Spectroscopic Studies of Oxygen-Bridged Copper (II) Cluster Somplexes; (II) Trinuclear Copper (II) Complex of Pyridine-2-Carbaldehyde Oxime

Abstract

Power electron paramagnetic resonance spectrum of the trinuclear complex Cu3L3 (OM)X2, xH20 (L=pyridine-2-carbaldehyde oxime, X=1/2 S04^2?, x=16.3) was recorded in the X-band region and interpreted in terms of a quarte (S=3/2) spin system.

Vibrational studies of the complex has also been undertaken and an assignment was made of the bands observed it the low frequency infrared and Raman spectra. It was shown that the central metallic core has a C3v syametry. Theoretical calculations of the frequencies of the vibrations related to this skeleton were performed and the results are it agreement with the experimental data.     

IR-Spectral Study of 2-Aminopyridine and Aniline Complexes with Palladium (II)

An IR-spectral study of sulphato- and chloro complexes of palladium (II) with 2-aminopyridine and aniline, respectively, is reported. The results obtained confirm the bidentate co-ordination of both 2-aminopyridine and SO₄ group in the case of sulphato-2-aminopyridine-palladium (II) leading to polynuclear structure of the complex in solution. The comparative investigation of sulphato-dianiline-palladium (II) suggests that the self-dependent ability of the SO₄ ^2- ion for bridging co-ordination can stabilize chain-like complexes of palladium (II) only in the solid state.     

IR- and UV-Spectral Study of Palladium(II) Complexes with 2-Aminopyridine Obtained in Sulphuric Acid and Alkaline Solutions

When obtained in sulphuric acid medium sulphato-2-aminopyridine-palladium (II) complex has a polynuclear structure, with a bridging coordination of both the sulphato-group and 2-aminopyridine. The complex keeps its polynuclear structure in alkaline solution, in which the substitution of sulphato ions by hydroxylic groups yields hydroxo-2-aminopyridine-palladium (II). The compounds discussed are the main components of activators used in currentless metallization of nonconducting surfaces.     

IR- and UV-Spectral Study on the Mechanism of 2-Aminopyridine Complexation with Palladium (II)

Abstract

The IR-spectra of Pd (II) complexes with 2-aminopyridine, obtained both in sulphuric acid and alkaline solution are studied in the region 1700- 1400 cm^?1. The structural conclusions are based on comparison with the IR- and UV-spectra of the free ligand and aminopyridinium sulphate, as well as of trans-dichloro-di-2-aminopyridine-palladium and deuterated at the amino group analogues of the investigated compounds.     

The Vibrational Spectra of Complexes with Planar Monothiooxamides. IV. The Copper(II) and Copper(I) Complexes of Neutral Monothiooxamides

The new complexes CuX₂(LH₂), CuX₂ (SH₃) (X = Cl, Br), CuX(LH₂), CuX(SH₃) (X = Cl, Br, I), CuX(H₄MTO)₂ (X = Cl, Br), Cul(H₄MTO) and CuX(H₃MMTO)₂ (X = Cl, Br, I), where LH₂ = N.N′-dimethyl-monothiooxamide, SH₃ = N(s)-methylmonothiooxamide, H₄MTO = monothiooxamide and H₃MMTO = N_(o)-methylmonothiooxamide, have been prepared. The complexes were characterized by elemental analyses, conductivity measurements, magnetic moments and spectroscopic (UV/VIS, FT-IR, Laser-Raman) studies. The vibrational analysis of the complexes has been given using NH/ND, CH₃/CD₃ and ⁶³cu/⁶⁵cu isotopic substitutions. The neutral monothiooxamides behave as monodentate ligands in the Cu(I) complexes coordinating through their thioamide sulfur atom. The ligands LH2 and SH₃ act as bidentate chelating agents in the Cu(II) complexes with ligated atoms being the thioamide sulfur and the amide oxygen.     

An Infrared Spectroscopic Study of Crystalline Copper (II) Propionate and Butyrate

Abstract

Abstract: The vibrational spectra of crystalline anhydrous copper (II) propionate and butyrate were studied by FT-IR spectroscopy. A detailed assignment of the spectra of both compounds is presented and discussed. It is shown that the presence of two non-equivalent sets of carboxylate ligands within the crystals gives rise to several band splittings, which are particularly evident in those bands ascribable to normal modes involving predominantly the -C_βH₃ or -C_βH₂-fragments. In addition, the vibrational assignments made for the studied molecules are shown to be very useful to help understanding the much more complex spectra of long chain copper carboxylates.     

