<Emphasis Type="Italic">bis</Emphasis>(<Emphasis Type="Italic">N,N</Emphasis>-diethylnicotinamide) <Emphasis Type="Italic">p</Emphasis>-chlorobenzoate complexes of Ni(II), Zn(II) and Cd(II)

Three novel mixed ligand complexes of Ni(II), Zn(II) and Cd(II) with p-chlorobenzote and N,N-diethylnicotinamide were synthesised and characterized on the basis of elemental analysis, FTIR spectroscopic analysis, solid state UV-Vis spectrometric and magnetic susceptibility data. The thermal behavior of the complexes was studied by simultaneous TG-DTA methods in static air atmosphere and the mass spectra data were recorded. According to microanalytical results, formulas of complexes are C₃₄H₄₀N₄O₈ClNi, C₃₄H₄₀N₄O₈ClZn and C₃₄H₄₄N₄O₁₀ClCd. The complexes contain two moles of coordination waters, two moles p-chlorobenzoate and two mole N,N-diethylnicotinamide (dena) ligands per formula unit. In these complexes, the p-chlorobenzoate and N,N-diethylnicotinamide behave as monodentate ligand through acidic oxygen and nitrogen of pyridine ring. The decomposition pathways and the stability of the complexes are interpreted in the terms of the structural data. The final decomposition products were found to be as metal oxides.     

Complexes of Cu(II) and Pd(II) with 2-R-1,3,11,11<Emphasis Type="Italic">c</Emphasis>-tetraazacyclopenta[<Emphasis Type="Italic">c</Emphasis>]phenanthrenes

Paramagnetic complexes CuL¹SO₄·0.5H₂O, CuL²SO₄·2H₂O and diamagnetic Pd(HL²)Cl₃ (L¹ = 2-methyl-1,3,11,11c-tetraazacyclopenta[c]phenanthrene complex (L² = 2-phenyl-1,3,11,11c-tetraazacyclopenta-[c]phenanthrene) were synthesized. The most probable structure of the complexes was suggested on the basis of the IR and ESR spectra. Coordination units of paramagnetic complexes contain N atoms of the bidentate cycle-forming ligands, L¹ and L² molecules. The square PdCl₃N unit of the diamagnetic complex includes the N atom of the triazole fragment of the monodentate ligand, (HL²)⁺ cation.     

Zinc(II) and cadmium(II) <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>'-Bis(2-<Emphasis Type="Italic">N</Emphasis>-Tosylaminobenzylidene) diaminodipropyliminates: Syntheses,structures, and photoluminescence properties

Chemical and electrochemical syntheses of the zinc(II) and cadmium(II) complexes with the tetradentate Schiff base (H₂L), the condensation product of 2-N-tosylaminobenzaldehyde with diaminodipropylamine, are carried out. The structures, compositions, and properties of the synthesized metal complexes are studied by elemental analyses, IR spectroscopy, ¹H NMR, UV spectroscopy, X-ray absorption spectroscopy, and quantum-chemical calculations. The structure of the cadmium(II) complex is determined by X-ray diffraction analysis (CIF file CCDC no. 1446393). The cadmium(II) and zinc(II) complexes exhibit luminescence in a CH₂Cl₂ solution in the blue spectral range (λ_PL = 425–428 nm) with the photoluminescence quantum yields ? = 0.20 and 0.75, respectively.     

