Synthesis,Crystal Structure and Luminescent Properties of a Novel Zinc(II) Complex of N-Acetyl-L-glutamic Acid and Imidazole Ligands

1 INTRODUCTION As is well known, some transition metal ions play an important role in controlling the behavior of many biological macromolecules and produce pro- found effects on their biological actions, medicine and people’s health[1～3]. Zinc is an essential com- ponent of many proteins. In the active sites of zinc enzymes, zinc is bound to the nitrogen of imidazole groups and oxygen of carboxylate groups of amino acids[4～6]. Additional interest in these proteins lies in the fact th…     

A Novel Proton Transfer Self‐Associated Compound from Dipicolinic Acid and Guanidine and Its Cadmium(II) Complex: Synthesis,Characterization, Crystal Structure,and Solution Studies

A novel 1:2 proton transfer self‐associated compound LH₂ , (GH⁺)₂(pydc^2—), was synthesized from the reaction of dipicolinic acid, pydcH₂, (2, 6‐pyridinedicarboxylic acid), and guanidine hydrochloride, (GH⁺)(Cl^—). The characterization was performed using IR, ¹H and ¹³C NMR spectroscopy and single‐crystal X‐ray diffraction. LH₂ · H₂O crystallizes in the space group C2/c of the monoclinic system and contains eight molecules per unit cell. The unit cell dimensions are: a = 26.480(5)Å, b = 8.055(2)Å, c = 14.068(3)Å. The first coordination complex (GH)₂[Cd(pydc)₂] · 2H₂O, was prepared using LH₂ and cadmium(II) iodide, and characterized by ¹H and ¹³C NMR spectroscopy and X‐ray crystallography. The crystal system is triclinic with space group P1¯ with one molecule per unit cell. The unit cell dimensions are: a = 8.5125(7)Å, b = 11.0731(8)Å, c = 13.2404(10)Å. The cadmium(II) atom is six‐coordinated with a distorted octahedral geometry. The two pydc^2— units are almost perpendicular to each other. The protonation constants of the building blocks of the pydc‐guanidine adduct, the equilibrium constants for the reaction of pydc^2— with guanidine and the stoichiometry and stability of the Cd²⁺ complex with LH₂ in aqueous solution were accomplished by potentiometric pH titration. The solution studies strongly support a self‐association between pydc^2— and GH⁺ with a stoichiometry for the Cd^II complex similar to that observed for the isolated crystalline complex. In fact, the [Cd(pydc)₂]^2— complex was found as the most abundant species in solution (> 90 %) at a pH >5.     

A New One-dimensional Complex Assembled by 4-Nitrobenzoic Acid and Bis(imidazol) Ligands:Syntheses,Structures and Theoretical Calculations

A new Zn(Ⅱ)coordination polymer,[Zn(nba)_2(mbix)]_(2n)(1,Hnba=4-nitrobenzoic acid,mbix=1,3-bis(imidazol-1-ylmethyl)-benzene),was synthesized and characterized by elemental analyses,IR spectra,TG,fluorescence spectroscopy,single-crystal and powder X-ray diffractions.It belongs to the triclinic system,■ space group,with a=9.341(2),b=13.029(3),c=23.660(6)?,α=99.603(6)°,β=90.461(6)°,γ=90.597(5)°,V=2838.9(12)?~3 and Z=2.It shows one-dimensional chains which are further linked by C–H···O hydrogen bonds andπ-πstacking interactions to yield a three-dimensional supramolecular structure.In addition,the Natural Bond Orbital(NBO)was analyzed in using the PBE0/LANL2DZ method built in Gaussian 09 Program.The calculation results indicated obvious covalent interaction between the coordinated atoms and Zn(Ⅱ)ion.     

Complex Formation of Copper(II) and Nickel(II) with Pyrrole Ligands in Aqueous Solution

Four new ligands, namely the N-substituted 2-(4-sulfonyl)-pyrrylmethyl derivatives of methylamine, glycine, ethylenediamine and iminodiacetic acid, were synthesized to investigate the coordinating tendency of pyrrolic nitrogen in aqueous solution. The complex formation of these ligands with Cu⁺⁺ and Ni⁺⁺ was studied by means of alkalimetric titrations. It is shown that the coordinating tendency of the deprotonated pyrrole group is similar to that of a deprotonated amide group. The deprotonated pyrrole group stabilizes the Cu⁺⁺ complexes of its iminodiacetate and ethylenediamine derivatives to an extent similar to that of a 2-pyridyl-methyl or 2′-aminoethyl group, despite the different basicity of these substituents. On the other hand, the neutral pyrrole group shows no coordinating tendency.     

