Di-2-pyridyl Ketone Benzoylhydrazone Research Articles

Spectrophotometric Determination of Zinc in Pharmaceutical and Biological Samples with Di‐2‐pyridyl Ketone Benzoylhydrazone: a Simple, Fast, Accurate and Sensitive Method

A simple, fast, accurate, and sensitive spectrophotometric method was developed to determine zinc(II). This method is based on the reaction of Zn(II) with di‐2‐pyridyl ketone benzoylhydrazone (DPKBH), at pH=5.5 and 50% (v/v) ethanol. Beeŕs law was obeyed in the range 0.020–1.82 µg mL−1 with a molar apsorptivity of 3.64×104 L mol−1 cm−1, and a detection limit (3δ) of 2.29 µg L−1. The action of some interfering ions was verified and the developed method applied to pharmaceutical and biological samples. The results were then compared with those obtained by using a flame atomic absorption technique.

Synthesis, characterization, properties and thermal study of nickel(II)/di-2-pyridyl ketone benzoylhydrazone complex

In this paper the interaction between nickel(II) and di-2-pyridyl ketone benzoylhydrazone (DPKBH) was studied. The synthesized complex shows the formula: Ni(DPKBH) 2. IR spectra show that interaction of the ligand with nickel(II) occurs through the CO group since the νCO frequency changed from 1686 cm −1 in the free ligand to lower frequencies in the complex. Two other interactions can be attributed to nitrogens from the azo and the pyridine group. Conductometric titrations showed the coordination of DPKBH to Ni(II) via anionic form. Thermal decomposition and differential scanning calorimetry (DSC) at 10 °C min −1 in N 2 are different for the ligand and the complex. The results from elementary analysis, mass spectrometry and the continuous variation method are given and discussed.

Kinetic Studies of the Fe(III)/DI-2-Pyridyl Ketone Benzoylhydrazone Complex Reduction By Sulfite

The reactions of HSO− 3 with Fe(III) in the presence of di-2-pyridyl ketone benzoylhydrazone (DPKBH) have been investigated at 4.2-7.2 pH. The decomposition reaction of Fe(III)/DPKBH has been studied as a function of total sulfite concentration using spectrophotometric techniques. The kinetics are controlled by the equilibrium [FeIII(DPKBH)(H2O)]2+ ⇌ [FeIII(DPKBH)(OH)]++H+, for which the hydrolysis constant was potentiometrically determined as 4.3 x 10-5M, at (25.0 ± 0.1)°C and 1.5 x 10-3M ionic strength. Both of those species undergo sulfite substitution and the significantly more labile species is the aqua complex. The formation constants of [FeIII(DPKBH)(SO3)] are 1.2 x 104 at pH 4.2 and 1.9 x 102M-1 at pH 6.2. The limiting rate constants, k, at high HSO− 3 concentrations are 3.5 x 10-2s-1 and 1.4 x 10-2s-1, respectively, at pH 4.2 and 6.2, I = 1.3 x 10-2M. The results are discussed with reference to the available literature data.

Amphoteric behavior of di-2-pyridyl ketone benzoylhydrazone in ethanol-water mixtures*

The ligand di-2-pyridyl ketone benzoylhydrazone (DPKBH) is widely used for the determination of transition metal ions in environmental samples. Due to its low solubility in water it is used in aqueous-ethanol (1:1) solvent and for higher sensitivity the pH must be properly adjusted. The properties of DPKBH solutions must be known at different ethanol-water percentages in order to achieve higher sensitivity and/or selectivity for metal analysis. The acid-base behavior of this reagent in aqueous-ethanol solvent and the dissociation/ionization constants (pK1 and pK2) of DPKBH have been determined in different aqueous-ethanol solvent mixtures (10, 20, 30 and 50 % V/V of ethanol) from potentiometric titrations at 25.0 ± 0.1° C. As the amount of ethanol increases from 10 to 30% the pK1 and pK2 values increased, but they decreased in 50% of the organic solvent. The results are correlated with the medium composition and its effects.

Amphoteric behavior of di-2-pyridyl ketone benzoylhydrazone in ethanol-water mixtures

The ligand di-2-pyridyl ketone benzoylhydrazone (DPKBH) is widely used for the determination of transition metal ions in environmental samples. Due to its low solubility in water it is used in aqueous-ethanol (1:1) solvent and for higher sensitivity the pH must be properly adjusted. The properties of DPKBH solutions must be known at different ethanol-water percentages in order to achieve higher sensitivity and/or selectivity for metal analysis. The acid-base behavior of this reagent in aqueous-ethanol solvent and the dissociation/ionization constants (pK1 and pK2) of DPKBH have been determined in different aqueous-ethanol solvent mixtures (10, 20, 30 and 50 % V/V of ethanol) from potentiometric titrations at 25.0 ± 0.1° C. As the amount of ethanol increases from 10 to 30% the pK1 and pK2 values increased, but they decreased in 50% of the organic solvent. The results are correlated with the medium composition and its effects.

