Bulletin of the Chemical Society of Ethiopia 2021-05-08T03:33:33+00:00 Prof. B.S. Chandravanshi Open Journal Systems A triannual publication of the Chemical Society of Ethiopia SALLE combined with LD-DLLME for pesticides analysis in sugar and soil samples 2021-05-07T13:24:32+00:00 T. Tolcha K. Gomoro N. Megersa <p>In this study, a modified salting-out-assisted liquid-liquid extraction (SALLE) combined with low density dispersive liquid-liquid microextraction (LD-DLLME) has been developed for quantitative determination of multiclass pesticide residues (atrazine, diazinon, ametryn, terbutryn, chlorpyrifos, dimethametryn, 4,4'-dichlorodiphenyldichloroethylene (4,4'-DDE), 4,4'-dichlorodiphenyldichloroethane (4,4'-DDD) and 4,4'-dichloro- diphenyltrichloroethane (4,4'-DDT)) levels in sugar and soil samples coupled with gas chromatography–mass spectrometry (GC-MS) detection. The extract was enriched after combining SALLE to LD-DLLME and enrichment factor obtained ranged 30-121. Under the optimum conditions, the linearity of the method was in the range of 6.25–100 ng g<sup>-</sup><sup>1</sup> for atrazine, ametryn, terbutryn, dimethametryn and 4,4'-DDT, and in the range of 2.5–100 ng g<sup>-</sup><sup>1</sup> for diazinon, chlorpyrifos and 4,4'-DDD, and in the range of&nbsp; 1–100 for 4,4'-DDE with correlation coefficient of&nbsp; 0.992 or better. The limits of detection (LODs) ranged from 0.01–0.25 ng g<sup>-</sup><sup>1</sup>. The precisions as %RSD, were below 10% for both matrices. The recoveries obtained from spiked sugar and soil samples at 5 and 50 ng g<sup>-1 </sup>ranged from 79 to 111%. The method was subsequently applied to real sugar and soil samples. All the pesticides investigated were not detected in the sugar sample. The soil sample was contaminated by atrazine and ametryn at concentration level of 0.3 and 0.2 ng g<sup>-1</sup>, respectively.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: SALLE, LD-DLLME, Extraction, Pesticide residues, Sugar, Soil</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 1-16.</p> <p>DOI: <a href=""></a>&nbsp;&nbsp;</p> 2021-05-07T00:00:00+00:00 Copyright (c) Development and validation of a single HPLC method for the determination of thirteen pharmaceuticals in bulk and tablet dosage form 2021-05-07T13:28:48+00:00 B. Tegegne B. S. Chandravanshi F. Zewge L. Pillay L. Chimuka <p>The aim of this study was to develop and validate a high performance liquid chromatography (HPLC) method for the determination of thirteen selected pharmaceutical compounds (metformin, amoxicillin, chloroquine, theophylline, trimethoprim, caffeine, norfloxacin, ciprofloxacin, acetylsalicylic acid, doxycycline hyclate, metronidazole, albendazole and cloxacillin) in bulk and tablet dosage form. Chromatographic separation using a Kromasil C<sub>18 </sub>column, gradient elution with aqueous formic acid (0.1%), methanol and acetonitrile, a UV absorption wavelength of 250 nm and a mobile phase flow rate of 1 mL/min over a 22 min run time was optimized for complete separation of the selected target compounds. The method was validated and results for: linearity, precision, sensitivity, accuracy, specificity, suitability and method robustness were obtained and met the ICH guidelines. Calibration curve correlation coefficients ranged from 0.9985-0.9998 and the percentage relative standard deviations for repeated analysis&nbsp;was below 5%, indicating acceptable method precision. The limits of detection (LODs) and quantification (LOQs) ranged from 0.020-0.27 µg/L and 0.080-0.91 µg/L, respectively. The accuracy study yielded recoveries in the ranges 86.0-102% for pure compounds and 90.9-106% for compounds in tablet dosage form. The method is robust for small or deliberate changes to the chromatographic parameters and found to be appropriate for analysis of tablets for the determination of the thirteen pharmaceuticals.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: Pharmaceuticals, Bulk determination, Tablet dosage, High performance liquid chromatography, Method development, ICH guidelines</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 17-31.