Synthesis,spectroscopic characterization and thermal behavior of metal complexes formed with (Z)-2-oxo-2-(2-(2-oxoindolin-3-ylidene)hydrazinyl)-N-phenylacetamide (H2OI)

Complexes of Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and U(IV)O₂ with (Z)-2-oxo-2-(2-(2-oxoindolin-3-ylidene)hydrazinyl)-N-phenylacetamide (H₂OI) are reported and have been characterized by various spectroscopic techniques like (IR, UV–Vis, ESR ¹H and ¹³C NMR) as well as magnetic and thermal (TG and DTA) measurements. It is found that the ligand behaves as a neutral tridentate, neutral tetradentate, monoanionic tridentate, monoanionic tridentate and dianionic tridentate. An octahedral geometry for all complexes except [Cu₂(H₂OI)(OAc)₄](H₂O)₂ and [Cu(HOI)Cl](H₂O)₂ which have a square planar geometry. Furthermore, kinetic parameters were determined for each thermal degradation stage of some studied complexes using Coats–Redfern and Horowitz–Metzger methods. The bond lengths, bond angles, HOMO, LUMO and dipole moments have been calculated to confirm the geometry of the ligand and the investigated complexes.     

Synthesis,characterization, NLO study,and antimicrobial activities of metal complexes derived from 3-(3-(2-hydroxyphenyl)-3-oxoprop-1-enyl)-4H-chromen-4-one and sulfanilamide

A series of metal(II) complexes ML (where M?=?Cu(II), Co(II), Ni(II), Zn(II), Mn(II), Cd(II), and VO(II)) have been prepared from 3-(3-(2-hydroxyphenyl)-3-oxoprop-1-enyl)-4H-chromen-4-one and sulfanilamide. The structures of the complexes have been investigated by elemental analysis, magnetic susceptibility, molar conductance, IR, UV-Vis, NMR, mass, and ESR spectral studies. Conductivity measurements reveal that the complexes are non-electrolytes, except the oxovanadium complex. Spectral and other data show square pyramidal geometry for oxovanadium and octahedral for the other complexes. The redox behaviors of the copper and vanadyl complexes have been studied through cyclic voltammetry. Antimicrobial activities of the compounds against several microorganisms indicate that some complexes have higher activity than free ligand. The compounds may serve as photoactive materials as indicated from their characteristic fluorescence properties. The second harmonic generation efficiency of the ligand was found to be higher than that of urea and KDP.     

Synthesis,characterization and coordination behavior of 2-(1-carboxyl-2-hydroxyphenyl)thiazolidine

The reaction of 3-formylsalicylic acid with 2-aminoethanethiol produces 2-(1-carboxyl-2-hydroxyphenyl)thiazolidine (H₂chptz) which remains in equilibrium in solution with its corresponding Schiff base, 3-carboxysalicylidenethioethanolimine (H₃mcsalim) having an NSO-donor set of atoms. The reactions of the thiazolidine ligand with different metal salts leading to the synthesis of many new metal complexes and organometallic derivatives have been studied. For all the complexes the dianion of the Schiff base, H₃mcsalim acts as a tridentate NSO donor ligand. The reactions of [(Hmcsalim)Ti(π-C₅H₅)Cl] and [(Hmcsalim)Sn(Me)Cl], isolated in this study, with Me₃SiE (where, E stands for SMe, NMe₂ and C≡CPh) have also been studied. The elemental analyses, magnetic susceptibilities, molar conductance values, EPR-study, CV, molecular weights and spectroscopic (UV-Vis, IR, ¹H NMR) data characterize all the compounds under study. Based upon these data the geometry of the compounds has also been proposed.     

Palladium(II) complexes with 1-allyl-3-(2-pyridyl)thiourea: Synthesis and spectroscopic characterization

New Pd(II) complexes with 1-allyl-3-(2-pyridyl)thiourea (APTU) of the formulas [Pd(C₉H₁₁N₃S)Cl₂] (I) and [Pd(C₉H₁₁N₃S)₂]Cl₂ (II) were obtained and examined by UV-Vis, IR, and 1H NMR spectroscopy. The conditions for the complexation reactions were optimized. The instability constants and molar absorption coefficients of these complexes were calculated. Comparison of the characteristic bands in the UV-Vis and IR spectra of the complexes and free APTU revealed that the ligand in both complexes is coordinated to the metal atom in the thione form in the bidentate chelating mode through the S atom of the thiourea group and the pyridine N atom. In the UV-Vis spectra of the complexes, the charge transfer bands (π → π* Py) and n → π* (C=N_Py), (C=S) experience hypsochromic shifts by 450–470 cm⁻¹ caused by the coordination of APTU to the metal ion, which gives rise to ligand-metal charge-transfer bands (C=N_Py → Pd, n → π* (C=S)) and (SPd). The protons in the 6-, 4-, and 3-positions of the pyridine ring and the thiourea NH proton in the chelate ring are most sensitive to the complexation.     

