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.     

Hexa(isothiocyanato)chromates(III) of Some Yttrium Group Lanthanide(III) and Europium Complexes with Nicotinic Acid: Synthesis and Crystal Structures

Double ionic complexes [M(C₅H₅NCOO)₃(H₂O)₂][Cr(NCS)₆] · nH₂O, where M = Eu (I), n = 1.15; Dy (II), Er (III), n = 1.5; M = Yb (IV), n = 2, have been synthesized by the reaction between M(NO₃)₃, M = Eu, Dy, Er, Yb, K₃[Cr(NCS)₆], and nicotinic acid (C₅H₅NCOO) in an aqueous solution and studied by chemical analysis, IR spectroscopy, and X-ray diffraction. Crystals of complexes I–IV are monoclinic, space group P2₁/n, Z = 4; a = 9.5358(2) Å, b = 25.4871(5) Å, c = 15.4303(4) Å, β = 105.513(1)°, V = 3613.6(1) ų, ρ_calcd = 1.799 g/cm³ for I, a = 9.5901(5) Å, b = 25.8599(15) Å, c = 15.6316(9) Å, β = 106.829(2)°, V = 3710.6(4) ų, ρ_calcd = 1.782 g/cm³ for II, a = 9.5640(3) Å, b = 25.8936(11) Å, c = 15.6498(7) Å, β = 106.895(2)°, V = 3708.3(3) ų, ρ_calcd = 1.791 g/cm³ for III, and a = 9.5049(2) Å, b = 25.6378(4) Å, c = 15.5120(3) Å, β = 106.934(1)°, V = 3616.1(1) ų, ρ_calcd = 1.864 g/cm³ for IV.     

Different structural types of copper(II) furan- and thiophencarboxylates: X-ray structural,EPR, spectral and magnetic analyses

Synthesis and characterization of eight new complexes of various structural types are reported. With 5-nitro-2-furancarboxylic acid (5-NO₂-2-fucH), two monomeric complexes, [Cu(5-NO₂-2-fuc)₂(H₂O)₂] (II) and [Cu(5-NO₂-2-fuc)₂(H₂O)₄] (III), as well as a dimeric complex with ethylnicotinate (Etnic), [Cu(5-NO₂-2-fuc)₂(Etnic)₂]₂ (V), were prepared. With other acids: 2,5-dimethyl-3-furancarboxylic acid (2,5-Me₂-3-fucH), 2-thiophencarboxylic acid (2-tpcH), 3-methyl-2-thiophencarboxylic acid (3-Me-2-tpcH) or 5-methyl-2-thiophencarboxylic acid (5-Me-2-tpcH), only dimeric complexes [Cu(2,5-Me₂-3-fuc)₂(H₂O)]₂ (I), [Cu(2,5-Me₂-3-fuc)₂(Etnic)]₂ (IV), [Cu(2-tpc)₂(Etnic)]₂ (VI), [Cu(3-Me-2-tpc)₂(Etnic)]2 (VII) and Cu(5-Me-2-tpc)₂(Etnic)]₂ (VIII) have been synthesised. Characterizations of the complexes were based on elemental analysis and infrared, electronic, EPR and magnetic measurements. Moreover, complexes III, V, VII and VIII were also studied by X-ray structural analysis. Two structural types of dimeric complexes were observed differing in the number of carboxylate bridges. Most of the dinuclear complexes exhibit the common “paddle-wheel” structural motif while the molecular structure of V contains two pentacoordinated copper(II) ions bridged by two carboxylate groups of two 5-nitro-2-furancarboxylate ligands resulting in the intramolecular copper-copper distance of 4.4960(8) Å. Magnetic properties (monomeric EPR signal and isotropic exhchange constant (J of approximately 0 cm^?1) of V confirmed a very weak magnetic interaction between copper centres.     