</p> <p>DOI: <a href=""></a></p> 2021-05-07T00:00:00+00:00 Copyright (c) Synthesis, characterization and antimicrobial activity of copper(II) Schiff base adducts of some p-substituted aniline Schiff bases 2021-05-07T13:50:07+00:00 A. O. Sobola G. M. Watkins R. O. Shaibu S. Adewuyi S. A. Amolegbe <p>The synthesis, characterization and antimicrobial activity of Cu(II) complexes of some <em>p</em>-substituted aniline Schiff base ligands have been carried out. The Schiff bases were obtained from salicylaldehyde and <em>o</em>-vanillin. The Cu(II) complexes have been characterized by elemental analysis, conductivity measurement, infrared and electronic spectral data. The complexes were obtained either as metal chelates [Cu(L)<sub>2</sub>] or Schiff base adducts (CuCl<sub>2</sub>.2LH).xH<sub>2</sub>O. The metal chelates were non-electrolytes while the Schiff base adducts exhibited 1:1 or 2:1 electrolytes in methanol. The Cu(II) complexes exhibited slight antimicrobial activity against <em>Escherichia coli</em> ATCC® 8739™*, <em>Staphylococcus aureus subsp. aureus </em>ATCC® 6538™*, <em>Bacillus subtilis subsp. spizizenii</em> ATCC® 6633™* and <em>Candida albicans</em> ATCC® 2091™*. The complexes exhibited significant antifungal activity.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: Metal Chelates, Schiff bases, Adducts, Cu(II) complexes, Salicylaldimines</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 33-42.</p> <p>DOI: <a href=""></a></p> 2021-05-07T00:00:00+00:00 Copyright (c) Solid-state synthesis and physico-chemical characterization of modified smectites using natural clays from Burkina Faso 2021-05-08T01:18:34+00:00 I. Garikoé B. Sorgho B. Guel I. Persson <p>Solid-state intercalation was applied to prepare organo-smectites using cationic surfactants and natural clays containing smectite at various surfactant/smectite ratios. The surfactants enter the interlayers of smectites causing a swelling of the clays. The used clays were collected in Siétougou and Diabari villages located in the eastern part of Burkina Faso. The solid-state intercalation was successful for all four surfactants applied, <em>n</em>-dodecyltrimethylammonium bromide, (<em>n</em>-C<sub>12</sub>H<sub>25</sub>(CH<sub>3</sub>)<sub>3</sub>NBr), <em>n</em>-tetradecyltrimethylammonium bromide, (<em>n</em>-C<sub>14</sub>H<sub>29</sub>(CH<sub>3</sub>)<sub>3</sub>NBr), <em>n</em>-hexadecyltrimethylammonium bromide (<em>n</em>-C<sub>16</sub>H<sub>33</sub>(CH<sub>3</sub>)<sub>3</sub>NBr) and di-<em>n</em>-dodecyldimethyl­ammonium bromide ((<em>n</em>-C<sub>12</sub>H<sub>25</sub>)<sub>2</sub>(CH<sub>3</sub>)<sub>2</sub>NBr) at different levels of the cation exchange capacity (CEC). The synthesized organo-smectites were characterized regarding relative density, structural and textural properties. XRPD data showed a systematic increase of the basal spacing of the unit cell of the smectite up to &gt;38 Å at 2.0-CEC loading of the surfactant. This increase indicates that the surfactants penetrated into the smectite interlayers with the surfactants being arranged parallel to the layers at low concentrations and almost perpendicular at high ones. FTIR spectra of the organo-smectites showed a decrease in the intensities of the water bands at around 1630 cm<sup>-1 </sup>and 3400 cm<sup>-1</sup>, and new specific bands close to 2920 cm<sup>-1 </sup>and 2850 cm<sup>-1</sup> were assigned to the asymmetric and symmetric stretching of CH<sub>2</sub> groups of the surfactants, respectively.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: Smectite, Organo-smectite, Surfactant, Intercalation</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 43-59.</p> <p>DOI: <a href=""></a></p> 2021-05-07T00:00:00+00:00 Copyright (c) Synthesis, spectral and sol-gel behavior of mixed ligand complexes of titanium(IV) with oxygen, nitrogen and sulfur donor ligands 2021-05-08T01:25:29+00:00 A. Srivastava N. Srivastava U. N. Tripathi <p>A new route to synthesize nano-sized Ti(IV) mixed ligand complexes have been investigated by the reaction of titanium(IV) chloride with ammonium salts of dithiophosphate and 3(2'-hydroxyphenyl)-5-(4-substituted phenyl) pyrazolines. The resultant complex is then treated with H<sub>2</sub>S gas to get sulfur bridged dimer of Ti(IV) complex, a precursor of TiS<sub>2</sub>. The morphology of the complexes was studied by employing XRD which shows that all the complexes are amorphous solid. Molecular weight measurements, elemental analysis in conjugation with spectroscopic (IR, <sup>1</sup>H NMR, <sup>13</sup>C NMR and <sup>31</sup>P NMR) studies revealed the dimeric nature of the complexes in which pyrazoline and dithiophosphate are bidentate. Scanning electron microscopic image and XRD indicate that the particles are in the nano range (50 nm). Putting all the facts together, coordination number six is proposed for titanium with octahedral geometry.