A novel improved synthesis of 3-aminopyrazine-2-carboxylic acid

A three step synthesis of 3-aminopyrazine-2-carboxylic acid ( 1 ) starting from pyrazine-2,3-dicarboxylic acid ( 5 ) is described. Diacid 5 is converted via the anhydride 6 into the ammonium salt of the half acid amide 7 which on Hofmann rearrangement gives the title compound in 55% overall yield.     

Synthesis,characterization and anti-bacterial activity of divalent transition metal complexes of hydrazine and trimesic acid

Transition metal complexes of trimesic acid and hydrazine mixed-ligands with a general formula M(Htma)(N₂H₄)₂, where, M = Mn, Co, Ni, Cu and Zn; H₃tma = trimesic acid, have been prepared and characterized by elemental, structural, spectral and thermal analyses. For the complexes, the carboxylate ν_asym and ν_sym stretchings are observed at about 1626 and 1367 cm^?1 respectively, with Δν between them of ～260 cm^?1, showing the unidentate coordination of each carboxylate group. The hydrazine moieties are present as bridging bidentates. Electronic and EPR spectral studies suggest an octahedral geometry for the complexes. All these complexes show three steps of decomposition in TGA/DTA. SEM images of CuO and MnO residues obtained from the complexes show nano-sized clusters suggesting that the complexes may be used as precursors for nano-CuO and nano-MnO preparation. The antimicrobial activities of the prepared complexes, against four bacteria have been evaluated.     

Synthesis,characterization and antifungal activity of glycylglycine Schiff base complexes of 3d transition metal ions

Summary Two new Schiff bases, N-4-hydroxysalicylidene-glycylglycine (K·GGRS·H₂O), N-O-vanillal-glycylglycine (K· GGVS·3H₂O) and their manganese(II), cobalt(II), nickel(II) and copper(II) complexes have been synthesized and characterized by elemental analysis, t.g.a., molar conductance, i.r. and u.v. spectral studies. The ¹³Cn.m.r. spectrum of one of the Schiff base ligands has been recorded. The results show that the ligand is coordinated to the central metal ion via amide nitrogen, imino nitrogen, phenolic oxygen and carboxyl oxygen to form a quadridentate complexes. Some of the complexes exhibit strong inhibitory action towards Candida albicans and Cryptococcus neoformans.     

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,characterization and antineoplastic activity of 5-chloro-2,3-dihydroxypyridine transition metal complexes

Synthetic procedures are described that allow access to cis-[Mo₂O₅(cdhp)₂]^2?, cis-[W₂O₅(Hcdhp)₂], trans-[OsO₂(cdhp)₂]^2?, trans-[UO₂(Hcdhp)₂], [ReO(PPh₃)(Hcdhp)₂]X (X =?Cl, I), [ReO₂(cdhp)₂]^?, [M(PPh₃)₂(cdhp)], [M(bpy)(cdhp)] (M(II) =?Pd, Pt), [Ru(YPh₃)₂(Hcdhp)₂] (Y =?P, As), [Rh(Hcdhp)₂Cl(H₂O)], [Rh(PPh₃)₂(Hcdhp)₂]ClO₄ and [Ir(bpy)(cdhp)Cl₂], where Hcdhp, cdhp are the deprotonated monoanion of 5-chloro-3-hydroxypyrid-2-one and dianion of 5-chloro-2,3-dihydroxypyridine, respectively. These complexes were characterized by their Raman, IR, ¹H NMR, electronic and mass spectra, conductivity, magnetic and thermal measurements. H₂cdhp, cis-K₂[Mo₂O₅(cdhp)₂], [Pd(bpy)(cdhp)] display a significant antineoplastic activity against Ehrlich ascites tumor cells (EAC).     

