Vibrational characterization and prooxidant activity of newly synthesized dysprosium(III) complex

The dysprosium(III) complex of 5-aminoorotic acid (HAOA) was synthesized by reaction of the respective inorganic salt in amounts equal to ligand, molar ratio of 1:3. The structure of the complex was determined by means of elemental analysis, FTIR and FT-Raman spectroscopies. Significant differences in the IR and Raman spectra of the complex were observed as compared to the spectra of the free ligand. Detailed vibrational analysis of HAOA and Dy(III)-AOA systems revealed that the binding mode in the complex was bidentate through the carboxylic oxygen atoms. Dy(III) complex of 5-aminoorotic acid (DyAOA) exhibited prooxidant properties in the presence of the model system X/XO. In the DyAOA complex, the ion diminished the antioxidant properties of the AOA ligands.     

New samarium(III) complex of 5‐aminoorotic acid with antioxidant activity

A samarium(III) complex (SmAOA) of 5‐aminoorotic acid (HAOA) was synthesized by reaction of the respective inorganic salt and ligand in a molar ratio of 1:3. The structure of the complex was determined by means of elemental analysis and UV–visible, NMR, Fourier transform infrared (FT‐IR) and FT Raman spectroscopies. Significant differences in the FT‐IR and FT Raman spectra of the complex were observed as compared to the spectra of the free ligand. Detailed vibrational analysis of HAOA and Sm(III)–AOA systems revealed that the binding mode in the complex was bidentate through the carboxylic oxygen atoms. The newly synthesized SmAOA showed antioxidant properties. The antioxidant activities of both HAOA and SmAOA were related to their electron donor properties. Copyright © 2015 John Wiley & Sons, Ltd.     

Anti-hepatocellular carcinoma,antioxidant, anti-inflammation and antimicrobial investigation of some novel first and second transition metal complexes

New coordination compounds of some selected metal ions from the first and second transition metals series with a Schiff base were synthesized and characterized. The Schiff base is derived from 4-Aminoantipyrine and 3-(hydroxyimino) butan-2-one. The compounds were characterized by different analysis tools like; elemental analysis, mass spectra, Fourier transform infrared (FTIR) as well as electronic spectra, magnetic measurements, molar conductance and thermal analysis technique. All complexes were formed with 1:1 (metal: ligand) stoichiometry except Mn (II) where 1:2 (Mn: ligand) is formed. Schiff base ligand interacted as a tridentate ligand by using the nitrogen atoms of the imine and the oximato groups and the carbonyl oxygen atom as donor groups with all studied metal ions except copper (II) and manganese (II) where the carbonyl oxygen is not shared in the coordination. These complexes show various physicochemical properties. X-ray powder diffraction shows different crystal systems; Cd (II) complex: hexagonal, Cu (II) complex: orthorhombic; and [Ni (II), Mn (II), Rh (III) & Pd (II)] complexes: monoclinic. All compounds showed potent cytotoxicity against the growth of human liver cancer cell lines. The square planar Pd (II) complex was more active than those of octahedral geometries of all other synthesized complexes. Cd (II) complex has the highest microbial growth inhibition than the rest of the prepared complexes. The docking active sites interactions were evaluated using the selected proteins EGFR tyrosine kinase and protein crystal structure of GlcN-O-P synthase. in vitro antioxidant assay revealed potent free radical scavenging activity of the three synthesized Cu (II), Pd (II) and Rh (III) complexes that exceeded the standard ascorbic acid. Pd (II) complex shows the most significant inhibition denaturation percent.     

Synthesis and biological activity of the pinostrobin oxime complex compounds with some d-metals

The process of the complex formation by the natural flavonoid pinostrobin (5-hydroxy-7-methoxyflavonone) oxime with the Cu(II) and Fe(III) ions in a water-ethanol medium was investigated. The metal: ligand ratio in the complex was determined by the saturation method. The results of the analysis of IR spectra and the data of mass-spectrometric studies of the structure of the obtained complex compounds are reported. The antiviral activity of the synthesized complexes with respect to the human immunodeficiency virus HIV-1 IIIB and HIV-2 ROD strains was studied. The antioxidant activity of the complexes, as well as the parent pinostrobin oxime ligand, was evaluated with respect to the diphenylpicrylhydrazyl (DPPH) radical and the 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical cation.     