Novel Transition‐Metal (M=Cr,Mo, W,Fe) Carbonyl Complexes with Bis(guanidinato)silicon(II) Ligands

The donor‐stabilized silylene 2 (the first bis(guanidinato)silicon(II ) complex) reacts with the transition‐metal carbonyl complexes [M(CO)₆] (M=Cr, Mo, W) to form the respective silylene complexes 7 – 10 . In the reactions with [M(CO)₆] (M=Cr, Mo, W), the bis(guanidinato)silicon(II ) complex 2 behaves totally different compared with the analogous bis(amidinato)silicon(II ) complex 1 , which reacts with [M(CO)₆] as a nucleophile to replace only one of the six carbonyl groups. In contrast, the reaction of 2 leads to the novel spirocyclic compounds 7 – 9 that contain a four‐membered SiN₂C ring and a five‐membered MSiN₂C ring with a M?Si and M?N bond (nucleophilic substitution of two carbonyl groups). Compounds 7 – 10 were characterized by elemental analyses (C, H, N), crystal structure analyses, and NMR spectroscopic studies in the solid state and in solution.     

Hydrothermal Synthesis, Crystal Structure and Magnetic Properties of a Novel Zero-dimensional Manganese(Ⅱ) Complex with 2,2''-Diphenic Acid and 1,10-Phenanthroline Ligands

A novel metal-organic coordination polymer [Mn3(2,2'-dipha)3(phen)6]n·3nH2O (2,2'-dipha = 2,2'-diphenic acid, phen = 1,10-phenanthroline) 1 has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, elemental analyses, IR spectroscopy, and magnetic susceptibility measurements. The crystal crystallizes in triclinic, space group P1- with a = 16.921(5), b = 18.307(5), c = 18.450(5) (A), α = 113.369(5), β = 108.529(5), γ = 102.984(5)° , V = 4553(2) (A)3, C114H72Mn13N12O14.25, Mr = 2002.66, Dc = 1.461 g/cm3, λ(MoKα)= 0.488 mm-1, the final F(000) = 2058, Z = 2, R = 0.0491 and wR = 0.0980 for 9087 observed reflections (Ⅰ＞2σ(Ⅰ)). In the crystal structure, the manganese atom is six-coordinated with two carboxylate oxygen atoms from different carboxylate groups of the same dipha and four nitrogen atoms from two different phen ligands, showing a slightly distorted octahedral geometry. Furthermore, it exhibits a zero-dimensional structure with dipha-Mn-phen- as building units. Variable-temperature magnetic measure shows an overall anti-ferromagnetic behavior for compound 1.     

CO(2) Fixation by Novel Copper(II) and Zinc(II) Macrocyclic Complexes. A Solution and Solid State Study

Solutions containing Zn(II) and Cu(II) complexes with [15]aneN(3)O(2) rapidly adsorb atmospheric CO(2) to give {[ZnL](3)(&mgr;(3)-CO(3))}.(ClO(4))(4) (2) and {[CuL](3)(&mgr;(3)-CO(3))}.(ClO(4))(4) (4) complexes. The crystal structures of both complexes have been solved (for 2, space group R3c, a, b = 22.300(5) ?, c = 17.980(8) ?, V = 7743(4) ?(3), Z = 6, R = 0.0666, R(w)(2) = 0.1719; for 4, space group R3c, a, b = 22.292(7) ?, c = 10.096(8) ?, V = 7788(5) ?(3), Z = 6, R = 0.0598, R(w)(2) = 0.1611), and the spectromagnetic behavior of 4 has been studied. In both compounds a carbonate anion triply bridges three metal cations. Each metal is coordinated by one oxygen of the carbonate, three nitrogens, and an oxygen of the macrocycle; the latter donor weakly interacts with the metals. Although the two compounds are isomorphous, they are not isostructural, because the coordination geometries of Zn(II) in 2 and Cu(II) in 4 are different. The mixed complex {[CuZn(2)L(3)](&mgr;(3)-CO(3))}.(ClO(4))(4) has been synthesized. X-ray analysis (space group R3c, a, b = 22.323(7) ?, c = 17.989(9) ?, V = 7763(5) ?(3), Z = 6, R = 0.0477, R(w)(2) = 0.1371) and EPR measurements are in accord with a &mgr;(3)-carbonate bridging one Cu(II) and two Zn(II) ions in {[CuZn(2)L(3)](&mgr;(3)-CO(3))}(4+). Both the Zn(II) and Cu(II) cations exhibit the same coordination sphere, almost equal to that found in the trinuclear Zn(II) complex 2. The systems Zn(II)/L and Cu(II)/Lhave been studied by means of potentiometric measurements in 0.15 mol dm(-)(1) NaCl and in 0.1 mol dm(-)(3) NaClO(4) aqueous solutions; the species present in solution and their stability constants have been determined. In both systems [ML](2+) species and hydroxo complexes [M(II)LOH](+) (M = Zn, Cu) are present in solution. In the case of Cu(II), a [CuL(OH)(2)] complex is also found. The process of CO(2) fixation is due to the presence of such hydroxo-species, which can act as nucleophiles toward CO(2). In order to test the nucleophilic ability of the Zn(II) complexes, the kinetics of the promoted hydrolysis of p-nitrophenyl acetate has been studied. The [ZnLOH](+) complex promotes such a reaction, where the Zn(II)-bound OH(-) acts as a nucleophile to the carbonyl carbon. The equilibrium constants for the addition of HCO(3)(-) and CO(3)(2)(-) to the [ZnL](2+) complex have been potentiometrically determined. Only [ML(HCO(3))](+) and [ML(CO(3))] species are found in aqueous solution. A mechanism for the formation of {[ML](3)(&mgr;(3)-CO(3))}.(ClO(4))(4) is suggested.     