Synthesis and characterization of heteroleptic Schiff base transition metal complexes: a study of anticancer,antimicrobial, DNA cleavage and anti-TB activity

In search of effective bioactive compounds, we have synthesized the new Co(II), Ni(II), and Cu(II) complexes of the Schiff base derived from 8-formyl-7-hydroxy-4-methylcoumarin and 2-hydrazino benzothiazole and characterized by analytical, spectroscopic (IR, NMR, UV–vis, Mass), magnetic, powder X-ray diffraction data (PXRD) and TGA studies. Elemental analysis suggests the stoichiometry of the synthesized complexes and the solution electronic spectral study revealed the octahedral geometry of the compounds. Thermal analysis shows the presence of water molecule outside the coordination sphere and powder-XRD patterns have been studied to test the degree of crystallinity of the complexes and unit cell calculations were made. All the synthesized compounds were tested against human ovarian cancer cell line (PA-1). The synthesized metal complexes exhibited enhanced activity against the tested bacterial (Staphylococcus aureus and Escherichia Coli) and fungal strains (Candida albicans and Aspergillus fumigatus) as compared to free ligand (LH). The results of the DNA-cleavage activity suggest that the ligand and its metal complexes can cleave CT-DNA at different degrees. Further, anti-tuberculosis activity was done using microplate almar blue assay. Among all these synthesized compounds, the Cu(II) complex exhibits good cleaving ability compared to other newly synthesized metal complexes.     

Synthesis,characterization, and anticancer activity of some metal complexes with a new Schiff base ligand

A new Schiff base ligand, 2-((E)-((4-(((E)-benzylidene)amino)phenyl)imino)methyl)-naphthalene-1-ol, was prepared by the reflux condensation of p-phenylenediamine with 2-hydroxy-1-naphthaldehyde and benzaldehyde. Metal complexes were prepared by reacting the ligand with metal salts: VCl₃, CrCl₃·6H₂O, MnCl₂·3H₂O, FeCl₃·6H₂O, CoCl₃·6H₂O, NiCl₂·6H₂O, CuCl₂·2H₂O, and ZnCl₂. The ligand and its metallic complexes were characterized by various techniques such as elemental analysis, AAS, NMR, IR, UV–Vis, TGA, DTA, XRD and TEM. The data confirmed that the ligand coordinated with the metal ions in a bidentate nature, bonding through its azomethine nitrogen atom and phenolic oxygen atom; this gave an octahedral geometry. The XRD patterns of the complexes indicated that they were of various structures: the Mn(II), Co(III), and Cu(II) complexes were triclinic, the ligand and Ni(II) complex were orthorhombic, the V(III) and Zn(II) complexes were hexagonal, the Cu(II) complex was monoclinic, and the Fe(II) complex was cubic. TEM analysis confirmed that the complexes were nanoscale in nature. The antibacterial and antifungal activities of the ligand and its complexes against Salmonella enterica serovar typhi and Candida albicans were investigated by the hole plate diffusion method. It was observed that the Co(II) and Zn(II) complexes had intermediate antibacterial activities, while the V(III) complex had the highest activity against C. albicans fungi. The in vitro anticancer activities of the ligand and its metal complexes were tested towards PC-3, SKOV3, and HeLa tumour cell lines, where they exhibited higher antitumour activities against these selected human cell lines than clinically used drugs such as cisplatin, estramustine, and etoposide.     

Synthesis,characterization and antimicrobial activity of a new macrocycle and its transition metal complexes

The semicarbazone (L¹) has been prepared by reaction of semicarbazide and glutaraldehyde (2 : 1) in distilled water and methanol (1 : 1). The reaction of semicarbazide, glutaraldehyde and diethyl oxalate in distilled water and methanol gave Schiff-base L², 1,2,4,7,9,10-hexaazacyclo-pentadeca-10,15-dien-3,5,6,8-tetraone. Complexes of first row transition metal ions Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) have also been synthesized. The ligand and its complexes were characterized by elemental analysis, molar conductance, magnetic moment measurements, IR, ¹H NMR, UV–Visible spectra and thermogravimetric analysis (TGA). Molar conductance values show that the complexes of Ni(II), Cu(II), Zn(II), Mn(II) and Co(II) are 1 : 2 electrolytes. On the basis of electronic spectral studies and molar conductance measurements an octahedral structure has been proposed for Mn(II) and Co(II) complexes, tetrahedral for Zn(II) complex and square planar for Ni(II) and Cu(II). The thermal behavior of the compounds, studied by TGA in a nitrogen atmosphere up to 800°C, reveal that the complexes have higher thermal stability than the macrocycle. All the synthesized compounds and standard drugs kanamycin (antibacterial) and miconazole (antifungal) have been screened against bacterial strains Staphylococcus areus, Escherichia coli and fungal strains Candida albicans, Aspergillus niger. The metal complexes inhibit growth of bacteria to a greater extent than the ligand.     

