Cobalt(II) complexes with pentadentate Schiff bases 2,6-diacetylpyridine hydrazones: Syntheses and structures

Seven new cobalt(II) complexes based on the Schiff bases, 2,6-diacetylpyridine bis(isonicotinoylhydrazone) (H₂L¹) and 2,6-diacetylpyridine bis(nicotinoylhydrazone) (H₂L²), are synthesized and studied by X-ray diffraction analysis: [Co(H₂L¹)(NCS)₂] · 2.25H₂O (I), [Co(H₂L²)(NCS)₂] · CH₃OH (II), [Co(H₂L²)(NCS)(H₂O)]NCS (III), [Co(H₄L¹)(NCS)₂](NO₃)₂ · 2H₂O (IV), [Co(H₄L¹)(NCS)₂][Co(NCS)₄] · 0.75H₂O (V), [Co(H₄L²)(NCS)₂][Co(NCS)₄] · 1.75H₂O (VI), and [Co(H₂L²)(NCS)(CH₃OH)]₂[Co(NCS)₄] · 2CH₃OH (VII) (CIF files CCDC 941186 (I), 1457906 (Ia), 1457905 (II), 941187 (III), 1457907 (IV), 1457908 (V), 1457909 (VI), and 941188 (VII)). The organic ligands in the complexes act as pentadentate neutral H₂L or doubly protonated (H₄L)²⁺ coordinated through the same set of donor atoms N₃O₂. In all compounds I–VII, the coordination polyhedron of the Co²⁺ ion in a complex with the Schiff bases has a shape of a pentagonal bipyramid. The hydrazones are arranged in the equatorial plane of the bipyramid. Its axial vertices are occupied by the nitrogen atoms of the NCS￣ anions in compounds I, II, and IV–VI and by the nitrogen atoms of NCS￣ and oxygen of the water molecule in compound III or methanol in compound VII. The NO ₃ ^- anions or [Co(NCS)₄]^2￣ complex anions obtained by the reactions are involved along with the NCS￣ anions in the formation of compounds IV–VII.     

Four Mixed 3d-4f 12-Metallacrown-4 Complexes: Syntheses,Structures and Magnetic Properties

The incorporation of Ln^III ions into the 12-metallacrown-4 topology affords the formation of four mixed 3d-4f pentanuclear complexes of compositions [NH(C₂H₅)₃]{[Ln(OAc)₄] [12-MC _Mn ^III _(N)shi-4]}·xH₂O (Ln = Sm (1), Gd (2), Tb (3), Dy (4); x = 0.5 for 1 and 3, x = 0.25 for 2, x = 0 for 4; H₃shi = salicylhydroxamic acid). Compounds 1–4 were obtained from the reactions of H₃shi with Mn(CH₃COO)₂·4H₂O and Ln(NO₃)₃·6H₂O, in the presence of N(C₂H₅)₃. They all contain a crown-like [Mn₄Ln(μ-NO)₄]¹¹⁺ core with four Mn^III atoms being at the rim of the crown and an Ln^III ion occupying the dome of the crown. The peripheral ligation about the core is provided by four η¹:η¹:µ acetate groups. The identity of the Ln^III ions slightly affects the 12-metallacrown-4 frameworks, as demonstrated by the gradual decrease of the distances between the Ln^III ions and the centres of the Mn₄ planes (1.85 Å for 1, 1.81 Å for 2, 1.80 Å for 3, and 1.77 Å for 4). Variable-temperature dc magnetic susceptibility studies were carried out on polycrystalline samples of 1–4. Antiferromagnetic interactions are determined for complexes 1–4.     