Self-assembly hydrogen-bonded supramolecular arrays from copper(II) halogenobenzoates with nicotinamide: Structure and EPR spectra

Nicotinamide was employed as a supramolecular reagent in the synthesis of six new copper(II) bromo-, iodo-, fluoro- and dibromobenzoate complexes. Structures of [Cu(2-Brbz)₂(nia)₂(H₂O)₂] (I), [Cu(2-Ibz)₂(nia)₂(H₂O)2] (II), [Cu(2-Fbz)₂(nia)₂(H₂O)₂] (III), [Cu(4-Brbz)₂(nia)₂(H₂O)₂] (IV), [Cu(3,5-Br₂bz)2(nia)₂(H₂O)2] (V), [Cu(F-Fbz)₂(nia)₂(H₂O)] · H₂O (VI) (nia = nicotinamide, 2-Brbz = 2-bromobenzoate, 4-Brbz = 4-bromobenzoate, 3,5-Br₂bz = 3,5-dibromobenzoate, 2-Ibz = 2-iodobenzoate, 2-Fbz = 2-fluorobenzoate, 4-Fbz = 4-fluorobenzoate) were determined using X-ray analysis. Compound [Cu(2-Brbz)₂(nia)₂] · 2H₂O (VII) was prepared by a new method and also characterized by X-ray powder diffraction and EPR spectroscopy. Compounds I–V are monomeric complexes with a square-bipyramidal coordination sphere around the Cu²⁺ ion. Complex VI is monomeric with coordination environment around the Cu²⁺ ion of a tetragonal-pyramid. Complexes I and VII present examples of coordination isomerism. Molecules of all compounds are connected by N—H?O and O—H?O hydrogen bonds from the NH₂ groups of nicotinamide and water molecules which create supramolecular hydrogen-bonding-coordination chains and networks.     

Structural study and magnetic properties of copper(II) thiophene-2-carboxylate with 4-pyridinemethanol and isonicotinamide

The synthesis and characterization of [Cu(5-Me-2-tpc)₂(4-pyme)₂] (I), [Cu(3-Me-2-tpc)₂(4-pyme)₂] (II), [Cu(2-tpc)₂(4-pyme)₂] (III), [Cu(2-tpc)₂(isonia)₂(2-tpcH)] (IV), [Cu(5-Me-2-tpc)₂(isonia)₂(5-Me-2-tpcH)] (V), [Cu₂(2-tpc)₄(4-pyme)₂] (VI), [Cu₂(3-Me-2-tpc)₄(isonia)₂] (VII) (where 2-tpc is 2-thiophenecarboxylate, 3-Me-2-tpc is 3-methyl-2-thiophenecarboxylate, 5-Me-2-tpc is 5-methyl-2-thiophenecarboxylate and 4-pyme is 4-pyridinemethanol and isonia is isonicotinamide) are reported. The complexes under study were characterized by electronic, IR and EPR spectroscopy, magnetic susceptibility over the temperature range and X-ray structure analysis. Structural studies revealed a distorted tetragonal-bipyramidal environment around the copper ion for monomeric complexes I–V. The structure of dimeric complexes VI and VII consists of units of the known paddle-wheel dicopper(II) tetracarboxylates, which are made up of four thiophene-2-carboxylate ions thus bridging the two copper atoms. The complex molecules of all compounds are connected through H-bonds into supramolecular chains or frameworks. The spectral and magnetic properties are discussed with regard to X-ray data.     

SOD mimetic activity of salicylatocopper complexes

Investigation of salicylatocopper complexes in the presence of a nitrogen donor ligand is a growing research area due to the interesting mimetic activities of such complexes. Here, three X-salicylatocopper (where X = 3-methyl, or 4-methoxy) complexes with three different N-donor ligands, [Cu(μ-menia)(3-Mesal)₂(menia)(H₂O)]₂ (I), Cu(3-Mesal)₂(denia)₂(H₂O)₂ (II), Cu(4-MeOsal)₂(2-pyme)₂ (III), are presented (where 3-Mesal = 3-methysalicylate, 4-MeOsal = 4-methoxysalicylate, menia = N-methylnicotinamide, 2-pyme = 2-pyridylmethanol). The complexes were characterized by elemental analysis, IR and UV-VIS spectrophotometry. Cyclic voltammetry and the superoxide dismutase activity of the prepared complexes in solution were measured and the complexes were characterized by means of the inhibition concentration IC₅₀. In addition, the superoxide dismutase (SOD) activity of these complexes was compared with those of the parent ligand copper acetate, native SOD enzyme, and the related copper complexes containing non-steroidal anti-inflammatory drugs. The resulting SOD activity was correlated to the composition, structure and redox stability of the prepared complexes. The best value of the inhibition concentration was found for complex I (IC₅₀ = 2.24 µM), which classifies this complex into a group of good superoxide scavengers.     

