Synthesis on Al-Mg Polynuclear Bridged-Complexes (I): Reactions of Aluminum-Trialkoxide with Magnesium-Di-N-Butyl

The reaction of magnesium di-n-butyl with alumium trialkoxide (R=C₂H_S, Sec·C₄H₉) gave the major product [Bu₂Mg Al(OR)₃]₂. which was characterized by elemental analysis, mass spectral data, infrared data and 2D-nuclear magnetic resonance spectral data. The nmr spectral data indicated that the most likely structure of the major products were cyclic with bridging butyl and alkoxide groups.     

Thermal and spectroscopic studies of terbium(III) and dysprosium(III) complexes with piperidin-4-ones

Terbium(III) and dysprosium(III) nitrate complexes with variously substituted 2,6-diphenylpiperidin-4-ones (L¹)-(L¹⁰) of general formula [Ln(L)(NO₃)₂(H₂O)₂]NO₃ have been synthesized. These complexes have been characterized by analytical, spectral and thermal studies. Molar conductance data show that these complexes are 1:1 electrolytes. The presence of two coordinated water molecules is confirmed by thermal and infrared spectral studies. IR spectral data indicate that piperidin-4-ones, in spite of having two coordinating sites, are monodentate, coordinating only through ring nitrogen. The IR and conductance data reveal the presence of two bidentate and one ionic nitrate groups. The nephelauxetic ratio (β), covalency factor (b^1/2) and Sinha’s parameter (δ) evaluated from electronic spectral data of dysprosium(III) complexes indicate a little covalency in metal-ligand bonding.     

The determination of the complex refractive indices of some concentrated aqueous salt solutions at submillimetre wavelengths

Recent developments in far infrared laser spectrometry and dispersive Fourier transform spectrometry have allowed the full spectral variation of both parts of the complex refractive indices of some aqueous salt solutions in the spectral region 25–450 cm^?1 to be determined. The salts studied were LiCl, LiClO₄, NaCl, NaClO₄, NaI, KCl, KBr, KI, KF, MgCl₂, Mg(ClO₄) and Bu₄NBr (tetrabutylammonium bromide). The results show that in the presence of some electrolytes the optical constants of the solution differ significantly from those of pure water, and that in localised spectral regions the absorption can be many times less than that of pure water.     

Complexes of lanthanide nitrates with N,N-diethylantipyrine-4-carboxamide

New complexes of lanthanide nitrates with N, N-diethylantipyrine-4-carboxamide (DEAP), with the general formulae [Ln₂(DEAP)₃] [NO₃]₆ (where Ln = La, Pr, Nd, Sm, Tb, Ho, Er, Yb and Y) have been isolated and characterized by chemical analysis and various physical methods such as electrolytic conductance, IR and¹³C NMR spectral data. Electrolytic conductance values and infrared spectral studies indicate that the nitrate groups are coordinated. Infrared and¹³C NMR spectral analysis show that the ligand DEAP is coordinated to the tripositive metal ion through the diethylcarboxamide carbonyl and antipyrine carbonyl oxygens in a bidentate fashion.     

Parallel vector analysis based soft resolution of spectral data from pH‐metric titration using symmetry constraint

In this study, a soft method is proposed to calculate concentration and spectral profiles for the two‐way spectral data from dissociation equilibria of polyprotic acids (H_nA). This method has four main distinct steps: (i) a fixed size moving window evolving factor analysis (FSMWEFA) was used to identify the local rank map, (ii) WFA was applied to calculate the concentration profiles of H_nA and Aⁿ⁻ (selection of the window for application of WFA was performed using EFA), (iii) PVA was used to calculate H_{n − 1}A to HA spectral profiles, and (iv) a symmetry constraint, in addition to the non‐negativity constraint, was utilized to obtain the unique concentration and spectral profiles from different acceptable sets of profiles. In the absence of any selective region in the spectral data, the proposed soft method resulted in unique solution without rotational ambiguity. This study is the first application of symmetry constraint on concentration profiles. The rotational ambiguity drastically decreased on considering the constraint of symmetry of the H_{n − 1}A and HA concentration profiles, in addition to non‐negativity of profiles. Simulated examples were used to confirm these approaches. Effect of closeness of dissociation constants on the estimated values of constants was investigated. The results showed that when the difference between pK_a values is more than 1.2, the obtained errors in the estimation of pK_a values are less than about 6.5%. The considered real data were from pH‐metric titration of fluorescein. The obtained spectral and concentration profiles and the estimated pK_a values for fluorescein were in good agreement with the previously reported data. Copyright © 2009 John Wiley & Sons, Ltd.     

