ESI MS, spectroscopic and PM5 semiempirical studies of Colchicine complexes with lithium, sodium and potassium salts

The colchicine complexes with Li⁺, Na⁺ and K⁺ cations have been synthesized and studied by ESI MS, ¹H and ¹³C NMR, FT-IR and PM5 semiempirical methods. It has been shown that colchicine forms stable complexes of 1:1 stoichiometry with monovalent metal cations. For Li⁺ cations also formation of the 2:1 stoichiometry complexes has been detected. The most stable structures of the complexes are those in which the acetamide groups are involved in the coordination process. The structures of the colchicine complexes with Li⁺, Na⁺ and K⁺ cations are visualized and discussed in details.     

Oligomycin A complex structures with some divalent metal cations studied by ESI MS and PM5 semiempirical methods

The ability of Oligomycin A (OLA) to form complexes with monovalent cations was studied by the ESI mass spectrometry and PM5 semiempirical method. At low cone voltage values the ESI MS spectra indicate that OLA formes stable 1:1 complexes with Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Zn²⁺ divalent cations irrespective of the stoichiometry. With increasing cone voltages the formation of the [OLA + M + (ClO₄ or Cl)]⁺ complexes was preferred. This process occurred simultaneously with the formation of fragmentary metal cation complexes with the exception of Pb²⁺ ions which does not form complexes with OLA molecule. PM5 semiempirical calculations allowed the visualizations of all structures of (OLA + M)²⁺ and [OLA + M + (ClO₄or Cl)]⁺ complexes as well as the fragmentary cations.     

Spectroscopic, mass spectrometry, and semiempirical investigations of a new 2-(2-methoxyethoxy)ethyl ester of Monensin A and its complexes with monovalent cations

A new 2-(2-methoxyethoxy)ethyl ester of Monensin A (MON7) has been synthesized and its capability of complex formation with Li⁺, Na⁺, and K⁺ cations has been studied by ESI MS, ¹H and ¹³C NMR, FT-IR, and PM5 semiempirical methods. ESI mass spectrometry indicates that MON7 forms complexes with Li⁺, Na⁺, and K⁺ of exclusively 1:1 stoichiometry which are stable up to cv = 70 V. The formation of complexes between MON7 and Na⁺ cations is strongly favored. Starting from about cv = 90 V fragmentation of the respective complexes is observed, primarily characterized by several dehydration steps. The structures of the MON7 complexes with Li⁺, Na⁺, and K⁺ cations are stabilized by intramolecular hydrogen bonds in which the OH groups are always involved. The structures are visualized and discussed in detail. It has been proved that the formation of a pseudo crown ring structure formed by MON7 is preferred in complexes with Na⁺ cations.     

Supramolecular formation by aromatic ring stacking and hydrogen bonding in lanthanide(III) complexes with amino acids and 1,10-phenanthroline

[Eu(ABA)(phen)₂(H₂O)₃](ClO₄)₃·3phen·4.5H₂O (1) and [Eu(Val)(phen)₂(H₂O)₃](ClO₄)₃·3phen·2H₂O (2) are two new europium complexes with amino acids and 1,10-phenanthroline (phen=1,10-phenanthroline, ABA=-amino butyl acid, Val= -valine). Their crystal structures were measured by X-ray crystallography. Europium atoms in both complexes are nine-coordinated with bidentate 1,10-phenanthroline and carboxylate anion of amino acids, and water molecules. In the solid state, 1 and 2 have a structure involving aromatic stacking of the coordinated and non-coordinated 1,10-phenanthroline and the oxygen atoms of non-coordinated perchlorate anions being H-bond acceptors connect [Eu(ABA)(phen)₂(H₂O)₃]³⁺·3phen·4.5H₂O or [Eu(Val)(phen)₂(H₂O)₃]³⁺·3phen·2H₂O in their structures. In their interactions, several C–HO bonds play an important role. Owing to their different amino acid ligands and the number of lattice water molecules, there is some difference in their hydrogen bond patterns in 1 and 2. The side chain of -valine is involved in the formation of C–HO bonds. Hydrogen bond and π–π interactions determine the supramolecular formation of three-dimensional net works of both complexes.     