Solvent Extraction-Spectrophotometric Determination of Nickel(II) in Natural Waters Using DI-2-Pyridyl Ketone Benzoylhydrazone

A new analytical method using the reagent di-2-pyridyl ketone benzoylhydrazone (DPKBH) as a colorimetric chelating agent for the spectrophotometric determination of Ni(II) in natural water samples wasestablished. This method involves a liquid-liquid extraction and was developed for determination of trace amounts of Ni(II). Under the established optimal conditions Ni(II) can be quantitatively extracted with DPKBH in chloroform. The yellow Ni(II)-complex exhibits one maximum absorbance at 406 nm. The chelated nickel(II) obeys the Beer's law and the method is suitable in the concentration range from 0.3 to 9.4 μg/L. In order to validate the method, Ni(II) concentration was determined in a water sample and the result was compared with the value obtained by AAS method. The results are in good agreement. When the spectrophotometric method was used, fluoride ions were added in order to mask the presence of iron, which can be present in water samples and is the principal interferent. The advantages of the proposed method are the short time required, high sensitivity, good precision and the use of non-expensive instrumentation.

Spectrophotometric Determination of the Stability Constants of Co(II) and DPKBH (DI-2-Pyridyl Ketone Benzoylhydrazone)

Abstract In order to have more information about the thermodynamic properties of the complexes formed by Cobalt(II) and DPKBH (di-2-pyridyl ketone benzoylhydrazone) and for the development of speciation methods for cobalt, the respective stepwise formation constants were determined in ethanolic solution 50% (V/V), at pH 5.3 and 25.0°C. The spectrophotometric method of corresponding solutions was used and the following overall formation constants were obtained: β1 = 5.305 × 106 M−1 and β2 = 8.476 × 1010 M−2. The molar absorptivities of the 1:1 (ε1) and 1:2 (ε2) complexes (Co(II):DPKBH) were determined to be 4.475 × 10 and 2.994 × 10 (M−1cm−1), respectively. The calculated distribution diagram shows the percentage of the species at equilibrium as a function of the free DPKBH concentration.

Stability, Stoichiometry, and Structure of Fe(II) and Fe(III) Complexes with Di-2-pyridyl Ketone Benzoylhydrazone: Environmental Applications

The stoichiometry, structure, and thermodynamics of Fe-(II) and Fe(III) complexes of di-2-pyridyl ketone benzoylhydrazone (DPKBH) were studied at pH 5.3 and 25.0 °C in water-ethanol solutions. The spectrophotometric method of corresponding solutions was used to obtain overall formation constants for the 1:1 (β_1 = 4.693 X 10^6 M^(-1)) and 1:2 (β_2 = 2.195 X 10^(10) M^(-2)) Fe(III)(H_20)_6^(3+)DPKBH complexes and 1:1(β_1 =1.217 X 10^5 M^(-1)) and 1:2 (β_2 = 7.814 X 10^9 M^(-2)) Fe(II)(H_2O)_6^(2+)-PKBH complexes. Conductance and pH titrations indicate that DPKBH coordinates preferentially as an anion, while FTIR analysis shows that DPKBH exists in the enol form and exhibits tridentate ligand behavior. DPKBH has been shown to be a useful analytical reagent for the simultaneous spectrophotometric determination of Fe(II) and Fe(III) in natural waters: Fe(H_20)_6^(3+) + DPKBH ⇆ Fe(H_2O_)_3- (DPKBH)^(3+) + 3H_2O and Fe(H_2O)_6^(3+) + 2DPKBH ⇆ Fe-(DPKBH)_2^(3+) + 6H_2O.

Spectrophotometric Determination of Uranium with Di-2-pyridyl Ketone Benzoylhydrazone

A method for the spectrophotometric determination of uranium (VI) by complexation with Di-2-pyridyl ketone benzoylhydrazone (DPKBH) in 50% (v/v) ethanolic solution is described. Uranium (VI) forms a 1:2 complex with DPKBH. The complex has a maximum absorbance at 377 um. Beer's law is obeyed over the range 0, 2 - 12 ug.m1' 1. The effect of pH, excess reagent, percentage of ethanol (v/v), stability of the complex and the tolerance limit of many metal ions and common anions have been reported. The method has been applied to the determination of uranium in Egyptian monazite sand.