Synthesis, characterization, antioxidant activity, and DNA-binding studies of 1-cyclohexyl-3-tosylurea and its Nd(III), Eu(III) complexes

A new ligand, 1-cyclohexyl-3-tosylurea (H(2)L), was prepared by condensation ethyl N-(3-tossulfonyl) carbamate and cyclohexanamine. Its two lanthanide(III) complexes, Ln(H(2)L)(3) . 3NO(3) [Ln=Nd (1), and Eu (2)], have been synthesized and characterized on the base of element analyses, ESI-MS, molar conductivities, IR spectra and thermogravimetry/differential thermal analysis (TG-DTA). In addition, the DNA-binding properties of the ligand and its complexes have been investigated by electronic absorption spectroscopy, fluorescence spectroscopy, circular dichroic (CD) spectroscopy and viscosity measurements. The experiment results suggest that the ligand and its two complexes bind to DNA via a groove binding mode, and the binding affinity of the complex 2 is higher than that of the complex 1 and the ligand. Furthermore, the antioxidant activity (superoxide and hydroxyl radical) of the ligand and its metal complexes was determined by using spectrophotometer methods in vitro. These complexes were found to possess potent antioxidant activity and be better than standard antioxidants like vitamin C and mannitol. In particular, complex 2 displayed excellent activity on the superoxide and hydroxyl radical.     

Synthesis,Structure and Impact of 5-Aminoorotic Acid and Its Complexes with Lanthanum(III) and Gallium(III) on the Activity of Xanthine Oxidase

The superoxide radical ion is involved in numerous physiological processes, associated with both health and pathology. Its participation in cancer onset and progression is well documented. Lanthanum(III) and gallium(III) are cations that are known to possess anticancer properties. Their coordination complexes are being investigated by the scientific community in the search for novel oncological disease remedies. Their complexes with 5-aminoorotic acid suppress superoxide, derived enzymatically from xanthine/xanthine oxidase (X/XO). It seems that they, to differing extents, impact the enzyme, or the substrate, or both. The present study closely examines their chemical structure by way of modern methods—IR, Raman, and ¹H NMR spectroscopy. Their superoxide-scavenging behavior in the presence of a non-enzymatic source (potassium superoxide) is compared to that in the presence of an enzymatic source (X/XO). Enzymatic activity of XO, defined in terms of the production of uric acid, seems to be impacted by both complexes and the pure ligand in a concentration-dependent manner. In order to better relate the compounds’ chemical characteristics to XO inhibition, they were docked in silico to XO. A molecular docking assay provided further proof that 5-aminoorotic acid and its complexes with lanthanum(III) and gallium(III) very probably suppress superoxide production via XO inhibition.     

稀土N-苯基邻氨基苯甲酸-1,10-邻菲咯啉二元、三元配合物的合成、表征及其光物理性质

合成了几种新型的稀土(钆,铕,铽)的N-苯基邻氨基苯甲酸-1,10-邻菲咯啉的二元、三元配合物.以元素分析、红外光谱和紫外光谱进行了表征,确定了组成.同时以低温磷光光谱确定了配体的三重态能级为24330cm^-1,研究了配体与稀土离子的能级匹配.详细讨论了配合物的光物理性质如发光性能和配体与稀土离子之间以及有机配体之间的分子内能量传递机制,结果发现,铽的N-苯基邻氨基苯甲酸-1,10-邻菲咯啉配合物的发光性能良好.     

吡唑啉酮类稀土配合物的发光性质研究

合成了一系列吡唑啉酮类稀土铽、铕、钐、钆、镝的配合物, 并采用元素分析、红外光谱和紫外-可见光谱对其进行了表征, 解析了铕配合物的晶体结构. 测定了配体的三重态能级, 研究了这4种配合物的发光性质. 并通过研究配体到稀土离子的能量传递过程, 合理地解释了这些稀土配合物发光性质的差异.     

Theoretical and Experimental Vibrational Characterization of Biologically Active Nd(III) Complex

The neodymium(III) complex of orotic acid (HOA) was synthesized and its structure determined by means of analytical and spectral analyses. Detailed vibrational analysis of HOA, sodium salt of HOA, and Nd(III)–OA systems based on both the calculated and experimental spectra confirmed the suggested metal–ligand binding mode. Significant differences in the IR and Raman spectra of the complex were observed as compared to the spectra of the ligand. The calculated vibrational wavenumbers, including IR intensities and Raman scattering activities, for the ligand and its Nd(III) complex were in good agreement with the experimental data. The vibrational analysis performed for the studied species, orotic acid, sodium salt of orotic acid, and its Nd(III) complex helped to explain the vibrational behaviour of the ligand’s vibrational modes, sensitive to interaction with Nd(III). In this paper we also report preliminary results about the cytotoxicity of the investigated compounds. The cytotoxic effects of the ligand and its Nd(III) complex were determined using the MTT method on different tumour cell lines. The screening performed revealed that the tested compounds exerted cytotoxic activity upon the evaluated cell lines.     

