ABSTRACT. In this study, the attempts were made to isolate secondary metabolites from the solvent extract of the dried leaves of Premna schimperi (P. schimperi). Thus, six compounds, namely, ent-8b,12-epidioxy-12b-hydroxylabda-9(11),13-dien-15-oic acid-g-lactone (1), 3,5,5'-trihydroxy-6,7,3',4'-tetramethoxyflavone (2) and 3,5,7,5'-tetrahydroxy-6,3',4'-trimethoxyflavone (3), p-hydroxycinnamic acid (4), luteolin (5) and 1-nonacosanol (6) were isolated and characterized by NMR, UV-Vis, MS and FTIR spectroscopic techniques. All the compounds; except luteolin (5) were reported for the first time from the leaves of P. schimperi. In addition, the GC-MS analysis of the essential oil of the plant leaves revealed 47 compounds, of which a-curcumene (16.38%), caryophyllene (10.73%), eugenol (6.85%), b-sesquiphellandrene (4.65%), g-gurjunene (4.55%), terpinen-4-ol (2.9%), g-eudesmol (4.43%), linalool (2.2%) and caryophyllene oxide (2.67%) were the major compounds. Furthermore, assessment of the antioxidant activities of the MeOH extract and compound 1 using the DPPH assay revealed 95.3% and 62.2% DPPH inhibition, respectively, at concentration of 100 μg/mL.
  KEY WORDS: P. schimperi, GC-MS, DPPH radical scavenging assay, Antioxidant activity, Acetylation
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1471-1486.DOI: https://dx.doi.org/10.4314/bcse.v37i6.14
  

ABSTRACT. An azo quinoline ligand, (E)-2-((4-iodophenyl)diazenyl)-8-hydroxyquinoline (IPDHQ), was synthesized by the coupling reaction of 4-iodoaniline diazonium salt with 8-hydroxyquinoline. The synthesized ligand and its Cd(II), Pd(II), Cu(II) and Hg(II) complexes were spectrally characterized by UV‒Vis spectrophotometry, FT-IR, mass spectral analysis, 1H-NMR, magnetic sensitivity and molar conductivity. The general formula of the Cd(II), Cu(II) and Hg(II) complexes is [M(L)2].Cl2.H2O with octahedral geometry, while the general formula of the Pd(II) complex is [M(L).Cl2].H2O with square planer geometry. A simple and rapid spectrophotometric procedure was suggested for the determination of Hg(II) using the synthesized ligand as a spectrophotometric reagent. By measuring the absorbance for the resulting orange complex at 430 nm, the linearity range was 0.5-15 µg mL-1, and the interfering effect was also studied. The synthesized azo ligand and its Hg(Ⅱ) complex were tested for their biological activity against four bacterial strains.
 KEY WORDS: Azo quinoline ligand, 8-Hydroxy quinoline, 4-Iodoaniline, Azo metal complexes, Spectrophotometric determination, Biological efficacy study
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1459-1470. DOI: https://dx.doi.org/10.4314/bcse.v37i6.13

ABSTRACT. 4-Sulfosalicylic acid (SSA) was used as a ligand to prepare new triphenyltin and dimethyl-tin complexes by condensation with the corresponding organotin chloride salts. The complexes were identified by different techniques, such as infrared spectra (tin and proton), magnetic resonance, and elemental analyses. The 119Sn-NMR was studied to determine the prepared complexes' geometrical shape. Two methods examined the antioxidant activity of (SSA) and prepared complexes; Free radical scavenging activity (DPPH) and CUPRRAC methods. Tri and di-tin complexes gave high percentage inhibition than ligands with both methods due to tin moiety; the triphenyltin carboxylate complex was the best compared with the others. Also, antibacterial activity was assessed by using the agar ditch method against (Escherichia coli) and (Staphylococcus aureus) bacteria. The complexes gave high activity in inhibition than the ligand derived. Also Triphenyltin carboxylate complex showed higher antibacterial activity than the dimethyltin complex against two types of bacteria (Escherichia coli) and (Staphylococcus aureus).
 KEY WORDS: Antioxidant activity, Antibacterial activity, Sulfosalicylic acid, Tri phenyl tin chloride, Escherichia coli, Staphylococcus aureus bacteria
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1435-1442. DOI: https://dx.doi.org/10.4314/bcse.v37i6.11