New catecholate complexes of triphenylantimony(V) based on 6-iminomethyl-3,5-di-<Emphasis Type="Italic">tert</Emphasis>-butylpyrocatechols N-functionalized by the aniline or phenol group

The following new triphenylantimony(V) catecholate complexes bearing the protonated imine group are synthesized from the new sterically hindered 3,5-di-tert-butylpyrocatechols (6-(CH=N-o-(C₆H₄–NH₂))-3,5-Cat)H₂ (H₂L¹) and (6-(CH=N-o-(C₆H₄–OH))-3,5-Cat)H₂ (H₂L²) containing in position 6 the iminomethyl group bonded to the aniline or phenol substituent: (6-(CH=NH⁺-o-(C₆H₄–NH₂))-3,5-Cat)SbPh₃X (X = Br (I), OMe (III)) and (6-(CH=NH⁺-o-(C₆H₄–OH))-3,5-Cat)SbPh₃X (X = Br (II), OMe (IV)). The molecular structure of complex III · CH ₃ OH in the crystalline state is determined by X-ray diffraction analysis (CIF file CCDC no. 1554694). The electrochemical properties of complexes III and IV are studied by cyclic voltammetry.     

New approach to the synthesis of polynuclear heterometallic pivalates with iron and manganese atoms

New hexanuclear Fe(III)–Mn(II, III) pivalates [Fe₂ ^III Mn₄ ^II(O)₂(Piv)₁₀(HPiv)₄] (I) or [Fe₄ ^III Mn₂ ^III(O)₂(Piv)₁₂(CH₂O₂)(HPiv)₂] · Et₂O (II) are synthesized using the solid-state thermolysis of [Fe₂Mn(O)(Piv)₆(HPiv)₃] (90°С). Complexes I and II differ by the ratio of iron and manganese ions, which depends on the atmospheric composition during thermolysis. The structures of compounds I and II are determined by X-ray diffraction studies. According to the parameters of the Mössbauer spectrum, complex I contains the Fe³⁺ ions in the high-spin state in the octahedral environment of oxygen atoms.     

Synthesis,crystal structures,and properties of copper(II) dicarboxylate complexes with [bis(2-pyridylcarbonyl)amido]

Four new complexes, [Cu₂(Bpca)₂(L¹)(H₂O)₂] · 3H₂O (I), [Cu₂(Bpca)₂(L²)(H₂O)₂] (II), [Cu₂(Bpca)₂(L³)] · 2H₂O (III), [Cu₂(Bpca)₂(L¹)(H₂O)] · 2H₂O (IV) (Bpca = bis(2-pyridylcarbonyl)amido, H₂L¹ = glutaric acid, H₂L² = adipic acid, H₂L³ = suberic acid, H₂L⁴ = azelaic acid) have been synthesized and characterized by single-crystal X-ray diffraction methods (CIF files CCDC nos. 1432836 (I), 1432835 (II), 817411 (III), and 817412 (IV)), elemental analyses, IR spectra. Structural analyses reveal that compounds I, II, and IV have similar structures [Cu(Bpca)]⁺ units bridged by dicarboxylate forming dinuclear units, whereas the dinuclear of compound III are edge-shared through two carboxylate oxygen atoms of different suberate anions. Hydrogen bonds are response for the supramolecular assembly of compounds I to IV. The temperature-dependent magnetic property of III was also investigated in the temperature range of 2 to 300 K, and the magnetic behaviour suggests weak antiferromagnetic coupling exchange.     

Hydrogen-Bond Directed Cyanide-Bridged Supramolecular 2D and 1D Bimetallic Coordination Polymers: Synthesis,Crystal Structure,and Magnetic Properties

By using K₂[Ni(CN)₄] as a building block and two Mn(III) compounds containing bicompartimental Schiff-base ligands as assembling segments, two new cyanide-bridged Ni–Mn complexes of the formula {[Mn(L¹)(H₂O)]₄[Ni(CN)₄]}[ClO₄]₂·2CH₃CN (1) and {[Mn(L²)(H₂O)]₂[Ni(CN)₄]}·CH₃CN H₂O (2) (L¹ = N,N’-1,2-propylene-bis(3-methoxysalicylideneiminate; L² = N,N’-1,2-propylene-bis(3-ethoxysalicylideneiminate) have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray analysis. Single Xray diffraction analysis revealed the cationic pentanuclear and neutral trinuclear structures for complexes 1 and 2, respectively, and indicated that the structure of the Schiff-base ligand had obvious influence on the structural types of the target cyanide-bridged complexes. Both cyanide-bridged complexes are self-complementary via coordinated aqua ligand from one complex and the free O₄ compartment from the neighboring complex, therefore giving supramolecular two-dimensional network and one-dimensional zig-zag chain structure. Study of magnetic properties revealed weak antiferromagnetic coupling within the Mn₂ dimer formed by the intermolecular hydrogen bond.     