Three New 1D Polymeric Zinc(II) and Cadmium(II) Azido Complexes Containing Noncoordinated Pyridine-<Emphasis Type="Italic">N</Emphasis>-oxide or 3-Picoline-<Emphasis Type="Italic">N</Emphasis>-oxide

Summary. The interaction of pyridine-N-oxide (pyNO) and 3-picoline-N-oxide (3picNO) with zinc(II) and cadmium(II) azides afforded complexes with empirical formulae Zn(N₃)₂(pyNO)(H₂O)₂, Zn(N₃)₂(3picNO)₂(H₂O)₂ and Cd(N₃)₂(3picNO)₂(H₂O)₂. The IR spectra of these complexes are measured and discussed. X-Ray single crystal diffraction showed for the first complex, which should be formulated as {[Zn(N₃)₂(H₂O)₂](pyNO)}_n, to consist of 1D chains of trans-[Zn(N₃)₂(H₂O)₂]_n, double end-on (-1,1) azido bridges and noncoordinated pyNO molecules. The other two complexes are isomorphous containing 1D trans-[M(N₃)₂(H₂O)₂]_n, double (-1,1) azido bridges, and hydrogen bonded noncoordinated 3picNO molecules. Each pyridine-N-oxide molecule forms three hydrogen bonds, whereas the 3-picoline-N-oxides form two hydrogen bonds. The metal centers exhibit distorted octahedral geometry.Received March 5, 2003; accepted May 15, 2003 Published online September 11,2003     

Binuclear Cobalt(II) Complexes with Biladiene-<Emphasis Type="Italic">a,c</Emphasis> in DMF

The reaction of cobalt(II) acetate with alkylbiladiene-a,c (H₂L) in DMF at 298.15 K was studied by spectrophotometry. The resulting binuclear complexes Co₂L(AcO)₂ and Co₂L₂ contain one or two coordinated biladiene-a,c ligands, depending on the ratio of the reagent concentrations. The compositions of the complexes were determined and the thermodynamic constants of their formation were calculated from spectrophotometric data with the use of the molar ratio method. It was assumed that the high thermodynamic stabilities of heteroligand binuclear complexes M₂L(AcO)₂ are responsible for the formation of double-stranded biladiene complexes M₂L₂.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 5, 2005, pp. 353–357.Original Russian Text Copyright © 2005 by Zakharova, Rumyantsev, Antina, Semeikin.     

Synthesis of (<Emphasis Type="Italic">E</Emphasis>)-<Emphasis Type="Italic">N</Emphasis>-(3-alkoxy-4-acyloxyphenylmethylene)-<Emphasis Type="Italic">N</Emphasis>-(<Emphasis Type="Italic">e</Emphasis>-cyclohexyl)amines

Previously unknown E isomers of azomethines (Schiff bases) were synthesized from vanillal and vanillin esters by their reaction with cyclohexylamine.     

Conformations and properties of <Emphasis Type="Italic">O</Emphasis>-Alkyl-<Emphasis Type="Italic">S</Emphasis>-(2-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dialkylamino)-ethylmethylthiophosphonates

Conformers of the biologically active compounds CH₃P(O)(OR)(SCH₂CH₂NR ₂ ^′ ), where (I) R = i-C₄H₉, R′ = C₂H₅ and (II) R = C₂H₅, R′ = i-C₃H₇, are calculated within the AM1 level of theory. The elongated and twisted forms with maximum and minimum distances between a nitrogen atom and those of a phosphorus tetrahedron, respectively, and bearing a syn and anti oriented alkoxy group relative to a phosphoryl oxygen, are studied. It is found that the differences between the energy, electronic, and geometric parameters of these forms are apparent in differences between their properties, e.g., the ability to participate in complexation and protonation, reactions that to some extent simulate the interaction between a substance and a biological object.     

Zinc(II) and cadmium(II) complexes with <Emphasis Type="Italic">o</Emphasis>-hydroxybenzoic acid or <Emphasis Type="Italic">o</Emphasis>-aminobenzoic acid and 2-methylimidazole

Mixed complexes of the type: Zn(Hsal)₂(2-MeHim)₂, Zn(Han)₂(2-MeHim)₂, Cd(Hsal)₂(2-MeHim)₂, Cd(Han)₂(2-MeHim)₂, where Hsal=OHC₆H₄COO⁻, Han=NH₂C₆H₄COO⁻, 2-MeHim=2-methylimidazol) have been synthesized and characterized by IR spectroscopic and X-ray diffraction studies. Single-crystal X-ray structure of Cd(Hsal)₂(2-MeHim)₂ has been obtained. Thermal behaviour of the compounds was investigated by thermal analysis (TG, DTG, DTA). A coupled TG-MS system was used to analyse the principal volatile products of complexes. Thermal decomposition pathways have been postulated.     