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: Titanium(IV), Dithiophosphate, Pyrazoline, Nano-sized, Sol-gel, Mixed ligand complexes</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 61-76.</p> <p>DOI: <a href=""></a> </p> 2021-05-07T00:00:00+00:00 Copyright (c) Synthesis, characterization, in-vitro anti-inflammatory and antimicrobial screening of metal(II) mixed diclofenac and acetaminophen complexes 2021-05-08T01:35:31+00:00 J. A. Obaleye A. A. Aliyu A. O. Rajee K. E. Bello <p>Mixed ligand complexes derived from diclofenac potassium salt (Kdc) and acetaminophen (ace) has been synthesized and proposed to have a general formula [MB] where M = Co<sup>2+</sup>, Ni<sup>2+</sup>, Cu<sup>2+</sup> and Zn<sup>2+</sup>and B = (ace)(dc)(H<sub>2</sub>O)<sub>2 </sub>except for Mn<sup>2+</sup> complex which exists as [Mn(ace)(dc)OH<sub>2</sub>]. The complexes were characterized by solubility, melting point, conductivity, elemental analyses, UV-Vis, FT-IR spectroscopy, X-ray powder diffraction (XRPD) study and magnetic susceptibility measurement. Electronic absorption spectra data are characteristic of octahedral structures for [MB]<em>. </em>The IR spectra revealed a bidentate coordination mode. In acetaminophen, the nitrogen and carbonyl-O atoms of the amide group were involved while the carboxylate oxygen atoms of potassium diclofenac were used; typical of a carboxylic acid derivative. The compounds were screened for <em>in-vitro </em>anti-inflammatory activity by inhibition of albumin denaturation assay and antimicrobial activity against bacteria strains: <em>Bacillus subtilis</em>, <em>Bacillus anthrax</em>,<em> Escherichia coli</em>, <em>Salmonella typhi </em>and a fungus <em>Aspergillus niger</em>. Some of the tested compounds showed moderate anti-inflammatory activity when compared to the standard drug diclofenac potassium salt. The <em>in-vitro</em> antimicrobial screening revealed an increased activity of the complexes against the bacteria isolates compared to the free ligands.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: Metal(II) ion, NSAIDs, Anti-inflammatory activity, Diclofenac potassium salt, XRPD, Antimicrobial activity</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 77-86.</p> <p>DOI: <a href=""></a> </p> 2021-05-07T00:00:00+00:00 Copyright (c) Bioactivities of holmium(III) and gadolinium(III) complexes of thymoquinone 2021-05-08T01:44:49+00:00 N. S. Awwad H. A. Ibrahium A. A. Shati M. A. Alshehri K. M. Al-Syaad M. Y. Alfaifi M. I. Mujallid M. Z. Bani-Fwaz H. S. M. Abd-Rabboh Y. H. Ju A. E. Fazary <p>Chemotherapeutic agents which are the main stay in cancer treatment are toxic with numerous contrary side effects. A number of chemical, physical, and computational techniques were applied to synthesize and elucidate the structural and functional characterization of the new designed bioligands and their metal complexes. Besides, several biological techniques for developing therapeutics and diagnostics agents of these new designed materials were used. The trivalent holmium(III) and gadolinium(III) metal complexes of thymoquinone (TQ) were synthesized. Toxicities and other bioactivites were undertaken with existing drug combinations and more effective tumor models will be established. The molecular structures of TQ-metal complexes were elucidated based on particular spectral approaches. The NF-kB (nuclear factor kappa-light-chain enhancer of activated B Cells) luciferase, elastase release, superoxide anion (O<sub>2</sub>•−) generation, and DPPH (1,1-diphenyl-2-picryl hydrazyl) free-radical scavenging activities of TQ and its synthesized complexes were elucidated and discussed. The core research is to use coordination and organometallic chemistry to design new bioligands and binary, ternary, mixed ligand, multi metal multi ligand complexes pursing a bio target continuously with structure-activity relationships (SARS).</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: Thymoquinone, Holmium, Gadolinium, Bioactivities</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 87-96.