Zn(II), Cd(II) and Hg(II) complexes of 6-amino-1-methyl-5-nitrosouracil

The following Zn(II), Cd(II) and Hg(II) complexes of neutral and deprotonated 6-amino-1-methyl-5-nitroso-uracil (HL) were prepared and studied by u.v.-vis, ¹H-NMR and i.r. techniques: ZnL₂·4H₂O,ZnL₂(H₂O)₂·H₂O, CdCl₂(HL)₂·2H₂O and HgL₂·2H₂O. In Zn(II) and Hg(II) complexes, the ligand is coordinated in anionic nitroso-phenolic form, acting as a bidentate ligand through the nitrogen and oxygen atoms of the 5-nitroso and 6-oxide groups, respectively. In the cadmium complex, the ligand seems to be either N,O- or only N-bound to the metal ion, with chlorine bridging. From the data obtained, molecular structures are proposed for each complex.     

Syntheses and crystal structures of three structurally similar dinuclear silver(I) complexes

Three terephthalato-bridged dinuclear silver(I) complexes with the formulae Ag₂(5map)₄(tphth), [Ag₂(6map)₄(tphth)] · 2H₂O, and [Ag₂(4map)₄(tphth)] · 2H₂O (5map = 5-methyl-2-aminopyridine, 6map = 6-methyl-2-aminopyridine, 4map = 4-methyl-2-aminopyridine, tphth = terephthalate), have been synthesized and characterized by elemental analysis and single crystal X-ray diffraction. The Ag atom in each of the complexes is three-coordinate in a trigonal geometry with one carboxylate O atom and two pyridine N atoms. The characteristic difference among the complexes is the positions for the methyl groups of the aminopyridine ligands. The crystals of the complexes are stabilized by intermolecular N–H···O and O–H···O hydrogen bonds. Electronic supplementary material  The online version of this article () contains supplementary material, which is available to authorized users.     

Synthesis,characterization and antimicrobial studies on cis-platinum(II) complexes of 5-nitrosouracil derivatives

Two complexes were obtained during the reactions of 6-amino-1-methyl-5-nitrosouracil (AMNU) and 6-methylamino-1-benzyl-5-nitrosouracil (MABNU) with cis-diaquadiamineplatinum(II) nitrate complex, cis-[Pt(NH₃)₂(H₂O)₂](NO₃)₂. The complexes were isolated in good yields as powdery precipitates. They were characterized through their elemental analysis, infrared, UV–vis, and ¹H NMR spectroscopies as well as thermal analyses. The obtained results indicated that, pyrimidine bases substitute easily aqua ligands and interact with Pt(II) ions as a monodentate ligand in the neutral and ionic form for the ligands AMNU and MABNU, respectively. The exocyclic oxygen atoms are the most probable binding site. Square planar structures, cis-form, were proposed in both cases. The free ligands, and their Pt(II) complexes were screened for their antimicrobial activities.     

Synthesis,spectroscopic and thermal studies on platinum(II) complexes of 5-nitrosouracil derivatives

Three complexes were obtained during reactions of 6-amino-1-methyl-5-nitrosouracil, 6-methylamino-1-methyl-5-nitrosouracil and 6-methylamino-1-benzyl-5-nitrosouracil with K₂PtCl₄. The complexes were isolated in good yields as powdery precipitates and characterized through elemental analysis, infrared and ¹H NMR spectroscopies, and thermal analysis. The pyrimidine bases easily substitute chloro ligands as a neutral monodentate ligand form. The exocyclic oxygen atoms are the probable binding sites rather than ring or exocyclic nitrogen atoms. trans Square planar structures were proposed in all cases.     

The study of thermal decomposition kinetics of zinc oxide formation from zinc oxalate dihydrate

This study is devoted to the thermal decomposition of ZnC₂O₄·2H₂O, which was synthesized by solid-state reaction using C₂H₂O₄·2H₂O and Zn(CH₃COO)₂·2H₂O as raw materials. The initial samples and the final solid thermal decomposition products were characterized by Fourier transform infrared and X-ray diffraction. The particle size of the products was observed by transmission electron microscopy. The thermal decomposition behavior was investigated by thermogravimetry, derivative thermogravimetric and differential thermal analysis. Experimental results show that the thermal decomposition reaction includes two stages: dehydration and decomposition, with nanostructured ZnO as the final solid product. The Ozawa integral method along with Coats–Redfern integral method was used to determine the kinetic model and kinetic parameters of the second thermal decomposition stage of ZnC₂O₄·2H₂O. After calculation and comparison, the decomposition conforms to the nucleation and growth model and the physical interpretation is summarized. The activation energy and the kinetic mechanism function are determined to be 119.7 kJ mol^?1 and G(α) = ?ln(1 – α)^1/2, respectively.     

