查看更多>>摘要：The complexes of europium(III) ions in binary and ternary systems with alpha-hydroxy acids and biogenic amine spermine were investigated. Studies have been performed in aqueous solution using the potentiometric method with computer analysis of the data. Analysis of the equilibrium constants of the reactions and spectroscopic data have allowed us to determine the type of coordination and effectiveness of the carboxyl groups in the process of complex formation in the systems studied. Furthermore, the results confirmed the occurrence of non-covalent interactions of protonated spermine with coordinated alpha-hydroxy acid. The effect of biogenic polyamine concentration was clearly confirmed, and their influence on the stability and coordination mode of ternary complexes was found.
Radu, IoanaTurcan, InaLukacs, Alexandru V.Bulai, Georgiana-Andreea...
11页
查看更多>>摘要：Gadolinium (Gd3+) substituted zinc manganese ferrite nanoparticles with nominal compositions Zn0.7Mn0.3GdxFe2-xO4 (where x = 0.000; 0.025; 0.050; 0.075; 0.100) were successfully synthetized using co precipitation method. The synthetized powders were calcined at 500 & nbsp;C and furthermore pressed into pellets and thermally treated at 650 & nbsp;C for a second time to obtain a more compact material. For the 500 C thermal treated samples, X-ray analysis revealed the formation of pure spinel ferrite phase, meanwhile for the 650 C thermal treated samples secondary phases appear which indicate that some of Gd3+ ions aren't able to remain in the structure of ferrite. The morphology of samples was investigated using scanning electron microscopy (SEM) and the images show agglomerated spherical nanoparticles within 20-30 nm size range. The magnetization curves recorded in +/- 10 kOe range indicate a superparamagnetic behavior of the synthetized ferrite samples. At low frequencies, the Gd3+ substituted ferrite samples corresponding to x = 0.050, 0.075 and 0.100 exhibit a resonant behavior of the dielectric losses dependence, while at high frequencies the lowest value was found for the sample with x = 0.025. The introduction of Gd3+ ions in the ferrite structure leads to a non-monotonous variation of AC electrical conductivity, which decrease from 2.55 x10(-6) S/m to 3 x10(-7) S/m. The ferrite samples have shown a good and reproducible response to the saturated acetone vapors and the highest sensitivity value (53%) was obtained for Zn0.7Mn0.3Gd0.025Fe1.9O4 ferrite sample. The response and recovery time varies between 36 and 56 s, respectively 80-116 s and both of these are independent of Gd3+ content.
查看更多>>摘要：Treatment of Cu(OAc)(2).H2O with salicylaldimine Schiff-base (C9H6N)N = CH(3,5-(Bu2C6H2OH)-Bu-t) (L1H), (Et2N) (CH2)(2)N = CH(3,5-(Bu2C6H2OH)-Bu-t) (L2H), (2-C5H4N)CH2N = CH(3,5-(Bu2C6H2OH)-Bu-t) (L3H) in refluxing ethanol afforded three mononuclear copper complexes [(L1)Cu(OAc)] (1), (L2)Cu(OAc) (2) and (L3)Cu(OAc) (3), respectively. The three new complexes were fully characterized using elemental analysis, IR and HR-MS, and Xray diffraction analysis. They all exhibited efficient catalytic activity in the oxidation of primary and secondary alcohols into the corresponding carbonyl derivatives with hydrogen peroxide (H2O2) as the oxidation agent. The catalytic system is operationally simple, clean and generates water as the only by-product.
查看更多>>摘要：The scarlet Sm (III) complexes with eight coordination number, as favoured by EDAX and elemental analytical data, were synthesized with fluorinated beta-keto carboxylic acid as primary ligand and neo, batho, phen, dmph, and bypy as secondary ligand. Binary and ternary complexes of Sm(III) ion [Sm(ligand)(3)2H(2)O], [Sm(ligand)3-secondary ligand] respectively were prepared by one-step grinding method. The complexes exhibit crystalline character, nanoparticle size and outstanding thermal stability, they also have high color purity and as warm orange light sources. In UV visible light, complexes display several characteristic emission transitions such as ((4)G(5/2) & RARR; H-6(5/2), (4)G(5/2) & RARR; H-6(7/2) and (4)G(5/2) & RARR; H-6(9/2)) under the excitation of Sm (III) ion. The scarlet luminescence in UV domain is accredited to the (4)G(5/2) & RARR; H-6(7/2) transition at 605 nm wavelength. The proton NMR and FT-IR data are reliable with coordination behavior of organic ligand and secondary ligand with Sm(III) ion. To understand the semiconducting nature, materiality in solar cell and photovoltaic devices with the help of HOMOLUMO bandgap analysis and Urbach energy were examined. The calculated Judd-Ofelt parameter is a crucial aspect to describe the rigidity and symmetry of complexes. The anti-microbial investigation demonstrated that all complexes are practically applicable in bioassays.
