Bulletin of the Chemical Society of Ethiopia

Risk assessment of selected endocrine disrupting compounds in selected raw foodstuffs sold on open markets in Zambia

2025-04-15T09:54:07+00:00

The aim of this study was to assess the presence and quantity of selected organic endocrine disrupting compounds (phthalates, DDT (dichlorodiphenyltrichloroethane) metabolites and 4-nonylphenol) in the selected raw foodstuffs (fish and vegetables) sold in open markets and to carry out a health risk assessment of the EDCs. QuEChERS (Quick, Effective, Cheap, Efficient, Rugged and Safe) technique was optimized for extraction and GC-MS (gas chromatography-mass spectrometry) was used for identification and quantification. 4-Nonylphenol and DDT metabolites were not detected in all the samples. The mean levels of DMP (dimethyl phthalate) ranged from 91.05 to 101.76 μg/kg, 77.14 to 123.82 μg/kg, and 85.65 to 98.55 μg/kg for samples from Kitwe, Lusaka and Kabwe, respectively. The mean concentrations of DEP (diethyl phthalate) ranged from 21.46 to 80.69 μg/kg, 63.93 to 161.67 μg/kg and 23.22 to 46.01 μg/kg for samples from Kitwe, Lusaka and Kabwe, respectively. DMP was lowest in tomato in all the towns. DEP was generally higher in spinach. The health risk analysis of DMP and DEP gave the hazard index, HI < 1. Though the health risk parameters for DMP and DEP are within the safety margins, consumers’ safety can only be guaranteed after a comprehensive risk analysis of other EDCs.

KEY WORDS: Raw foodstuffs, Fish, Vegetables, QuECHERS, DDT, Phthalates

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1227-1244.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.1

Effervescent-assisted deep eutectic solvent-based dispersive liquid-liquid microextraction of Cr(VI) in aqueous samples

2025-04-15T09:59:19+00:00

Effervescent-assisted deep eutectic solvent-based dispersive liquid-liquid microextraction (EA-DES-DLLME) was developed for the selective extraction and preconcentration of Cr(VI) in water samples before its spectrophotometric determination. Before using the method, Cr(IV) ions present in the samples were complexed with 1,5-diphenylcarbazide (DPC) in an acidic medium. Experimental parameters that influenced the extraction efficiency of the method including sample pH, volume of DPC, type and volume of DES, type and concentration of effervescent agents, extraction time, stability of the complex, and selectivity were thoroughly investigated. Under optimal conditions, the method showed excellent linearity ranging from 50 to 3200 µg L⁻¹, with a coefficient of determination (R²) of 0.9991. The limits of detection and quantification (LOD and LOQ) of the method were 3 and 10 µg L⁻¹, respectively. Intra- and inter-day precision studies conducted at three concentration levels yielded relative standard deviation (RSD) values of ≤ 3.3 and 7.2, respectively. The method’s robustness, assessed at wavelengths of 535 to 545 nm had RSD < 4.3. The method provided an enrichment factor of 13.52 and recoveries between 81.1 and 111.2%. Overall, the developed method is applicable and selective for the determination of Cr(VI) in aqueous samples.

KEY WORDS: Cr(VI), Deep eutectic solvent, Dispersive liquid-liquid microextraction, 1,5-Diphenylcarbazide, Effervescence-assisted extraction, Water samples

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1245-1256.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.2

Formulation and quality evaluation of ready-to-drink coffee brew from date seed powder