Synthesis,crystal structure and characterization of a series of complexes constructed from coordinated Lanthanides(III) and the heteropolyanion [SiMo12O40]4−

The reaction of α-[SiMo₁₂O₄₀]^4? with trivalent cations Ln³⁺ and N-methyl-2-pyrrolidone leads to a series of complexes of formula [Ln(NMP)₄(H₂O) _n ]H[SiMo₁₂O₄₀]?·?2NMP?·?mH₂O [where Ln?=?La (1), Pr (2), Nd (3), Sm (4), Gd (5), n?=?4, Ln?=?Dy (6), Er (7), n?=?3. NMP?=?N-methyl-2-pyrrolidone]. The syntheses, X-ray crystal structures, IR, and ESR spectra and thermal properties of the complexes 1, 2, 4, 6, 7 have been reported previously. Here, we report X-ray crystal structures, IR, UV, ESR spectra and thermal properties of the complexes [Nd(NMP)₄(H₂O)₄]H[SiMo₁₂O₄₀]?·?2NMP?·?1.5H₂O (3), and [Gd(NMP)₄(H₂O)₄]H[SiMo₁₂O₄₀]?·?2NMP?·?H₂O (5). In addition, the electrochemical behaviour of this series of complexes in aqueous solution and aqueous-organic solution has been investigated and systematic comparisons have been made. All these complexes exhibit successive reduction process of the Mo atoms.     

Tb(III) complexes with 1-phenyl-3-methyl-4-stearoyl-pyrazol-5-one as a material for luminescence Langmuir–Blodgett films

Abstract

Synthesis and properties of new luminescent amphiphilic Tb(III) complexes [TbL₃·2H₂O]·3H₂O, TbL₃·bipy, [H₃O][TbL₄]·6H₂O and [H₃O][TbL′₃L]·H₂O, where HL is 1-phenyl-3-methyl-4-stearoylpyrazolone-5 and HL′ is 1-phenyl-3-methyl-4-formylpyrazolone-5, are reported. The complexes have been characterized by elemental and thermal analysis, FTIR and luminescence spectroscopy methods. Formation and properties of Langmuir–Blodgett films of the complexes are described.     

Synthesis of palladium(II) complexes with 3-amino-5-methyl-5-(4-pyridyl)-hydantoin: cytotoxic and antimicrobial investigations and comparison with their platinum analogues

Two new Pd(II) complexes with 3-amino-5-methyl-5-(4-pyridyl)-hydantoin (AMPH) were synthesized: cis-[Pd(AMPH)₂Cl₂]·2H₂O and cis-[Pd(AMPH)₂Br₂]·H₂O. The complexes were characterized by physico-chemical and spectroscopic methods. The determination of crystal water content in the complexes was defined by Karl Fisher titration. The cytotoxic effects of these complexes were examined on a panel of human tumor cell lines. Qualitative antimicrobial assays on three pathogenic microorganisms of the new complexes, their analogues with 5-methyl-5-(4-pyridyl)-hydantoin(MPH) and their platinum analogues were made. Cis-[Pd(mpyh)₂Br₂]·H₂O showed significant activity against C. albicans.     

Four Complexes with the Rigid Ligand 1,4‐Bis(1H‐imidazol‐4‐yl)benzene and Varied Carboxylate Ligands

Four metal‐organic coordination polymers [Co₂(L)₃(nipa)₂]·6H₂O ( 1 ), [Cd(L)(nipa)]·3H₂O ( 2 ), [Co(L) (Hoxba)₂] ( 3 ) and [Ni₂(L)₂(oxba)₂(H₂O)]·1.5L·3H₂O ( 4 ) were synthesized by reactions of the corresponding metal(II) salts with the rigid ligand 1,4‐bis(1H‐imidazol‐4‐yl)benzene (L) and different derivatives of 5‐nitroisophthalic acid (H₂nipa) and 4,4′‐oxybis(benzoic acid) (H₂oxba), respectively. The structures of the complexes were characterized by elemental analysis, FT‐IR spectroscopy and single‐crystal X‐ray diffraction. Complexes 1 and 3 have the same one‐dimensional (1D) chain while 2 is a 6‐connected twofold interpenetrating three‐dimensional (3D) network with α ‐Po 4¹²·6³ topology based on the binuclear Cd^II subunits. Compound 4 features a puckered two‐dimensional (2D) (4,4) network, and the large voids of the packing 2D nets have accommodated the uncoordinated L guest molecules. An abundant of N–H···O, O–H···O and C–H···O hydrogen bonding interactions exist in complexes 1–4 , which contributes to stabilize the crystal structure and extend the low‐dimensional entities into high‐dimensional frameworks. Lastly, the photoluminiscent properties of compounds 2 were also investigated.     