Complex Formation Between Ferric(III), Chromium(III), and Cupric(II) Metal Ions and (O,N) and (O,O) Donor Ligands with Biological Relevance in Aqueous Solution

The complexation equilibria of L-norleucine and gallic acid were studied in aqueous solutions at 25.00 °C and ionic strength 0.15 mol⋅dm⁻³ (NaNO₃), by means of potentiometry and spectrophotometry. The ferric (Fe^III), chromium (Cr^III), and cupric (Cu^II) complexing abilities of L-norleucine and gallic acid, along with their overall stability constants, were obtained with the HYPERQUAD 2008 program from the potentiometric data. The concentration distributions of the various complex species in solution were evaluated and discussed. UV–visible spectroscopic measurements were carried out to give qualitative information about the composition of the complexes formed in these solutions. The cytotoxic activities of the binary and ternary metal complexes of L-norleucine and gallic acid were tested and evaluated against HEp-2 (human laryngeal carcinoma), Daoy (human medulloblastoma), MCF-7 (human breast adenocarcinoma), and WiDr (human colon adenocarcinoma) tumor cell lines. Also, their antioxidant activities were examined by free radical scavenging assay.     

Podand‐Based Dimeric Chromium(III)–Salen Complex for Asymmetric Henry Reaction: Cooperative Catalysis Promoted by Complexation of Alkali Metal Ions

A new kind of podand‐based dimeric salen ligand was synthesized, and its association with potassium cations was investigated by ¹H NMR spectroscopy. The corresponding Cr^III–salen dimer was assembled by a supramolecular host–guest self‐assembly process and was then used as a catalyst in highly efficient and enantioselective asymmetric Henry reactions. Regulation by KBAr_F (BAr_F=[3,5‐(CF₃)₂C₆H₃]₄B) led to remarkable improvements in yield (by up to 58 %) and enantioselectivity (for example, from 80 % ee to 96 % ee).     

A Novel Proton Transfer Compound Containing 2, 6‐Pyridinedicarboxylic Acid and Creatinine and its Zinc(II) Complex — Synthesis,Characterization, Crystal Structure,and Solution Studies

The 1:1 proton transfer compound LH₂, (creatH)⁺ (pydcH)^?, has been prepared from the reaction of creatinine, creat, and dipicolinic acid, pydcH₂, (2, 6‐ pyridinedicarboxylic acid) and characterized using IR, ¹H and ¹³C NMR spectroscopy. The first coordination complex (creatH)[Zn(pydc)(pydcH)]·4H₂O, was prepared using LH₂ and zinc(II) nitrate, and characterized using IR, ¹H and ¹³C NMR spectroscopy and single crystal X‐ray crystallography. The crystal system is triclinic with space group with two molecules per unit cell. The unit cell dimensions are a = 8.085(2) Å, b = 10.802(4) Å, c = 13.632(4) Å, α = 104.98(2)°, β = 90.31(2)° and γ = 92.55(3)°. The structure has been refined to a final value for the crystallographic R factor of 0.0381 based on 3003 reflections. The zinc atom is six‐coordinated with a distorted octahedral geometry. The (pydc)^2? and (pydcH)^? units are almost perpendicular to each other. Extensive hydrogen bondings between carboxylate groups, (creatH)⁺ and water molecules throughout the zinc(II) complex as well as π–π stacking and ion pairing play important roles in stabilizing the corresponding lattices. The protonation constants of the building blocks of the pydcH₂‐creat adduct, the equilibrium constants for the reaction of (pydc)^2? with creat and the stoichiometry and stability of the Zn^II complex with LH₂ in aqueous solution were accomplished by potentiometric pH titration. The solution studies support a self‐associated (creatH)⁺(pydcH)^? as the most abundant species at pH = 3.4. The stoichiometry of the crystalline complex (i.e. (creatH) [Zn(pydc)(pydcH)])and that of the most abundant species detected in solution were found the same.     