Four novel metal–organic frameworks based on 3,4,7,8-tetramethyl-1,10-phenanthroline: Syntheses,structures, and thermal properties

Four novel metal–organic frameworks, [Cu(Tmp)₂(H₂O)] · NO₃ (I) (Tmp = 3,4,7,8-tetramethyl-1,10-phenanthroline), [Mn(Tmp)₂(H₂O)₂] · 2NO₃ · H₂O (II), [Pb(Tmp)(CH₃COO)₂] · 3H₂O (III) and [Zn(Tmp)₂(H₂O)₂] · 2NO₃ · 2H₂O (IV), have been synthesized and characterized by single crystal X-ray diffraction (CIF files CCDC nos. 88362–88365 for I–IV, respectively), IR spectroscopy, elemental analysis and thermogravimetric analysis. Both I and II complexes are crystallized in monoclinic system with space groups C2/c, P2₁/c, respectively, while III and IV complexes are crystallized in triclinic system with space groups \(P\overline 1 \). Generally, these crystal structures are stabilized by O–H···O hydrogen bonds and π–π interactions between the phenanthroline rings of neighboring molecules. Thermogravimetric analyses of compounds I–IV display considerable thermal stability.     

Tetraphenylphosphonium carboxylates and sulfonates. Synthesis and structure

The reaction of the pentaphenyphosphorus solvate Ph₅P·1/2PhH (I) with carboxylic and sulfonic acids was used to synthesize tetraphenylphosphonium carboxylates Ph₄POC(O)R, R = C₆H₄(2-OH) (II), C₆H₄ (2-COOH) (III), H (IV), Me (V), CCl₃ (VI), Ph (VII), PhCH=CH (VIII), CH₂CH₂C(O)OH (IX), CH=CHC(O) OH(X), and CH₂C(O)OH (XI) and tetraphenylphosphonium sulfonates Ph₄POSO₂Ar, Ar = Ph (XII), C₆H₄Me₄ (XIII), and C₆H₃(-COOH)(4-OH) (XIV). Compound XII was also prepared from compound I and SO₃ in benzene. According to X-ray diffraction data, the crystals of I contain two types of crystallographically independent molecules with a slightly distorted trigonal-bipyramidal configuration [Ia, CaxPCax 178.44(8)°, P- C_ax 1.985(2), 1.987(2) Å, P-C_eq 1.854(2), 1.846(2), 1.840(2) Å; Ib, C_axPC_ax 178.45(9)°, P-C_ax 1.980(2), 1.975 (2) Å, P-C_eq 1.840(2), 1.846(2), 1.854(2) Å]. In the cations of compounds II, III and XIV, the coordination of the phosphorus atom is tetrahedral [CPC angle: II, 106.2(2)?111.6(1)°; III, 104.01(6)?113.03(6)°; XIV, 107.54 (6)?112.79(6)°]; the anions contain intramolecular O-H?O hydrogen bonds between the hydroxyl hydrogen atom and carboxyl oxygen atom (II, 1.34; III, 1.23; and XIV, 1.83 Å).     