Nongpiur, Carley Giffert L.Diengdoh, Danny F.Nagar, NupurPoluri, Krishna Mohan...
10页
查看更多>>摘要：Half-sandwich mono and dinuclear ruthenium, rhodium and iridium complexes (1-9) have been synthesized with ligands L1 {N'-(9H-fluoren-9-ylidene) thiophene-2-carbohydrazide}, L2 {N'-(9H-fluoren-9-ylidene)-3methoxybenzohydrazide} and L3 {N'-(9H-fluoren-9-ylidene) isonicotinohydrazide}. The neutral mononuclear bidentate complexes were obtained by treatment of the hydrazone ligands (L1, L2) with metal precursors [(arene)MCl2]2 (arene = p-cymene, Cp*; M = Ru, Rh and Ir) in a 1:2 ratio. Reactions of [(arene)MCl2]2 with L3 in both 1:2 and 1:1 metal dimer to ligand ratios have yielded neutral dinuclear complexes where L3 acts as a tridentate ditopic ligand. Single-crystal X-ray diffraction studies have determined the solid-state structures of eight complexes (1-7, 9). In vitro antibacterial activities of the synthesized ligands and complexes were evaluated against human pathogenic bacteria. These compounds were evaluated for their in vitro antioxidant activity by using the DPPH assay. The binding capacity of complex 2 to SM-DNA was elucidated using fluorescence spectroscopy.
查看更多>>摘要：The synthesis and characterisation of new anionic iridium(II) complexes (NH4)(2)[IrCl4(kappa N-2,N'-H(2)biim)](2) center dot 5H(2)O (1) and ((CH3)(2)NH2)[IrCl4(kappa N-2,N'-PyBIm)] center dot H2O (2) are presented in this article. Spectroscopic methods (H-1, C-13 and N-15 NMR, FTIR, UV-Vis) were used to characterize these new complexes. Solid-state structural analysis (SC-XRD) of complexes 1 and 2 shows a slightly distorted octahedral geometry of Ir(III) ions, which is constructed by one chelating kappa 2N,N'-2,2'-biimidazole (H2biim (1)) or 2-(2'-pyridyl)benzimidazole (PyBIm (2)) and four chloride ions. In the crystal structures, the presence of organic ligands containing NH groups favours the formation of strong hydrogen bonds (XH center dot center dot center dot Cl (X = O, N, C)), which have significant impact on the crystal structure forming 2D (1) and 3D (2) systems during the self-assembly process. Additionally, preliminary studies of the biological activity of the obtained complexes were performed. Considering the above properties, the observed stronger binding affinity of complex 1 to DNA and HSA can be interpreted in terms of changes in the number of hydrogen bonds that are potentially formed with the target molecule. Furthermore, higher reactivity towards NADH and the lower reactivity towards GSH were observed for complex 2. Both complexes showed moderate cytotoxicity against selected cancer cell lines (LoVo, MV-4-11, MCF-7) and did not show toxicity towards normal cells (BALB/3T3). The cytotoxicity of 2 may be compromised by a weaker interaction with DNA, HSA or GSH and a stronger reactivity towards NADH.
Douvris, ChrisLampropoulos, ChristosMatatov, DavidWink, Donald J....
8页
查看更多>>摘要：Thermally stable cycloheptatrienyl metal complexes bearing the trifluoromethyl moiety are reported for the first time. While the syntheses, properties and structural characterizations of transition metal complexes of the type [(eta(5)-C5H5)MLnCF3] are well known in organometallic chemistry, analogous chemistry of the elusive [(eta(7)-C7H7) MLnCF(3)] complexes was just recently disclosed by the syntheses of Mo complexes such as [(eta 7-C7H7)Mo(CO) (PMe3)CF3] (I). Nevertheless, complex I and similar complexes were found to be of extreme thermal instability, indicative in the fact that their purification and isolations require low temperature chromatography. Advancing past the stability hindrance, we report herein the syntheses of the W complexes [(eta(7)-C7H7)W(CO)(2)CF3] (II), and [(eta(7)-C7H7)W(CO)(PMe3)CF3] (III), which are found to be indefinitely thermally stable, a fact that allowed the study of complex II by X-ray crystallography. In addition, the first DFT studies on I-III, as well as their eta(5)-C(5)H(5 )analogues, were performed both in the gas phase and with the implicit diethyl ether effects included, the structures, energetics, NBO charges, and frontier MOs were investigated. For the eta(7)-C7H7-complexes, the metal change from Mo to W was shown to significantly increase the singlet-triplet energy difference, whereas for the eta 5-C5H5-complexes the metal change essentially has no effect on this difference, which is in line with the experimental findings. Comparison of the calculated structure of complex II with its X-ray structure showed quite reasonable agreement with the experimental data. The negative NBO charges on W in the C5H5-complexes were calculated to be significantly lower than in the C7H7-complexes, which again is completely in line with the stability profile of the complex.
