Abdalla M. Khedr

Synthesis, characterization, thermal, and antimicrobial studies of binuclear metal complexes of sulfa-guanidine Schiff bases

A series of metal complexes of Schiff bases derived from condensation of sulfa-guanidine with 1-benzoylacetone (H2L1), 2-hydroxybenzophenol (H2L2), dibenzoylmethane (H2L3), 5-methylisatine (H2L4), and 1-methylisatine (H2L5) have been synthesized. The complexes are characterized by elemental analysis, molar conductance, magnetic moment measurements, IR, UV–Vis, 1H NMR, and ESR spectra, as well as thermogravimetric analysis. The low molar conductance values indicate the complexes are nonelectrolytes. IR and 1H NMR spectra show that H2L1–H2L5 are coordinated to metal ions by two bidentate centers. Mn(II), Co(II), Ni(II), and Cu(II) complexes display paramagnetic behavior, whereas the Zn(II)-complex was diamagnetic. All studies confirm the formation of an octahedral geometry for [Cu2L1(AcO)2(H2O)6] · 3H2O (1), [Mn2L4(AcO)2(H2O)6] · 2H2O (6), [Ni2L4(AcO)2(H2O)6] · 2H2O (8), a tetrahedral geometry for [Cu2L2(AcO)2(H2O)2] (2), [Cu2(L4)2] (4), [Co2(L4)2] · 2H2O (7) and [ZnHL4(AcO)(H2O)] · 2H2O (9) and a trigonal bipyramid geometry for [Cu2L3(AcO)2(H2O)4] (3) and [Cu2HL5(AcO)3(H2O)3] · H2O (5). H2L4 was most effective on Gram negative, Gram positive bacteria, and fungi (diameters inhibition zone ranged between 10.5–27.5 mm) after 24 and 48 h, respectively. Complex 8 showed moderate antimicrobial activity. Its minimum inhibitory concentration (MIC) against Escherichia coli, Bacillus subtilis, Candida albicans and Aspargllus flavas was 20 mg L–1. The compound proved to be of moderate toxicity and its LD50 was 20 mg L–1.

A comparative study of solid and liquid inner contact benzalkonium chloride ion-selective electrode membranes

A comparative study was made between two designs of benzalkonium ion (Bz)-selective electrodes: a silver-coated (solid contact) called electrode A and a PVC membrane (liquid inner contact) called electrode B based on benzalkonium-phosphomolybdate (Bz-PM) as ion-exchanger complex. Electrode A has a linear dynamic range from 2.0×10(-8) to 1.0×10(-2) mol L(-1), with a Nernstian slope of 60±0.3 mV/decade and a detection limit of 2.0×10(-8) mol L(-1). Electrode B shows linearity over the concentration range from 2.0×10(-7) to 1.0×10(-2) mol L(-1), with a Nernstian slope of 55±1.2 mV/decade and a limit of detection of 1.5×10(-7) mol L(-1). Electrode A showed better performance than electrode B. The detection limit of benzalkonium chloride (BzCl) was effectively improved by a solid contact ion-selective electrode (SC-ISE), rather than the traditional liquid inner contact electrode that gives lower detection limits because of diminished ion fluxes. The present electrodes show clear discrimination of BzCl from several inorganic, organic ions, sugars and some common drug excipients. The sensors were applied efficiently for determination of BzCl in its pharmaceutical preparations (eye, ear and nasal drops) using standard addition and the calibration curve methods.

Spectrophotometric Studies of the Reaction of Zinc(II) with Some Azo‐Triazol Compounds and Its Application to the Spectrophotometric Determination of Microamounts of Zinc(II)

Abstract A new, simple, and sensitive quantitative spectrophotometric method for the rapid determination of zinc(II) using six azo compounds based on 3‐amino‐1,2,4‐triazole, namely {3‐(2,4‐dihydroxy‐1‐phenylazo)‐1,2,4‐triazole) (I), 3‐(2‐hydroxy‐5‐methyl‐1‐phenylazo)‐1,2,4‐triazole) (II), 3‐(2‐hydroxy‐5‐acetyl‐1‐phenylazo)‐1,2,4‐triazole) (III), 3‐(2‐hydroxy‐5‐ethylcarboxylate‐1‐phenylazo)‐1,2,4‐triazole) (IV), 3‐(2‐hydroxy‐5‐formyl‐1‐phenylazo)‐1,2,4‐triazole) (V), and 3‐(2‐hydroxy‐5‐bromo‐1‐phenylazo)‐1,2,4‐triazole) (VI), has been developed for use in aqueous media containing 40% (v/v) methanol. Linear calibration graphs are obtained up to 2.6, 5.9, 5.2, 5.2, 8.2 and 9.0 µg mL−1 using ligands I, II, III, IV, V, and VI, respectively. Absorption maxima, molar absorptivities, and Sandells sensitivities of 1:2 (M:L) complexes were found to be 490, 530, 505, 520, 550, and 510 nm, 4.86×104, 2.10×104, 1.26×104, 0.10×104, 0.19×104, and 0.29×104 L mol−1 cm−1, and 0.0014, 0.0031, 0.0052, 0.0662, 0.0348, and 0.0225 µg cm−1 for ligands I, II, III, IV, V, and VI, respectively. Using the masking agents, the color reactions are free from interference by more than 30 ions investigated. The method has been applied to the spectrophotometric determination of trace amounts of zinc in pharmaceutical formulations and human hair samples. A study of some zinc solid complexes showed that chelation takes place through one nitrogen atom of the azo group and proton displacement from the hydroxyl group.

