Isothiocyanate controlled architecture,spectroscopic, and magnetic behavior of copper(II) l–arginine complexes

Abstract

We synthesized an l–arginine complex with the formula [Cu(l–Arg)₂(NCS)]·(NCS)·H₂O (1) (l–Arg = l–arginine). Two cis-chelated l–arginine zwitterions form the basal plane, while the weakly N-bonded isothiocyanate is located at the apex of the distorted square pyramidal structure (τ?=?0.143). The non-coordinated NCS^? anions held layers together in a 3-D supramolecular network. The crystal structure, spectroscopic (FT–IR, Raman, NIR–Vis–UV, EPR) and magnetic properties of 1 have been compared with [Cu(l–Arg)(NCS)₂] (2). For 1, two absorptions are observed for ν(C?=?N) stretching vibrations, corresponding to NCS^? ions N-bonded to the central Cu(II) (2077?cm^?1) and in the lattice (2057?cm^?1). In 2 a single band is observed at 2102?cm^?1, indicating equivalent NCS^? ions in the structure. The EPR spectra of complexes show anisotropic signal with g_⊥ and g_|| 2.062, 2.235 (1), and 2.08, 2.225 (2) characteristic for cis-N₂O₂ and N₃O donor sets in the xy plane, respectively. The unpaired electron mainly occupies the d_x2–y2 orbital, also confirmed by the single envelope of d–d bands at ca. 16,000?cm^?1 for 1 and 16,500?cm^?1 for 2. The magnetic properties ofcompounds are characteristic of a very weak antiferromagnetic interaction with J?=??0.055?cm^?1 and J?=??0.096?cm^?1 for 1 and 2, respectively.     

Calibration of Circular Dichrometers

Abstract

The tris (hydroxymethyl)aminomethane salt of d-10-camphorsulfonic acid (TRIS-CSA) provides a convenient, non-hygroscopic alternative to the parent compound in the calibration of circular dichrometers. The molecular ellipticities, [6], of TRIS-CSA at 291 and 191 nm are 8015± 11 and -16, 130± 40 deg cm² dmol^?1, respectively. The circular dichroism (CD) maxima in terms of δε are 2.429 1 cm^?1 mol^?1 at 291 nm and -4.888 1 cm^?1 mol^?1at 191 nm. TRIS-CSA has an ORD peak at 306.5 nm, a zero crossover at 292 nm, and a trough at 270.5 nm (molecular rotation, [M]_306.5=4475± 10, [M]_270.5= -5615± 10 deg cm² dmol^?1), and a molar absorptivity, ε, of 35.9± 0.2 1 cm^?1 mol^?1 at 286 nm.     

Extract-Photometric Determination of Vanadium with Isophthaldihydroxamic Acid

Abstract

The spectrophotometric study of violet complex isophthaldihydroxamic acid-vanadium extracted into solution of trioctylmethylammonium chloride in ethylacetate was made (λ_max = 380 nm, ? = 7500 l.mol^?1.cm^?1; λ_max = 510 nm, ? = 5510 l.mol^?1 .cm^?1; stoichiometries, 1:1 and 1:2, V:reagent). A new method for the extract-spectrophotometric determination of V(V) in the range 14–80 μg of vanadium is proposed.     

Synthesis,crystal structures,and magnetic properties of methoxido-bridged dinuclear MnIII complexes derived from tri-dentate chelating ligands

Two new doubly methoxido-bridged Mn^III dinuclear complexes, [Mn^III(mphp)(μ-OCH₃)(CH₃OH)]₂·2CH₃OH (1) and ([Mn^III(ahbz)(μ-OCH₃)(CH₃OH)]₂·2CH₃OH (2), have been synthesized by using the tridentate ligands H₂mphp (H₂mphp = 2-methyl-6-(pyrimidin-2-yl-hydrazonomethyl)-phenol) and H₂ahbz (H₂ahbz = N-(2-amino-propyl)-2-hydroxy-benzamide). The complexes have been characterized by single-crystal X-ray diffraction analysis and magnetic measurements. Complexes 1 and 2 have a similar dimeric molecular structure. Two [Mn(L)(CH₃OH)]⁺ moieties (L^2? = mphp^2? or ahbz^2?) are bridged by two μ-OCH₃^? groups in the axial-equatorial asymmetric manner. The coordination geometry of Mn^III is an axially elongated octahedron with two oxygens of a methanol ligand and a methoxido ligand situated at the axial positions. Magnetic measurements indicate that 1 and 2 exhibit antiferromagnetic behavior with the fitting parameter of J = ?1.49(3) cm^?1, D = ?1.3(1) cm^?1, g = 1.98(1) and zJ′ = ?0.18(4) cm^?1 for 1, and J = ?1.6(2) cm^?1, D = 4.5(3) cm^?1, g = 2.06(1) and zJ′ = 1.4(1) cm^?1 for 2 on the basis of the spin Hamiltonian ? = ?2J?_Mn1?_Mn2.     