Culpepper, Johnathan D.Lee, KyounghoonDaly, Scott R.
8页
查看更多>>摘要：Here we report a convenient synthesis of new diphosphoramidite ligands derived from 1,8,10,9-triazaboradeca-lin (TBD) and describe their complexes with group 10 metals. Treating the chlorinated and structurally char-acterized ligand precursor (Cl)TBDPhos (L1) with four equivalents of HOR (R = C3H7 or C3HF6) in the presence of NEt3 yielded the diphosphoramidite ligands iPrOTBDPhos (L2) and F-iPrOTBDPhos (L3) in good yields. L2 and L3 were used to prepare a variety of Ni, Pd, and Pt complexes with chloride and 1,2-benzenedithiolate ligands so their structures and spectroscopic properties could be compared to similar complexes with methoxy-substituted( MeO)TBDPhos such as (MeOTBDPhos)PdCl2, which is reported here for the first time. Single-crystal XRD studies on the ((ROT)BDPhos)PtCl2 complexes revealed that increasing the size of alkoxy substituents from MeO to iPrO to F-iPrO decreases the P-M-P bite angle from 97.47(3) in ((MeO)TBDPhos)PtCl2 to 93.98(4) in (F-iPrOTBDPhos)PtCl2. Similar changes were observed in the dithiolate complexes (iPrOTBDPhos)Pt(S2C6H4) and (F-iPrOTBDPhos)Pt (S2C6H4), and the structural studies revealed longer Pt-P bond distances compared to the dichloride complexes that correlated to ca. 1000 Hz decrease in their 195Pt-31P coupling constants. No significant changes were observed in the ligand bond distances in complexes containing the methoxy and isoproxy-substituted ligands, but complexes with fluorinated F-iPrOTBDPhos revealed subtle, but significant differences in their P-N, P-O, and B-N distances that reflect substituent-induced electronic changes in the ligand. Overall, this work establishes a more convenient synthetic entry into the chemistry of alkoxy-substituted TBDPhos ligands for ongoing studies with these and related transition metal complexes.
查看更多>>摘要：Two new Anderson-type polyoxometalate (POM)-based metal-organic complexes, namely: H[Cd(L) (CrMo6(OH)(6)O-18)].2H(2)O (1) and H[Co(L)(CrMo6(OH)(6)O-18)(H2O)(2)].3H(2)O (2) (L = N, N'-bis(3-pyridinecarbox-amide)-1,4 cyclohexane) have been successfully synthesized under hydrothermal condition and characterized in detail. For 1, the [CrMo6(OH)(6)O-18](3)-anion adopts hexadentate coordination pattern connecting with binuclear Cd-2(II) unit to form a two-dimensional (2D) layer, which is further expanded into a three-dimensional framework by the L ligands. In 2, The CrMo6 anions exhibit tetradentate coordination mode to connect the metal ions constructing a 2D layer. The L ligand does not play a linkage role and only suspend on the 2D network, which is different from complex 1. The influence of central metal ions on the architectures was discussed. The electro-catalytic reduction of potassium bromate and the electrocatalytic oxidation of ascorbic acid by complexes 1 and 2 were investigated. These title complexes could be regarded as amperometric sensors for the detection of potassium bromate and ascorbic acid. In particular, complex 1 shows the lowest detection limit for these two substances, suggesting its better electrochemical performance.
Munoz-Hernandez, Miguel- AngelGarcia, Omar J.Velazquez-Carmona, Miguel-AngelCortes-Llamas, Sara A....
5页
查看更多>>摘要：Two lithium bis(pyrazolyl)dialkylaluminates were prepared from equimolar amounts of [Li((t)Bu(2)pz)], AlR3 (R = Me, Bu-i) and (t)Bu(2)pzH. Characterization was accomplished by microanalysis and spectroscopic methods as well as SCXRD. An important feature of these aluminates in solid state, is the presence of one Al-alkyl center dot center dot center dot Li agostic intramolecular interaction despite having used a coordinating solvent (THF) in the synthetic route.
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Elsevier