</p> <p>DOI: <a href=""></a></p> 2021-05-07T00:00:00+00:00 Copyright (c) Mn(II), Co(II), Ni(II), and Cu(II) complexes of amino acid derived Schiff base ligand: Synthesis, characterization and in-vitro antibacterial investigations 2021-05-08T01:52:47+00:00 A. O. Rajee H. F. Babamale A. Lawal A. A. Aliyu W. A. Osunniran A. O. Sheriff M. Lawal J. A. Obaleye <p>Four complexes of Mn(II), Co(II), Ni(II) and Cu(II) with Schiff base ligand (H<sub>3</sub>L) derived from 2-amino-3-methylbutanoic acid and acetylacetonate were synthesized. All complexes were characterized by elemental analysis, Fourier-transform infrared spectroscopy and electronic spectroscopy. The results confirmed the coordination of the ligand to metals in tridentate fashion via the hydroxyl oxygen, the azomethine nitrogen and the enolic acetylacetonate oxygen. Antimicrobial activities were established for all complexes, free ligand and ciprofloxacin for comparison. Both the ligand and its metal complexes were active against Gram-positive and negative bacterial strains. The Cu(II) complex, showed highest antibacterial activity among the complexes screened. Other complexes displayed considerable antibacterial activity. Octahedral geometry was proposed for the metal(II) complexes with the Schiff base.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: Schiff base, Amino acid, Metal Complexes, Antibacterial agents</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 97-106.</p> <p>DOI: <a href=""></a></p> 2021-05-07T00:00:00+00:00 Copyright (c) Synthesis, characterization, and photocatalytic efficiency of a new smart PdO oxide nanomaterials for using in the recycling and sustainable wastewater treatment 2021-05-08T01:55:44+00:00 M. S. Refat H. A. Saad A. A. Gobouri M. Alsawat K. Belgacem B. M. Majrashi A. M. A. Adam <p>Nanostructured PdO materials with promising catalytic properties were successfully synthesized by the controlled thermal decomposition in air of three Pd(II) complexes containing Pd(II) ion, ofloxacin drug and amino acid. The Pd(II) complexes which were used as precursors were [Pd(OFL)(Gly)]Cl, [Pd(OFL)(Ala)]Cl, and [Pd(OFL)<sub>2</sub>]Cl<sub>2</sub>, where Gly is glycine amino acid, Ala is alanine amino acid, and OFL is ofloxacin. Structural and morphological properties of the synthesized PdO materials were obtained using FTIR, XRD, SEM, and EDX techniques. The XRD results confirm the tetragonal structure of PdO. The obtained PdO materials were tested as a catalyst for the heterogeneous degradation of H<sub>2</sub>O<sub>2 </sub>solution. The results revealed that PdO could effectively degrade H<sub>2</sub>O<sub>2</sub>.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: PdO, Nanoparticles, Photocatalytic efficiency, Wastewater treatment</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 107-118.</p> <p>DOI: <a href=""></a></p> 2021-05-07T00:00:00+00:00 Copyright (c) Luminescent, sorptive and antibacterial potential of bismuth-organic framework 2021-05-08T02:04:18+00:00 S. Iram T. Khurshid S. Latif M. Imran F. Kanwal L. Mitu <p>Metal organic frameworks are formed by the three-dimensional linkage of metal cores and organic linkers. In this work, bismuth-based metal organic framework (Bi-MOF) has been synthesized by using 5-hydroxyisophthalic acid (H<sub>2</sub>HIA) as linker via hydrothermal method. The said MOF was structurally characterized by UV/Vis, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), <sup>1</sup>H NMR, energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA) and X-ray diffraction technique. This MOF showed highly porous structure with surface area 1096 m<sup>2</sup>/g as determined by BET analysis. A model batch adsorption experiment was performed to evaluate the efficiency of methylene blue (MB) dye removal from aqueous media. It was found that monolayer adsorption capacity calculated from the Langmuir isotherm was 0.6240 mg/g. Bi-MOF was also screened for its antibacterial and luminescent behavior.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: Bismuth, Metal-organic Frameworks, Luminescence, Sorption</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 119-128.