Copper(II) coordination compounds with 8-quinolinaldehyde semicarbazone: Synthesis and structure

A series of compounds of the general formula Cu(HL)X₂ · nH₂O (compound I, X = ClO₄, n = 3; compound II, X = NO₃, n = 2; compound III, X = Cl, n = 0.5; compound IV, X = 1/2SO₄, n = 0) is isolated by the reactions of the copper(II) salts with quinolinaldehyde semicarbazone (HL). Regardless of the reactant ratio, only the compounds with a metal to ligand mole ratio of 1: 1 are formed, where the organic reactant is coordinated in the molecular form. The X-ray diffraction analyses of the [Cu(HL)(NO₃)(H₂O)](NO₃) · H₂O (II) and [Cu(HL)Cl₂] · 0.5H₂O(III) compounds show their substantially different organizations of the molecular structures depending on the specifics of the acido ligand. An ionic structure with one NO ₃ ^? anion incorporated into the inner coordination sphere of the metal as a bidentate chelate ligand is observed in compound II. Molecular tetragonal pyramidal complexes associated into a dimer due to the bridging function of one coordinated Cl^? anion are formed in structure III. The coordination polyhedron of the copper atom in structures II and III is an asymmetrically extended tetragonal bipyramid. The CuClCu angle equal to 90° and the distance between two planes in compound III equal to 2.978 Å determine the insignificant antiferromagnetic interaction in this compound (g = 2.1, J = ?2.5 cm^?1).     

Ni(II) complexes with optically active bis(menthane), pinano-para-menthane ethylenediaminodioximes and pinano-para-menthane, bis(pinane) propylenediaminodioximes: Synthesis, structures, and properties

Reactions of Ni(NO₃)₂ · 6H₂O) in EtOH(iso-PrOH) with optically active bis(menthane) ethylene-diaminodioxime (H₂L¹), pinano-para-menthane ethylenediaminodioxime (H₂L²), pinano-para-menthane propylenediaminodioxime (H₂L³) and bis(pinane) propylenediaminodioxime (H₂L⁴) were used to synthesize [Ni(H₂L¹)NO₃[NO₃ · 2H₂O (I), [Ni(HL²)]NO₃ (II), [Ni(HL³)]NO₃ (III), and [Ni(HL⁴)]NO₃ (IV). X-ray diffraction study of paramagnetic complex I (μ_eff = 3.04 μB and diamagnetic complexes II and III revealed their ionic structures. A distorted octahedral polyhedron N₄O₂ in the cation of complex I is formed by the N atoms of tetradentate cycle-forming ligand, i.e., the H₂L¹ molecule, and the O atoms of the NO ₃ ^? anion acting as a bidentate cyclic ligand. In the cations of complexes II and III, containing a pinane fragment, the coordination core NiN₄ has the shape of a distorted square formed on coordination of tetradentate cycle-forming ligands, i.e., anions of the starting dioximes. The structure of diamagnetic complex IV is likely to be similar to the structures of complexes II and III.     

Transition metal complexes of a hydrazone derived from hydralazine hydrochloride and 3,5-di-tert-butylsalicylaldehyde

Mononuclear Co(III), Ni(II) and Cu(II) coordination compounds of (E)-1-(3,5-di-tert-butyl-2-hydroxybenzylidene)-2-(phthalazin-1-yl)hydrazine (LH) were prepared and characterized by physicochemical and spectroscopic methods. The metal-to-ligand ratio was found to be 1:2 in [Co(L)₂]Cl·2H₂O (1) and [Ni(L)₂]·2H₂O (2), while it is 1:1 in [Cu(L)Cl]·2CH₃OH (3). The X-ray crystal structures of LH and complex 1 is are reported. LH shows monobasic behavior, coordinating through NNO donor atoms. The complexes were investigated for their antimicrobial properties. Complexes 1 and 3 show excellent antibacterial and antifungal activities, respectively.     

