Bulletin of the Chemical Society of Ethiopia

A new method for determining isoniazid drug by flow injection analysis with a merging zone technique

2025-01-22T09:24:01+00:00

This study investigated the designing of a simple and rapid flow injection (FI) system and the determination of Isoniazid in a prepared aqueous solution. The principle of the method depended on the indirect reaction of the isoniazid drug with copper(II)-neocuproine (Cu(II)-NCPR) complex after acidifying the aqueous medium. The yellow-orange and charge transfer complex had maximum absorption at 455 nm. The optimum conditions of the FIA were studied. The calibration graph of isoniazid was constructed with a linear range of 0.10 to 10.00 mg/L, and a linearity (r²) value of 0.9988. The detection and quantification limits were 0.073 and 0.221 mg/L, respectively. The molar absorptivity (ε) was 56.68×10⁴ L/mol.cm and Sandell's sensitivity was 0.84 ×10^-3 µg/cm. The manufactured local valve was characterized by inexpensive, easily running, high repeatability (n = 6) at an RSD of 2.18%, and the dead volume was zero. The dispersion coefficient values were 1.91, and 1.53 for both concentrations of 0.60, and 4.00 mg/L, respectively. The sampling rate of the analysis for the FIA system was 63.00 samples per hour. The proposed analytical flow injection method was successfully applied to standard aqueous solutions and tablets of isoniazid.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 601-613.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.1

Derivative spectrophotometric determination of quinine, adenine and metoclopramide hydrochloride in their binary mixture using zero–crossing technique

2025-01-22T09:29:44+00:00

A first–derivative spectrophotometric procedure has been applied for the simultaneous quantification of quinine–adenine or quinine–metoclopramide hydrochloride in their mixes using “zero–crossing” measuring approach. The first–derivative spectra of quinine and adenine allowed the determination of quinine (1.5–17.9 µg/mL) in the presence of 4.3 µg/mL of adenine, and adenine (5.4–27.0 µg/mL) in presence of 9.0 µg/mL of quinine. In the binary mixture of quinine–metoclopramide hydrochloride, the first–derivative spectra of quinine and metoclopramide hydrochloride allowed the determination of quinine (11.95–95.62 µg/mL) in presence of 5.4 µg/mL of metoclopramide hydrochloride, and metoclopramide hydrochloride (1.34–21.52 µg/mL) in existence of 29.88 µg/mL of quinine. A statistical scrutiny of the provided practical data was used to perform a critical assessment of the recommended approaches.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 615-628.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.2

Vitamin C content and antioxidant activity of eight selected vegetables widely consumed in Addis Ababa, Ethiopia

2025-01-22T09:35:45+00:00

The objectives of the study were to determine vitamin C content using iodometric titration and its antioxidant activity as a DPPH assay by UV−Vis spectrophotometric method in eight shade-dried vegetables purchased from Addis Ababa in open markets. The linear range of standard vitamin C was in the range 3.2–52 mg/L with a correlation coefficient of R² = 0.994. The vitamin C content was found in the increasing order in eggplant 6.83 mg/100 g < carrot 11.05 mg/100 g < beetroot 15.32 mg/100 g < Swisschard 16.22 mg/100 g < cauliflower 17 mg/100 g < lettuce 21 mg/100 g < cabbage 32.49 mg/100 g < green chili 49.18 mg/100 g. The percentage recoveries of vitamin C in the vegetables ranged from 95.61 to 102.4%, indicating its good reliability. The antioxidant activity of eight vegetables was increasing, namely in eggplant 12.48 mg/100 g < carrot 30.55 mg/100 g < beetroot 30.55 mg/100 g < cauliflower 42.98 mg/100 g < Swisschard 44.57 mg/100 g < lettuce 63.48 mg/100 g < cabbage 100.9 mg/100 g < green chili 106.8 mg/100 g. The results also revealed a strong correlation (R² = 0.9508) between vitamin C contents in the vegetables and their antioxidant activities.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 629-641.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.3

Investigating the comparative adsorption of methyl orange and methyl green on commercial bentonite

2025-01-22T09:39:27+00:00

This paper presents the utilization of commercial bentonite obtained from Biochem Chemopharma Company, in France, as an adsorbent for the anionic dye methyl orange (MO) and cationic dye methyl green (MG) in aqueous solutions. The material was analyzed using X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Nitrogen adsorption at 77 K and thermogravimetric analysis (TGA) were performed for characterization. The study evaluated the impact of various experimental parameters such as contact time, solution pH, adsorbent dose, initial dye concentration, and temperature. Batch adsorption studies revealed that MO exhibited a maximum of 90 mg/g in an acidic medium, with an equilibrium time of 20 min and an adsorbent dosage of 1 g/L. On the other hand, MG demonstrated maximum adsorption of 165 mg/g in a natural medium, with an equilibrium time of 5 minutes and an adsorbent dose of 0.6 g/L. The adsorption of MO followed a pseudo-first-order kinetic model and the isotherms were well-fitted by the Freundlich model for MO and both Freundlich and Langmuir models for MG. Thermodynamic analysis indicated an exothermic, spontaneous, and physical adsorption process. Lastly, the adsorption performance of commercial bentonite for MO was compared with that of MG.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 643-657.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.4

New oxomolybdenum(IV) complexes with adducted monodentate ligands, spectroscopic characterization, DFT calculations, biological and antioxidant activity