联咪唑镍、镉配合物的合成、晶体结构及其与DNA相互作用

分别通过水热法和室温挥发法合成了2,2'-联咪唑(H₂biim)镍、镉配合物([Ni(H₂biim)₃](phth)(phth,邻苯二甲酸根)(1)、[Cd(H₃biim)₂Cl₄](2)),并通过X射线单晶衍射、元素分析和红外等技术手段对它们进行了表征。 单晶X衍射结果表明,配合物1的配离子中心镍离子周围的配体以3个中性联咪唑分子形式分别进行二齿螯合配位,构成六配位的畸变八面体构型,邻苯二甲酸根离子在外界与配体形成丰富的氢键;而在配合物2中,两个联咪唑配体却以含有氢质子的阳离子H₃biim⁺形式与中心镉离子单齿配位,镉离子同时结合4个氯原子形成六配位配位环境。 通过紫外光谱、荧光光谱和黏度法测试结果表明配合物1和2分别与小牛胸腺DNA(ct-DNA)以经典插入和部分插入模式进行相互作用。     

Influence of solvent and counter ion on complexes of 2,5-bis(2-pyridyl)-1,3,4-oxadiazole with iron (II) and (III) studied by electrospray ionization mass spectrometry

The effect of solvent and counter ion on the complexes of 2,5-bis(2-pyridyl)-1,3,4-oxadiazole (1) with Fe+2 and Fe+3 has been studied by electrospray ionization mass spectrometry (ESI/MS). As expected, upon ESI conditions the metal reduction proceeds, but it can be deduced that complexes with Fe+2 are favored over those with Fe+3. When methanol is used as solvent, the formation of complexes of stoichiometry 2:1 and 1:1 with counter ion attached (monovalent anion) is favored, for example, [1(2)+FeCl]+ ion. The use of methanol/water (1/1) as solvent favors the formation of complexes of stoichiometry 2:1 and 3:1, namely doubly charged [1(2)+Fe]+2 and [1(3)+Fe]+2 ions. The complexes containing anion of oxidative properties (ClO4-, NO3-), when the higher cone voltage is applied, yield unusual species [1n+FeOm]+ (n=1, 2; m=1, 2). The use of divalent counter ion (SO4(-2)) resulted in formation of complexes containing two iron cations, namely [1n+Fe2SO4]+2 (n=2, 3, 4) ions. These ions can be regarded as Fe-1 complexes bridged by a sulfate anion.     

Synthesis and X-ray crystal structures of bis(bis(μ2-2-aminoethanolato–N,O,O)–cobalt(III))–cobalt(II) hydrate, tris(biscyclohexylammonium)μ-hydroxo–bis(μ2-nitro–N,O)–hexanitro–dicobaltate(III) and biscyclohexylammonium nitrate(III)

Two new cobalt complexes: Co₃(NO₂)₄(NH₂CH₂CH₂O)₄·H₂O (1) and (NH₂(C₆H₁₁)₂)₃[Co₂(NO₂)₈OH]·3H₂O (2) and the compound (NH₂(C₆H₁₁)₂)NO₂ (3) were synthesised and their structures have been determined using single-crystal X-ray diffraction. Compound 1 consists of two centrosymmetrical trinuclear complexes and a water molecule of crystallization. Ligands coordinated to Co atoms are nitro and aminoethanolato groups. Structure 2 is built up of biscyclohexylammonium cations, dinuclear anions with hydroxo and nitro groups coordinated to Co atoms and water molecules. The coordination of Co atoms in both structures is roughly octahedral.     