Binuclear Mixed Metal Complexes of V(IV), Mo(III), and U(VI) o‐Cresolphthalein Complexonates with Other Metal Ions

Abstract Heterobinuclear V(IV), Mo(III), U(VI), Mn(II), Co(II), Ni(II), and Cu(II) ion complexes of ortho‐cresolphthalein complexone (o‐CPC) were prepared and characterized. Elemental and thermal analyses as well as IR, electronic, or ESR spectra and magnetic moment determinations were utilized for the investigation of the complexes. Some complexes were also subjected to polarographic and cyclic voltammetric studies. From the data of these investigations, the structural formulae, the mode of bonding, and geometry of the complexes were obtained. Cyclic voltammetry (CV) and DC polarographic studies were utilized to establish the presence of the metal ions.

Synthesis, spectroscopic, and thermal analyses of trinuclear Mn(II), Co(II), Ni(II), and Zn(II) complexes with some sulfa derivatives

New bi- and trihomonuclear Mn(II), Co(II), Ni(II), and Zn(II) complexes with sulfa-guanidine Schiff bases have been synthesized for potential chemotherapeutic use. The complexes are characterized using elemental and thermal (TGA) analyses, mass spectra (MS), molar conductance, IR, 1H-NMR, UV-Vis, and electron spin resonance (ESR) spectra as well as magnetic moment measurements. The low molar conductance values denote non-electrolytes. The thermal behavior of these chelates shows that the hydrated complexes lose water of hydration in the first step followed by loss of coordinated water followed immediately by decomposition of the anions and ligands in subsequent steps. IR and 1H-NMR data reveal that ligands are coordinated to the metal ions by two or three bidentate centers via the enol form of the carbonyl C=O group, enolic sulfonamide S(O)OH, and the nitrogen of azomethine. The UV-Vis and ESR spectra as well as magnetic moment data reveal that formation of octahedral [Mn2L1(AcO)2(H2O)6] (1), [Co2(L1)2(H2O)8] (2), [Ni2L1(AcO)2(H2O)6] (3), [Mn3L2(AcO)3(H2O)9] (5), [Co3L2(AcO)3(H2O)9] · 4H2O (6), [Ni3L2(AcO)3(H2O)9] · 7H2O (7), [Mn3L3(AcO)3(H2O)6] (9), [Co2(HL3)2(H2O)8] · 4H2O (10), [Ni3L3(AcO)3(H2O)9] (11), [Mn3L4(AcO)3(H2O)9] · H2O (13), [Co2(HL4)2(H2O)8] · 5H2O (14), and [Ni3L4(AcO)3(H2O)9] (15) while [Zn2L1(AcO)2(H2O)2] (4), [Zn3L2(AcO)3(H2O)3] · 2H2O (8), [Zn3L3(AcO)3(H2O)3] · 3H2O (12), and [Zn3L4(AcO)3(H2O)3] · 2H2O (16) are tetrahedral. The electron spray ionization (ESI) MS of the complexes showed isotope ion peaks of [M]+ and fragments supporting the formulation.

Synthesis, spectral, thermal analyses, molecular modeling, and antimicrobial activities of Cu(II)-complexes with 1,3,4-oxadiazole Schiff-base derivatives

Seven Cu(II)-complexes with 2-amino-5-substituted aryl-1,3,4-oxadiazole Schiff bases are presented. The donors and possible geometries of the complexes were investigated by elemental and thermal (differential thermal analysis and thermogravimetric analysis) analyses, molar conductance, magnetic moments, IR, 1H-NMR, ESR, UV-Vis, and mass spectra. The ligands are bidentate, coordinating through the nitrogen of azomethine and the nearest nitrogen to it. The results are supported by 3-D molecular modeling of 2 using CS Chem 3-D Ultra Molecular Modeling and Analysis Program. The investigated complexes have been screened for in-vitro antibacterial (Escherichia coli and Staphylococcus aureus) and antifungal (Aspergillus flavus and Candida albicans) activities. The qualitative and quantitative antimicrobial activities prove that the complexes are very active against the tested microorganisms.