Synthesis, Spectral and Thermal Analyses of Novel Bi- and Polyhomonuclear Complexes of Pyrimidine Bisazo-dianil Derivatives

Seven new bi‐ and polyhomonuclear transition metal complexes with three polyhydroxlated bisazodianil ligands were synthesized and characterized. The ligands were derived from condensation of 6‐(5‐formyl‐2‐hydroxyphenylazo)‐2,4‐dihydroxypyrimidine with aliphatic diamines (H₈L¹, H₈L² and H₆L³). The data of elemental and thermal analyses, molar conductance measurement, IR, electronic and ESR spectra as well as magnetic moment measurements support the formation of [L¹Co₇Cl₆(H₂O)₁₀]·22H₂O ( 1 ), [H₂L²Mn₆Cl₆(H₂O)₈]·3H₂O·2EtOH ( 3 ), [L²Co₈Cl₈(H₂O)₁₂]·24H₂O ( 4 ), [H₄L³Co₂Cl₂(H₂O)₂]·8H₂O·2EtOH ( 6 ) with a tetrahedral geometry and [H₂L¹Ni₅Cl₄(H₂O)₁₆]·19H₂O·EtOH ( 2 ), [L²Ni₈Cl₈(H₂O)₂₈]·8H₂O·EtOH ( 5 ) with an octahedral geometry while [H₆L³Cu₃(H₂O)₇]Cl₃·10H₂O ( 7 ) has a distorted tetrahedral arrangement. The mode of bonding between the metal ions and the ligand molecules is determined and the metal‐metal interaction was studied. The activation thermo‐kinetic parameters for the thermal decomposition steps of the complexes E*, ΔH*, ΔS*, and ΔG* were calculated.     

Coordination compounds of neodymium(III) with acyldihydrazones of saturated dicarboxylic acids and 3-methyl-1-phenyl-4-formylpyrazol-5-one

Coordination compounds of neodymium(III) with acylhydrazones of saturated dicarboxylic acids and 3-methyl-1-phenyl-4-formylpyrazol-5-one are synthesized and studied. The structure of complex [Nd₂(H₂L²)₃] · Me₂SO · CH₃OH · 6H₂O is determined from the X-ray diffraction data for the isostructural lanthanum complex. The complex is binuclear and contains nine-vertex coordination polyhedra bound by three hydrocarbon spacers. Solid samples of the studied neodymium complexes exhibit luminescence in the near-infrared spectral range (λ = 874, 904, and 1059 nm) characteristic of this ion.     

Oxalate-2-ethanolamine complexes of some bivalent cations (Mn,Co, Ni,Cu, Zn and Cd)

On the refluxing ofM(II) oxalate (M=Mn, Co, Ni, Cu, Zn or Cd) and 2-ethanolamine in chloroform, the following complexes were obtained: MnC₂O₄·HOCH₂CH₂NH₂·H₂O, CoC₂O₄·2HOCH₂CH₂NH₂, Ni₂(C₂O₄)₂·5HOCH₂CH₂NH₂·3H₂O, Cu₂(C₂O₄)₂·5HOCH₂CH₂NH₂, Zn₂(C₂O₄)₂·5HOCH₂CH₂NH₂·2H₂O and Cd₂(C₂O₄)₂·HOCH₂CH₂NH₂·2H₂O. Following the reaction ofM(II) oxalate with 2-ethanolamine in the presence of ethanolammonium oxalate, a compound with the empirical formula ZnC₂O₄·HOCH₂CH₂NH₂·2H₂O¹ was isolated. The complexes were identified by using elemental analysis, X-ray powder diffraction patterns, IR spectra, and thermogravimetric and differential thermal analysis. The IR spectra and X-ray powder diffraction patterns showed that the complexes obtained were not isostructural. Their thermal decompositions, in the temperature interval between 20 and about 900°C, also take place in different ways, mainly through the formation of different amine complexes. The DTA curves exhibit a number of thermal effects.     