ABSTRACT. The transportation of minerals/ores in form of slurry through pipelines is an alternative, effective and also eco-friendly mode of transportation. Surfactants extracted from the plant sources are gaining high interest for the formulation and stabilization of high concentrated solid-water slurries. In this work, the role of a novel bio-surfactant extracted from Colocasia esculenta (L.) Schott on the stabilisation of iron ore slurry (IOS) was studied and reported first time. The collected iron ore powder (IOP) and dried IOS samples were analysed with the help of XRF, XRD, SEM and EDS analysis. The results confirmed that the surfactant molecules (present in aqueous Colocasia esculenta (L.) Schott) coated well on iron surface and forms an effective barrier between the iron ore (IO) particles. The studied rheological parameters for the slurry indicated non-Newtonian flow behaviour.
 KEY WORDS: Iron ore slurry, Colocasia esculenta (L.) Schott, XRD, SEM, rheological measurements
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1459-1470. DOI: https://dx.doi.org/10.4314/bcse.v37i6.13

ABSTRACT. Two mixed-ligand complexes of Ru(III) ions were synthesized and used to generate nanostructured RuO2 oxide. Complex A contains gatifloxacin (L1), the amino acid glycine (L2), and Ru(III) ions in a 1:1:1 ratio. Complex B contains gatifloxacin (L1), the amino acid alanine (L3), and Ru(III) ions in a 1:1:1 ratio. The synthesized complexes were characterized using UV-Visible and IR spectroscopies, molar conductance, elemental analyses, thermogravimetry, XRD, and SEM-EDX techniques. In both complexes, the L1 ligand acts as a bidentate and uses the nitrogen atoms of the piperazine ring to capture the Ru(III) ions, while the L2 and L3 ligands capture the Ru(III) ions using their oxygen atom of the carboxylate group and the nitrogen atom of the amino group. The atmosphere around the Ru(III) ion is octahedral, and the complexes were formulated as [RuL1L2(H2O)2]Cl2 and [RuL1L3(H2O)2]Cl2 for Complex A and Complex B, respectively. Complex A was directly decomposed in air at 600 °C for 3 h to produce RuO2 oxide (Oxide A), and complex B was decomposed under the same conditions to produce RuO2 oxide (Oxide B). Morphologically, oxide A and oxide B have a coral reef-like texture with large holes and cavities.
 KEY WORDS: Gatifloxacin, Ru(III) ion, Glycine, Alanine, Morphology, RuO2 oxide
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1443-1457. DOI: https://dx.doi.org/10.4314/bcse.v37i6.12

ABSTRACT. This research presents the efficiency of surfactant-modified (SMNZ) and unmodified natural-zeolite (UNZ) in the immobilization of Cr3+, Pb2+, and Cd2+ in the soil system. Phillipsite is identified as a major component of the host zeolite. Soil mixed with 20% UNZ retained the highest amount of all metals on the top layer of the soil-zeolite column. The lowest transfer of metals into the maize crop was observed at 30 mg of UNZ/kg soil. The experimental conditions such as pH, dose, stirring speed, contact time, and initial metal ions concentration showed significant effect on adsorption of Cr3+, Pb2+, and Cd2+ onto both unmodified and modified zeolite (phillipsite). The maximum adsorption (mg/kg) onto control soil, soil mixed with SMNZ and UNZ was 67.1, 90.9, 151.5 for Cr3+, 84.8, 120.5, 238.1 for Pb2+, 83.3, 116.3 and 212.8 for Cd2+ respectively. Thus, the use of natural zeolite, particularly UNZ has an important role in controlling the mobility of Cr3+, Pb2+, and Cd2+ metal ions in the soil system and thus their transfer to plant system.
 KEY WORDS: Zeolite, Immobilization, Heavy metals, Column, Pot trial, Batch
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1351-1368. DOI: https://dx.doi.org/10.4314/bcse.v37i6.5

ABSTRACT. In the current study, a novel visible light-active photocatalyst CuS/TiO2 nanocomposite was synthesized by a template-free hydrothermal method. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of synthesized nanocomposites and the structural characteristics of synthesized nanoparticles were characterized and confirmed by the X-ray diffraction (XRD) technique. The morphology and particle size of synthesized nanocomposites were measured by a field emission scanning electron microscope (FESEM), which revealed an average particle size of around 30 nm. The optimized efficiency of the fabricated photocatalyst was assessed for the photodegradation of rhodamine B (RhB) dye. It was observed that the photodegradation efficiency of CuS/TiO2-Y composites having a molar ratio of 1:1 for RhB was found to be 89.54% under visible light irradiation.
 KEY WORDS: CuS/TiO2 nanocomposite, Heterojunction structure, Rhodamine B, Photodegradation, Visible light irradiation
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1553-1564. DOI: https://dx.doi.org/10.4314/bcse.v37i6.19