Synthesis,crystal structure,and DNA-binding studies of a one-dimensional copper(II) polymer bridged both by oxamidate and thiocyanato ligands

A new one-dimensional copper(II) polymer, [Cu₄(dmapox)₂(SCN)₄(CH₃OH)₂] _n , where dmapox is the dianion of N,N′-bis[3-(dimethylamino)propyl]oxamide, was synthesized and characterized by elemental analysis, conductivity measurement, IR, and electronic spectral studies. The crystal structure of the copper(II) complex has been determined by X-ray single-crystal diffraction. The complex crystallizes in triclinic, space group P ? 1 and exhibits infinite one-dimensional copper(II) polymeric chain bridged both by bis-tridentate μ-trans-dmapox and μ-1,3-thiocyanato ligand. The environment around the copper(II) atom can be described as distorted square-pyramid. The Cu···Cu separations through the oxamidate and thiocyanato bridges are 5.246(2) Å (Cu1–Cu1ⁱ), 5.2649(14) Å (Cu2–Cu2ⁱⁱ), and 5.8169(15) Å (Cu1–Cu2), respectively. The interaction of the copper(II) complex with herring sperm DNA (HS-DNA) has been investigated by using absorption and emission spectral and electrochemical techniques and viscometry. The results reveal that the copper(II) complex may interact with DNA in the mode of groove binding with the intrinsic binding constant of 2.56 × 10⁵ M^?1.     

Transition metal chemistry of oxime-containing ligands,part XI. Copper(II) complexes of syn-phenyl-2-pyridylketoxime and syn-methyl-2-pyridylketoxime

Summary Some copper(II) complexes of the types: Cu(HPPK)-(PPK)X, Cu(HMPK)(MPK)X (where HPPK = syn-phenyl-2-pyridylketoxime, HMPK = syn-methyl-2-pyridylketoxime and X = Cl^–, Br^–, I^–, NO₃ ^–, SCN^– or SeCN^–) Cu(HPPK)₂SO₄ 3 H₂O and Cu(HMPK)₂SO₄ · 3 H₂O were synthesized and characterized by analysis, magnetic susceptibility, e.s.r., reflectance and i.r. spectral measurements. The spectral data suggest that Cu(HPPK)(PPK)X and Cu(HMPK)(MPK)X containcis square-coplanar [Cu(HPPK)(PPK)]⁺ and [Cu(HMPK)(MPK)]⁺ units respectively, linked by weakly coordinated anions, giving infinite polymeric highly distorted octahedral chain structures, whereas Cu(HPPK)₂SO₄ · 3H₂O and Cu(HMPK)₂SO₄ · 3 H₂O have acis distorted octahedral structure containing two ligand molecules of ketoxime and a bidentate sulphate group. The polycrystalline e.s.r. spectra suggest a distorted octahedral stereochemistry for the Cu^II ion involving a ground-state. By using e.s.r. and reflectance spectral data, the orbital reduction parameters, k₁₁ and k₁ were calculated and interpreted in terms of molecular orbital coefficients.     

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 structure investigation of Co(III) complex salts with the perrhenate anion

Complex salts of the composition [Co(NH₃)₆](ReO₄)₃·2H₂O (I), [Co(en)₃](ReO₄)₃ (II), [Co(NH₃)₅H₂O](ReO₄)₃·2H₂O (III), and [Co(NH₃)₅Cl](ReO₄)₂·0.5H₂O (IV) are obtained. Their crystal structures are determined by single crystal XRD. Crystallographic characteristics: (I) a = 9.9797(3) Å, b = 12.6994(3) Å, c = 14.7415(4) Å, β = 102.870(1)°, C2/c space group; (II) a = 8.0615(3) Å, b = 8.4483(4) Å c = 8.8267(4) Å, α = 61.923(2)°, β = 89.552(2)°, γ = 72.295(2)°, P1 space group; (III) a = 8.0086(4) Å, b = 12.9839(6) Å, c = 17.5122(7) Å, β=91.858(1)°, P2₁/n space group; (IV) a = 14.9446(3) Å, b = 14.6562(4) Å, c = 12.2434(4) Å, Cmc2₁ space group.     