Three new manganese(II) coordination complexes based on tetrazole carboxylate ligands

Reactions of three tetrazole carboxylate ligands, namely 5-(4-pyridyl)tetrazole-2-acetic acid (Hpytza), 1,3,5-tris(tetrazol-5-yl)benzene-N2,N2′,N2″-triacetic acid (H₃tzpha) and 5-aminotetrazole-1-propanoic acid (Hatzpa) with Mn(NO₃)₂·6H₂O in the presence of KOH afforded three new complexes, [Mn(pytza)₂] (1), [Mn₃(tzpha)₂(H₂O)₁₂]·2CH₃OH·10H₂O (2) and [Mn(atzpa)₂(H₂O)₂] (3), respectively. These complexes were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Complex 1 displays a three-dimensional network while 2 and 3 show one-dimensional chains. Furthermore, the luminescence properties of these complexes were investigated at room temperature in the solid state.     

Three metal complexes based on tetrazolyl ligands: Hydrothermal syntheses,crystal structures,and fluorescence properties

Three new complexes based on 1-tetrazole-4-imidazole-benzene (Tibz), namely, [Cd(Tibz)₂(H₂O)₂] _n (I), [Mn(Tibz)₂(H₂O)₄] · 2H₂O (II) and [Co(Tibz)₂(H₂O)₄] · 2H₂O (III) have been synthesized through hydrothermal method and structurally characterized by element analyses, IR spectroscopy and single-crystal X-ray diffraction analyses (CIF files CCDC nos. 1443867 (I), 1443868 (II), 1443869 (III)). Single-crystal X-ray diffraction reveals that complex I is a 1D double-chain architecture, II and III are both mononuclear complexes. The results of single-crystal X-ray diffraction analyses indicate that the hydrogen bond and π··· π stacking exist in the complexes, which make great contribution to the stabilities of complexes I–III. The fluorescent properties of these complexes have also been studied in the solid state at room temperature.     

Synthesis,crystal structure,and magnetic characterization of two manganese Schiff-base-containing complexes

The reactions of [Mn^III(3-MeOSalen)(H₂O)₂]⁺ (Salen = N,N-ethylenebis(salicylideneaminato) dianion) with (Et₄N)₄[M(CN)₈] (M = Mo, W) have been investigated and one mononuclear manganese(II) complex [Mn^II(Salen)(H₂O)] (I) and one bimetallic ion-pair complex [Mn^III(3-MeO-Salen)(H₂O)₂]₄[W(CN)₈] · DMSO · 4H₂O (II) were obtained unexpectedly and characterized by element and single crystal structure analysis. Single crystal X-ray diffraction (CIF files CCDC nos. 1456365 (I) and 1456366 (II)) showed that the Mn²⁺ ion in complex I is five-coordinated involving in a distorted square pyramid. Furthermore, with the help of the intermolecular hydrogen bond interactions, this complex can be constructed into interesting one-dimensional zig-zag chain structure. For complex II, the coordination sphere of Mn³⁺ ion is an elongated octahedron. Additional, the four mononuclear manganese(III) units are self-complementary through the coordinated aqua ligand from one molecule and the free O(4) compartment from the neighboring molecule, giving supramolecular dimmers structure. Investigation of the magnetic susceptibility of the two complexes reveals the overall weak antiferromagnetic interactions between the adjacent manganese centers caused by H-bond interactions.     

Structure and photoluminescence of Zn(II) and Сd(II) complexes with chiral bis-pyridine containing fragments of natural (–)-α-pinene

Complexes ZnLCl₂ (I) and [CdLCl₂] _n (IV), where L is chiral bis-pyridine containing fragments of natural monoterpenoide (–)-α-pinene are synthesized. Single crystals of [ZnLCl₂]·CH₂Cl₂ (II), [ZnLCl₂]·i-PrOH (III), and IV compounds are grown. The crystal structures of II and III are composed of mononuclear ZnLCl₂ complex molecules and solvate CH₂Cl₂ and i-PrOH molecules; the coordination polyhedron of the zinc atom Cl₂N₂ is a distorted tetrahedron. According to the single crystal XRD data, complex IV is a 1D coordination polymer; the coordination core CdN₂Cl₄ is a distorted octahedron and Cl atoms are bridging ligands. In the structures of II, III, and IV the L molecule functions as a bidentate chelate ligand. In the solid phase, complexes I and IV exhibit photoluminescence in the visible range (λ_max 505 nm and 460 nm respectively). The band intensity in the photoluminescence spectra of I and IV complexes considerably exceeds the band intensity in the spectrum of free L.     