2025-04-15T10:06:51+00:00

The aim of this research was to prepare ready-to-drink coffee from date seed powder and to evaluate the coffee drink during storage at 40 ℃. The proximate composition, physicochemical properties, total phenolic content, total flavonoid content, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the powder were determined. The total suspended solids (TSS) and pH of the ready to coffee drink decreased by increased the ADSP during 10 days of storage. Total phenolic content (TPC) ranged from 678.99-203.79 GE/100 g dry weight in different ready to coffee drink. The half-maximal inhibitory concentration (IC₅₀) at the beginning was (23.67 - 42.12 µg/mL) indicating that ready-to-drink coffee has a very strong antioxidant activity. Increasing the storage periods decreased the TSS. The lightness values (L*-value) increased with time values whereas a* (red/green value) and b*- (blue/yellow value) values decreased. Microbial studies revealed that the total viable count for coffee ranged from 8.84×10¹ to 5.07×10⁶ CFU/mL on the 8th day of storage. The sensory analysis indicated that the ready-to-drink coffee incorporated with 15% coffee brew was more acceptable than the others. This study suggests that date seeds can be considered a potential raw material for ready-to-drink coffee.

KEY WORDS: Agglomeration, Cold brewing, Solubility, Ready-to-drink coffee, Antioxidant activity

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1257-1272.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.3

Synthesis, spectral studies and antioxidant study of metal-coordinated azo-dye of pyridine and its analytical application for spectrophotometric micro-determination of copper(II)

2025-04-15T10:12:35+00:00

A novel azo dye ligand namely (2-(pyridin-3-yldiazenyl)naphthalen-1-ol (HPYNA), was synthesized by the coupling reaction of diazonium salt of 3-aminopyridine with naphthol. The palladium(II) complex for HPYNA ligand was prepared by reacting palladium(II) ions with the HPYNA ligand. These synthesized compounds were characterized using different techniques, including mass, ¹H-NMR, infrared, and UV-Vis spectroscopy. The infrared results show that the azo ligand reacts as a bidentate via the oxygen atom of phenol and nitrogen atom of the azo group. The palladium(II) complex is square-planer with diamagnetic properties depending on the results of electronic transitions and magnetic sensitivity. The HPYNA ligand and palladium complex showed significant activity as antioxidants by DPPH method. Trace levels of copper in synthetic urine sample can be successfully determined using the validated method. And finally, the proposed method showed selectivity, in addition to have high accuracy and control.

KEY WORDS: Azo dye, Naphthol, DPPH, Palladium(II) complex, Synthetic urine

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1273-1282.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.4

Malachite green adsorption from aqueous medium by chitosan assisted silver nanoparticles (AgNPs): Isotherm and thermodynamics studies

2025-04-15T10:16:59+00:00

The contamination of water by toxic, non-biodegradable dyes like malachite green (MG) presents serious environmental and health risks, demanding effective and sustainable removal strategies. This study explores the adsorption of MG from aqueous solutions using silver nanoparticles (AgNPs) as adsorbents. The synthesized AgNPs were characterized using FTIR, XRD, UV-Visible spectrophotometry, and SEM. XRD confirmed a face-centered cubic crystalline structure, while SEM images showed both spherical and irregular granular shapes. FTIR spectra displayed peaks between 1005 and 1646 cm⁻¹, indicating phosphonate bond formation between –NH₃⁺ groups of chitosan and –PO₃²⁻ moieties of sodium tripolyphosphate (NaTPP) during cross-linking. Adsorption experiments revealed that all tested factors significantly affected MG uptake by the AgNPs, demonstrating their potential for effective dye removal from aqueous environments. AgNPs effectively remove MG in acidic conditions of pH of 4.7, contact time of 80 min, and temperature of 45 °C, indicating that electrostatic interactions primarily drive. The adsorption models were best described by Tempkin isotherms. The findings suggest that AgNPs are promising adsorbents for MG removal from aqueous environments.