Kinetic model of copper electrodeposition in sulfate solution containing trisodium citrate complexing agent

Simultaneous solution of two kinetic models of electrodeposition of copper in sulfate solution is studied in this paper. Bulk concentration of species involved in the numerical solution was calculated using MATLAB software. COMSOL Multiphysics software was used for the numerical solution of copper electrodeposition. Numerical results were evaluated using experimental data obtained by linear sweep voltammetry technique. The experimental data was almost fitted using COMSOL optimization physic module. It was found that kinetic parameters of Cu²⁺ (k^1Cu), Cu¹⁺ (k_2Cu), and CuCitH (k_1CuCitH) and diffusion coefficient and charge transfer coefficient of Cu²⁺ (\({D_{C{u^{2 + }}}}\), α_Cu1), Cu¹⁺ (α_Cu2) and CuCitH (D_CuCitH, α_CuCitH) affect the fitting of the experimental data with the computed ones. The variables such as concentration profiles and optimum kinetic parameters that cannot be experimentally measured were achieved by analysis of the model. The parameters, that not affect the fitting, were recognized and kept constant when using the optimization.     

Low-melting salts with the [Cr<Superscript>III</Superscript>(NCS)<Subscript>4</Subscript>(1,10-phenanthroline)]<Superscript>−</Superscript> complex anion: Syntheses,properties, and structures

Four new low melting salts, “Ionic Liquids” consisting of the [Cr^III(NCS)₄(Phen)]^? complex monoanion and imidazolium based cations A, with A = 1-ethyl-3-methylimidazolium (EMIm), 1-butyl-3-methylimidazolium (BMIm), 1,3-dimethyl-2,4,5-triphenylimidazolium (DML), and 1,2,3,4,5-pentamethyl-imidazolium (PMIm), were investigated. Single-crystal X-ray investigations established the structures of the four compounds. (EMIm)[Cr(NCS)₄(Phen)] (I): triclinic, \(P\bar 1\), a = 8.1382(6), b = 10.4760(8), c = 16.003(1) Å, α = 90.330(4)°, β = 94.759(4)°, γ = 107.305(4)°, Z = 2, R ₁(F)/wR ₂(F ²) = 0.0650/0.1770; (BMIm)[Cr(NCS)₄(Phen)] (II): triclinic, \(P\bar 1\), a = 8.5545(4), b = 9.8620(4), c = 16.6762(6) Å, α = 92.503(2)°, β = 97.517(2)°, γ = 91.249(2)°, Z = 2, R ₁(F)/wR ₂(F ²) = 0.0393/0.0848; (DML)[Cr(NCS)₄(Phen)] · C₃H₆O (III): triclinic, \(P\bar 1\), a = 11.0475(9), b = 13.589(1), c = 14.582(1) Å, α = 83.013(4)°, β = 87.116(4)°, γ = 70.333(5)°, Z = 2, R ₁(F)/wR ₂(F ²) = 0.0407/0.1023; (PMIm)[Cr(NCS)₄(Phen)] · C₃H₆O (IV): orthorhombic, Pbca, a = 17.379(1), b = 16.514(1), c = 22.304(1) Å, Z = 8, R ₁(F)/wR ₂(F ²) = 0.0460/0.1107 (in addition III and IV contain co-crystallized acetone molecules). Each compound was characterized by elemental analysis, NMR, IR, und UV-Vis spectroscopy. Magnetic properties were derived from NMR investigations (EVANS method). All four compounds are paramagnetic with effective magnetic moments of spin-only Cr^III. Melting points were obtained from DSC measurements. All melting points are higher than required for “Ionic Liquids”, but nevertheless “low” for molten salts.     

Surface disordering of classic and superionic crystals: A description in the framework of the stern model

The surface potential (φ_S) in ionic crystals: binary compounds of the type NaCl and superionic oxygen conductors of the type M _{1 ? c} ^IV Me _c ^III O_{2 ? c/2} are calculated with the aid of the Stern model. Effect of the energy of formation of defects, concentration of accessible sites (N _S), and concentration of admixtures on the temperature dependences of φ_S(T) is studied. Instances of high and low potentials are analyzed. It is demonstrated that the surface potential increases proportionally to the difference between the adsorption energies of individual defects, provided the absolute value of |ΔG _i| (ΔG _i < 0) and concentration N _S are sufficiently large. Values of isoelectric temperatures in NaCl crystals doped with admixtures of other valence are calculated. An attempt is undertaken to describe experimental data for silver halides with the aid of the model. Calculations of the surface potential in superionic oxygen conductors show that increasing concentration of surface vacancies is accompanied by segregation of the admixture cations in the surface layer.     