</p> <p>DOI: <a href=""></a></p> 2021-05-07T00:00:00+00:00 Copyright (c) Synthesis, characterization, thermal analysis and biological study of new thiophene derivative containing o-aminobenzoic acid ligand and its Mn(II), Cu(II) and Co(II) metal complexes 2021-05-08T02:08:00+00:00 M. S. Refat T. A. Altalhi G. H. Al-Hazmi J. Y. Al-Humaidi <p>New ligand containing 2-(2,4-dioxo-4-thiophen-2-yl-butyrylamino)-benzoic acid (HL) merged moiety was synthesized and characterized by FT-IR, elemental analyses, mass spectra and <sup>1</sup>H-NMR spectral. In the present study, the attempts were carried to form complexes of HL ligand with some transition metal ions (Mn<sup>II</sup>, Cu<sup>II</sup> and Co<sup>II</sup>) of well-defined at the (1:1) ratio of the components in the dimethyl sulfoxide&nbsp;(DMSO) solvent. All complexes have been studied by FTIR spectra, elemental analyses, thermal analysis, molar conductivity, electronic spectra and magnetic moment. The HL ligand produced as a bidentate chelate with interactive metal ions. All the results suggested octahedral geometry to complexes and have the formulae [M(HL)(Cl)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>].<em>n</em>H<sub>2</sub>O where M = Mn(II), Cu(II) and Co(II). The IR spectra of the complexes were assigned and compared with the data in literature. The kinetic and thermodynamic results such as <em>E</em>*, Δ<em>H</em>*, Δ<em>S</em>* and Δ<em>G</em>* were calculated based o the TGA/DTG curves using Coats and Redfern and Horowitz and Metzger approximation methods. Furthermore, the resultant complexes were evaluated for the anti-bacterial and anti-fungal potential.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: 2-(2,4-Dioxo-4-thiophen-2-yl-butyrylamino)-benzoic acid, Transition metal complexes, FTIR, TGA, Antimicrobial test</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 129-140.</p> <p>DOI: <a href=""></a></p> 2021-05-07T00:00:00+00:00 Copyright (c) Phytochemical studies of Melilotus officinalis 2021-05-08T02:10:57+00:00 M. A. Sisay W. Mammo E. E. Yaya <p>GC-MS analysis of the <em>n</em>-hexane extract of <em>Melilotus officinalis </em>seeds revealed twelve compounds with a combined area percentage of 98.33% predominantly, (9<em>Z</em>,12<em>Z</em>)-octadecadienoic acid (20.22%, 366 ppm), 14-methylpentadecanoic acid (19.52%, 353 ppm) and (9<em>E</em>)-octadecenoic acid (15.94%, 289 ppm). Two compounds, namely, <em>cis</em>-coumaric acid-2-O-<em>β</em>-D-glucopyranoside (<em>cis</em>-melilotoside, <strong>1</strong>) and 1,2-benzopyrone (coumarin, <strong>2</strong>), were isolated from the MeOH extract of the seeds of <em>M. officinalis</em>. The structures of isolated compounds were determined by spectroscopic techniques such as NMR, UV-Vis, and FTIR. The MeOH extract of <em>M. Officinalis </em>was also tested for its antioxidant activity using DPPH assay. The extract showed 29.87% DPPH inhibition at concentration of 100 μg/mL.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: <em>Melilotus officinalis</em>, Fatty acid methyl esters, Esterification, GC-MS, DPPH radical scavenging assay, Antioxidant activity</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 141-150.</p> <p>DOI: <a href=""></a></p> 2021-05-07T00:00:00+00:00 Copyright (c) Investigations on structural, optical, and impedance spectroscopy studies of titanium dioxide nanoparticles 2021-05-08T02:14:48+00:00 S. C. Vella Durai E. Kumar D. Muthuraj <p>This article explains a novel synthesis for producing titanium dioxide (TiO<sub>2</sub>) nanoparticles by a sol-gel technique using titanium tetraisopropoxide as a titanium source. The synthesized nanoparticles were analyzed using many measurements like X-ray diffraction (XRD), HRTEM, absorption UV spectroscopy, FTIR, and ac impedance spectroscopy. X-ray peaks were used to calculate the crystallite size and lattice strain by Williamson–Hall method. Crystallite size calculated from x-ray diffraction using the Scherrer equation gives an approximate size and cannot be used for measurements. TiO<sub>2</sub> nanoparticles are found to possess a tetragonal structure with a crystalline size around 12 nm. Particle size was confirmed by HRTEM images. The optical studies response for the nanoparticles showed the possible visible absorption peaks for TiO<sub>2</sub> nanoparticles are 323 nm. Bandgap energy (E<sub>g</sub>) of the TiO<sub>2</sub> nanoparticle calculated from UV visible absorption spectra is discussed, and the bandgap is 3.14 eV. FTIR spectra showed vibration bands of the Ti-O network. AC Conductivity properties of TiO<sub>2</sub> nanoparticles are studied in the frequency range 1 to 8 MHz at varying temperatures. The conductivity of the TiO<sub>2</sub> nanoparticle is found to be constant in the low angular frequency region. Dielectric parameters were analyzed at different temperatures and frequencies.