Spectroscopic Study of the Interaction of Mitoxantrone with Copper(I), Copper(II), and Neocuproine

Both reductive and oxidatlve mode of metabolism have been hypothesized for the antitumor agent mitoxantrone. This work aims to better understand the redox properties of mitoxantrone in the presence of the physiological redox couple, copper(I)/copper(II), by means of polarograpy and spectrophotometry. The first quasi-reversible one-electron reduction of mitoxantrone to the semiquinone and the second reduction to the hydroquinone have been shown to be considerably affected by copper. Visible spectra of mitoxantrone-copper mixtures in nitrogen and oxygen purged solutions taken in a one-week period exhibit varying degrees of complexation and oxido-reduction.

When copper(II), neocuprolne and mitoxantrone are mixed in a certain ratio in pH 7. 4 phosphate buffer solution, two new peaks at 584 and 632 nm emerge in the spectra indicating a ternary charge transfer complex. The complex atoichiometry was established as Cu(IT): neocuproine: tritoxan-trone = 2:4:1 by Job's method of continuous variations. The ternary complex is sensitive to the relative concentrations of mitoxantrone and copper(II), an excess of the latter giving rise to complete red ox products. This complex may be important in modeling the drug's oxidative mode of ant tumor action.     

Electronic Studies of Copper(II) Complexes of Amino Acids. III. EPR Spectra of Some Vitamin B6 Schiff Base Analogs

Schiff base coordination compounds of amino acids are good models to study the transamination reaction^2,3 of vitamin B₆. Several studies^4-6 have focused on the preparation, characterization and spectra study of these Schiff base coordination compounds, represented schematically in Figure 1, where R has been varied. In our continued studies of Cu(II) coordination compounds of amino acids, we have prepared a series of compounds with alanine (R=CH₃) and either a 4 or 5 substituent on the ring (X=H, OH, NO₂, Cl). In order to obtain as many of the EPR magnetic parameters as possible⁷, we prepared solid solutions in Zn(II) matrices with a Zn(II) to Cu(II) ratio of about 95:5. In this fashion we were able to reduce the dipole coupling and to calculate the [sgrave] molecular orbital coefficients for this important new series of compounds.     

Spectroscopic and computational studies on self‐assembly complexes of bis(pyrrol‐2‐ ylmethyleneamine) ligands linked by alkyl spacers with Cu(II)

Bis(pyrrol‐2‐ylmethyleneamine) ligands and their mononuclear monomeric and dinuclear dimeric self‐assembly complexes with Cu(II) were investigated by means of IR and Raman spectroscopies and density functional theory. The ground‐state geometries were calculated by using the Becke Lee Yang Parr composite exchange‐correlation functional (B3LYP) and a combined basis set (LanL2DZ for Cu; 6–31G(d) for C, H, N), and they were compared with the single‐crystal X‐ray diffraction (XRD) structures. The DFT‐calculated Cu N bond lengths are generally higher by 0.001–0.040 Å than those determined through XRD. The vibrational spectra were also calculated at the same level of theory for the optimized geometries. The calculated wavenumbers were scaled by a uniform scaling factor and compared with the experimental fundamentals. The predicted spectra are in good agreement with the experimental ones with the deviations generally less than 30 cm⁻¹. In comparison with the spectra of the ligands, the coordination effect shifts the υ(CN) wavenumber by about 50 cm⁻¹ toward a lower value. Because of the weak intermolecular C H···Cu hydrogen bond, the Cu N stretching mode is shifted toward a lower wavenumber. Copyright © 2006 John Wiley & Sons, Ltd.     

DFT study of magnetic coupling in bis(pyridine-2-carboxylate)-copper(II) polymorphs

The method for exchange coupling parameter J calculations using a broken-symmetry treatment is extended to three-dimensional periodic DFT calculations for three antiferromagnetic polymorphic forms of Cu(pca)₂, pca = pyridine-2-carboxylate. The calculated values (<1 cm⁻¹) are slightly underestimated in comparison with experimental data. For comparison with the cluster treatment, the J values are rationalized using the nearest-neighbors model for polymeric chains.     