Thermal studies on metal complexes of 5-nitrosopyrimidine derivatives

The following Zn(II), Cd(II), Hg(II) and Hg(I) complexes of 4-amino-1,6-dihydro-2-methylthio-5-nitroso-6-oxopyrimidine (MTH) have been prepared and their thermal behaviour studied by TG and DSC techniques: Zn(MT)₂·3H₂O, Cd(MT)·H₂O. Cd(MTH)Cl₂, Hg(MTH)Cl₂ and Hg₂(MT)(NO₃). The dehydration and dehalogenation enthalpy values were calculated.     

A linear cyclic oximate-bridged ­tetracopper(II) complex

The crystal structure of the title complex, tetrakis­[μ-6-amino-3-methyl-4-aza­hex-3-en-2-one oximato(1–)-κ⁴N,N′,N′′:O]tetracopper(II) tetraperchlorate 0.6-hydrate, [Cu₄(C₆H₁₂N₃O)₄](ClO₄)₄·0.6H₂O, shows the cation to be an oximate-bridged tetramer composed of four 6-amino-3-methyl-4-aza­hex-3-en-2-one oxime ligands and four copper(II) ions and to have crystallographically imposed symmetry. Each Cu^II atom is four-coordinated by the three N atoms of one oxime ligand and by the O atom of another oxime ligand in a distorted square-planar geometry.     

Synthesis,spectral, thermal,solid state d.c. electrical conductivity,fluorescence and biological studies of lanthanum(III) and thorium(IV) complexes of 24-membered macrocyclic triazoles

A series of La(III) and Th(IV) complexes have been synthesized by template condensation of 2,6-diformyl-4-methylphenol, bis-(4-amino-5-mercapto-1,2,4-triazol-3-yl)alkanes and La(NO₃)₃ ·?6H₂O/Th(NO₃)₄ ·?5H₂O in 2 : 2 : 1 molar ratio in ethanol. These complexes were characterized by elemental analyses, magnetic susceptibility, molar conductance, spectral (IR, UV–Vis, ¹H-NMR, FAB-mass), thermal, fluorescence and solid state d.c. electrical conductivity studies. The complexes are insoluble in water but soluble in DMF and DMSO. The observed molar conductance values indicate non electrolytes. Elemental analyses suggest 1 : 1 stoichiometry, [La(L^I–IV)(NO₃)(H₂O)₂] ·?3H₂O and [Th(L^I–IV)(NO₃)₂(H₂O)₂] ·?3H₂O. Spectroscopic studies indicate that coordination occurs through phenolic oxygen after deprotonation, nitrogen of azomethine group and bridging bidentate nitrates. The solid state d.c. electrical conductivity indicates semiconducting nature. All the Schiff bases and their La(III) and Th(IV) complexes were evaluated for biological properties; some compounds show promising results.     

Metal complexes of macrocyclic ligands. Part XXIV. Binuclear complexes with tetraazamacrocycle-N,N′,N″,N‴-tetraacetic acids

The three ligands H₄dota, H₄teta, and H₄heta give binuclear complexes with Cu²⁺ and Ni²⁺, the spectral properties of which have been studied. The structures of Cu₂(dota)·5H₂O and Cu₂(teta)·6H₂O have been established by X-ray diffraction analysis.     

Synthesis and study of cobalt(II), nickel(II), and copper(II) complexes with 4-(4-hydroxyphenyl)-1,2,4-triazole

New complexes of Co(II), Ni(II), and Cu(II) nitrates, chlorides, and perchlorates with 4-(4-hydroxyphenyl)-1,2,4-triazole (L) were obtained and examined by single-crystal X-ray diffraction, X-ray powder diffraction, and electronic absorption and IR spectroscopy. The cations of all the complexes have linear trinuclear structures. Ligand L is coordinated to the metal ions in a bidentate bridging fashion through the N(1) and N(2) atoms of the heterocycle. The coordination polyhedron of the metal atoms is a distorted octahedron. The molecular and crystal structures of the complexes [Co₃L₆(H₂O)₆](ClO₄)₆ · 3C₂H₅OH · 3.75H₂O and [M₃L₆(H₂O)₆](ClO₄)₆ · 6H₂O (M = Cu²⁺ and Ni²⁺) were determined.     