KEY WORDS: Malachite green (MG), Silver nanoparticles (AgNPs), Sodium tripolyphosphate, Adsorption, Cross-linking, Electrostatics attraction

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1283-1299.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.5

Copper(I) and zinc(II) complexes containing 4-methoxybenz- aldehyde thiosemi- carbazone and triphenylphosphine ligands, synthesis, characterization, and theoretical studies

2025-04-15T10:25:32+00:00

A new thioamide ligand, 4-methoxybenzaldehyde thiosemicarbazone (L), containing sulfur, nitrogen, and oxygen atoms, was synthesized via condensation of 4-methoxybenzaldehyde with thiosemicarbazide. New tetrahedral copper(I) and zinc(II) complexes of the prepared ligand and triphenylphosphine (Ph₃P) as a co-ligand have been synthesized. The ligand and its complexes were characterized by magnetic susceptibility, elemental analysis, molar conductivity, FT-IR, UV-Vis, and ¹H, ¹³C, ³¹P-NMR techniques. The FT-IR spectra indicated that the (L) ligand coordinates with the metal ions through sulfur and nitrogen atoms, forming a five-membered chelate ring. Elemental analysis and ¹H-NMR spectroscopy confirmed the mononuclear structure of complexes 2, 3, and 4, while complex 1 exhibited a dinuclear configuration. DFT calculations indicated that the synthesized complexes are less thermodynamically stable than the free ligands, with ΔE values of 2.6776 eV, 2.9699 eV, 2.8912 eV, and 0.4996 eV for complexes 1, 2, 3, and 4, respectively. Among the complexes, complex 4 (S = 4.0032 eV) exhibited the highest softness, and all complexes were found to be softer compared to the free ligand. In this study, the results suggest that electron transitions in complexes are easier than in free ligands, which suggest their potential use in photocell technologies in the future.

KEY WORDS: Thioamide, Cu(I) complexes, Zn(II) complexes, NBO analysis, DFT calculations

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1301-1316.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.6

Synthesis, characterization and evaluation of anticancer and antioxidant activity of new azo dye derivatives from tryptamine and complexes

2025-04-15T10:30:33+00:00

This new azo dye 3-((2-(1H-indol-3-yl) ethyl) diazenyl) quinoline-2-ol was subsequently used to prepare a series of complexes with the metal ions of Cr⁺³, Cu⁺², VO⁺², Mn⁺²and Mo⁺⁶. The compounds identified by ¹H and ¹³C-NMR, FT-IR, UV-Vis, mass spectroscopy, as well as TGA, DSC, and C.H.N., conductivity, magnetic susceptibility, metal and chlorine content. The results showed that the ligand behaves in a bidantate, and that the complexes gave octahedral, excepting for VO⁺² square pyramid was given, that all complexes are non-electrolytes. The effectiveness of mention the compounds in inhibiting free radicals was evaluated by the ability to act as an antioxidant was measured using DPPH as a free radical and gallic acid as a standard substance, the IC₅₀ value was determined, because the ligand was found to have a higher ability to inhibit free radicals, and the ability to inhibit the complexes varied according to the IC₅₀ value. The anti-breast cancer efficacy of the compounds was evaluated at five concentrations each, the results showed that the IC₅₀ value for ligand was 49.86 µg/mL, while the Mo complex gave 25.48 µg/mL, Cu complex gave 123.8 µg/mL, meaning that the Mo-complex gave a higher inhibition value than ligand and Cu.

KEY WORDS: Antioxidant (DPPH), Azo dye complexes, Tryptamine, Thermal analysis, Anticancer

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1317-1334.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.7

Synthesis and characterization of gallic acid complexes with cobalt(II), nickel(II), and copper(II) ions: Spectral analysis, x-ray structures, and microscopic imaging