Spectrophotemetric determination of cobalt in aqueous solution using di-2-pyridyl ketone derivatives

A method for the spectrophotometric determination of cobalt(II) is presented, with a comparison of the binary complexes formed by cobalt(II) with di-2-pyridyl ketone nicotinoylhydrazone (DPKNH), di-2-pyridyl ketone 2-thiophenoylhydrazone (DPKTH) and di-2-pyridyl ketone benzoylhydrazone (DPKBH) in 50% (v/v) ethanolic solution. Cobalt(II) forms 1:2 complexes with the three reagents. Maximum absorbance is at 372 nm for Co(II)-DPKNH, at 389 nm for Co(II)-DPKTH and at 370 nm for Co(II)-DPKBH. Ranges of linearity, effects of pH and excess reagent, sensitivity, stability of the complexes and tolerance limits of ions are reported. It was concluded that the system with DPKTH is the best, followed by DPKNH and then DPKBH. The method was applied to the determination of cobalt in different alloys.

Differential pulse polarography and voltammetry of di-2-pyridyl ketone benzoylhydrazone

The differential pulse polarographic (DPP) and voltammetric (DPV) behaviour of di-2-pyridyl ketone benzoylhydrazone (DPKBH), has been investigated over a wide pH range (2.1–11.5). The effect of various operational parameters on the reduction current are discussed and the mechanism of the electrode reaction is also included. Both methods DPP and DPV are applied for the analytical determination of this reagent and the detection limits are found to be 1.24 μmol/l and 0.86 μmol/l, respectively. The DPP behaviour of DPKBH in the presence of Pb(II), Cd(II) and Cu(II) is studied and the behaviour of the Cu(II)-DPKBH complex is fully investigated. The voltammetric determination of Cu(II), based on the accumulation of its complex at the hanging mercury drop electrode, is described. Statistical analysis of the calibration curve data is included.

Spectrophotometric Determination of Cobalt with Di-2-Pyridyl Ketone Benzoylhydrazone

Abstract A method for the spectrophotometric determination of cobalt (II) by complexation with di-2-pyridyl ketone benzoylhydrazone (DPKBH) in 50% (v/v) ethanolic solution is described. Cobalt (II) forms a 1:2 complex with DPKBH. The complex has maximum absorbance at 370 nm. Beer's law is obeyed over the range 0.1 – 2.8 μg.ml−1. The effect of pH, effect of excess reagent, stability of the complex and the tolerance limit of many metal ions have been reported. The method is applied to the determination of cobalt in different alloys containing other metals ions.

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

Abstract 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.

Ligands with the “ONNN” Group as Chelating and Preconcentrating Substances of Heavy Metal Ions: Aroylhydrazone Derivatives from Di-2-Pyridyl Ketone

The synthesis of the electronic and infrared spectra of di-2-pyridyl ketone salicyloylhydrazone (DPKSH) and di-2-pyridyl ketone benzoylhy-drazone (DPKBH) is reported. Ultraviolet absorption spectra have been applied for determining the dissociation constants: DPKSH, pK1 = 3.5 and pK2 = 6.85; DPKBH, pK1 = 2.75 and pK2 = 10.6. These pK a values are interpreted as a function of the ortho-position of the OH group. Chelating properties of both tridentate ligands have been investigated. DPKSH forms a larger number of metal chelates in acidic media than does DPKBH. Also, it is concluded that DPKSH is a more suitable compound than DPKBH to preconcentrate and to determine heavy metal ion traces as it is inferred from the data obtained by flame AAS.

Solvent extraction and spectrophotometric determination of iron(II) with di-2-pyridyl ketone benzoylhydrazone

Di-2-pyridyl ketone benzoylhydrazone (DPKBH) was used for the spectrophotometric determination of trace amount of iron(II) in connection with the extraction process. The green iron(II) complex with a maximum absorbance at 379 and 686 nm is quantitatively extracted into benzene from aqueous solution buffered to pH 4.7 – 6.0. Beer's law is obeyed over the range 0–30 μg of iron in 10 ml of benzene at 686 nm. The molar absorptivity of the complex is 1.59 × 10 4 liters mol −1 cm −1. The relative standard deviation for 16.8 μg of iron was 0.48% at this wavelength. The proposed method is relatively selective for iron(II) and is satisfactorily applied to the determination of the total iron in natural waters. The proton dissociation constants of the ligand determined spectrophotometrically were p K a1 = 3.18 and p K a2 = 10.87 at 25 °C and μ = 0.1.

Extraction-Spectrophotometric Determination of Palladium(H) with Di-2-pyridyl Ketone Benzoylhydrazone

A method for the extractive spectrophotometric determination of palladium(II) with di-2-pyridyl ketone benzoylhydrazone (DPKBH) has been studied. The method is based on the formation of the palladium(II)-DPKBH complex which is extracted into benzene from sulfuric acid solution in the presence of chloride ions. The extracted species has absorption maxima at 455 and 481nm with the molar absorptivity of 9.38×103 Lmol-1 cm-1 at the former wavelength. Beer′s law is obeyed over the range 0-10μg ml-1 of palladium at 455nm. The proposed method is selective in the presence of tartaric or citric acid and has been satisfactorily applied to the determination of palladium in a dental alloy and in palladium-catalyst samples.