Synthesis,characterization, powder XRD and antimicrobial-antioxidant activity evaluation of trivalent transition metal macrocyclic complexes

The in vitro antimicrobial and antioxidant activities of metal complexes derived from 1,8-diaminonaphthalene and 5,5-dimethylcyclohexane-1,3-dione were evaluated. The complexes were synthesized by template method in the presence of trivalent metal salts, resulting in the formation of tetraaza macrocyclic complexes of the type [M (C₃₆H₃₆N₄) X] X₂, where M = Cr(III), Fe(III) and X = Cl^–, NO₃^–, CH₃COO^–. The synthesized complexes were characterized with the aid of elemental analyses, molar conductance measurements, magnetic susceptibility measurements, electronic, IR, mass and powder XRD studies. Based on various studies, a five-coordinated square pyramidal geometry was proposed for these complexes. The X-ray diffraction studies suggest a monoclinic crystal system for the complexes.     

Synthesis,characterization and catalytic activity of polymer anchored transition metal complexes toward oxidation reactions

The polymer-anchored Schiff base complexes of Cu(II), Co(II), Ni(II), Mn(II) and Fe(III) were prepared by reacting polystyrene amine with 2-pyridinecarbaldehyde followed by loading of metal atom in methanol. These complexes were characterized by using different physico-chemical and spectroscopic methods. The catalytic activity of these polymer-supported metal catalysts was tested for the oxidation of various olefins and alcohols. Influence of various reaction parameters, such as reaction temperature, reaction time, oxidant, substrate-to-oxidant mole ratio and nature of solvent, was studied for the oxidation of cyclohexene with these catalysts. Among the catalysts studied, Cu-Cat showed higher catalytic activity toward oxidation reactions than the other catalysts. Moreover, hot filtration experiments proved that these catalysts are truly heterogeneous and can be reused a number of times without significant loss of activity.     

2-苯基-4-硒唑甲酸过渡金属配合物的合成、结构及生物活性研究

合成了2-苯基-4-硒唑甲酸配体(HL)和相应的6个过渡金属配合物[ML2(H2O)2](M=Co,Ni,Cu,Cd)1～4,[ZnL2](5),[CuL2(py)2](6).用元素分析、红外光谱、热重分析等表征手段确定了配合物的组成;用单晶X射线衍射测定了配合物3和6的结构;用溴化乙锭荧光探针初步研究了它们与DNA作用的强度和模式;考察了配体和配合物对大肠埃氏杆菌(E.coliJM109)、大肠杆菌(E.coli,DH5α)、表皮葡萄球菌(S.epidermidis)、金黄色葡萄球菌(S.aureus)、鲍曼不动杆菌(baumanii)、草绿色链球菌(S.viridans)6种细菌的抗菌活性及对正常细胞293T和肿瘤细胞RAW264.72的体外增殖抑制作用.     