2025-04-15T10:33:39+00:00

This study examines the synthesis, characterization, thermal stability, and microscopic analysis of gallic acid (abbreviated as GA) complexes formed with three transition metal ions: Co(II), Ni(II), and Cu(II). The researchers carried out a multi-step process, beginning with a series of chemical reactions between GA, acting as an organic ligand, and the respective metal ions. These reactions were conducted at a temperature of 65 °C and a pH of approximately 8, with a molar ratio of 2:1 between the GA ligand and the metal ion. The resulting products were referred to as the GA-Co complex, the GA-Ni complex, and the GA-Cu complex. Various physicochemical techniques were employed to thoroughly understand the structural, compositional, morphological, and thermal properties of the generated GA-Co, GA-Ni, and GA-Cu complexes, contributing to the field's knowledge. The synthesized complexes with Co(II), Ni(II), and Cu(II) ions have formulae of (NH₄)₂[Co(NH₄HL)₂(H₂O)₂].4H₂O, (NH₄)₂[Ni(NH₄HL)₂(H₂O)₂].6H₂O, and (NH₄)₂[Cu(NH₄HL)₂(H₂O)₂].5H₂O, respectively. The complexation of the GA ligand with metal ions altered the microstructural features of the pristine ligand, as observed in the TEM images, indicating that the complexation significantly affected the microstructure of the synthesized materials.

KEY WORDS: Gallic acid, Metal ions, Spectroscopic techniques, Thermal decomposition, TEM

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1335-1348.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.8

Synthesis and characterization of a number of complexes of Pt(II), Pd(II), Cd(II) and Zn(II) with new ligands containing oxygen

2025-04-15T10:37:26+00:00

New mononuclear complexes of some transition metal ion with di-dentate ligand have been synthetized and characterized. The Pt(II), Pd(II), Cd(II) and Zn(II) complexes were synthesized by directly reaction of the above ligand with metal chlorides in (1:1) (ligand:metal) molar ratio in ethanolic medium. Formulated complexes classified by elementary analysis, spectral exploration (FTIR, UV/Vis), ¹H-NMR measure, conduction measure and electronic spectra rates suggest tetrahedral geometric for every metal complex, with the exception of Pt(II) complexes, which have octahedral geometry, and Pd(II) compound, which have square planar geometry and the study of inhibiting effect on the growth of different types of bacteria which are strains staph. aurous and Klebsiella pneumoniae. The results indicate that all complexes have strong effect on different types of bacteria.

KEY WORDS: Dicarboxlate, Direct reaction, Tetrahedral geometry, Ligand, Mononuclear, Complexes

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1349-1361.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.9

Thermal, morphological, and DFT studies on the scandium(III) sulfa drugs complexes

2025-04-15T10:40:37+00:00

Four scandium(III) sulfa drug complexes were studied based on thermal, kinetic, morphological and computational investigations. The isolated solid complexes were synthesized by 1:2 molar ratios between scandium(III) chloride and four kinds of sulfa drugs; sulf-1 = sulfadimidine (1), sulf-2 = sulfanilamide (2), sulf-3 = sulfamethoxazole (3) and sulf-4 = sulfadiazine (4). The molecular formulae for the isolated complexes are [Sc(sulf-1)₂(Cl)₂]Cl (5), [Sc(sulf-2)₂(Cl)₂]Cl (6), [Sc(sulf-3)₂(Cl)₂]Cl (7) and [Sc(sulf-4)₂(Cl)₂]Cl (8). TGA thermograms for complexes (5-8) were utilized to study the different degradation steps. Moreover, the kinetic and thermodynamic functions have been calculated based on the data speculated for compounds (5-8). The surface morphology of (5-8) was studied by scanning electron microscopy (SEM). The compounds (5-8) exhibit favorable crystallinity, as X-ray powder diffraction (XRD) confirmed. The nano-scale of the samples was confirmed by the transmission electron microscopy (TEM) images. Furthermore, the DFT calculations for (1-8) were performed. The bond lengths for (5-8) are reduced or increased rather than that of free drug molecules due to complexation. Bond angles of compounds (5-8) predict the octahedral geometry (Oh) of Sc(III). The calculated vibrational spectra for compounds (5-8) were compared to the experimental IR, which may give quite differences attributed to different phases of measurement.