How Are Hydrogen Bonds Perturbed in Aqueous NaClO4 Solutions Depending on the Concentration?: A Near Infrared Study of Water

We have performed spectroscopic measurements on the vibrational combination bands of OH-bending (ν₂) and asymmetric OH-stretching (ν₃) modes of water in aqueous NaClO₄ solutions with an absorption spectrometer in the near infrared region. The concentration dependence of the spectral shape of the ν₂ + ν ₃ band around the wavelength of 2 μm was investigated, where the NaClO₄ concentration was varied by a factor of 200. The spectral shape depends significantly on the concentration of NaClO₄ and the spectral width of the saturated aqueous solution becomes narrower to about half of that of pure water. The concentration dependence is analyzed from the viewpoint of water molecules with a different number of hydrogen bonds. The perturbation effect of ions on hydrogen bonds between water molecules is discussed.     

Distortion of the coordination polyhedron in mononuclear copper(II) complexes. Optical absorption and electron spin resonance studies on some five-coordinate copper(II) complexes

The preparation and spectral properties are reported for a series of ten mixed-ligand copper(II) complexes of the form [Cu(A)(B)_n](X), where A is acetylacetonate anion, B represents a mono- or bidentate ligand such as morpholine, piperidine, isonicotinic acid hydrazide, 2,2′-bipyridine, 1,10-phenanthroline and X is variously NO^?₃ or ClO^?₄ anion and n = 1 or 2. The coordination of the anions and ligands has been demonstrated by infrared and electronic spectral methods. Electron spin resonance spectral data show the square-pyramidal five-coordinated arrangement around copper(II) in these complexes. Parameters such as g₆, g_⊥, A₆, A_⊥, 〈g〉 and 〈A〉 calculated from electron spin resonance data in solid and solution state at room temperature as well as frozen solution indicate the presence of the unpaired electron in the d_x2_?y2 or d_z2 orbital. These results are in good agreement with electronic and photoacoustic spectral studies.     

New silver(I) pyridinecarboxylate complexes: synthesis,characterization, and antimicrobial therapeutic potential

Silver(I) pyridinecarboxylates (AgPIC (1), AgNIC (2), [Ag(HDIPIC)]·0.75H₂O (3), PIC?=?picolinate, NIC?=?nicotinate, HDIPIC?=?dipicolinate) were prepared by solvothermal syntheses and their characterization were completed by elemental, spectral, and thermal analyses. To assign the pyridinecarboxylate coordination mode in the complexes, detailed mid-infrared spectral data and Δ(ν_as???ν_s) comparisons were accomplished. In addition, silver(I) pyridinecarboxylate antimicrobial activities and stability by ¹H NMR spectra were determined. Moreover, the spectral, thermal, and antimicrobial properties of silver(I) and previously prepared zinc(II) pyridinecarboxylates were compared and discussed.     

Polymer complexes: XLIX—Supramolecular modeling of bonding in novel rare earth polymeric rhodanine drug complexes

Novel supramolecular rare earth polymeric hydrazone complexes of 5-sulphadiazineazo-3-phenyl-2-thiaxo-4-thiazolidinone (HL) of the composition [(Ln)₂(HL)₃(NO₃)₆]_n (where Ln = La(1), Y(2), Pr(3), Nd(4), Sm(5), Gd(6) and Ho(7)) have been prepared and characterized on the basis of their chemical analyses, magnetic measurements, conductance, visible and IR spectral data. Composition, conductance and IR spectral data of complexes show that all these act as a tetradentate ligand. Electronic spectra indicate weak covalent character in the metal–ligand bond. The spectra of Nd³⁺ and Ho³⁺ show characteristic f–f transitions and the metal–ligand covalency in % has been evaluated. The spectral properties of the above polymeric complexes are also discussed.     

Spectral interference in the determination of Ho,Tm and Ga as dopants in single crystals of potassium titanylphosphate by inductively coupled plasma atomic emission spectrometry

The present article discusses the spectral interferences affecting the determination of Ga, Ho and Tm as dopants in single crystals of potassium titanylphosphate (KTiOPO₄) by inductively coupled plasma atomic emission spectrometry (ICP-AES). The Q concept, as proposed by Boumans and Vrakking [Spectrochim. Acta Part B 43 (1988) 69] was used for this study, which covers: (a) spectral data for potassium, titanium and phosphorous as interferents (at a concentration of 4 mg/ml) in 400 pm wide spectral windows around the prominent lines of the analytes; (b) a database of Q values for line interferences (Q_I) and for wing interferences (Q_W); and (c) the interelement interferences in doubly doped crystals of KTP.     

