-oxo bridges and J ₂ is the exchange coupling across the di-µ-oxo bridge). The compound breaks down in three steps when heated from room temperature to 900°C. The final ash of the compound is confirmed by infrared spectrum with standard MnO₂.     

Two copper complexes based on nitronyl nitroxide with different halides: structures and magnetic properties

Complexes based on different halogen-substituted nitronyl nitroxide radicals and Cu(II), Cu₃(hfac)₆(NIT-Ph-F)₂ (1) and Cu₃(hfac)₆(NIT-Ph-Cl)₂ (2) (hfac = hexafluoroacetylacetonate; NIT-Ph-F = 2-(4′-fluorophenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide; NIT-Ph-Cl = 2-(4′-chlorphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), were synthesized and characterized structurally and magnetically. X-ray crystal structure analyses show that 1 and 2 have similar centrosymmetric five-spin structures consisting of three Cu(II) ions bridged by two nitroxide ligands. The Cu(II) is coordinated by six oxygens to form an octahedron, while the five coordination of the terminal Cu(II) ion is square pyramidal. Magnetic measurements reveal strong antiferromagnetic interactions between Cu(II) ions and radicals in 1 (J = ?38.9 cm^?1) and weak antiferromagnetic interactions between Cu(II) ions and radicals in 2 (J = ?1.23 cm^?1), which may be explained by the bond length of the Cu–O_rad (2.468(2) Å) in 1, which is shorter than that (2.514(2) Å) in 2, and the dihedral angle (73.17(1)°) of the plane O7–O8–Cu(2)–O7A–O8A with the moiety O5–N1–C11–N2–O6 in 1 is smaller than (77.82(1)°) in 2.     

Synthesis,crystal structures,spectral, electrochemical and magnetic properties of di-µ-phenoxido-bridged dinuclear copper(II) complexes with N-salicylidene-2-hydroxybenzylamine derivatives: axial coordination effect of dimethyl sulphoxide molecule

The template reaction of salicylaldehyde and its substituted derivatives and 2-hydroxy-5-bromobenzylamine or 2-hydroxy-5-chlorobenzylamine with copper(II) acetate in dimethyl sulphoxide (dmso) afforded eight dinuclear Cu(II) complexes, [Cu₂(L)₂(dmso)₂] (H₂ L = N-salicylidene-2-hydroxy-5-bromobenzylamine, N-salicylidene-2-hydroxy-5-chlorobenzylamine and their 5-bromo, 5-nitro and 5-methyl-substituted salicylidene derivatives). These Cu(II) complexes were characterised by IR and UV-VIS-NIR spectroscopy, electric conductivity, cyclic voltammetry, and temperature dependence of magnetic susceptibilities (4.5–300 K). In the THF solution, the complexes are nonelectrolytes and exhibit a characteristic CT band due to phenoxido-bridging at 360–384 nm. In the cyclic voltammograms, an irreversible reduction process was observed at ?1.18–1.54 V vs Fc/Fc⁺. Single-crystal X-ray crystallography revealed that two Cu(II) ions were bridged by the two phenoxido-oxygen atoms of the two Schiff-base ligands with axial coordination of dmso molecules forming a square pyramid with a Cu-Cu distance of 3.0628(8)–3.0931(6) °A. In accordance with the crystal structures, the magnetic interaction between the two Cu(II) ions is relatively anti-ferromagnetic with ?2J value of 386–575 cm^?1. The axial coordination effect of the dmso molecule was discussed in relation to the correlation between the Cu-O-Cu angle and the ?2J value.     