KEY WORDS: Scandium, Sulfa-drugs, TGA, SEM, TEM, DFT, Coats-redfern, Complexes, Nano-particles

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1363-1380.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.10

Mesomorphic and themochmical behavior of a Cu(II)-cyclam ionic liquid: A novel approach to metallomesogens

2025-04-15T10:44:22+00:00

The metalomesogenic compounds exhibit captivating optical, magnetic, and electrical characteristics makes promising candidates for diverse applications in the fields of display devices, sensors, and molecular electronics. In this study, we focused on synthesizing the dark-purple powder of metallomesogen [Cu(Cy)(L)₂](X)₂.2H₂O, where Cy represents cyclam (1,4,8,11-tetraazacyclotetradecane), X is 4-BrC₆H₄COO-, and L is 4-Hexadecyloxypyridiene. The synthesis process involved four distinct steps. Differential scanning calorimetry (DSC) analysis revealed phase transitions at 42.3 °C (crystal-to-mesophase), 81.3 °C (mesophase-to-mesophase), and 111.7 °C (mesophase-to-isotropic liquid). Polarized optical microscopy (POM) confirmed the formation of characteristic optical textures upon cooling, indicative of a stable mesophase at 78.0 °C. The magnetic susceptibility measurements showed a magnetic moment of 1.7 Bohr magnetons, consistent with a mononuclear copper complex in a distorted octahedral geometry. These findings demonstrate the potential of this metallomesogen for applications in advanced display devices and sensors.

KEY WORDS: Metallomesogens, Ionic liquid, Cyclam, 4-Hexadecyloxypyridiene, Copper

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1381-1394.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.11

Synthesis, characterization, and computational analysis of chromium trioxide and amino acid-derived metal complexes

2025-04-15T10:48:32+00:00

This study focused on the preparation and characterization of six metal-based complexes, synthesized through the reaction of chromium trioxide (CrO₃) with a range of different amino acids in a methanol solvent. The amino acids investigated included glycine (Gly), L-alanine (Ala), L-serine (Ser), L-proline (Pro), L-cysteine (Cys), and S-methyl-L-cysteine (MeCys). The synthesis procedure of the CrO₃-Amino acid complexes involved several steps: preparation of individual methanolic solutions of amino acids, addition of CrO₃ solution, refluxing at approximately 65 °C for 3 hours, precipitation, separation, and purification of the final CrO₃-Amino acid complexes. Infrared (FTIR) analysis suggested that the amino acids captured CrO₃ through both amino and carboxylate groups. Thermal analysis offered insights into the two-stage degradation process of the synthesized CrO₃-Amino acid complexes. Finally, the synthesized CrO₃-Amino acid complexes were computationally analyzed, encompassing geometry optimization and energy parameter calculations using the density functional theory (DFT) method. The total energy calculations reveal that the synthesized CrO₃-Amino acid complexes are more stable and have lower total energy compared to their corresponding free amino acids, suggesting the formation of more stable complexes.

KEY WORDS: Metal complexes, Amino acids, CrO₃, Thermal decomposition, Computational calculations, Geometry optimization

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1395-1410.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.12

Synthesis, characterization, antimicrobial, antioxidant activities, and in silico study of new azo disperse dyes containing pyrazole and pyrazolo[1,5-a]pyrimidine rings