Syntheses,crystal structures,and magnetic properties of 1-D coordination polymers

Three coordination polymers of Robson-type macrocycles, {[Cu₄L¹(4,4′-bipy)₂]·4ClO₄·H₂O}_∞ (1), {[Cu₄L²(4,4′-bipy)₄]·2CH₃CN·4ClO₄·2H₂O}_∞ (2), and {[Zn₂L²(4,4′-bipy)₂]·(ClO₄)₂}_∞ (3) (where H₂L¹ and H₂L² are the [2?+?2] condensation products of 1,3-diaminopropane with 2,6-diformyl-4-methylphenol and 2,6-diformyl-4-fluorophenol, respectively), have been synthesized and characterized. Magnetic susceptibility was measured for 1 and 2 from 2 to 300?K. The optimized magnetic data were J?=?–368.5?cm^?1, J′?=?40.5?cm^?1 with R?=?1.69?×?10^?6 for 1 and J?=?–291.22?cm^?1, J′?=?83.74?cm^?1, ρ = 0.00168 with R?=?1.8?×?10^?11 for 2, respectively. The data reveal strong antiferromagnetic interactions between two Cu(II) ions in the macrocyclic unit and ferromagnetic interaction between the Cu(II) ions in two adjacent macrocyclic units for 1 and 2.     

Analytical Properties of 4, 4′-Biazobenzenediazoaminobenzene and its Applications in Spectrophotometry

Abstract

The spectral characteristics and analytical properties of 4, 4′-Biazobenzenediazoaminobenzene as a new chromogenic reagent have been described and the optimum conditions for reaction with eight metal ions are presented. In the presence of Triton X-100 and sodium tetraborate solution, the reagent can be used for the determination of Hg, Ni, Cd. The molar absorptivities are 1.8×10⁵ l.mol^?1. cm^?1 at 515 nm for mercury, 2.0×10⁵ l.mol^?1. cm^?1 at 540 nm for nickel, and 1.8×10⁵ l.mol^?1.cm^?1 at 526 nm for cadmium. The recommended procedure has been used for the spectrophotometric determination of cadmium in waste water.     

Extraction and Spectrophotometric Determination of Zirconium(IV)

Abstract

A sensitive and selective method for the extraction and spectrophotometric determination of Zr(IV) with N-p-chlorophenyl-3,4-,5-trimethoxycinnamohydroxamic acid (PTCHA) has been developed. The binary complex of Zr(IV)-PTCHA is extracted from 2–6 M HCl into chloroform, having a maximum absorbance at 385 nm; molar absorptivity 2.1 × 10⁴ 1 mol^?1 cm^?1. A ternary complex with xylenol orange (Zr-PTCHA-XO) have been studied in chloroform-ethanol media, which absorbs at 540 nm; molar absorptivity 4.3 × 10⁴ 1 mol^?1 cm^?1. The present method is applied for the analysis of zirconium in standard samples.     

Liquid-Liquid Extraction,Photometric and Atomic Absorption Spectrophotometric Determination of Mercury