Copper(II), nickel(II), palladium(II) and iron(III) complexes of 2-(3-phthalhydrazidylazo)-1,3-diketones

Neutral complexes of three phthalhydrazidylazo-1,3-diketones [phthalhydrazidylazo-acetylacetone (H₂PAA),-benzoylacetone (H₂PBA) and-dibenzoylmethane (H₂PDM)] with Cu(II), Ni(II), Pd(II) and Fe(III) have been synthesised and characterized on the basis of their analytical data, magnetic moment, molar conductance and IR and¹H NMR spectral data. Dibasic tridentate coordination of the ligands is brought out by the above spectral data. Half-wave potentials and far IR spectral data of the Cu(II) complexes indicate that the H₂PAA complex is the most stable. M?ssbauer spectra of the Fe(III) complexes reveal that delocalisation of the metald electrons with the chelate ring decreases with increasing capability of the pendant groups of the ring for cross conjugation.     

Komplexe von Lanthanidnitraten mit 2-Methylpyridin-1-oxid

Complexes of lanthanide nitrates with 2-methylpyridine-1-oxide of the formuleLn(2-MePyO)₃(NO₃)₃ whereLn=Nd, Sm, Tb, Dy and Yb and La(2-MePyO)₃(NO₃)₃·2H₂O have been prepared and characterized by chemical analyses, IR spectral, conductance andDTA data. IR spectral data have been interpreted in terms of the coordination of the ligand to the metal through the oxygen of the N–O group. Conductance and IR spectral data show that all the nitrate groups are bidentate and that two of the nitrate groups are bound to the metal in a different manner than the other.     

Spectral accuracy of molecular ions in an LTQ/Orbitrap mass spectrometer and implications for elemental composition determination

In addition to mass accuracy, the ability of a mass spectrometer to faithfully measure the isotopic distribution of an ion, defined as spectral accuracy, is also important. Although time-of-flight mass spectrometers are reported to possess high spectral accuracy capability compared with other mass spectrometers, the Orbitrap has not yet been investigated. Ten natural products (moxidectin, erythromycin, digoxin, rifampicin, amphotericin B, rapamycin, gramicidin S, cyclosporin A, vancomycin, and thiostrepton) ranging in molecular weight from 639 to 1663 Da were measured on an LTQ/Orbitrap mass spectrometer with resolving power settings of 7.5, 15, 30, 60, and 100 K. The difference in the observed profile isotope pattern compared with the theoretical calculation after peak shape calibration, denoted spectral error, was calculated using the program MassWorks (Cerno Bioscience, Danbury, CT, USA). Spectral errors were least at 7.5 K resolving power (≤3%) but exceeded 10% for some compounds at 100 K. The increasing spectral error observed at higher resolving power for compounds with complex fine structure might be explained by the phenomena of isotopic beat patterns as observed in FTICR. Several compounds with prominent doubly charged ions allowed comparison of spectral accuracies of singly-versus doubly-charged ions. When using spectral error to rank elemental compositions with formula constraints (C_0–100H_0–200N_0–50O_0–50Cl_0–5S_0–5) and a mass tolerance ≤2 parts-per-million, the correct formula was ranked first 35% of the time. However, spectral error considerations eliminated >99% of possible elemental formulas for compounds with molecular weight >900 Da.     

Komplexe von Lanthanidnitraten mit 2-Methylpyridin-1-oxid

Complexes of lanthanide nitrates with 2-methylpyridine-1-oxide of the formuleLn(2-MePyO)₃(NO₃)₃ whereLn=Nd, Sm, Tb, Dy and Yb and La(2-MePyO)₃(NO₃)₃·2H₂O have been prepared and characterized by chemical analyses, IR spectral, conductance andDTA data. IR spectral data have been interpreted in terms of the coordination of the ligand to the metal through the oxygen of the N–O group. Conductance and IR spectral data show that all the nitrate groups are bidentate and that two of the nitrate groups are bound to the metal in a different manner than the other.     

电感耦合等离子体发射光谱法测定地质样品中钨时对锌的光谱干扰校正

采用硝酸-氢氟酸-高氯酸消解样品,电感耦合等离子体发射光谱法测定地质样品中的钨.讨论了Zn 207.908对W 207.911的光谱干扰,并应用光谱干扰系数校正法(IEC)校正干扰.结果表明:Zn对W的光谱干扰可以用IEC进行有效的消除,进行光谱校正后的结果明显优于未加校正的试验结果.     

An infrared and Raman spectroscopic study of the Hofmann-type complexes and clathrates: M(piperidine)2Ni(CN)4; M(piperidine)2Ni(CN)4·1.5G (M=Cd, Co, Ni or Cu; G=benzene)

New Hofmann-type complexes and clathrates of the forms M(piperidine)₂Ni(CN)₄ and M(piperidine)₂Ni(CN)₄·1.5G (M=Cd, Co, Ni or Cu; G=benzene) were prepared in powder form and their infrared and Raman spectra are reported. The spectral features suggest that these compounds are similar in structure to the Hofmann-type clathrates except for the copper compounds. The complex and clathrate of Cu have different spectral features in comparison with its analogues due to the Jahn-Teller effect.     