2025-04-15T10:53:04+00:00

New N,N-dimethyl-N'-(5-oxo-4-(aryldiazenyl)-2,5-dihydro-1H-pyrazol-3-yl)formimidamide 5a-c are formed by reaction of 5-amino-1H-pyrazol-3(2H)-one derivatives 4a-c with N,N-dimethylformamide dimethyl acetal (DMF-DMA). Compounds 5a-c serve as excellent precursors for the synthesis of new disazo pyrazole disperse dyes, When refluxed with hydrazine hydrate or active methylene reagents 8a,b, leading to N''-(3-hydroxy-4-(arylaza)-1H-pyrazol-5-yl)formimidohydrazide 7a-c or pyrazolo[1,5-a]. pyrimidines 11a–e. In vitro studies were carried out to evaluate antioxidant properties of the produced compounds in comparison to standard, BHT. The results indicated that all the compounds exhibited varying levels of antioxidant activity at different doses. Compound (7b) exhibited an IC50 value comparable to that of BHT, while the other compounds demonstrated varying levels of activity and IC50 values in comparison to BHT. Regarding antimicrobial activity, compounds 7a, 7b and 11c exhibited antibacterial efficiency against Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis with inhibition zone diameters of 14.33, 12.33, and 12.33 mm, respectively. In silico study of eleven pyrazole compounds with S. aureus 2XCT demonstrated strong hydrogen bonds, short distance interactions, and the highest binding energies were displayed by compounds 5b and 11a with binding energy of -6.6 and -6.2 kcal/mol, respectively.

KEY WORDS: Pyrazoles, DMFDMA, Antimicrobial, Antioxidant, Molecular docking, Disperse dyes, Pyrazolo[1,5-a]pyrimidines

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1411-1424.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.13

Preferential solvation of difenoconazole in binary solvent mixtures of methanol and ethanol in water at several temperatures

2025-04-15T10:59:31+00:00

The present investigation used the inverse Kirkwood-Buff integrals technique to determine the best solvation parameters for DIF in two distinct alcoholic aqueous solutions, spanning a temperature range from 293.15 K to 323.15 K. The analysis demonstrated that the values of displayed a nonlinear trend concerning the composition of the co-solvent. The solvation parameters ( ) for DIF in various aqueous solutions revealed nonlinear variations that were contingent upon the concentration of the co-solvent. Notably, positive values were recorded in mixtures with all compositions for methanol and 0.00 < x₁< 0.33-0.35 and 0.50 < x₁< 1.00 for ethanol. Conversely, DIF demonstrates a preference for alcohol as the solvent in aqueous mixtures. At 323.15 K, the methanol (1) + water (2) mixtures show the highest preferential solvation of DIF by alcohol, while the ethanol (1) + water (2) mixtures exhibit the lowest.

KEY WORDS: Difenoconazole, Binary solvents, Inverse Kirkwood–Buff integrals, Preferential solvation

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1425-1435.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.14

Charge-transfer complexes formed between 1-hydroxybenzotriazole versus iodine and picric acid electron acceptors: electronic, infrared and morphological characterizations

2025-04-15T11:01:50+00:00

A charge-transfer process between an electron-rich and an electron-deficient component creates molecular assemblies, which have several uses in a variety of electronic, optical, sensor, and catalysis fields. Therefore, this study was focused on getting some knowledge about the intermolecular charge transfer complexes between the 1-hydroxybenzotriazole (HBT) with picric acid (PA) and iodine (I₂) as π and σ acceptors. The charge-transfer interaction of the HBT electron donor and the PA acceptor has been studied in methanol solvent. The resulting data referred to the formation of the new CT-complex with the general formula [(HBT)(PA)]. The 1:1 stoichiometry of the reaction was discussed upon the on elemental analysis and photometric titration. On the other hand, the 1:1 HBT-iodine (I₂) charge-transfer complex has been studied spectrophotometrically in chloroform at room temperature with general formula [(HBT)(I₂)]. The electronic absorption bands of (I₂) are observed at ~ 510 nm. Raman laser spectrum of the brown solid iodine complex has two clear vibration bands at 165 and 113 cm^-1 due to I₂ stretching frequency, respectively. The scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) of two HBT charge-transfer complexes were discussed.

KEY WORDS: Benzotriazole, Charge transfer, Electron acceptors, Spectroscopic, Morphology

Bull. Chem. Soc. Ethiop. 2025, 39(7), 1437-1450.

DOI: https://dx.doi.org/10.4314/bcse.v39i7.15