Abstract

A selective and sensitive spectrophotometric and atomic absorption spectrophotometric method is developed for the determination of traces of mercury with N-phenylcinnamohydroxamic acid (PCHA) in the environment. Mercury is extracted into a chloroform solution of PCHA at pH 8.5-10.0 and determined by AAS. The mercury hydroxamate binary complex is yellow in colour having a maximum absorbance at 390 nm and molar absorptivity 4.3 × 10³ 1 mol^?1 cm^?1, sandell sensitivity 0.0466 μg/cm². The ternary system using 1-(2-pyridylazo)-2-naphthol has molar absorptivity 8.82 × 10³ 1 mol^?1 cm^?1 at 550nm, sandell sensitivity 0.0228 μ/cm². Beer's law is obeyed in the concentration range of 2.37-38.0 ppm and 0.80-19.5 ppm of mercury for binary and ternary system, respectively. The extraction of Hg-PCHA binary system is studied with a liquid cation exchanger, bis-(2-ethyl hexyl) phosphoric acid (HDEHP) and found to have better selectivity than Hg-PCHA-PAN system. The molar absorptivity of the Hg-PCHA-HDEHP system is 8.82 × 10³ 1 mol^?1 cm^?1 at 390 nm and Beer's law is obeyed in the concentration range of 0.47-20 ppm of mercury.

The present method is applied to the determination of mercury in eye drops, aurvedic drugs and environmental samples.     

THE EPR SPECTRA OF TETRADENTATE SCHIFF BASE COMPLEXES OF COPPER (II) I. N,N'-Bis-(acetylacetone) ethylenediimine and N,N'-Bis-(1,1,1-trifluoroacetylacetone) ethylenediimine

Abstract

The EPR spectrum of N, N'-bis-(acetylacetone)ethylenediimino Cu(II), [Cu-en(acac)₂], and N, N'-bis-(1,1,1-trifluoroacetylacetone)ethylenediimino-Cu(II), [Cu-en(tfacac)₂], have been studied in doped single crystals of the corresponding Ni(II) chelate. The parameters in the usual doublet spin-Hamiltonian are found to be: Cu[en(acac)₂], g_z =2.183 ± 0.003, g_x =2.047 ± 0.004, g_y =2.048 ± 0.004, A_z =204.8 × 10^?4cm^?1, A_x =31.5 × 10^?4cm^?1, A_y =27.1 × 10^?4 cm^?1, A_zN= 12.8 × 10^?4 cm^?1 and A_xN =A_yN =14.3 × 10^?4 cm^?1: Cu[en(tfacac)₂], g_z =2.192 ± 0.002, g_x =2.048 ± 0.004, g_y =2.046 ± 0.004, A_z =200.8 × 10^?4 cm^?1, A_x =31.1 × 10^?4 cm^?1, A_y =28.3 × 10^?4 cm^?1, A_zN =12.8 × 10^?4 cm^?1 and A_xN =A_yN =14.6 × 10^?4 cm^?1. These parameters are related to coefficients in the molecular orbitals of the complex. It is found that the α-bonding is quite covalent and there is significant in-plane σ-bonding. From the nitrogen hyperfine structure it is determined that the hybridization on the nitrogen is sp².     

Spectrophotometric Determination of Antimony (III) By Solvent Extraction with Mandelic Acid and Malachite Green

Abstract

A sensitive and selective method has been developed for the spectrophotometric determination of antimony in the tervalent oxidation state. It was found that antimony (III) reacts with mandelic acid to form a complex anion extractable into chlorobenzene with malachite green in weak acidic media (pH 2.2 to 3.5) at room temperature and is determined indirectly by measuring the absorbance of malachite green in the extract at 628 nm. The calibration graph is linear for antimony (III) over the range 0.088–1.8 mg 1^?1 (7.2 × 10^?7–1.5 × 10^?5 mol 1^?1) with the apparent molar absorptivity ε × 6.9 × 10⁴ 1 mol^?1 cm^?1. Antimony (V) was slightly extracted in the presence of phosphate buffer with ε × 2.7 × 10³ 1 mol^?1 cm^?1.     

Spectrophotometric Determination of Diphenadione Via its Metal Complexes

Abstract

Spectrophotometric procedure is described for the quantitative determination of diphenadione [2-(diphenylacetyl)-1,3-indandione], based on direct spectrophotometric measurements of the absorbances of its iron (III), iron (II) and cobalt (II), metal complexes at 488 nm, 505 nm and (334 nm, 372 nm), respectively. The drug reacts with metals in the ratio of 3:1 and 2:1 for iron (III) and for both iron (II) and cobalt (II) respectively. The obtained complexes have apparent molar absorptivities of 1.48 × 10³ 1 mol^?1 cm^?1, 0.714 × 10³ 1 mol^?1cm^?1 and (1.70 × 10³ 1 mol^?1cm^?1, 1.93 × 10³ 1 mol^?1cm^?1) for iron (III), iron (II) and cobalt (II) complexes, respectively. The procedure is suggested for the determination of 51–400 μg.ml^?1 diphenadione via the iron (II) complex and 35–170 μg.ml^?1 diphenadione via both cobalt (II) and iron (III) complexes. The suggested procedure has accuracies of 99.79 ± 0.67%, 99.64 ± 0.37% and (100.09 ± 0.53%, 99.99 ± 0.42%) for the metal complexes of iron (III), iron (II) and cobalt (II), respectively.     