Mercury(II) Biosorption Using <Emphasis Type="Italic">Lessonia</Emphasis> sp. Kelp

Lessonia nigrescens and Lessonia trabeculata kelps have been tested for the sorption of mercury from aqueous solutions. A pretreatment (using CaCl₂) allowed stabilizing the biomass that was very efficient for removing Hg(II) at pH 6–7. Sorption isotherms were described by the Langmuir equation with sorption capacities close to 240–270 mg Hg g⁻¹ at pH 6. The temperature had a negligible effect on the distribution of the metal at equilibrium. The presence of chloride anions had a more marked limiting impact than sulfate and nitrate anions. The uptake kinetics were modeled using the pseudo-second-order equation that fitted better experimental data than the pseudo-first-order equation. The particle size hardly influenced sorption isotherms and uptake kinetics, indicating that sorption occurs in the whole mass of the biosorbent and that intraparticle mass transfer resistance was not the limiting rate. Varying the sorbent dosage and the initial metal concentration influenced the equilibrium, but the kinetic parameters were not drastically modified. Metal can be eluted with hydrochloric acid, citric acid, or acidic KI solutions.     

Synthesis and characterization of <Emphasis Type="Italic">bis</Emphasis>(nicotinamide) <Emphasis Type="Italic">m</Emphasis>-hydroxybenzoate complexes of Co(II), Ni(II), Cu(II) and Zn(II)

The mixed-ligand m-hydroxybenzoate complexes of Co(II), Ni(II), Cu(II) and Zn(II) with nicotinamide were synthesized and characterized. The chemical, FT IR and UV-vis spectrophotometric, thermal and mass spectral analyses, magnetic susceptibility measurements revealed that the compounds contain two water molecules, two m-hydroxybenzoate (m-hba) and two nicotinamide (na) ligands per formula unit. m-Hydroxybenzoate and nicotinamide ligands bind to the metal atoms monodentately through their acidic oxygen and pyridinic nitrogen atoms, respectively. The thermal decomposition pathways and the stability of the complexes are interpreted in the terms of the structural data.     

Preparation and polymerization mechanism of dihydroxy-capped PCL,poly(CL-<Emphasis Type="Italic">b</Emphasis>-PEG-<Emphasis Type="Italic">b</Emphasis>-CL) and poly(DTC-<Emphasis Type="Italic">b</Emphasis>-CL-<Emphasis Type="Italic">b</Emphasis>-DTC)

The ring opening polymerization of ε-caprolactone (CL) was initiated by glycol and yttrium tri(2,6-di-tert-butyl-4-methylphenolate)s (Y(OAr)₃), preparing dihydroxy-capped poly (ε-caprolactone) (PCL) with controllable molecular weight. ¹H NMR and SEC analyses indicate that two kinds of active species and corresponding PCL with different structures exist in the system. Increasing the ratio of glycol to Y(OAr)₃ benefits the formation of monofunctional active species. However, poly(ethylene glycol) (PEG)/Y(OAr)₃ system only contains sole bifunctional active species to synthesize copolymer of CL with PEG (poly(CL-b-PEG-b-CL)). Dihydroxycapped PCL as macroinitiator can further initiate the polymerization of 2,2-dimethyltrimethylene carbonate (DTC). Thus, triblock copolymer of CL with DTC (poly(DTC-b-CL-b-DTC)) has been prepared.     