Synthesis and structural characterization of two copper complexes with long rigid ligands

Two copper complexes with long rigid ligands, Cu(Tta)₂(L¹) (I), and Cu(Tta)₂(L²) (II), where L₁ = (E)-3-(4-(1H-benzo[d]imidazol-1-yl)-(4-phenyl)phenyl)-1-phenylprop-2-en-1-one, L² = (E)-3-(4-(1H-imidazol-1-yl)phenyl)-1-(4-phenyl)phenyl)prop-2-en-1-one), have been synthesized and characterized. The single-crystal X-ray analysis (CIF files CCDC nos. 1409671 (I) and 1409672 (II)) for complexes I and II demonstrates that each copper ion assumes a distorted square-pyramidal MO₄N polyhedron in which four oxygen atoms come from the Tta ligands, and one nitrogen atom comes from the N-donor ligand. Both of the complexes are linked into 3D networks through weak intermolecular interactions.     

X-ray study of rhodium(III) sulfates

Compounds with compositions [Rh(H₂O)₆]₂(SO₄)₃·4H₂O (I), (H₃O)[Rh(H₂O)₆](SO₄)₂ (II), [Rh(H₂O)₅OH](SO₄)·0.5H₂O (III), and [Rh(H₂O)₆]₂(SO₄)·(H₂SO₄) _x ·5H₂O (IV) have been studied. The crystal structures of II, III, and IV were determined. All compounds crystallized in the monoclinic crystal system. Crystal data for II: a = 7.279(2) Å, b = 10.512(7) Å, c = 15.806(3) Å, β = 96.71(3)°, space group P2₁/n, Z = 2, d _calc = 2.334 g/cm³; III: a = 20.433(4) Å, b = 7.820(2) c = 11.215(2) Å, β = 114.14(1)°, space group C2/c, Z = 8, d _calc = 2.559 g/cm³; IV: a = 6.2250(4 Å), b = 27.0270(12) Å, c = 7.2674(5) Å, β = 97.04(3)°, space group P2₁/c, Z = 4, d _calc = 2.143 g/cm³. The compounds were studied by IR spectroscopy and powder X-ray diffraction. All of the isolated crystalline phases are sparingly soluble in ethanol and well soluble in water.     

Azidokomplexe in nicht-wäßrigen Lösungen, 1. Mitt.: Co(II), Ni(II) und Cu(II) in Acetonitril,Trimethylphosphat und Dimethylsulfoxid

The formation of azido complexes is investigated inDMSO, TMP andAN by spectrophotometric, potentiometric (Tl/TlN₃-electrode) and conductometric methods. The following coordination forms were established: [CoN₃]⁺ (octahedral, inTMP), [Co(N₃)₂] (tetrahedral, inTMP, AN andDMSO), [Co(N₃)₄]^2? (tetrahedral, inTMP, AN andDMSO); Ni(N₃)₂ and [Ni(N₃)₄]^2? (either, inTMP, AN andDMSO), [CuN₃]⁺ and [Cu(N₃)₂] (both inTMP, AN andDMSO), [Cu(N₃)₃]^? (tetrahedral, inTMP andAN) and [Cu(N₃)₄]^2? (tetrahedral, inTMP, AN andDMSO).     

Synthesis of Cu(II) and Mn(III) Complexes Involving Derivatives of Pyridine

Two complexes with derivatives of pyridine as ligands were synthesized and characterized. From the reaction of 2-pyridinecarboxaldehyde oxime with Cu(OAc)₂ · H₂O afforded the complex C₂₀H₃₀N₆O₁₂Cu₃ (I), and the use of 3-hydroxy-2-pyridinecarboxylic acid with anhydrous MnCl₂ · 4H₂O led to the formation of another complex C₁₂H₁₄N₂OCl₂Mn (II). They were characterized by X-ray diffraction (CIF files CCDC nos. 568718 (I) and 1568880 (II)), NMR, IR and elemental analysis. For I: terigonal, space group R\(\bar 3\)/H, a = 42.548(3), c = 10.2774(9) Å, V = 16113(2) ų, Z = 18, ρ_calcd = 1.367 Mg/m³, the final R factor was R₁ = 0.0945, 6662 for reflections were observed with I > 2σ(I), wR = 0.162 for all data. For II: triclinic, Pī, a = 5.6174(9), b = 7.7259(13), c = 9.7160(16) Å, α = 70.444(3)°, β = 88.009(3)°, γ = 89.818(3)°, V = 397.09(11) ų, Z = 1, ρ_calcd = 1.840 Mg/m³, the final R factor was R₁ = 0.0281, 4280 for reflections were observed with I > 2σ(I), wR = 0.0775 for all data.     