Synthesis, characterization, antioxidant activities, and DNA-binding studies of (E)-N'-[1-(pyridin-2-yl)ethylidene]isonicotinohydrazide and its Pr(III) and Nd(III) complexes

A new ligand, (E)-N'-[1-(pyridin-2-yl)ethylidene]isonicotinohydrazide (HL), was prepared by condensation of 2-acetylpyridine and isonicotinohydrazide in ethanol. Its two lanthanide(III) complexes, [Nd(III)(L)(2)(NO(3))(CH(3)OH)(2)]·CH(3)CH(2)OH (1), and [Pr(III)(L)(2)(NO(3))(CH(3)OH)(2)]·CH(3)CH(2)OH (2), have been synthesized and characterized on the basis of element analyses, molar conductivities and IR spectra. The structure of complex 2 has been confirmed by X-ray diffraction. In addition, the DNA-binding properties of the two complexes have been investigated by electronic absorption spectroscopy, fluorescence spectroscopy, circular dichroic (CD) spectroscopy and viscosity measurements. The experimental results suggest that the two complexes bind to DNA via a groove binding mode, and the binding affinity of complex 2 is higher than that of complex 1. Furthermore, the antioxidant activities (superoxide and hydroxyl radical) of the ligand and its metal complexes were determined by spectrophotometry methods in vitro. These complexes were found to possess potent antioxidant activity and be superior to standard antioxidant like mannitol.     

Synthesis, characterization, and pharmacokinetic evaluation of a potential MRI contrast agent containing two paramagnetic centers with albumin binding affinity

A dinuclear gadolinium(III) complex of an amphiphilic chelating ligand, containing two diethylenetriamine-N,N,N',N',N'-pentaacetate (DTPA) moieties bridged by a bisindole derivative with three methoxy groups, has been synthesized and evaluated as a potential magnetic resonance imaging (MRI) contrast agent. Nuclear magnetic relaxation dispersion (NMRD) measurements indicate that at 20 MHz and 37 degrees C the dinuclear gadolinium(III) complex has a much higher relaxivity than [Gd(DTPA)] (6.8 vs 3.9 s(-1) mmol(-1)). The higher relaxivity of the dinuclear gadolinium(III) complex can be related to its reduced motion and larger rotational correlation time relative to [Gd(DTPA)]. In the presence of human serum albumin (HSA) the relaxivity value of the noncovalently bound dinuclear complex increases to 15.2 s(-1) per mmol of Gd3+, due to its relatively strong interaction with this protein. The fitted value of the binding constant to HSA (Ka) was found to be 10(4) M(-1). Because of its interaction with HSA, the dinuclear complex exhibits a longer elimination half-life from the plasma, and a better confinement to the vascular space compared to the commercially available [Gd(DTPA)] contrast agent. Transmetalation of the dinuclear gadolinium(III) complex by zinc(II) has been investigated. Biodistribution studies suggest that the complex is excreted by the renal pathway, and possibly by the hepatobiliary route. In vivo studies indicated that half of the normal dose of the gadolinium(III) complex enhanced the contrast in hepatic tissues around 40 % more effectively than [Gd(DTPA)]. The dinuclear gadolinium(III) complex was tested as a potential necrosis avid contrast agent (NACA), but despite the binding to HSA, it did not exhibit necrosis avidity, implying that binding to albumin is not a key parameter for necrosis-targeting properties.     

A facile preparation of donut-like supramolecular tannic acid-Fe(III) composite as biomaterials with magnetic,conductive, and antioxidant properties

Tannic acid (TA) complexes with various metal ions are prepared in buffer solutions by readily adjusting the pH, but there is no normalizing method to produce ferric tannate complexes. In this study, TA-Fe(III) complex was prepared in reverse microemulsion medium by reaction of TA as ligand with Fe(III) in 1:3 ligand:metal ion molar ratio. The complex was characterized by SEM, AFM, FT-IR, elemental analysis, AAS measurement, and Brunauer-Emmett-Teller (BET) method. Furthermore, magnetic susceptibility was tested with the Gouy method, and electronic spectral studies of TA-Fe(III) complex were completed with solid UV–vis measurements. The thermal stability was also studied by TGA analysis. These studies show that the ligand molecules have octahedral arrangement around Fe(III) and the complex is paramagnetic. The bandgap energy of the complex was calculated as 3.42 eV with solid UV–vis analysis. To determine antioxidant activity of the complex, Total Phenol Content (TPC) and Trolox Equivalent Antioxidant Concentration (TEAC) methods were used. The complex has great antioxidant properties with TPC = 45 ± 1 mg L^?1 GAE and TEAC = 296 ± 2 mM trolox g^?1 for dry sample.     