Structure of Alkali Lignins Fractionated from Ricinus communis and Bagasse. 3. IR Spectra

Abstract

The lignin fractions isolated by one- and multistage soda and sulfate cookings showed almost identical IR spectra, indicating the similarity of the lignin skeletal structure throughout the plant. However, the absorbances reveal some differences. Similarity of the spectra includes: 1) chelation and bonding of the hydroxyl groups. 2) Stretching vibration of C-H bonds in methyl, methoxyl, and methylene groups. 3) Stretching vibration of C≡N. 4) Carbonyl unconjugated β-ketone, conjugated acids, or esters at 1725 cm^?1. There is no change in the intensity of absorption at this band from that at 1515 cm^?1 with the cooking stage. 5) Aromatic skeletal vibration at 1610 and 1515 cm^?1, affected by ring substituents at 1425 cm^?1. 6) The band at 1465 cm^?1 showed a higher intensity for soda and soluble kraft lignins than for insoluble kraft ones. 7) The band at 1370 cm^?1, assigned to phenolic OH bending, is affected by the methoxyl group. 8) The absence of condensed guaiacyl and the presence of syringyl and uncondensed guaiacyl. Assignments for hardwood lignin are shown for soda and soluble kraft lignins of bagasse, while those for softwood lignin are shown for soda, soluble, and insoluble kraft lignins of Ricinus communis and for insoluble kraft lignin of bagasse. A relation exists between the carbohydrate's lignin and the band at 920 cm^?1. Lignins from Ricinus communis are of higher guaiacyl to syringyl ratios than those from bagasse. The presence of C—S vibration and the absence of thiol groups for kraft lignins are indicated.     

Absorption Spectra of 4f Electron Transitions of Neodymium and Erbium with 8-Hydroxyquinoline-5-sulphonic Acid and Diethylamine Systems and Its Analytical Application

Abstract

In this paper the absorption spectra of 4f electron transitions of the systems of neodymium and erbium with 8-hydroxyquino-line-5-sulphonic acid and diethylamine have been studied by normal and third-derivative spectrophotometry. Their molar absorptivities are 80 l.mol^?1.cm^?1 for neodymium and 65 l.mol^?1.cm^?1 for erbium. Use of the third-derivative spectra, eliminates the interference by other rare earths and increases the sensitivity for Nd and Er. The derivative molar absorptivities are 390 1.mol^?1.cm^?1 for Nd and 367 1.mol^?1.cm^?1 for Er. The calibration graphs were linear up to 11.8 μg/ml of Nd and 12.3 μg/ml of Er, respectively. The relative standard deviations evaluated from eleven independent determinations of 7.2 μg/ml (for Nd) and 8.3 μg/ml (for Er) are 1.3% and 1.4%, respectively. The detection limits (signal to noise ratio = 2) are 0.2 μg/ml for Nd and 0.3 μg/ml for Er. The method has been developed for determining those two elements in mixture of lanthanides by means of the third-derivative spectra and the analytical results obtained are satisfactory.     

Raman Spectroscopic Determination of the Degree of Cationic Modification in Waxy Maize Starches

ABSTRACT

Waxy (essentially amylose-free) maize starch was chemically modified to varying degrees by treatment with 3-chloro-2-hydroxypropyltrimethyl ammonium chloride (CHPTAC), and the degree of cationic modification was determined by a standard wet chemistry method. FT-Raman spectra of the modified starches were taken, and a characteristic Raman band ～761 cm^?1 was found. This 761 cm^?1 Raman band's intensity depended on the level of cationic modification of the starch. The ratio of intensity of the ～761 cm^?1 band to a ～715 cm^?1 C-C stretch Raman band (used as an internal standard) was plotted versus the amount of cationic modification derived by titration analysis, and a linear fit was obtained with a correlation of 0.998. The FT-Raman spectroscopy method presented here demonstrates a rapid non-destructive way to determine the level of cationic modification of waxy maize starch, and should be suitable for use with cationic modified starches of any amylose content.     