Synthesis and properties of copper(II) complexes with a chiral dioxatetraazamacrocyclic ligand based on a natural monoterpene, (+)-3-carene

The copper(II) compounds [CuL](NO₃)₂ · H₂O (I), [CuL](ClO₄)₂ · H₂O (II), CuLCl₂ · 3H₂O (III), and CuLBr₂ · 4H₂O (IV), where L is a chiral dioxatetraazamacrocyclic ligand based on the natural monoterpene (+)-3-carene, have been synthesized. According to IR and EPR spectroscopy, L acts as a tetradentate chelating ligand coordinated through the N atoms of the NH and C=N groups. The NO ₃ ^? anions in I and the ClO ₄ ^? anions in II are outer-sphere. I and II have a planar coordination core CuN₄, III has a CuN₄ClO coordination core, and IV has a CuN₄Br₂ coordination core.     

Synthesis of five-coordinate manganese(I) carbonyl complex [(CO)<Subscript>3</Subscript>Mn (-S,-Se-C<Subscript>6</Subscript>H<Subscript>3</Subscript>-4-Me)]<Superscript>−</Superscript>: influences of non-innocent ligand to the structure,reactivity and electrochemical property

Oxidative addition of Br₂ to [Mn(CO)₅]^? leads to the formation of [(CO)₄MnBr], followed by the ligand exchange of bromide to [S,Se-C₆H₃-4-Me] ₂ ^2? to form complex (CO)₃Mn (µ-? ⁴-SC₆H₃-4-(CH₃)Se-SeC₆H₃-4-(CH₃)S)Mn(CO)₃ (1). A new five-coordinate complex [(CO)₃Mn(-S,-Se-C₆H₃-4-CH₃)]^? (2) can be synthesized through two different routes: (a) oxidative addition of diselenide [HS,Se-C₆H₃-4-Me]₂ to the [Mn(CO)₅]^? followed by deprotonation and ligand dissociation to generate complex 2; (b) reduction of diselenide bonds of complex 1 by [BH₄]^? to produce 2. Drop-wise addition of HBF₄·OEt₂ at 0 °C results in the formation of complex 1. The X-ray analysis shows that complex 2 has relative short Mn–Se and Mn–S bond distances compare to the published structures of cis-[(CO)₄Mn(EPh)₂]^? (E = S and Se; Liaw et al. in J. Chin. Chem. Soc. 43:427–431, 1996; Liaw et al. in Inorg. Chem. 35:2530, 1996). Interestingly, exposure of the coordinated unsaturated complex 2 under CO_(g) atmosphere resulted in complex cis-[(CO)₄Mn(-S,-Se-C₆H₃-4-Me)]^? (3) being formed. After purging the solution of complex 3 with N₂, it was reconverted completely back to complex 2; this observation was characterized by FTIR. The cyclic voltammetry scan of complex 2 shows a quasi-reversible redox couple with E _1/2 = ?1.94 V and I _pa/I _pc = 0.68. Ligand [HS, Se-C₆H₃-4-CH₃]₂ and complexes 1 and 2 are all characterized by IR, UV–Vis, NMR, EA and X-ray single crystal diffraction.     

Reactions of Chalcogenide β-Diiminate Nickel Complexes with Samarium Bis(pentamethylcyclopentadienide)