Synthesis,characterization and luminescence properties of Eu(III) and Tb(III) complexes with novel pyrazole derivatives and 1,10-phenanthroline

Two novel pyrazole-derived ligands, 3-chloro-6-(3,5-dimethyl-1H-pyrazol-1-yl)picolinic acid (CDPA) and 3-chloro-6-(3,5-dimethyl-1H-pyrazol-1-yl)-N-phenylpicolinamide (CDPP) were prepared by 3,6-dichloropicolinic acid (DCPA). Their complexes with terbium(III) and europium(III) were synthesized. The complexes were characterized by elemental analysis, infrared spectra, ¹H NMR and TG–DTG. Furthermore, the above complexes using 1,10-phenanthroline as a secondary ligand were also synthesized and characterized. The luminescence properties of these complexes in solid state were investigated. The results suggested that Tb(III) complexes exhibit more efficient luminescence than Eu(III) complexes and the fluorescence of the complexes with 1,10-phenanthroline as a secondary ligand was prominently stronger than that of complexes without this ligand., and the three ligand (DCPA), (CDPP) and (CDPA) are excellent sensitizers to Eu(III) and Tb(III) ion.     

Synthesis and characterization of a Eu-containing polymer precursor featuring thenoyltrifluoroacetone and 5-acrylamido-1,10-phenanthroline

A polymerizable ligand, 5-acrylamido-1,10-phenanthroline (L), was synthesized. Its Eu(III) complex with 2-thenoyltrifluoroacetone (HTTA) was prepared and characterized by elemental analysis, IR, MS, and ¹H NMR spectra. The photophysical properties of the complex were studied in detail by using UV, luminescence spectra, luminescence lifetime and quantum yield. The complex shows a remarkable luminescence quantum yield at room temperature (40.1%) upon ligand excitation and a long ⁵D₀ lifetime (590 μs), which makes it not only a promising light-conversion molecular device but also an excellent luminescent polymer precursor.     

Synthesis,Crystal Structure,DNA‐binding Properties and Antioxidant Activity of a Copper(II) Complex with Naphthalimide Schiff Base

The Schiff N‐allylamine‐4‐(ethylenediamine‐5‐methylsalicylidene)‐1,8‐naphthalimide (H₂L) and its copper(II) complex, [Cu(HL)₂] · 0.5DMF, were synthesized and characterized. The crystal structure of the Cu^II complex reveals a slightly distorted square‐planar arrangement provided by two N and O donors from two deprotonated ligands. In addition, the DNA‐binding properties of the ligand and Cu^II complex were investigated by fluorescence spectra, electronic absorption, and viscosity measurements. The experimental studies of the DNA‐binding properties indicated that the ligand and Cu^II complex reacted with DNA via intercalation binding mode, and binding affinity for DNA takes the order: ligand > Cu^II complex. The antioxidant assay in vitro suggested that both exhibited potential intensely antioxidant properties, and the ligand is more effective than its Cu^II complex.     

Synthesis, characterization and luminescence property of N,N'-di(pyridine N-oxide-2-yl)pyridine-2,6-dicarboxamide and corresponding lanthanide (III) complexes

A new ligand, N,N'-di(pyridine N-oxide-2-yl)pyridine-2,6-dicarboxamide (LH2) and its several lanthanide (III) complexes (La, Eu, Gd, Tb, Y) were synthesized and characterized in detail based on elemental analysis, conductivity measurements, IR, 1H NMR, MS (FAB) and UV spectra and TG-DTA studies. The results indicated that the composition of these binary complexes is [Ln(LH2)(NO3)2.H2O]NO3.nH2O (n=0-1); while the ligand has a good planar structure with strong hydrogen bonds. The fluorescence spectra exhibits that the Tb (III) complex and the Eu (III) complex display characteristic metal-centered fluorescence in solid state while ligand fluorescence is completely quenched. However, the Tb (III) complex displays more effective luminescence than the Eu (III) complex, which is attributed to especial effectivity in transferring energy from the lowest triplet energy level of the ligands (T) onto the excited state (5D4) of Tb (III) than that (5D1) of Eu (III).     