Synthesis, characterization and antiproliferative activity of transition metal complexes with 3-(4,5-diphenyl-1,3-oxazol-2-yl)propanoic acid (oxaprozin)

A series of novel Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes with oxaprozin (Hoxa), a non-steroidal anti-inflammatory drug, has been synthesized. The drug and complexes have been characterized by elemental and thermogravimetric (TG) analysis, Fourier transform (FT)-IR, 1H-NMR, 13C-NMR, UV-Vis spectroscopy and magnetic susceptibility measurements. The (pseudo)octahedral geometry has been proposed for all complexes based on electronic spectra and magnetic moments. With exception of the Cu(II) complex, where bridging bidentate mode of COO groups has been found, FT-IR spectra confirmed chelately coordinated COO groups in the other complexes. The general formula of the complexes is [M(H2O)2(oxa)2 ·χH2O, with χ=2 for M=Mn, Co and Ni and χ=1.5 for Zn. The binuclear Cu(II) complex, [Cu2(H2O)2(OH)(oxa)3]·2H2O, has strong Cu-Cu interactions of antiferromagnetic type. The complexes and Hoxa did not exhibit the cytotoxic effect to peritoneal macrophages. For the first time these complexes have been tested for their in vitro antiproliferative activity against human colon and breast cancer cell lines, HCT-116 and MDA-231, respectively. For all investigated compounds significant antiproliferative effects have been observed. Ni(II) complex has been shown to be a promising antiproliferative agent exerting excellent activity against HCT-116 even in nanomolar concentrations.     

Synthesis, characterization and antimicrobial activity of 3d transition metal complexes of a biambidentate ligand containing quinoxaline moiety

A new series of oxovanadium(IV), chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), and copper(II) complexes of the 3-hydrazino quinoxaline-2-one (HQO) were prepared and characterized. The ligand exhibits biambidenticity. It behaves as a bidentate ON donor in oxovanadium(IV), iron(III) and copper(II) complexes and as a bis bidentate ONNN donor in chromium(III), manganese(II), cobalt(II) and nickel(II) complexes. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, thermal, infrared, ¹H NMR, electronic spectra, magnetic susceptibility and conductivity measurements. An octahedral geometry was suggested for all the complexes. All the complexes show subnormal magnetic moments. The ligand, HQO, and its complexes were tested against one strain Gram +ve bacteria (Staphylococcus aureus), Gram −ve bacteria (Escherichia coli). The prepared metal complexes exhibited higher antimicrobial activities than the parent ligand.     

Synthesis, structural characterization, and antifungal activity of Schiff bases and their transition metal mixed-ligand complexes

Mixed-ligand complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) have been prepared with biologically active Schiff bases, viz. potassium salt of o-hydroxyacetophenoneglycine [KHL] and bis(benzylidene)ethylenediamine [A¹] or thiophene-o-carboxaldene-p-toluidine [A²]. The synthesized mixed-ligand complexes have been characterized on the basis of elemental analysis, thermogravimetric analysis, magnetic measurements, and electronic and infrared spectra. The mixed-ligand complexes show higher antifungal activity as compared to the free ligands, metal salts, and the control (dimethylsulfoxide) but moderate activity as compared to the standard fungicides (bavistin and emcarb). This text was submitted by the authors in English.     

Synthesis,crystal structure,DNA interaction and anticancer evaluation of pyruvic acid derived hydrazone and its transition metal complexes

A novel tridentate chelating ligand, Ethyl 2‐(2‐(2‐chlorobenzoyl)hydrazono)propanoate and its late transition metal complexes were synthesized, characterized and evaluated for anticancer behavior. The structures were elucidated with the help of elemental analyses, spectral (vibrational, electronic, NMR and mass) and thermo‐gravimetric techniques. Single crystal X‐ray crystallographic studies of the ligand suggest an orthorhombic lattice structure with Pna21 space group. The interaction of ligand and complexes with DNA (CT‐DNA) has been extensively studied using absorption, emission, viscosity and thermal denaturation studies with E. coli DNA. The DNA cleavage ability of ligand and metal complexes was tested using plasmid pBR322 DNA by gel electrophoresis method. The ligand and its copper complex have been evaluated for their in vitro anticancer activity against human cancer cells of different origin such as KB (Oral), A431 (Skin), Mia‐Pa‐Ca (Pancreases), K‐549 (Lung), K‐562 (Leukemia), MCF‐7 (Breast) and VERO by MTT assay and the apoptosis assay was carried out with acridine orange/ethidium bromide (AO/EB) staining method. The studies suggest that ligand and copper complex exhibit significant cytotoxic activity on KB, MCF‐7, A‐431, Mia‐Pa‐Ca‐2 an d A‐549 cell lines compared to K‐562 and VERO cell lines.     