The reactions of [(L^iPrNi)₂(μ-η²:η²-S₄)] (I) and [(L^iPrNi)₂(μ-η²:η²-Se₂)] (II) (L^iPr = CH[C(Me)N(2,6- ⁱ Pr₂C₆H₃)]₂) with decamethylsamarocene [Sm(Cp*)₂(Тhf)₂] (Cp* = η⁵-C₅Me₅) are studied. It is assumed that the reactions afford hetero-d/f-metal complexes. However, these complexes are not observed but the transfer of chalcogens from Ni to Sm and the formation of [(Sm(Cp*)₂(Тhf))₂(μ-S)] (III) and [(Sm(Cp*)₂(Тhf))₂(μ-Se)] (IV) occur. The second reaction products are [(L^iPrNi)₂(μ-η²:η²-S₂)] (V) in the case of sulfur and [(L^iPrNi^I)₂(μ-η⁶:η⁶-C₇H₈)₂] (VI) in the case of selenium. All reaction products have been described previously, but compounds III and V are isolated as new crystalline phase, the structures of which are determined by X-ray diffraction analysis (CIF files CCDC nos. 1559045 (V) and 1559046 (III)).     

Cyan-Blue Luminescence and Antiferromagnetic Coupling of CN-Bridged Tetranuclear Complex Based on Manganese(III) Schiff Base and Hexacyanoferrate(III)

A new tetranuclear cyanide-bridged Mn^III–Fe^III complex based on manganese(III) Schiff base and hexacyanoferrate(III) units, [Mn(L)(MeOH)₂][{Mn(L)}{Fe(CN)₆}{Mn(L)(MeOH)}].2MeOH, [H₂L?=?N,N′-bis(2-hydroxy-1-naphthalidenato)-1,2-diaminopropane] (1), has been synthesized and characterized by elemental analysis, UV–Vis, FT-IR, PXRD, single crystal X-ray analyses, magnetic and photoluminescence measurements. Complex 1 consist of one trinuclear cyanido-bridged anion, in which [Fe(CN)₆]^3? anion bridge [Mn(L)]⁺ and Mn(L)(MeOH)}]⁺ cations via two C≡N groups in the cis positions, and also one isolated manganese [Mn(L)(MeOH)₂]⁺ cation. DC magnetic susceptibility and magnetization studies showed that complex 1 indicates an antiferromagnetic coupling between low-spin Fe(III) and high-spin Mn(III) through the cyanide bridges. In addition, the complex 1 displays a strong cyan-blue luminescence emission in the solid state condition at room temperature. This behavior might be seen easily from the chromaticity diagram. Thus, the complex may be a good promising cyan-blue OLED developing electroluminescent materials for flatted or curved panel display applications due to the fact that it has such features.     

Biomimetic oxidation of catechol employing complexes formed in situ with heterocyclic ligands and different copper(II) salts

In the present work, catecholase activity is presented. The complexes were prepared by condensation of the organic ligand pyrazolyl L ₁ –L ₄ and copper(II) ion in situ. The pyrazolyl compounds L ₁ –L ₄ used in this study are: L ₁ is (3,5-dimethyl-pyrazol-1-ylmethyl)-(4-methyl-pyridin-2-yl)-pyrazol-1-ylmethyl-amine; L ₂ is 1-{4-[(3,5-dimethyl-pyrazol-1-ylmethyl)-pyrazol-1-ylmethyl-amino]-phenyl}-ethanone; L ₃ is 1-{4-[(3,5-dimethyl-pyrazol-1-ylmethyl)-[1,2,4]triazol-1-ylmethyl-amino]-phenyl}-ethanone, and L ₄ is 2-[(3,5-dimethyl-pyrazol-1-ylmethyl)-[1,2,4]triazol-1-ylmethyl-amino]-6-methyl-pyrimidin-4-ol, and copper ions salts Cu(II) are (Cu(CH₃COO)₂, CuCl₂, Cu(NO₃)₂ and CuSO₄). In order to determine factors influencing the catecholase activity of these complexes, the effect of ligand nature, ligand concentration, nature of solvent and nature of counter anion has been studied. The best activity of catechol oxidation is given by the combination formed by one equivalent of ligand L ₂ and one equivalent of Cu(CH₃COO)₂ in methanol solvent which is equal to 9.09 µmol L^?1 min^?1. The Michaelis–Menten model is applied for the best combination, to obtain the kinetic parameters, and we proposed the mechanism for oxidation reaction of catecholase.