Mamdouh S. Masoud

Spectral and magnetic properties of phenylazo-6-aminouracil complexes

Complexes of Co(II), Ni(II) and Cu(II) with substituted phenylazo-6-aminouracils containing (-H, p-OH, p-CH(3), p-OCH(3) p-COOH) have been synthesized and characterized by elemental analysis, magnetic measurements and spectral measurements (IR, UV-Vis, ESR). Infrared spectra assigned the fundamental bands of the major groups, O-H, N-H, C-H, C=O, C=N, N=N, C-N and C-O (nu, delta and gamma modes of vibrations). The absence of nu(OH) and the appearance of nu(C=O) in the infrared spectra of the free ligands of 5-(p-tolyl and p-anisylazo)-6-aminouracil, assigned the keto structure, whereas in cases of 5-(phenyl, p-hydroxyphenyl and p-carboxyphenylazo)-6-aminouracil ligands, the data showed strong nu(OH) and nu(C=O) bands to assign keto-enol tautomerisms. The modes of interactions between the ligands and the metals were discussed, where oxygen and nitrogen atoms (of amino-amide groups) are involved in chelation. The azo group was not involved in chelation for all the prepared complexes except those of copper complexes derived from 5-(phenyl, p-tolyl, p-hydroxyphenyl and p-carboxyphenylazo)-6-aminouracils. The room temperature effective magnetic moment values, the Nujol mull spectra and ESR proved that all the prepared complexes were of octahedral geometry, except the nickel complex derived from 5-(phenylazo)-6-aminouracil and cobalt complex derived from 5-(p-carboxy-phenylazo)-6-aminouracil were square planar.

Synthesis, computational, spectroscopic, thermal and antimicrobial activity studies on some metal-urate complexes

New sixteen uric acid metal complexes of different stoichiometry, stereo-chemistries and modes of interactions were synthesized using different metals Cr, Mn, Fe, Co, Ni, Cu, Cd, UO(2), Na and K. The synthesized complexes were characterized by elemental analysis, spectral (IR, UV-Vis and ESR) methods, thermal analysis (TG, DTA and DSC) and magnetic susceptibility studies. Molecular modeling calculations were used to characterize the ligation sites of the free ligand. Furthermore, quantum chemical parameters of uric acid such as the energies of highest occupied molecular orbital (E(HOMO)), energies of lowest unoccupied molecular orbital (E(LUMO)), the separation energy (ΔE=E(LUMO)-E(HOMO)), the absolute electronegativity, χ, the chemical potential, P(i), the absolute hardness, η and the softness (σ) were obtained for uric acid. Eight different microbial categories were used to study the antimicrobial activity of the free ligand and ten of its complexes. The results indicate that the ligand and its metal complexes possess antimicrobial properties. The stoichiometry of iron-uric acid complex was studied by using different spectrophotometric methods.

2-thiouracil-based cobalt(II), nickel(II) and copper(II) complexes

SummaryCobalt(II), nickel(II) and copper(II) complexes of 2-thiouracil and its arylazo derivatives were prepared. The elemental analysis suggest a range of 1∶1, 2∶1 and 1∶3 stoichiometries. Electronic spectra and magnetic susceptibility measurements were used to infer the structures and the i.r. spectra of the ligands and their complexes to identify the type of bonding.

Electrical conductivity properties of some O-substituted arylazo — Barbiturate complexes at different temperatures

Electrical conductivity properties of someo-substituted arylazo-barbiturate complexes at different temperatures are studied. The σo, ΔE andEg values are determined. The copper complexes derived from −H, −CH3 and −OCH3 substituted organic compounds are with semiconducting properties at low temperatures and insulator at high temperatures. All the carboxy and the cobalt and the the nitro complexes, and nickel-methyl complexes are of semiconducting behaviour. The data are explained in the light of extrensic and lattice vibrations and the width of the forbidden energy gap properties.ZusammenfassungBei verschiedenen Temperaturen wurden die elektrischen Leitfähigkeitseigenschaften einiger o-substituierter Arylazobarbiturat-Komplexe untersucht und Werte für σo,ΔE undEg ermittelt. Die durch H-, CH3- und OCH3-Substitution der organischen Verbindungen erhaltenen Kupferkomplexe zeigen bei niedrigen Temperaturen Halbleiter- und bei hohen Temperaturen Isolatoreigenschaften. Alle Carboxy- und Nitrokomplexe sowie die Kobalt- und die Nickel-Methyl-Komplexe zeigen Halbleiterverhalten. Die Ergebnisse werden angesichts von Störstellen- und Gitterschwingungen und der Breite der verbotenen Energiezone erklärt.