A Fourier-transform ion-cyclotron-resonance study of the reactions of polycyclic aromatic hydrocarbon cations with molecules of interstellar interest

The reactivity of naphthalene and pyrene radical cations and their derivatives (C₁₀H_n⁺, n=6,7,8,9), C₁₆H_n (n=9,10,11) has been studied with molecules of interstellar interest in an ion cyclotron resonance apparatus. The radical cations C₁₀H₈⁺ and C₁₆H₁₀⁺ are unreactive with H₂,CO,H₂O and NH₃. Adduct formation is the only channel for almost all reactions of C₁₀H₇⁺ with these molecules. The implications of these results for the stability of polycyclic aromatic hydrocarbon (PAH) cations in the interstellar medium are briefly discussed. Exploratory studies of the ion chemistry of a larger PAH, coronene, have also been done.     

Crystal structure and luminescence property of ternary terbium p-aminobenzoic acid complexes with different second ligands

Ternary terbium complexes with p-aminobenzoic acid (HL), [TbL₃(DMSO)(H₂O)]₂ (1), [TbL₃(DMF)(H₂O)]₂ (2) and [TbL₃(Bpy)(H₂O)]₂·2H₂O (3) (DMSO=dimethyl sulfoxide, DMF=N, N- dimethylformamide, Bpy=2, 2′- bipyridyl) have been synthesized, and their crystal structures determined. The luminescence properties of these complexes, including both the emission quantum yield and the fluorescence lifetime, have been investigated. The effect of a second ligand on the crystal structure and luminescence property of the ternary terbium p-aminobenzoic acid complexes, and the relationship between luminescence properties and crystal structure, including coordination mode of the L⁻ ligand and the characteristics of a second ligand, are discussed.     

二苯羧酸类稀土配合物对藤黄微球菌抑制作用的微量热研究

合成了4例二苯羧酸类稀土配合物:[Re_2(oba)_3(H_2O)_5]·H_2O[Re=La(1)、Ce(2)、Sm(3)、Er(4)](oba=4,4'-二羧基二苯基醚),利用元素分析、红外光谱和粉末X射线衍射等技术手段对其结构及组成进行了表征,热重分析表明,4例配合物具有良好的热稳定性。采用微量热法,实时跟踪监测4种目标配合物对藤黄微球菌的抑制作用,得到了热谱曲线。依据热动力学模型对热谱曲线进行解析,计算了生长和抑制过程的热动力学函数,在不同浓度配合物存在时,获得了细菌生长速率常数(k)、最大产热功率(P_(max))、传代时间(t_G)以及抑制率(I)等参数。结果表明,4种配合物对藤黄微球菌均具有抑制作用,抑菌效果依次为:[Er_2(oba)_3(H_2O)_5]·H_2O(4)[Sm_2(oba)_3(H_2O)_5]·H_2O(3)[Ce_2(oba)_3(H_2O)_5]·H_2O(2)[La_2(oba)_3(H_2O)_5]·H_2O(1)。     

Synthesis and Crystal Structure of Complex:[K(DB24C8)(H2O)]2[Pd(SCN)4]0.5H2O

Crown ethers can form complexes with inorganic and organic cations. Much attention has been focused on characterizing the structure of crown ether complexes. However, the X-ray structures of dibenzo-24-crown-8 compelxes:[K(DB24C8)(H₂O)]₂[Pd(SCN)₄]0.5H₂O.     

Preparations and characterizations of two MOFs constructed with hydroxylphenyl imidazole dicarboxylate

Using the hydrothermal reactions of Mn(Ⅱ) and Ba(Ⅱ) salts with 2-(3-hydroxylphenyl)-1H-imidazole-4,5-dicarboxylic acid(m-OHPhH_3IDC),two novel metal-organic frameworks,namely,{[Mn(mOHPhHIDC)(H_2O)]2H_2O}_n(1) and {[Ba(m-OHPhH_2IDC)_2(H_2O)_3]-2H_2O)_n,(2) have been synthesized and structurally characterized by single-crystal X-ray crystallography,elemental analyses,and IR spectroscopy.Complex 1 features a novel non-interpenetrated three-dimensional(3,4)-connected network with one-dimensional open channels.Complex 2 exhibits a two-dimensional layered structure with rhombic grids.The role of the central metals in the formation of final architectures has been discussed.Furthermore,luminescent and thermal properties of the two complexes have been studied.     