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: Conductivity, Dielectric, Nanoparticles, Titanium dioxide, Structural studies</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 151-160.</p> <p>DOI: <a href=""></a></p> 2021-05-07T00:00:00+00:00 Copyright (c) Green synthesis of MgO nanoparticles using Moringa oleifera leaf aqueous extract for antibacterial activity 2021-05-08T02:20:08+00:00 A. Fatiqin H. Amrulloh W. Simanjuntak <p>Nanoparticle fabrication using plant extracts is an important alternative method because it is non-toxic, biocompatible, and environmentally friendly. In this study, green synthesis of MgO nanoparticles using <em>Moringa oleifera</em> leaf water extracts was conducted by mixing the extract and a solution of magnesium chloride. The product was characterized using different techniques, <em>i.e. </em>UV-Visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The UV-Vis spectrum of MgO nanoparticles shows an absorption at 280 nm. The size of the synthesized MgO nanoparticles ranges from 20-50 nm. The antibacterial activity of MgO nanoparticles was seen from the zone of inhibition against <em>Staphylococcus aureus</em> (6.3 mm) and against <em>Escherichia coli</em> (6 mm). MgO nanoparticles have been successfully fabricated using <em>M</em><em>oringa</em><em> oleifera</em> leaf aqueous extracts, providing an alternative method for synthesizing MgO nanoparticles.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: Antibacterial activity, <em>Escherchia coli</em>, MgO nanoparticles, <em>Moringa oleifera</em>, <em>Staphylococcus aureus</em></p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 161-170.</p> <p>DOI: <a href=""></a></p> 2021-05-07T00:00:00+00:00 Copyright (c) Studies on physico-mechanical behaviour of kenaf/glass fiber reinforced epoxy hybrid composites 2021-05-08T02:23:35+00:00 A. H. Birniwa S. S. Abdullahi M. Y. Yakasai A. Ismaila <p>In this study, various treated, untreated, and treated kenaf/glass fiber composites were fabricated using epoxy resin. A portion of kenaf fibers were subjected to treatment with alkali, sub-portion was taken for benzoyl peroxide and potassium permanganate prior to composite fabrication. This treatment on the composite material was undertaken to achieve improved modification of the interface between the matrix and fiber bond. A portion of the glass fiber was used for enhancing the mechanical properties of the hybrid composite. The tensile strength, flexural, density, water absorption and chemical resistance of the composites were analyzed using standard methods. FTIR was conducted on the fiber to ascertain the chemical treatment on the fibers, FESEM was used for the morphological study. The results obtained showed that the tensile and flexural strength improved from 46.45-298.3 kgf, and 10.5-54.7 kgf, respectively, in the composite samples. Chemical resistance of the kenaf fiber treated potassium permanganate composite improved compared to the untreated fiber composite in both cases. The density and water absorption properties of the composites were found to decrease in the treated fibers compared to untreated fiber composites, this treated composites showed less water absorption and density. The FTIR result revealed that reaction has taken place between the fiber and the treatment reagent. Hence, fiber modification has improved the properties of the composites due to increase in fiber-matrix interaction.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: Chemical properties, Epoxy resin, Hybrid, Kenaf, Mechanical strength, Natural fiber</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 171-184.