Complexation copper(II) or magnesium ions with d-glucuronic acid – potentiometric,spectral and theoretical studies

Results of potentiometric and spectral studies have shown that in d-glucuronic acid (GluA) with Cu²⁺ or Mg²⁺ systems, the complexes ML and ML(OH)_x are formed. Overall stability constants (log β) and equilibrium constants (log K_e) were calculated for all complex forms. The mode of coordination for each form was concluded on the basis of spectral values, Vis, EPR, and chemical shifts in the ¹³C NMR. According to spectral analysis, Cu(GluA) exists in two possible forms, which confirm the occurrence of the coordination dichotomy in the system. The main center of interactions in the hydroxyl complexes Cu(GluA)(OH)_x and MgGluA are oxygens from the carboxyl group. Differences in the coordination mode in the copper(II) and magnesium systems at low pH were observed.     

A dual-wavelength overlapping resonance Rayleigh scattering method for the determination of chondroitin sulfate with nile blue sulfate

To date, there is no study on bioethanol processing-induced changes in molecular structural profiles mainly related to lipid biopolymer. The objectives of this study were to: (1) determine molecular structural changes of lipid related functional groups in the co-products that occurred during bioethanol processing; (2) relatively quantify the antisymmetric CH₃ and CH₂ (ca. 2959 and 2928 cm⁻¹, respectively), symmetric CH₃ and CH₂ (ca. 2871 and 2954 cm⁻¹, respectively) functional groups, carbonyl CO ester (ca. 1745 cm⁻¹) and unsaturated groups (CH attached to CC) (ca. 3007 cm⁻¹) spectral intensities as well as their ratios of antisymmetric CH₃ to antisymmetric CH₂, and (3) illustrate the molecular spectral analyses as a research tool to detect for the sensitivity of individual moleculars to the bioethanol processing in a complex plant-based feed and food system without spectral parameterization. The hypothesis of this study was that bioethanol processing changed the molecular structure profiles in the co-products as opposed to original cereal grains. These changes could be detected by infrared molecular spectroscopy and will be related to nutrient utilization. The results showed that bioethanol processing had effects on the functional groups spectral profiles in the co-products. It was found that the CH₃-antisymmetric to CH₂-antisymmetric stretching intensity ratio was changed. The spectral features of carbonyl CO ester group and unsaturated group were also different. Since the different types of cereal grains (wheat vs. corn) had different sensitivity to the bioethanol processing, the spectral patterns and band component profiles differed between their co-products (wheat DDGS vs. corn DDGS). The multivariate molecular spectral analyses, cluster analysis and principal component analysis of original spectra (without spectral parameterization), distinguished the structural differences between the wheat and wheat DDGS and between the corn and corn DDGS in the antisymmetric and symmetric CH₃ and CH₂ spectral region (ca. 2994–2800 cm⁻¹) and unsaturated group band region (3025–2996 cm⁻¹). Further study is needed to quantify molecular structural changes in relation to nutrient utilization of lipid biopolymer.     

Improving prediction selectivity for on-line near-infrared monitoring of components in etchant solution by spectral range optimization

The components (H₃PO₄, HNO₃, CH₃COOH and water) in an etchant solution have been accurately measured in an on-line manner using near-infrared (NIR) spectroscopy by directly illuminating NIR radiation through a Teflon line. In particular, the spectral features according to the change of H₃PO₄ or HNO₃ concentrations were not mainly from NIR absorption themselves, but from the perturbation (or displacement) of water bands; therefore, the resulting spectral variations were quite similar to each other. Consequently partial least squares (PLS) prediction selectivity among the components should be the most critical issue for continuous on-line compositional monitoring by NIR spectroscopy. To improve selectivity of the calibration model, we have optimized the calibration models by finding selective spectral ranges with the use of moving window PLS. Using the optimized PLS models for each component, the resulting prediction accuracies were substantially improved. Furthermore, on-line prediction selectivity was evaluated by spiking individual pure components step by step and examining the resulting prediction trends. When optimized PLS models were used, each concentration was selectively and sensitively varied at each spike; meanwhile, when whole or non-optimized ranges were used for PLS, the prediction selectivity was greatly degraded. This study verifies that the selection of an optimal spectral range for PLS is the most important factor to make Teflon-based NIR measurements successful for on-line and real-time monitoring of etching solutions.