Synthesis of 1-(2-hydroxyphenyl)-2,4-imidazolidinedione derivatives through cyclic transformations of ethyl 2-oxo-3(2H)-benzoxazoleacetate derivatives

A series of ethyl 2-oxo-3(2H)-benzoxazoleacetate derivatives 2 have been synthesized. By reaction with ammonia, primary amines or hydrazine, these compounds 2 were transformed into 1-(2-hydroxyphenyl)-2,4-imidazolidinedione derivatives 4, 5 and 6 , respectively. Some of these new hydantoins 4 , treated with phosphorus oxychloride, gave 3H-2-oxoimidazo[2,1-b]benzoxazole derivatives 9 . Ethyl 2-oxo-3(2H)-benzoxazolepropionate ( 10 ) was prepared by a Michaël reaction of ethyl acrylate with 2-benzoxazolone ( 1a ). With 10 , no cyclic transformation was observed in the presence of ammonia or alkylamine.     

Synthesis and alkylation ofN-methylmorpholinium 5-cyano-4-(3- and 4-hydroxyphenyl)-2-oxo-1,2,3,4-tetrahydropyridine-6-thiolates

The reactions of 3- or 4-hydroxybenzaldehydes with cyanothioacetamide and Meldrum's acid in the presence ofN-methylmorpholine affordedN-methylmorpholinium 5-cyano-4-(3-or 4-hydroxyphenyl)-2-oxo-1,2,3,4-tetrahydropyridine-6-thiolates, respectively. The resulting compounds were used in the synthesis of substituted 6-alkylthio-1,2,3,4-tetrahydropyridin-2-ones. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2333–2336. December, 1999.     

Novel 3d-metal complexes with 1,2-diamino-3-(2-benzothiazolyl)-4(5H)-ketopyrrole: Synthesis,spectroscopic and structural investigations

A series of new 3d-metal complexes have been prepared by the reaction of M(CH₃COO)₂ (M = Zn(II), Co(II), Ni(II)) and 1,2-diamino-3-(2-benzothiazolyl)-4(5H)-ketopyrrole (HL) in a methanol (3) or a methanol/dmf (1, 2) medium. All the complexes have been studied by elemental analyses, electronic and IR spectroscopies. The zinc(II) complex 1 and the ligand HL have been investigated using the method of ¹H NMR-spectroscopy at various temperatures. The disappearance of the signal from one proton of the amino group H(5) in the spectrum of complex 1 confirmed the existence of the ligand in the deprotonated form. According to the data of the ¹H NMR-spectroscopy, the ligand HL is coordinated to zinc(II) through the nitrogen atom of the deprotonated amino group and the nitrogen atom of the benzothiazole substituent. These data are in agreement with X-ray structural studies for the ligand HL and the zinc(II) complex 1.     

Synthesis,spectral, thermal and electrochemical characterization of metal(II) complexes with 1-S-methylcarbodithioate-4-substituted thiosemicarbazides

1-S-Methylcarbodithioate-4-substituted thiosemicarbazides (L¹-L³) have been prepared and confirmed by spectral data and elemental analysis. Co(II), Ni(II), Cu(II), Cd(II) and Zn(II) complexes with L¹-L³ have been prepared and characterized by elemental and thermal analyses, molar conductance, magnetic moment, as well as spectral data (IR, ¹H NMR, mass and electronic spectra). The molar conductance data reveal that the chelates are non-electrolytes. The IR and ¹H NMR spectra showed that L¹-L³ are deprotonated in the complexes and act as binegative SNNS donors. The electronic spectra of the complexes as well as their magnetic moments provide information about geometries. Thermogravimetric analysis of some complexes suggests different decomposition steps and ending with metal sulfide as final product. The redox properties of the complexes are explored by cyclic voltammetry.     