Synthesis and characterization of 5-(arylazo)thiobarbituric acids and their complexes

SummaryS-(Arylazo)thiobarbituric acids and their complexes, derived from cobalt(II), nicke(II) and copper(II) were characterized by elemental analyses and spectral measurements. The1H n.m.r. and i.r. spectra show the ligands to be in the keto-thione form. The strength of the intramolecular hydrogen-bonding is influenced by the electronic requirements of the aryl ring substituents.

Characterization and Dating of Blue Ballpoint Pen Inks Using Principal Component Analysis of UV–Vis Absorption Spectra, IR Spectroscopy, and HPTLC

Abstract:  The ink of pens and ink extracted from lines on white photocopier paper of 10 blue ballpoint pens were subjected to ultraviolet–visible (UV–Vis) spectroscopy, infrared (IR), and high‐performance thin‐layer liquid chromatography (HPTLC). The Rf values and color tones of the bands separated by thin‐layer chromatography (TLC) analysis used to classify the writing inks into three groups. The principal component analysis (PCA) investigates the pen responsible for a piece of writing, and how time affects spectroscopy of written ink. PCA can differentiate between pen ink and ink line indicates the influence of solvent extraction process on the results. The PCA loadings are useful in individualization of a questioned ink from a database. The PCA of ink lines extracted at different times can be used to estimate the time at which a questioned document was written. The results proved that the UV–Vis spectra are effective tool to separate blue ballpoint pen ink in most cases rather than IR and HPTLC.

Structural chemistry of azo complexes

SummaryComplexes of CoII, NiII, CuII, PdII, and PtIV with 2,4,5-trihydroxybenzoic acid and its substituted phenylazoderivatives have been prepared, together with some mixed-metal (Co, Cu or Ni, Cu) complexes of itsm-nitro,m-carboxy andm-hydroxyarylazo derivatives. The stereochemistries and the modes of bonding of the complexes were elucidated by spectral and magnetic susceptibility measurements.

Palladium(II)-kojic acid interaction

SummaryThe interaction of palladium(II) with the bidentate kojic acid compound, HL, was studied. The pkL and pkc (1∶1) values 7.65±0.15 and 5.22±0.10 were determined in aqueous media in the presence of different solvents (dioxane, MeOH, EtOH, Me2CO and DMF) at variable concentrations (20–50% v/v solvent/H2O). A reddish brown square planar 1∶1 solid palladium kojic acid complex, PdLCl·H2O, was prepared and characterized.

Synthesis and characterization of barbituric and thiobarbituric acid complexes

SummarySynthesis of barbituric and thiobarbituric acid complexes derived from cobalt(II), nickel(II) and copper(II) salts were carried out. The elemental analyses suggest a range of stoichiometries, 1∶1, 1∶2 and 1∶3. Electronic spectra and magnetic susceptibility measurements were used to infer the structures. The i.r. spectra of the ligands and their complexes are used to identify the type of bonding.

Ligating Properties of 5-Nitrobarbituric Acid

The dissociation constant of 5-nitrobarbituric acid and the stability constants of its Co II , Ni II and Cu II complexes were determined potentiometrically. The thermodynamic parameters of dissociation were evaluated. The effect of solvents on the pK values was explained from aquation and solvation views. 5-Nitrobarbituric acid solid complexes of Mn II , Co II , Ni II , Cu II and Zn II , and the mixed metals, Fe-Co, Fe-Ni were prepared and characterized based on elemental analysis, spectra (electronic, IR, and Mössbauer), magnetism and thermal measurements.