Molecular modeling,spectral, and biological studies of 4-formylpyridine-4 N-(2-pyridyl) thiosemicarbazone (HFPTS) and its Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Cd(II), Hg(II), and UO2(II) complexes

The present work describes the preparation and characterization of some metal ion complexes derived from 4-formylpyridine-⁴ N-(2-pyridyl)thiosemicarbazone (HFPTS). The complexes have the formula; [Cd(HFPTS)₂H₂O]Cl₂, [CoCl₂(HPTS)]·H₂O, [Cu₂Cl₄(HPTS)]·H₂O, [Fe (HPTS)₂Cl₂]Cl·3H₂O, [Hg(HPTS)Cl₂]·4H₂O, [Mn(HPTS)Cl₂]·5H₂O, [Ni(HPTS)Cl₂]·2H₂O, [UO₂(FPTS)₂(H₂O)]·3H₂O. The complexes were characterized by elemental analysis, spectral (IR, ¹H-NMR and UV–Vis), thermal and magnetic moment measurements. The neutral bidentate coordination mode is major for the most investigated complexes. A mononegative bidentate for UO₂(II), and neutral tridentate for Cu(II). The tetrahedral arrangement is proposed for most investigated complexes. The biological investigation displays the toxic activity of Hg(II) and UO₂(II) complexes, whereas the ligand displays the lowest inhibition activity toward the most investigated microorganisms.     

Synthesis,spectral, thermal and crystallographic investigations on oxovanadium(IV) and manganese(III) complexes derived from heterocyclic β-diketone and 2-amino ethanol

Novel mononuclear oxovanadium(IV) and manganese(III) complexes [VO(L¹)₂·H₂O] (1); [VO(L²)₂·H₂O] (2); [VO(L³)₂·H₂O] (3); [Mn(L¹)₂]ClO₄·H₂O (4); [Mn(L²)₂] ClO₄·H₂O (5); [Mn(L³)₂]ClO₄·H₂O (6) were prepared by condensation of 1 mol of VOSO₄·5H₂O or Mn(OAc)₃· 2H₂O with 2 mol of ligand HL¹, HL² or HL³ (where HL¹ = 4-[(2-hydroxy-ethylamino)-methylene]-5-methyl-2- phenyl-2,4-dihydro-pyrazol-3-one; HL²=4-[(2-hydroxy-ethylamino)-methylene]-5-methyl-2-p-tolyl-2,4-dihydro-pyrazol-3-one; HL³=4-{4-[(2-hydroxy-ethyl-amino)-methyl]-3-methyl-5-oxo-4,5-dihydropyrazol-1-yl} benzene sulfonic acid). The resulting complexes were characterized by elemental analyses, molar conductance, magnetic and decomposition temperature measurements, electron spin resonance, FAB mass, IR and electronic spectral studies. From TGA, DTA and DSC, the thermal behaviour and degradation kinetic were studied. Electronic spectra and magnetic susceptibility measurements indicate distorted octahedral stereochemistry of oxovanadium(IV) complexes and regular octahedral stereochemistry of manganese(III) complexes. Hamiltonian and bonding parameters found from ESR spectra indicate the metal ligand bonding is partial covalent. The X-ray single crystal determination of one of the representative ligand was carried out which suggests existence of amine-one tautomeric form in the solid state. The ¹H-NMR spectra support the existence of imine-ol form in solution state. The LC-MS studies sustain the¹H-NMR result. The electronic structure of the same representative ligand was optimized using 6-311G basis set at HF level ab initio studies to predict the coordinating atoms of the ligand.     

Metal Ion‐tuned Complexes based on Benzene‐1, 2, 4, 5‐tetracarboxylic Acid and the Semirigid Ligand 1, 4‐Bis(2‐methylbenzimidazol‐1‐ylmethyl) Benzene

Abstract. Two metal‐organic coordination polymers [Co(bmb)(btc)_0.5]_n( 1 ) and {[Zn(bmb)_0.5(btc)_0.5(H₂O)] · 0.5bmb · H₂O}_n ( 2 ) [H₄btc = benzene‐1, 2, 4, 5‐tetracarboxylic acid, bmb = 1, 4‐bis(2‐methylbenzimidazol‐1‐ylmethyl) benzene] were prepared under hydrothermal conditions. Single‐crystal X‐ray diffraction indicates that both complexes have a 2D framework structure with (4 · 6²) (4² · 6² · 8²) topology. Interestingly, the hydrogen bonds in 2 form a fascinating meso‐helix. The catalytic activity of 1 for oxidative coupling of 2, 6‐dimethylphenol (DMP) and the photoluminescence properties of 2 were investigated. Furthermore, the complexes were investigated by IR spectroscopy and thermogravimetric analysis.