2-苯基喹啉-4-甲酸稀土配合物的研究

制备了十五种稀土与2-苯基喹啉-4-甲酸的配合物,确定其组成为REA₃·2H₂O(RE=Y,La-Nd,Sm-Lu,A=C₁₆H₁₀NO₂^-);研究了IR、UV、H-NMR、分子荧光光谱、摩尔电导、溶解性及热稳定性等。     

Synthesis,Crystal Structures and Catalysis of Dinuclear Cd(Ⅱ) Complexes Bridged by Unusual (N,O,O′)-Coordinated α-Amino Acids

Four dinuclear amino acid cadmium(Ⅱ) complexes [Cd₂(tren)₂(dl-alaninato)](ClO₄)₃·H₂O(Ⅰ), [Cd₂(tren)₂·(l-alaninato)](ClO₄)₃·H₂O(Ⅱ), [Cd₂(tren)₂(dl-phenylalaninato)](ClO₄)₃(Ⅲ) and [Cd₂(tren)₂(l-phenylalaninato)]· (ClO₄)₃(Ⅳ), constructed from mixed ligands of tris(2-aminoethyl)amine(tren) and racemic or natural amino acids( amino acids=dl- or l-alanine, and dl- or l-phenylalanine), have been synthesized and characterized by X-ray crystallography. The structural analysis of complexes Ⅰ and Ⅲ reveals that the cadmium centers are coordinated by one tren ligand and one amino acid molecule with the unusual (N,O,O′)-bridged mode, resulting in asymmetric chromophores of CdN₄O and CdN₅O in complex Ⅰ, CdN₄O₂ and CdN₅O in complex Ⅲ, respectively. The utility of the four complexes as efficient water-compatible Lewis acid catalysts for the direct aldol reaction in water was examined. The reaction proceeded smoothly to afford the corresponding β-hydroxy ketones in up to 99% yield. Moreover, the diastereoselectivity of the reaction favors the formation of the syn-isomers.     

Anion control of isomerism, crystal packing and binding properties in a mononuclear zinc complex

The coordination chemistry of the tetradentate pyridyl N-donor ligand cis-3,5-bis-[2-pyridinyleneamin]-trans-hydroxycyclohexane (DDOP) has been investigated with zinc(II) nitrate and triflate. The resulting complexes, [Zn(DDOP)(H₂O)(NO₃)](NO₃) (1), and [Zn(DDOP)(H₂O)(OTf)](OTf) (2) differ not only in their counterions, but also the arrangement of the axial ligands and their solid state hydrogen bonded networks. Isothermal titration calorimetry was used to assess the difference in binding properties exhibited by the two zinc complexes at physiological pH in an aqueous environment. A series of coordinating amino acids were found to preferentially bind to the mononuclear zinc triflate (1) complex over the corresponding nitrate (2) assembly, with histidine exhibiting a two centre binding mode.     

Enthalpies de formation de l'acide fluorhydrique dans les solutions ternaires HF/HX/H2O (HX = HCl, H2SO4) IV — Enthalpies de formation de l'acide fluorhydrique dans les solutions ternaires H2SO4/HF/H2O

The enthalpies of mixing of aqueous hydrofluoric and sulfuric acids and the enthalpies of dilution of the ternary solutions HF/H₂SO₄/H₂O at fixed concentration of HF or H₂SO₄ have been measured. The standard enthalpies of formation of HF in these solutions have been derived.     