</p> <p>DOI: <a href=""></a></p> 2021-05-07T00:00:00+00:00 Copyright (c) Copper-based glass-ceramic as an efficient catalyst in the synthesis of pyrazolo[1,5-a] pyrimidineunder solvent-free condition with docking validation as Covid-19 main protease (Mpro) inhibitor 2021-05-08T03:25:41+00:00 A. M. Abdelghany T. K. Khatab A. S. Hassan <p>Copper-based oxide glass-ceramic was successfully synthesized through the single-step melt annealing technique. Synthesized glass-ceramics was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) supported with energy dispersive X-ray (EDX) and mapping. Pyrazolo[1,5-<em>a</em>]pyrimidines <strong>5a-f </strong>were synthesized <em>via</em> the reaction of 5-amino-1<em>H</em>-pyrazole-4-carboxamide (<strong>1</strong>) with enaminones <strong>2a-f </strong>in the presence of synthesized oxide glass-ceramic catalyst powder under solvent-free condition. The molecular docking study demonstrated that the COVID-19 main protease (M<sup>Pro</sup>) inhibitor.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: Pyrazolopyrimidine, Enaminones, Copper-based catalysis, Solvent-free, COVID-19</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 185-196.</p> <p>DOI: <a href=""></a></p> 2021-05-07T00:00:00+00:00 Copyright (c) Green synthesis of silver nanoclusters via Melia azedarach plant and their potential towards catalytic reduction of 4-nitrophenol 2021-05-08T03:29:59+00:00 F. Ahmad F. Nawaz M. Khan W. Munib S. W, Hassan M. Shah <p>Biomolecules present in the plant extracts have potential to reduce metal ions to nanoclusters by a single-step green synthesis approach. In the current study, we have synthesized the silver nanoclusters (AgNCs) from a medicinal plant, <em>Melia azedarach </em>and studied their catalytic activity toward the reduction of 4-nitophenol to 4-aminophenol and organic dyes. Morover, the phytochemical analysis of the plant extract was carried out in order to determine the bioactive compounds present in it. Metallic nature of the synthesized AgNCs was verified by X-ray diffraction study, while their morphology and size of was confirmed by transmission electron microscopy and Zetasizer, respectively. The study revealed that they were 56±2 nm in size and formed clusters. Fourier transformed infrared spectroscopy gives information about the different functional groups present in synthesized these NCs. Furthermore, the important catalytic applications, such as catalytic reduction of 4-nitrophenol in the presence of mild reducing agent NaBH<sub>4</sub> and the catalytic degradation of organic dyes was monitored by FTIR. Therefore, these results indicate that the obtained nanomaterials have important applications in industrial areas.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: Green synthesis, Silver nanoclusters, Catalytic reduction, Characterization</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 197-206.</p> <p>DOI: <a href=""></a></p> 2021-05-07T00:00:00+00:00 Copyright (c) NMR characterization and free radical scavenging activity of pheophytin ‘A’ from the leaves of Dissotis rotundifolia 2021-05-08T03:32:32+00:00 C. Friday O. UchennaIgwe U. C. Akwada <p><em>Dissotis rotundifolia</em> is used traditionally in various parts of Africa for the treatment of various ailments. The air dried and pulverized leaves of <em>Dissotis rotundifolia</em> was extracted with distilled n-hexane and ethylacetate, using Soxhlet apparatus. Isolation and purification were carried out using column and thin layer chromatographic techniques. Fraction B14 gave a single spot on thin layer chromatography with a retention factor (Rf) value of 0.57. Characterization of B14 was doneusing <sup>1</sup>H-NMR, <sup>13</sup>C-DEPT, COSY, HSQC, HMBC and by direct comparison with literature values and pheophytin A was proposed as the structure of the compound. Pheophytin A exhibited a free radical scavenging activity of 10.10±0.05 and 19.51±0.02% at minimum and maximum concentrations of 1.00 and 4.00 mg/mL, respectively. The acclaimed ethnomedicinal uses of <em>D. rotundifolia</em> by the African natives could be linked to the presence of pheophytin A and other phytoconstituents in the plant. This is the first report of the isolation of pheophytin A from<em> D. rotundifolia</em>.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>KEY WORDS</strong>: <em>Dissotis rotundifolia</em>, Pheophytin A, Chromatographic techniques, Free radicals, NMR</p> <p>&nbsp;</p> <p>Bull. Chem. Soc. Ethiop. <strong>2021</strong>, 35(1), 207-215.</p> <p>DOI: <a href=""></a></p> <p>&nbsp;</p> <p>&nbsp;</p> <p>&nbsp;</p> 2021-05-07T00:00:00+00:00 Copyright (c)