Syntheses,structural determination,and binding studies of nine-coordinate multinuclear (mnH)2[EuIII(egta)]2·6H2O and binuclear (mnH)4[EuIII2(dtpa)2]·6H2O

Two lanthanide complexes, (mnH)₂[Eu^III(egta)]₂·6H₂O (1) (H₄egta = ethyleneglycol-bis-(2aminoethylether)-N,N,N′,N′-tetraacetic acid) and (mnH)₄[Eu^III₂(dtpa)₂]·6H₂O (2) (H₅dtpa = diethylenetriamine-N,N,N′,N″,N″-pentaacetic acid), have been synthesized and characterized by FT-IR spectroscopy, thermal analysis, and single-crystal X-ray diffraction. X-ray diffraction reveals that 1 is multinuclear nine-coordinate and crystallizes in the monoclinic crystal system with space group C2/c. The obtained cell dimensions are a = 38.513(3)?Å, b = 13.5877(8)?Å, c = 8.7051(5)?Å, β = 99.6780(10)°, and 4490.6(5)?ų. Each methylamine (mnH⁺) cation in 1, through hydrogen bonds, connects three adjacent [Eu^III(egta)]^? anions. The [Eu^III(egta)]^? anions connect one another forming a 1-D multinuclear zigzag chain structure along the c-axis. Complex 2 is nine-coordinate binuclear structure with tricapped trigonal prismatic conformation and crystallizing in the monoclinic crystal system, but with space group P2₁/n. The obtained cell dimensions are a = 9.9132(8)?Å, b = 24.1027(18)?Å, c = 10.7120(10)?Å, β = 109.1220(10)°, and 2418.2(3)?ų. For 2, there are two kinds of methylamine cations (mnH⁺) connecting [Eu^III₂(dtpa)₂]^4? complex anions and lattice waters through hydrogen bonds, leading to formation of a 2-D ladder-like layer structure.     

Variation in crystalline architectures through supramolecular interactions in copper(II) complexes with tridentate N2O donor Schiff bases

Three copper(II) complexes, [Cu(L¹)(H₂O)(ClO₄)]·0.5H₂O (1), [Cu(L²)(H₂O)(ClO₄)]·0.5H₂O (2), and [Cu(L²)(NCNC(OCH₃)NH₂)]ClO₄ (3), where HL¹ = 4-bromo-2-(-(quinolin-8-ylimino)methyl)phenol and HL² = 1-(-(quinolin-8-ylimino)methyl)naphthalen-2-ol, have been prepared and characterized by elemental analysis, IR, UV–vis and fluorescence spectroscopy and single-crystal X-ray diffraction studies. The copper(II) centers assume five-coordinate square-pyramidal geometries in 1 and 2, whereas square planar copper(II) is present in 3. A methanol molecule has been inserted in the pendant end of the ligated dicyanamide in 3. Various supramolecular architectures are formed by hydrogen bonding, π?π, C–H?π, and lp?π interactions.     

Syntheses,crystal structures,and magnetic properties of 1-D coordination polymers

Three coordination polymers of Robson-type macrocycles, {[Cu₄L¹(4,4′-bipy)₂]·4ClO₄·H₂O}_∞ (1), {[Cu₄L²(4,4′-bipy)₄]·2CH₃CN·4ClO₄·2H₂O}_∞ (2), and {[Zn₂L²(4,4′-bipy)₂]·(ClO₄)₂}_∞ (3) (where H₂L¹ and H₂L² are the [2?+?2] condensation products of 1,3-diaminopropane with 2,6-diformyl-4-methylphenol and 2,6-diformyl-4-fluorophenol, respectively), have been synthesized and characterized. Magnetic susceptibility was measured for 1 and 2 from 2 to 300?K. The optimized magnetic data were J?=?–368.5?cm^?1, J′?=?40.5?cm^?1 with R?=?1.69?×?10^?6 for 1 and J?=?–291.22?cm^?1, J′?=?83.74?cm^?1, ρ = 0.00168 with R?=?1.8?×?10^?11 for 2, respectively. The data reveal strong antiferromagnetic interactions between two Cu(II) ions in the macrocyclic unit and ferromagnetic interaction between the Cu(II) ions in two adjacent macrocyclic units for 1 and 2.