Synthesis and Spectroscopic Studies of Metal (II) Tetracyanonickelate Complexes with 1,3-Thiazolidine-2-thione

Two new Hofmann-type complexes, M (1,3-thiazolidine-2-thione)₂ Ni(CN)₄ (where M = Ni and Cd), were synthesized and characterized by elemental analysis, magnetic susceptibility data, IR and Raman Spectroscopy. Their structure consist of planar infinite polymeric layers of {M-NI(CN)₄}∞. 1,3-thiazolidine-2-thione coordinated to M atom above and below this layers is monodentate and S-bonded in these complexes.     

Solvatochromism of Ternary Iron (II) Diimine Cyanide Complexes in 2-Ethyl-2-(hydroxymethyl) 1,3-Propanediol (Trimethylol Propane)

The solvatochromic behaviour of bis-(2,2′-bipyridyl)-biscyanoiron (II) and 2,2′- bipyridyltetracyanoiron (II) in 2-ethyl-2-(hydroxymethyl)-1,3-propanediol has been established. The significance and sensitivities of the solvatochromic shifts of these charge-transfer bands are outlined for the two iron complexes above.     

A Novel Captopril Chemiluminescence System for Determination of Copper(II) in Human Hair and Cereal Flours

A novel chemiluminescence (CL) reaction, captopril–H₂O₂, for determination of Cu(II) at nanogram per milliliter level in batch-type system has been described. The method relies on the catalytic effect of Cu(II) on the oxidation of captopril with hydrogen peroxide in alkaline medium. The optimization step was performed using univariate methodology and the factors studied were: pH and concentrations of the utilized reagents. Under the optimum conditions, calibration plot was linear in the range of 0.1–2.0 ppm. Limit of detection was 30 ppb and relative standard deviation for five replicate determinations of 0.8 ppm Cu(II) was 1.89%. The proposed method was successfully applied to the determination of Cu(II) in human scalp hair and cereals, rice and wheat, flour with satisfactory selectivity and sensitivity. The results were validated by comparison with a standard method (FAAS). The possible mechanism of the new CL reaction has also been discussed.     

Simultaneous Spectrophotometric Determination of Iron(II) and Iron(III) in Mixtures Using Di-2-pyridyl Ketone Benzoylhydrazone

A method for simultaneous spectrophotometric determination of total iron, iron(II) and iron(III) in mixtures containing other metal ions has been described. The method is based on the complexation of iron with di-2-pyridyl ketone benzoylhydrazone (DPKBH) in 50% (v/v) ethanolic solution. Iron(II) complex with DPKBH exhibits two absorption maxima at 360 and 650 nm. meanwhile iron(II1) complex with DPKBH exhibits only one maximum at 360nm. Iron(II) and iron(III) complexes with DPKBH have similar behaviour at 360nm. Iron forms 1:2 complexes with the reagent. Beer's laws are obeyed over the ranges 0.1–2 μgml-1 and 0.4–5 μgrn1-l for iron(II) complexes at 360 and 650nm respectively. Iron(III) showed results similar to those obtained for iron(II) at 360nm. The effect of pH, effect of excess reagent. the stability of complexes. and the tolerance limit of many metal ions have been reported. The method is applied to the determination of total iron, iron(I1). and iron(II1) in synthetic solutions.     

Synthesis,Spectroscopic and Antimicrobial Studies of Lead (II) Complexes of Schiff Bases Derived From Amino Acids and Isatins

A new series of lead (II) complexes have been synthesized with Schiff bases derived from isatins and amino acids. These ligands act as bidentate species and coordinate to the metal atom through the azomethine nitrogen and carboxylate oxygen atom via deprotonation. The synthesized complexes have been characterized by elemental analysis, conductance measurements, and molecular weight determinations. The mode of bonding of the complexes has been suggested on the basis of infrared, UV-visible, and ¹H- and ¹³C-NMR spectroscopy, and probable structures have been assigned to these complexes. Few representative ligands and metal complexes have also been screened for their antifungal and antibacterial activities. Molecular modeling and analysis for bond lengths and bond angles have also been carried out for one of the representative compound, [Pb(L³)₂], to substantiate the proposed structures.     