ABSTRACT. In this study, the concentration and risk of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in 9 composite samples around the vicinity of an Asphalt plant in North Central, Nigeria, was evaluated. Aqua-regia wet digestion was used for heavy metals extraction in the water samples while atomic absorption spectrometry was used quantification. For PAHs, liquid-liquid extraction was used for extraction while gas chromatography-mass spectrometry was used for quantification of PAHs in the extracts. The risk assessment was estimated using the hazard index (HI) and incremental lifetime cancer risk (ILCR) in all the samples studied. The results showed that Cd and Cr were present in concentrations higher than their permissible limits in water set by World Health Organization, while Pb was not detected. Total concentration of 14 PAHs ranged between 6.47–390 mg L-1 and were within the WHO permissible limits. High molecular weight PAHs were dominant (71.54%) relative to low molecular weight PAHs (28.46%). The risk assessment results revealed that 100% ILCRtotal values recorded for heavy metals were higher than the recommended limit. While 37.5% of ILCRtotal values recorded for PAHs were higher than the recommended values, implying that residents are exposed to health risks from both metals and PAHs.
 KEY WORDS: Asphalt plant, Heavy metals, Polycyclic aromatic hydrocarbons,Water, Risk assessment
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1337-1349. DOI: https://dx.doi.org/10.4314/bcse.v37i6.4

ABSTRACT. 4-Tert-butylbenzohydrazone ligand was synthesised by reacting 4-tert-butylbenzohydrazide with dehydroacetic acid. Afterward, the Cu(II), Ni(II), Co(II), and Mn(II) complexes of 4-tert-butylbenzohydrazone were synthesised. All the synthesised compounds were characterised using elemental analysis, ESI-MS, IR, 1H-NMR and 13C-NMR spectroscopic methods. ESI-MS studies revealed ligand to metal stoichiometry of 1:1 for the Cu(II) complex, 2:1 for the Ni(II), Co(II), and Mn(II) complexes. IR studies showed that the ligand was coordinated to the metal ions through ONO donor atoms. The 1H NMR revealed that deprotonation did not occur in the ligand. Thus, the hydroxyl oxygen and the secondary amine nitrogen did not participate in the coordination. The proposed structures of the compounds conform with the analytical results.
 KEY WORDS: 4-Tert-butylbenzohydrazone, Metal complexes, Structure, Elucidation
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1411-1422. DOI: https://dx.doi.org/10.4314/bcse.v37i6.9
  

ABSTRACT. In this study, for the detection of taurine in philological fluids, modified electrodes were prepared from glassy carbon electrodes with MWCNT (multi-wall carbon nanotube) + Cu(NO3)2  + carbon-based material. A carbon-based material was obtained by carbonization of Pinus sylvestris branch needles (CPS). Cu(NO3)2  and MWCNT structure (Cu(NO3)2/MWCNT) were added to the carbon-based material and the obtained mixture was used in the modification of the glassy carbon electrode surface. The surface morphology and structure of the prepared electrodes were characterized by electron microscopy scanning (SEM) and atomic force microscopy (AFM). Taurine detection with a modified electrode was made by cyclic voltammetry (CV) in 0.1 M KCl (vs. Ag/AgCl). The calibration curve of the modified electrode for taurine in the 10-150 µM range showed a linear response, and R2 value was 0.976. Limit of detection (LOD) and limit of quantification (LOQ) of the modified electrode were found 19 µM and 9.75 µM, respectively. The application of the electrode as a chemical sensor was carried out with commercially available energy drink samples. Satisfactory results have been obtained from the samples. The sensor can be used for routine taurine analysis. This electrode can quickly determine the amount of taurine in real samples with 90% accuracy in two minutes.
 KEY WORDS: Taurine detection, Modified electrode, MWCNT, Sensor, Cyclic voltammetry
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1565-1576. DOI: https://dx.doi.org/10.4314/bcse.v37i6.20