Synthesis, spectral analysis, and molecular modeling of bioactive Sn(II)-complexes with oxadiazole Schiff bases

Sn(II)-complexes of seven 2-amino-5-substituted-aryl-1,3,4-oxadiazole Schiff bases have been synthesized and characterized by various physico-chemical studies. Their structures have been confirmed by elemental analyses, infrared, 1H NMR, UV-Vis, and mass spectral studies as well as thermal decomposition. Conductance measurements in methanol show these complexes to be non-electrolytes, and the molecular weight determinations support the proposed molecular formulae. The molecular structures of the complexes have been optimized by CS Chem 3-D Ultra Molecular Modeling and Analysis Program showing tetrahedral geometry. The bio-efficacy of the complexes has been examined against the growth of bacteria (Escherichia coli and Staphylococcus aureus) and fungi (Aspergillus flavus and Candida albicans) in vitro to evaluate their anti-microbial potential.

Structure elucidation, protein profile and the antitumor effect of the biological active substance extracted from sea cucumber Holothuria polii

Holothuria polii (Delle Chiaje, 1823) (Holothuriidae) is a sea cucumber inhabiting Mediterranean Sea coast of Egypt. The bioactive compound of its tegument has antifungal, antibacterial and antiparasitic effects. The present study aims to elucidate the structure of the bioactive material of H. polii for pharmacological and chemotaxonomic purposes. Furthermore, the study demonstrates its efficacy as a cytotoxic agents against two tumor cell lines HCT116 (colon adenocarcinoma cell line) and MCF7 (breast adenocarcinoma cell line). The biological active compound of the ethanol extract has been characterized by means of infrared (IR), proton-nuclear magnetic resonance (1H NMR), ultraviolet–visible (UV–Vis) and mass spectra. Protein profile was carried out using sodium dodecyl sulfate polyacrylamide gel electrophoresis. Cytotoxic activity was carried out according to sulforhodamine-B assay. IR, 1H NMR, UV–Vis and mass spectra showed that the extracted bioactive material is a nonsulfated hexaosides called bivittoside. This glycoside is composed of aglycone and a glycosidic chain (carbohydrate chain) enclosed with six sugar units, including xylose, glucose, 3-O-methylglucose and quinovose. There were no traces of dissolved proteins. The preliminary cytotoxic assay of bivittoside exhibited significant cytotoxic activity against two types of cultured tumor cell lines of HCT116 and MCF7. The half-maximal inhibitory concentration was 17.4 µg/ml and 18 µg/ml for MCF7 and HCT116, respectively. Although H. polii belongs to the genus Holothuria, the lacking of sulfate group and the fact that it contains up to six monosaccharides make it different from this genus. The present study suggests separation of H. polii from its genus to a new one. On the other hand, results support the hypothesis that H. polii bioactive compound has an antitumor effect.

Mononuclear and homobinuclear vanadium(IV), chromium(III), molybdenum(III), and uranium(VI) chelates with ortho-cresolphthalein complexone

Mononuclear and homobinuclear o-cresolphthalein complexone complexes with VO2+, Cr3+, MoO+, and UO2 2+ have been prepared and their structures investigated. The empirical formulas, the mode of bonding, and the geometry of the complexes were obtained from elemental and thermal analyses, IR, electronic and ESR spectra, magnetic moment determinations, DC and CV polarographic studies.

Synthesis, characterization, molecular modeling, and thermal analyses of bioactive Co(II) and Cu(II) complexes with diacetylmonoxime and different amines

Condensation of diacetylmonoxime with 2-amino-5-mercapto-1,3,4-thiadiazole, 2-amino-1,3,4-thiadiazole or 3-amino-5-methylisoxazole in the presence of Co(II) and Cu(II) salts with different anions produced nine complexes. The synthesized complexes have been characterized by elemental analyses, molar conductivities, thermal analyses, magnetic moments, IR, electron spin resonance, and UV-Vis spectral studies. The spectral data show that sulfur, oxygen, and nitrogen participate in chelation with the metal ions. The complexes are tetrahedral, octahedral, or square planar based on the amine used and the nature of anion. Molar conductance measurements of the complexes in DMF indicate non-electrolytes. CS Chem 3-D Ultra Molecular Modeling and Analysis Program has been used for optimization of the molecular structures of some complexes. In vitro cytotoxicities of the complexes were tested against different carcinoma cell lines. Antimicrobial activities of the complexes were screened against Gram-positive (Staphylococcus aureus), Gram negative bacteria (Escherichia coli), and fungal species (Aspergillus flavus, Candida albicans, and Microsporum canis).