Antioxidant,Antimicrobial and Antitumor Studies of Transition Metal Complexes Derived from N-(2-Aminoethyl)-1,3-Propanediamine with DFT Calculations and Molecular Docking Investigation

New expected biologically active complexes for some of the first (Mn (II), Ni (II), Cu (II) and Zn (II)) and second (Rh (III) and Cd (II)) transitional metals rows with N-(2-Aminoethyl)-1,3-propanediamine as a ligand (AEPD)have been synthesized. All synthesized complexes were formed with 1:1 (metal: AEPD) stoichiometry except Ni (II) 1:2 (Ni: AEPD). The compounds were characterized by different analysis tools such as; elemental analysis, Fourier transform infrared (FTIR), ¹H-NMR, mass spectra, thermal analysis, electronic spectra, magnetic measurement and molar conductance techniques. AEPD ligand interacted with all metal ions as tridentate ligand by using the nitrogen atoms. On the other hand, density functional theory (DFT) calculations have been performed to confirm the optimized geometrical structures for both AEPD and its complexes. Furthermore, coordination compounds were screened for their potential antibacterial activities against six pathogenic bacteria as well as one kind of fungi in comparison to standard antibiotics by agar well diffusion method. The results show that most of the complexes exhibit antibacterial and antifungal activities against these organisms. Rh (III)-AEPD complex exhibited the strongest antibacterial effect followed by the Cd (II) complex but as antifungal agents Cd (II) was the first and the second was Rh (III). Also, the anticancer activity was screened for these metal complexes against growth of human liver cancer HEPG2 tumor cell line and this inhibition activity of Cd (II) chelate was noticed to be more active with lowest IC₅₀ than that of all other synthesized complexes. Unfortunately, Mn (II) and Rh (III) chelates lacked anticancer activity. The docking active sites interactions were evaluated using the selected protein for anticancer activity. Finally, antioxidant activity was studied. Mn (AEPD) showed maximum activity followed by complex of Rh (III).     

The synthesis, photoluminescence and energy transfer mechanism of a reactive Eu(III)-complex intermediate of white light phosphor

A reactive Eu(III)-complex intermediate of white light phosphor was synthesized using benzoylactone, 1,10-phenanthroline and undecylenic acid as ligands. The structure of the complex was characterized by elemental analysis and FT-IR spectra. The luminescent properties were investigated by fluorescence spectra and UV?Cvis absorption spectra. The results indicate that the complex emitted the characteristic peaks of the Eu(III) ion when being excited at 367?nm, revealing that the complex can be excited by 365?nm of ultraviolet. The energy of the highest occupied molecular orbital and the lowest unoccupied molecular orbital as well as the singlet state and triplet state energy level of the ligands were calculated with the Gaussian03 program package. Intramolecular energy transfer mechanism was studied and an energy transfer diagram was sketched to illuminate the energy transfer process. The Eu(III)-copolymer was synthesized by the free radical copolymerization of the Eu(III)-complex and methyl methacrylate. XRD analysis indicates that the Eu(III)-complex in the copolymer was dispersed much more uniformly into the polymer matrix than that in the doped polymer. The photoluminescent properties of the Eu(III)-polymer suggest that the Eu(III)-complex is a good candidate of red light moiety in white light phosphor.     

Synthesis,characterization and cytotoxic/cytostatic activity of Sm(III) and Gd(III) complexes

New Sm(III) and Gd(III) complexes of deprotonated 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (Acenocoumarol) were synthesized and characterized using FT-IR, FT-Raman, NMR spectra, and elemental analyses. The vibrational study gave evidence for the coordination of ligand to lanthanide ions. The ligand and its lanthanide(III) complexes were tested for their cytotoxic/cytostatic activity against two tumor cell lines and peritoneal mouse macrophages. The Sm(III) and Gd(III) complexes exhibit good activity against melanoma B16 and fibrosarcoma L929 and are stronger inhibitors of tumor cell proliferation than the ligand. Besides their cytotoxicity to tumor cells, Acenocoumarol and its gadolinium(III) and samarium(III) complexes modulate NO generation in activated macrophages.     

Synthesis and spectroscopic properties of rare earth picrate complexes with a new biphenylamide

The new ligand N-benzyl-2-{2'-[(benzyl-ethyl-carbamoyl)-methoxy]-biphenyl-2-yloxy}-N-ethyl-acetamide (L) and its complexes of rare earth picrates were synthesized. The complexes were characterized by elemental analysis, IR, UV-vis spectra and conductivity measurements. The fluorescence properties of the europium complex in solid state and in CHCl(3), ethyl acetate, acetone, acetonitrile and DMF were investigated. Under the excitation, the europium complex exhibited characteristic emissions of europium. The lowest triplet state energy level of the ligand indicates that the triplet state energy level of the ligand matches better to the resonance level of Eu(III) than Tb(III) ion.