Synthesis,characterization and cytotoxic activity of organoruthenium(II)-halido complexes with 5-chloro-1H-benzimidazole-2-carboxylic acid

Three new ruthenium(II)-arene halido complexes, [(η⁶-p-cymene) RuX(L)] (1–3), were synthesized in a reaction of [(η⁶-p-cymene)RuX₂]₂ with 5-chloro-1H-benzimidazole-2-carboxylic acid (HL) in ethanol (X^– = Cl^– (1), Br^– (2), I^– (3)). The complexes were characterized by elemental analysis, mass spectrometry, IR, ¹H and ¹³C NMR spectroscopy. The cytotoxic activity of the ligand precursor and its ruthenium complexes was tested by MTT assay in human cancer cell lines: lung adenocarcinoma (A549), myelogenous leukemia (K562) as well as in one normal human fetal lung fibroblast cell line (MRC-5). The results show that ruthenium(II)-arene complexes possess enhanced cytotoxicity when compared to HL in the range of concentrations up to 300 µM. In terms of halido ligand substitution, cytotoxic activity toward A549 and K562 cell lines in 1–3 serie significantly increased (e.g., IC₅₀ values for K562: 1: 205.76 µM; 2: 174.77 µM; 3: 83.97 µM). All studied compounds were found to be ineffective toward MRC-5. Hydrolysis of 1–3 was followed by UV-vis spectroscopy at 25?°C, revealing ligand-substitution reactions at the Ru(II) center. Compounds 2 and 3 underwent rapid hydrolysis ranging from a few minutes for the aquation to ca. 20?min, confirming typical Ru-arene behavior in aqueous solutions.     

两个苯甲羟肟酸有机锡配合物的合成、结构及抗癌活性

合成了2个苯甲羟肟酸有机锡配合物：[(o-Cl-C₆H₄CH₂)₂Sn (C₆H₅CONO)₂](1)和[(o-CH₃-C₆H₄CH₂)₂Sn (C₆H₅CONO)(C₆H₅COO)](2)。通过元素分析、红外光谱、核磁共振氢谱、热重分析、单晶X射线衍射等方法对配合物进行了结构表征,对其结构进行量子化学从头计算和体外抗癌活性研究。结果显示：配合物均为单锡核结构,配合物1为六配位的畸变八面体构型,配合物2为五配位的畸变三角双锥构型;配合物1对人宫颈癌细胞(HeLa)、肝癌细胞(HuH-7)和肺腺癌细胞(H1975)显示出比临床使用的顺铂强的抑制活性,而配合物2的抑制活性要弱得多。     

Synthesis, spectral characterization of Schiff base transition metal complexes: DNA cleavage and antimicrobial activity studies

A new series of transition metal complexes of Cu(II), Ni(II), Co(II), Mn(II), Zn(II), VO(IV), Hg(II) and Cd(II) have been synthesized from the Schiff base (L) derived from 4-aminoantipyrine, 3-hydroxy-4-nitrobenzaldehyde and o-phenylenediamine. Structural features were obtained from their elemental analyses, magnetic susceptibility, molar conductance, mass, IR, UV-Vis, ¹H NMR and ESR spectral studies. The data show that these complexes have composition of ML type. The UV-Vis, magnetic susceptibility and ESR spectral data of the complexes suggest a square-planar geometry around the central metal ion except VO(IV) complex which has square-pyramidal geometry. The redox behaviour of copper and vanadyl complexes was studied by cyclic voltammetry. Antimicrobial screening tests gave good results in the presence of metal ion in the ligand system. The nuclease activity of the above metal complexes shows that Cu, Ni and Co complexes cleave DNA through redox chemistry whereas other complexes are not effective.