Synthesis of <Emphasis Type="Italic">N,N</Emphasis>-disubstituted (<Emphasis Type="Italic">Z</Emphasis>)-<Emphasis Type="Italic">O</Emphasis>-methylnicotinamide oximes

A number of (Z)-N,N-dialkyl- and (Z)-N-acyl-N-alkyl-O-methylnicotinamide oximes was synthesized. Their configuration was confirmed by the NOESY experiment. Evaluation of fungicidal activity of compounds obtained was performed.     

<Emphasis Type="Italic">Z</Emphasis>-and <Emphasis Type="Italic">E</Emphasis>-conformers of <Emphasis Type="Italic">N</Emphasis>-chloroacetylcytisine

N-Chloroacetylcytisine was synthesized by acylation of (–)-cytisine. Stable Z- and E-conformers with respect to rotational isomerism around the N-12–CO bond were found in PMR spectra at room temperature. The point at which PMR resonances of the Z- and E-conformers coalesced upon heating was measured. The transition barrier between the conformers was estimated.     

Mono-<Emphasis Type="Italic">meso</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-butylporphyrin

Summary. Treatment of meso-tetra(tert-butyl)porphyrin with sulfuric acid/n-butanol affords a mixture of porphyrin and mono-tert-butylporphyrin in relatively high yield.     

Molecular structure of <Emphasis Type="Italic">N</Emphasis>-(<Emphasis Type="Italic">o</Emphasis>-and <Emphasis Type="Italic">p</Emphasis>-hydroxybenzyl)cytisine

The molecular structures of N-(o-and p-hydroxybenzyl)cytisine were investigated by NMR spectroscopy, x-ray structure analysis, and molecular modeling. It was found that NMR resonances of the OH and aromatic protons in N-(o-hydroxybenzyl)cytisine were doubled because of the presence of two conformers in solution. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 165–168, March–April, 2008.     

The yeast <Emphasis Type="Italic">ISN1</Emphasis> (<Emphasis Type="Italic">YOR155c</Emphasis>) gene encodes a new type of IMP-specific 5'-nucleotidase

Background  

The purine salvage enzyme inosine 5'-monophosphate (IMP)-specific 5'-nucleotidase catalyzes degradation of IMP to inosine. Although this enzymatic activity has been purified and characterized in Saccharomyces cerevisiae, the gene encoding IMP 5'-nucleotidase had not been identified.     

Thermodynamics of coordination interactions of cobalt(II) and zinc(II) acetates with hexamethyltetrabutyl-substituted biladiene-<Emphasis Type="Italic">a,c</Emphasis>

The thermodynamics of the reaction of cobalt(II) and zinc(II) acetates with 1,3,7,13,17,19-hexamethyl-2,8,12,18-tetrabutylbiladiene-a,c (H₂L) in dimethylformamide (298.15 K) was studied by spectrophotometric and calorimetric titration. It was found that H₂L and Zn(II) form a mononuclear porphyrine-like complex ZnL, and in the case of Co(II), a binuclear biligand complex Co₂L₂ with a doubly interlaced structure is formed. Thermodynamic characteristics of the formation of Co(II) and Zn(II) complexes with biladiene-a,c in DMF at 298.15 K were determined. In the template synthesis of macrocyclic compounds from H₂L, it is more efficient to use Zn²⁺ than Co²⁺ ion as the template.     

Synthesis of 7-(furan-2-yl)-7,8,10,10a-tetrahydro-6<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">c</Emphasis>]-chromen-6,9(6a<Emphasis Type="Italic">H</Emphasis>)-diones

Methods of synthesis were developed for 7-(furan-2-yl)-substituted 7,8,10,10a-tetrahydrobenzo[c] chromen-6,9-diones by regioselective [4+2]-cycloaddition of coumarin-3-carboxylic acids to 2-(3-trimethylsiloxybuta- 1,3-dien-1-yl)furans. The [4+2]-cycloaddition was efficiently catalyzed with L-proline.