Synthesis, spectroscopic characterization, electrochemical behaviour, reactivity and antibacterial activity of some transition metal complexes with 2-(N-salicylideneamino)-3-carboxyethyl-4,5-dimethylthiophene

Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes with a potentially tridentate Schiff base, formed by condensation of 2-amino-3-carboxyethyl-4,5-dimethylthiophene with salicylaldehyde were synthesized and characterized on the basis of elemental analyses, molar conductance values, magnetic susceptibility measurements, UV-vis, IR, EPR and NMR spectral data, wherever possible and applicable. Spectral studies reveal that the free ligand exists in a bifunctionally hydrogen bonded manner and coordinates to the metal ion in a tridentate fashion through the deprotonated phenolate oxygen, azomethine nitrogen and ester carbonyl group. On the basis of electronic spectral data and magnetic susceptibility measurements, suitable geometry has been proposed for each complex. The EPR spectral data of the Cu(II) complex showed that the metal-ligand bonds have considerable covalent character. The Ni(II) complex has undergone facile transesterification reaction when refluxed in methanol for a lengthy period. X-ray diffraction studies of Cu(II) complex showed that the complex has an orthorhombic crystal lattice. In view of the biological activity of thiophene derivatives, the ligand and the complexes were subjected to antibacterial screening. It has been observed that the antibacterial activity of the ligand increased on chelation with metal ion.     

Synthesis, characterization and spectroscopic studies of copolymer of styrene with 4-oxe-4(P-hydroxyl phenylamino) but-2-enoic acid and corresponding fluorescent macromolecular lanthanide(III) complexes

Copolymer of styrene with 4-oxe-4(P-hydroxyl phenylamino) but-2-enoic acid (PSHPEA) and its luminescent lanthanide complexes Ln-PSHPEA (Ln = La, Eu, Tb and Y) were synthesized and characterized by means of elemental analysis, FT-IR, thermogravimetric analysis and fluorescence determination. The results showed that the carboxylic groups on the chain of the copolymer acted as bidentate ligands coordinated to lanthanide ions, but the amido carbonyl groups, amino N and hydroxy groups had not taken part in coordination; the coordination degree of -COO⁻/Ln³⁺ which determined the content of metal ions in the macromolecular complexes, was closely dependent on both the pH value of the solution and the molar ratio of St to 4-oxe-4(P-hydroxyl phenylamino) but-2-enoic acid in the polymer ligand. The fluorescence determination showed that the complexes exhibited characteristic fluorescence with comparatively high brightness and good mono-chromaticity. Typical relationship between emission intensity and Ln³⁺ ions content in macromolecular complexes exhibited some extent of fluorescence concentration quenching in our studies. The emission intensity of Tb-PSHPEA complexes was much stronger than that of Eu-PSHPEA complexes, which was attributed to especial effectivity in transferring energy from the lowest triplet energy level of the ligand onto the excited state (⁵D₀) of Tb³⁺ ion than that (⁵D₄) of Eu³⁺ ion.     

Novel oxorhenium complexes with 2-(2′-hydroxyphenyl)-2-benzothiazolinato ligand: X-ray studies,spectroscopic characterization and DFT calculations

The [ReOX₂(hbt)(EPh₃)] (X = Cl, Br; E = As, P) chelates have been prepared in the reactions of [ReOX₃(EPh₃)₂] complexes (X = Cl, Br; E = P, As) with 2-(2′-hydroxyphenyl)-2-benzothiazole (hbtH) in acetone. From the reactions of [ReOX₃(PPh₃)₂] with hbtH two kind of crystals [ReOX₂(hbt)(PPh₃)] · MeCN and [ReOX₂(hbt)(PPh₃)] with different arrangement of halide ions (cis and trans) were isolated, whereas the [ReOX₃(AsPh₃)₂] oxocompounds react with hbtH to give only cis-halide isomers. The complexes were structurally and spectroscopically characterised. The electronic structures of both [ReOBr₂(hbt)(PPh₃)] isomers have been calculated with the density functional theory (DFT) method. The TDDFT/PCM calculations have been employed to produce a hundred of singlet excited-states starting from the ground-state geometry optimized in the gas phase of cis- and trans-halide isomers of [ReOBr₂(hbt)(PPh₃)] and the UV–Vis spectra of these complexes have been discussed on this basis.     