Lanthanide and Transition Metal Coordination Polymers via Hydrothermal Reaction

Studies on the syntheses, structures and properties of lanthanide-transition metal complexes are of current great interest, because they can provide good models for investigation of the nature of magnetic exchange interaction between 3d and 41metal ions in the magnetic materials containing rare earth metals. Many of such studies were focused on discrete complexes which were synthesized from the conventional self-assembly reactions in solution. Although several infinite lanthanide-transition metal complexes containing organic ligands have been obtained by conventional solution synthetic method, the polymeric complexes have been poorly explored. Recently we try to use organic ligands for designing magnetic complexes comprising lanthanide and transition metal ions, especially Gd-Cu, Gd-Zn and Gd-Ag couple,with infinite structures, and hope to provide useful messages for the modeling of the magnetic exchange in magnetic materials. Herein reported are a series of lanthanide and transition metal polymeric complexes[{Gd₂M₃(pydc)₆(H₂O)₁₂}·4H₂O]_n and[{Gd₄M₂(pydc)₈(H₂O)₁₂}·4H₂O]_n (M=Cu, Ag,Zn) with 1D chain and 3D wave-like structure, which were prepared from the hydrothermal reactions of Gd₂O₃, pyridine-2,5-dicarboxylic acid (H₂pydc) and Zn(OAc)₂ or MO, respectively.     

Influence of protonation on crystal packing and thermal behaviour of tert-butylammonium decavanadates

Two tert-butylammonium decavanadate(V) salts with the formulae [(CH₃)₃CNH₃]₆[V₁₀O₂₈] · 8H₂O (1) and [(CH₃)₃CNH₃]₄[H₂V₁₀O₂₈] (2), have been synthesized and their crystal structures have been determined by means of single-crystal X-ray diffraction. The crystal structure of compound 1 is stabilized by electrostatic forces and an extensive network of hydrogen contacts involving anions, cations and water molecules. The anions and cations of this compound are arranged in layers perpendicular to the [010] direction following the sequence, cation-anion-cation. In the crystal structure of compound (2), each dihydrogen decavanadate(V) anion is joined to three adjacent polyanions by means of O(6)---H ··· O(4) hydrogen contacts forming layers parallel to the plane ( 01) and the hydrophobic groups of the cations are disposed in layers parallel to the anionic sheets. The thermal behaviour of both compounds has been studied. Compound 1 is an octahydrate and its thermal decomposition begins at 70°C with the loss of water of crystallization, while compound 2 is anhydrous and is consequently more stable, with decomposition starting at 200°C.     

Characterization and crystal structures of copper(II), cobalt(II), and nickel(II) complexes with two kinds of piperidine carboxylic acids

Copper(II) complex with -piperidine-3-carboxylic acid ( -Hpipe-3):[Cu( -pipe-3)₂(H₂O)] and cobalt(II) and nickel(II) complexes with piperidine-4-carboxylic acid (Hpipe-4):[M(Hpipe-4)₂(H₂O)₄]Cl₂ (M: Co, Ni) have been prepared and characterized by means of IR and powder diffuse reflection spectra, thermal analysis, and magnetic susceptibility. The crystal structures of these complexes have been determined by X-ray diffraction. The crystal of [Cu( -pipe-3)₂(H₂O)] is orthorhombic with the space group Pbcn. The copper atom is in a square pyramidal geometry, ligated by two carboxylato oxygen atoms, two nitrogen atoms, and a water molecule. One molecule of this complex consists of either -piperidine-3-carboxylic acid or -piperidine-3-carboxylic acid. The crystals of [M(Hpipe-4)₂(H₂O)₄]Cl₂ are monoclinic with space group P2₁/n. In these complexes the metal atom is in an octahedral geometry ligated by two carboxylato oxygen atoms and four water molecules.     

Preparation and crystal structure of new samarium complexes with glutamic acid

Samarium complexes with glutamic acid containing cationic [Sm₂(Glu)₂(H₂O)₈]⁴⁺ units have been prepared and characterized by using elemental analysis, infrared absorption spectra and thermal analysis. In addition, the crystal and molecular structure of [Sm₂(Glu)₂(H₂O)₈](ClO₄)₄·3H₂O was determined by X-ray diffraction. The presence of glutamic acid in the Sm coordination sphere allows the formation of a singular extended 2D arrangement. Sm atoms are nine coordinated, in a monocapped square antiprism geometry. They are connected by means of different μ-COO⁻ bridges, involving - and γ-carboxylate groups of the amino acid.