Bis(citrato)germanates of bivalent 3<Emphasis Type="Italic">d</Emphasis> metals (Fe,Co, Ni,Cu, Zn): Crystal and molecular structure of [Fe(H<Subscript>2</Subscript>O)<Subscript>6</Subscript>][Ge(HCit)<Subscript>2</Subscript>] · 4H<Subscript>2</Subscript>O

In continuation of a systematic study of bis(citrate)germanates, we synthesized a number of heterometallic germanium(IV) and 3d metal complexes based in citric acid (H₄Cit) with the molecular formula [M(H₂O)₆][Ge(HCit)₂] · nH₂O, where M = Fe, n = 4 (I); Co, n = 2 (II); Ni, n = 2 (III); Cu, n = 1 (IV); Zn, n = 3 (V). The complexes were characterized by elemental analysis, X-ray diffraction, thermogravimetry, and IR spectroscopy. The X-ray diffraction analysis of compound I was performed. Crystals are monoclinic, a = 10.091(4) Å, b = 11.126(4) Å, c = 10.996(4) Å, β = 100.966(6)°, V = 1212.1(8) ų, Z = 4, space group P2₁/n, R1 = 0.0561 for 2266 reflections with I > 2σ(I). Compound I is composed of centrosymmetric octahedral complexes-[Ge(HCit)₂]^2? anions and [Fe(H₂O)₆]²⁺ cations—and crystallization water molecules. Structural units in compound I are combined by a hydrogen bond system.     

Syntheses and luminescence of four supramolecular coordination complexes with flexible ligand

Four d ¹⁰-based complexes with chemical formulae {[Zn(L¹)₂(H₂O)₂(4,4′-Bipy)₂] (I), {[Zn₂(L¹)₄(Mi)] · 4H₂O} (II), {[Zn(L¹)₂(Phen)] · H₂O} (III) {[Cd(L¹)₂(Phen)] · 2H₂O} (IV) (HL¹ = p-hydroxy phenylacetic acid, 4,4′-Bipy = 4,4′-bipyridine, Phen = 1,10-phenanthroline, Mi = 1,4-bis(imidazol-1-yl)butane) have been synthesized and structurally characterized by single crystal X-ray diffraction (CIF files CCDC nos. 1047119 (I), 1047120 (II), 1047121 (III), 1047122 (IV)). The significant effect of assistant ligands and metal ions on assembly of I?IV has been demonstrated, which leads to the formation of distinct crystalline products. Complexes I?IV show various coordination motifs with different existing forms and coordination modes of the organic ligands. Furthermore, extend supramolecular networks are connected by secondary interactions such as hydrogen-bonding and aromatic stacking. The thermal stability and luminescent properties of the compounds were discussed in detail.     

Investigation of the Binding Properties of the Cosmetic Peptide Argireline and Its Derivatives Towards Copper(II) Ions

Isothermal titration calorimetry, potentiometric titration and circular dichroism spectroscopy were used to study the interaction of copper(II) ions with Argireline (Ac-Glu-Glu-Met-Gln-Arg-Arg-NH₂) and three of its point mutation derivatives: Glu-Ala-Met-Gln-Arg-Arg-NH₂ (AN1), Glu-Ala-His-Gln-Arg-Arg-NH₂ (AN2) and Glu-Ala-Met-Gln-Ala-Arg-NH₂ (AN3). Under the experimental conditions (20 mmol·L^?1 Caco solution, pH 6, 298.15 K), copper(II) ions form 1:1 complexes with the peptides Argireline, AN1, and AN2. The complexation reactions are entropy-driven processes. The stability of the resulting complexes increases in the order log₁₀K_Cu(AN1) < log₁₀K_{Cu(Argireline)} < log₁₀K_Cu(AN2). The relationship between the point mutations of Argireline and the binding properties of these peptides towards copper(II) ions is discussed.