Synthesis,characterization, and thermal behavior of palladium(II) complexes containing 4-iodopyrazole

The mononuclear pyrazolyl complexes [PdCl₂(HIPz)₂] (1), [PdBr₂(HIPz)₂] (2), [PdI₂(HIPz)₂] (3), [Pd(SCN)₂(HIPz)₂] (4), and [Pd(NHCOIPz)₂] (5) have been prepared. Compound 1 was obtained from the displacement of acetonitrile from [PdCl₂(CH₃CN)₂] precursor by the 4-iodopyrazole (HIPz) ligand, whereas 2–5 were synthesized by substitution of the chlorido in 1 by the respective anionic group. The compounds were characterized by elemental analysis, infrared spectroscopy, and ¹H NMR spectroscopy. The thermal behavior of 1–5 has been studied by TG and DTA. The thermal stability of [PdX₂(HIPz)₂] compounds varies according to the trends X = Cl^? < I^? ? SCN^?< Br^?. No stable intermediates were isolated during the thermal decompositions due to the overlap of the degradation processes. The final products of the thermal decompositions were characterized as metallic palladium by X-ray powder diffraction.     

Green synthesis of 1,3,4-oxadiazole derivatives based on N-arylidene-2-(1-oxo-4-(4-phenoxyphenyl)phthalazin-2(1H)-yl)acetohydrazide as potential antitumor agents

Design of a new series of 1,3,4-oxadiazole derivatives was achieved in good yield via treatment of N-arylidene-2-(1-oxo-4-(4-phenoxyphenyl)phthalazin-2(1H)-yl)acetohydrazide with cerium (IV) ammonium nitrate as a catalyst. They can be formulated also using one-pot reaction of 2-(1-oxo-4-(4-phenoxyphenyl)phthalazin-2(1H)-yl)acetohydrazide, aromatic aldehyde and cerium (IV) ammonium nitrate in dichloromethane. The structural formulas of all synthesized products were elucidated based on their elemental and spectral analyses. In addition, MTT assay was used to evaluate antitumor activity of the synthesized molecules and some of them showed potent activity in comparison with Doxorubicin as a standard drug.     

Synthesis of 1-(3',4'-dihydroxyphenyl)-7-(4"-hydroxyphenyl)- 4hepten-3-one

Natural diarylheptanoids have significant bioactivities. Some of them are potent inhibitors against prostaglandin biosynthesizing enzyme (PG synthetase) and 5-lipoxygenase (LT synthetase)1-2. Compound 1 was firstly isolated from Alnus rubra bark3. So far its synthesis has not been reported yet. Herein, we report the synthesis of compound 1. Meantime, compound 24 was also obtianed as an intermediate. Compound 7 and 16 were converted to compound 10 and 18 respectively, because compound 1…     

Synthesis and Crystal Structure of 4-Salicylimine-3,5-bis(2-hydroxyphenyl)-1,2,4-triazole

1 INTRODUCTION 1, 2, 4-Triazole and its derivatives have gained great attention as ligands to transition metals by the fact that they unite the coordination geometry of both pyrazoles and imidazoles, and in addition exhibit a strong and typical property of acting as bridging ligands between two metal centers. In this bridging capacity, the 1, 2, 4-triazole ligands show a great coordination diversity, especially when the triazole nucleus are substituted with additional donor groups[1]. In…     

Synthesis, spectroscopic and thermal characterization of some transition metal complexes of folic acid

Compounds having general formula: [M(FO)(Cl)(x)(H(2)O)(y)].zH(2)O, where (M=Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II), FO=folate anion, x=2 or 4, y=2 or 4 and z=0, 1, 2, 3, 5 or 15) were prepared. The obtained compounds were characterized by elemental analysis, infrared as well as electronic spectra, thermogravimetric analysis and the conductivity measurements. The results suggested that all folate complexes were formed by 2:1 molar ratio (metal:folic acid) as a bidentate through both of the two carboxylic groups. The molar conductance measurements proved that the folate complexes are electrolytes. The kinetic thermodynamic parameters such as: E*, DeltaH*, DeltaS* and DeltaG* were estimated from the DTG curves. The antibacterial evaluation of the folic acid and their complexes was also done against some Gram positive/negative bacteria as well as fungi.     

Synthesis of 1-(3,5-di-tert-butyl-4-hydroxyphenyl)-2-r-benzimidazoles

Reaction of 2,6-di-tert-butyl-1,4-benzoquinone with o-phenylendiamine gives 2,6-di-tert-butyl-1,4-benzoquinone-4-(N-o-aminophenyl)imine which reacts smoothly with heterocyclic, aromatic and aliphatic aldehydes to form (1-(3,5-di-tert-butyl-4-hydroxyphenyl)-2-substituted benzimidazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 483–485, April, 1990.