Novel Bis(2‐cyanoketene‐S,S‐/S,N‐acetals): Versatile Precursors for Novel Bis(aminopyrazole) Derivatives

A synthesis of novel bis(aminopyrazoles) by the reaction of hydrazine hydrate with the appropriate bis(2‐cyanoketene‐S,N‐acetals) was reported. The latter compounds were prepared by treatment of bis(cyanoacetamides) with phenyl isothiocyanate in KOH/EtOH and subsequent alkylation with methyl iodide. The utility of bis(2‐cyanoketene‐S,S‐acetals) as building blocks for novel bis(aminopyrazoles) was also investigated.     

Bis(Diethyldithiocarbamato)Antimony(III) Derivatives with Oxygen- and Sulfur-Donor Ligands: Synthesis,Esi-Mass,and Spectral Characterization

Abstract

Replacement reactions of bis(diethyldithiocarbamato)antimony(III) chloride have been carried out with oxygen and sulfur donor ligands such as disodium oxalate, sodium acetate, sodium salicylate, benzoic acid, thioglycolic acid, acetylacetone, thiphenol, ethane-1,2-dithiol, and 2,2-dimethylpropane-1,3-diol to give mixed bis(diethyldithiocarbamato)antimony(III) derivatives of the corresponding ligands. These derivatives have been characterized by the physicochemical [melting point and molecular weight determination, elemental analysis (C, H, N, S, and Sb)], spectral [FT-IR, far-IR, NMR (¹H and ¹³C)], ESI-mass, powder XRD, and SEM studies.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional figures and tables]     

Hydrothermal Synthesis, Crystal Structure and Magnetic Properties of a Novel Zero-dimensional Manganese（Ⅱ） Complex with 2,2′-Diphenic Acid and 1,10-Phenanthroline Ligands

A novel metal-organic coordination polymer [Mn3(2,2′-dipha)3(phen)6]n·3nH2O (2,2′-dipha = 2,2′-diphenic acid, phen = 1,10-phenanthroline) 1 has been hydrothermally synthe- sized and structurally characterized by single-crystal X-ray diffraction, elemental analyses, IR spectroscopy, and magnetic susceptibility measurements. The crystal crystallizes in triclinic, space group P1 with a = 16.921(5), b = 18.307(5), c = 18.450(5) , α = 113.369(5), β = 108.529(5), γ = 102.984(5)o, V = 4553(2) 3, C114H72Mn3N12O14.25, Mr = 2002.66, Dc = 1.461 g/cm3, μ(MoKα) = 0.488 mm1, the final F(000) = 2058, Z = 2, R = 0.0491 and wR = 0.0980 for 9087 observed reflections (I > 2σ(I)). In the crystal structure, the manganese atom is six-coordinated with two carboxylate oxygen atoms from different carboxylate groups of the same dipha and four nitrogen atoms from two different phen ligands, showing a slightly distorted octahedral geometry. Fur- thermore, it exhibits a zero-dimensional structure with dipha-Mn-phen- as building units. Variable- temperature magnetic measure shows an overall anti-ferromagnetic behavior for compound 1.     

Complexation and Electronic Spectra of Neodymium(III)–Amino Acid–1,10-Phenanthroline Systems in Aqueous Solution

Complexation of neodymium(III)-glutamate(glu)-phenanthroline(phen), neodymium(III)-aspartate(asp)-phenanthroline(phen) ternary systems and the corresponding binary systems in aqueous solution are discussed at various values of pH. Based on change regularity of hypersensitive transition intensities, the neodymium(III)-aspartate-phenanthroline ternary complex has a general formula of Nd(asp)₃phen, but the composition of the complex of Nd(III) with glutamate and phenanthroline is complicated and has not been determined. The electronic spectra of these complexes were studied, Slater-Condon parametersF _k ^s and the Lande parameter ξ_4f were obtained. The rms deviation between calculated and observed energy levels is less than 43 cm⁻¹. Bonding in these complexes are also investigated and bonding parameters calculated. The results show that Nd(III) and amino acids form complexes by ionic linkage with carboxylic oxygens, but with some weak covalency. Besides, the degrees of covalency in ternary complexes are larger than those in binary complexes.