Isonitroso-4-Methyl-2-Pentanone for Solvent Extraction and Spectrophotometric Determination of Palladium (II) at Trace Level

Abstract

Isonitroso-4-methyl-2-pentanone (HIMP) is proposed as a new reagent for extraction and photometric determination of Pd(II). The reagent forms a yellow complex with palladium in the pH range 4.0-5.0. The complex extracted into chloroform was measured at 330 nm. The molar absorptivity was found to be 5.37 × 10³ 1 mol^?1 cm^?1 and Sandell's sensitivity 20 ng cm^?2 Beer's law was obeyed over the concentration range 0.1-10.0 μg/ml of palladium. The method is applicable for palladium estimation in Ores and catalysts.     

Spectrophotometric Determination of Trace Amounts of Ascorbic Acid

Abstract

Colourless silver-gelatin complex is quantitatively reduced by ascorbic acid to yellow silver sol in water within the pH range 7.5–10.0 at room temperature. The determination of 1–10μg/ml of ascorbic acid is possible at 415 nm in the presence of glycine, alanine, fructose, sucrose, citric, tartaric, oxalic, malic, succinic acids and also in the presence of various reducing agents. The molar absorptivity of ascorbic acid at the δ_max is found to be 21500 lit mol^?1 cm^?1 and the Sandell sensitivity of the sol is 8.18x10^?3 μg ascorbic acid cm^?2 for 0.001 absorbance. The relative standard deviation is ±0.22% and the confidence limit (20 determinations, 95%) being 8.806±0.0093%.     

Spectrometric Determination of Nitrite in Aqueous Solution by the Diazotization-Coupling Method with p-Aminobenzophenone-N-(1-Naphthyl)-Ethylenediamine

Abstract

Nitrite ion at low concentration is determined spectrometrically by diazotization of p-aminobenzo-phenone and coupling of the resulting diazonium cation with N-(1-naphthy1)-ethylene-diamine to form a reddish-violet coloured water-soluble azo dye with maximum absorption at 555 nm. The method is suitable for the determination of nitrite over the range of 0.04–1.00 ppm. Beer's law is obeyed over this range of concentrations. The observed molar absorptivity and Sandell's sensitivity of the azo dye are 7.0 × 10⁴ mol^?1 cm^?1 and 6.5 × 10^?4 μg cm^?2, respectively. Interferences due to other ions were studied to test the selectivity.     

A Spectrophotometric Study of the Determination of Copper with Dithiooxamide in Acidic Media

Abstract

A spectrophotometric method for the determination of copper has been developed based on the development of a red color in acidic solution using dithiooxamide as the chromogenic agent. The molar absorptivity is 7.04 × 10³ 1. mol^?1 cm^?1 at 525 nm. Relatively few ions interfere.     

Spectrophotometric Determination of Cobalt in Vitamin Preparations,Steel and Iron Using 2-Hydroxy- 1-Naphthaldehyde Guanylhydrazone

Abstract

A new spectrophotometric determination of cobalt with 2-hydroxy-1-naphthaldehyde guanylhydrazone in acid medium is described. The method is developed on the basis of a yellow cobalt (III) complex (molar absorptivity 1.32×10^?4 L.mol^?1.cm^?1 at 416 nm, stoichiometry 2:1). The method was applied to the determination of cobalt in vitamin preparations, steel and high-purity iron.     

Spectrophotometric Determination of Gadolinium(III) With O-Hydroxyhydroqoinonephthalein in Mixed Micelles of N-Hexadecylpyridinilm Chloride and Brij 35

Abstract

A sensitive, simple and selective spectrophotometric method for the determination of gadolinium(III) is proposed using o-hydroxyhydroquinonephthalein(Qnph), by analogy with phenylfl-uorone(Phfl), in the presence of N-hexadecylpyridinium chlo-ride(HPC)-Brij 35 mixed surfactants. The calibration curve is rectilinear in the range of 0 – 16.0 μg per 10 ml at 590 nm with an apparent absorption coefficient(?) of 1.2 × 10⁵ 1 cm^?1 mol^?1 and Sandell sensitivity of 0.0013 μg/cm² gado-linium(III).