1-(6-硝基-2-苯并噻唑)-3-(4-硝基苯)-三氮烯与铜显色反应的研究及应用

在TritonX-100表面活性剂存在下,pH为10.0-11.0的Na2B4O7-NaOH缓冲溶液中,1-(6-硝基-2-苯并噻唑)-3-(4-硝基苯)-三氮烯(NBTNPT)与铜生成2:1配合物。配合物的最大负吸收峰是540nm,表观摩尔吸光系数为1.15×105L·mol-1·cm-1。Cu2 的质量浓度在0-360μg/L符合比耳定律。测定铝合金样品中的微量铜,结果满意。     

Simulation of the Electron Paramagnetic Resonance Spectrum of the Triplet Ground State Dimer Di-μ-(Pyridine N-Oxide)Bis[Bisnitrato(Pyridine N-Oxide)Copper(II)]

The EPR spectrum of the triplet ground state dimer di-μ-(pyridine N-oxide)bis[bisnitrato(pyridine N-oxide)copper(II)] has been reported recently¹. Of the very few triplet ground state copper(II) dimers with resolved metal hyperfine structure^2,3, the EPR spectrum of this complex is most complete. Previously, the analysis of the spectra of triplet ground state copper(II) complexes, in order to extract magnetic parameters, has been made using the equations reported by Wasserman et al.⁴ The best magnetic parameters should be obtained from a simulation of the experimental spectrum. We wish to report here the computer simulation of the EPR spectrum of a powdered sample of [Cu(II) (PYO)₂ (NO₃)₂]₂.     

Utilization of ultrasonic irradiation as a green and effective strategy to prepare poly(N-vinyl-2-pyrrolidone)/modified nano-copper (II) oxide nanocomposites

The present paper describes the result of investigations into preparation of novel nanocomposites (NCs) based on poly(N-vinyl-2-pyrrolidone) (PVP) as a biocompatible polymer and modified copper (II) oxide nanoparticles (NPs) as a nano-filler. To achieve optimum NCs properties, different ratios of modified copper (II) oxide NPs (3, 5, and 7 wt%) were used to fabricate PVP NCs and also the ultrasonic irradiation was utilized to perform these processes as a fast and effective method. Subsequently, the structure of the obtained nanohybrids was characterized by various techniques. The suitable incorporation between PVP matrix and modified CuO NPs can be seen from the FT-IR spectra. The obtained NCs indicated an efficient thermal improvement in comparison to the pristine polymer. Also, the uniform dispersion of modified CuO NPs in the PVP matrix was detected by FE-SEM and EDX. According to UV absorption spectra, it is clear that these NCs can be used in UV protecting applications.     

红外光谱法用于肉苁蓉属中药鉴别研究

采用傅里叶变换红外光谱(FTIR)及其二阶导数谱和二维相关红外光谱对传统名贵中药材肉苁蓉、管花肉苁蓉和盐生肉苁蓉进行鉴别研究。结果表明,肉苁蓉与管花肉苁蓉的红外谱图有明显区别,相似系数仅0.623 3;而肉苁蓉与盐生肉苁蓉的峰形和峰位均极其相似,相似系数达0.904 8,仅从一维图上无法看出两者的成分差异,但通过二阶导数谱中1 730(1 738),816 cm-1处的峰形差异可发现二者的一些成分含量存在较明显差异。二维相关谱更直观地反映出三者的差异,它们的自动峰个数均不相同。可见,红外光谱法基本可以实现了对肉苁蓉属３种药材的鉴别,而且具有快速、有效和无损等优点。     

新试剂2,7-双(5-羧基-1,3,4-三氮唑偶氮)-变色酸作为络合滴定铜指示剂的研究

研究了新试剂2,7-双(5-羧基-1,3,4-三氮唑偶氮)-变色酸(简称BCTZACA)作为络合滴定铜的指示剂的分析性能。在pH4.5-6.0范围内,加入8滴BCTZACA指示剂,用EDTA标准溶液进行络合滴定,终点由蓝色变为橙黄色,变色敏锐,准确度高,用于试剂样品和合金中铜的测定,结果与标准值相符,RSD(n=6)为0.11%-0.45%。