2025-01-22T09:43:46+00:00

Oxomolybdenum(IV) complexes with chemical formula [MoO(ATP)(DIAB)(AMP)] (C1), [MoO(ATP)(DIAB)(Atri)] (C2), [MoO(ATP)(HNQ)(AMP)] (C3) and [MoO(ATP)(HNQ)(Atri)] (C4) have been synthesized and studied using different spectral methods, including atomic absorption, FTIR, UV-Vis., mass spectroscopy, magnetic sensitivity, electrical conductivity, and C.H.N.S. analysis. The ligands were 2-aminothiophenol (ATP), 3,4-diaminobenzoic acid (DIAB), 2-hydroxy-1,4-naphthoquinone (HNQ), 6-amino-2-methylpyridin (AMP), and 3-amino-1,2,4-triazole (Atri). The FTIR spectra confirm (DIAB, AMP, and Atri) were coordinated by amine nitrogen, whereas the (HNQ) ligand was by oxygen, and the (ATP) by nitrogen and sulfur atoms. The υ(S-H) band vanished in comparison to the (ATP) ligand, this demonstrates how Mo(IV) and the sulfur atom. The (HNQ) ligand's oxygen atoms work in tandem with the Mo(IV). Mo(IV) complexes with d² are paramagnetic. All complexes have been suggested to have an octahedral structure based on computed and experimental evidences. Two Gram-positive and two Gram-negative bacteria were used to test the (ATP) ligand and the produced complexes' activity. The complexes showed an expanded zone of inhibition, indicating that they were more lipophilic than the free (ATP) ligand. Finally, the antioxidant activity of the complexes was tested, and the result showed the following order: Gallic acid ˃ C3 ˃ C2 ˃ C4 ˃ C1 in 60 min.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 659-672.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.5

New (2Z)-1-(2,4-dinitrophenyl)-2-[(2E)-3-(2-nitrophenyl)prop-2-en-1-ylidene]hydrazine and its V(II) and Ni(II) complexes: synthesis, characterization and in silico sars-CoV-2 inhibition studies

2025-01-22T09:47:59+00:00

Hydrazones are an important family of compounds with an azomethine proton (-NHN=CH-), which have been reported to possess high biological activity such as antioxidants, anti-consultants, analgesics, antimicrobial, anti-protozoals, anti-parasitic, anti-platelets, cardio-protective, anti-diabetic, anti-HIV and anti-helminthic. This research was aimed at synthesizing a new aniline hydrazone and its V(II) and Ni(II) complexes, and in silico SARS-CoV-2 inhibition studies. The (2Z)-1-(2,4-dinitrophenyl)-2-[(2E)-3-(2-nitrophenyl)prop-2-en-1-ylidene]hydrazine (DNEAA) was synthesized by the reaction of 2,4-dinitrophenylhydrazine and 3-(2-nitrophenyl)prop-2-enal. DNEAA and its V(II) and Ni(II) complexes were synthesized and characterized by UV-visible, FTIR, and NMR spectroscopy. Molecular docking was performed using Auto Dock Vina software. Spectroscopic analysis suggested that DNEAA coordinated with the metal ions through azomethine nitrogen, NH, two NO₂ and two Cl^-. An octahedral geometry was proposed for the metal complexes. The ability of DNEAA to chelate V(II) and Ni(II) is hereby assured. Molecular docking results gave binding energies >9.5 kcal/mol. Following these findings, it is recommended that biological studies and preclinical and clinical trials against SARS-CoV-2 protease be carried out.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 673-686.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.6

Synthesis, characterization, DFT, molecular docking, and in vitro screening of metal chelates incorporating Schiff base

2025-01-22T09:57:00+00:00

The new complexes were formed by reacting Mn(II), Co(II), Ni(II), and Cu(II) with unsymmetrical Schiff base ligands, HL¹ and HL² , in a [1M:1L] molar ratio. Complexes were synthesized with high yields. Metal chelate structures were identified through FT-IR, elemental analyses, magnetic moment, and molar conductivity measurements. According to FT-IR findings, the Schiff base ligand HL¹ acts as tridentate by binding with metal ions, confirming tetrahedral geometry. While the ligand HL² is tetradentate, magnetic moment research indicated an octahedral structure. Theoretical calculations were performed using DFT. The synthesized complexes were tested for antibacterial activity against two types of Gram-positive bacteria: S. aureus and Gram-negative K. pneumoniae. Further molecular docking analysis revealed information about the ligand's binding energy and interaction with the protein receptor (ID:3BFV) of the bacteria.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 687-701.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.7

Synthesis of indole borate ligand with Ni(II) and Cu(II) complexes

2025-01-22T10:02:48+00:00

A new borate derivative (2,2',2'',2'''-((ʎ⁴-boranetetrayl)tetrakis(1H-indole-1,3-diyl))tetraacetic acid)(BIN) was synthesized from the reaction of indole-3-acetic acid (IAA) with sodium tetrahydroborate NaBH₄ at a 4:1 mole ratio. This ligand was characterized by ¹HNMR, FTIR, electronic spectra (UV-Vis.) thermal analysis (TG and DTG), elemental analysis (CHN) and melting point. Nickel and copper complexes were also synthesized and characterized by CHN, UV-Vis, atomic absorption, FTIR, melting point, magnetic susceptibility and molar conductivity. Results of analyses were in agreement with suggested structures. The results showed that the structure of nickel complex was octahedral while the copper complex was square planar and both complexes were nonelectrolytes. Antimicrobial activity against four kinds of bacteria Staphylococcus aureus and Streptococcus (G⁺), E. coli and Pseudomonas aeruginosa (G^‒) as well as one fungus Candida albican exhibited that the copper complex has higher antimicrobial activity. Total antioxidant results showed that the BIN ligand has higher activity at 50 and 100 μg/mL while the copper complex has more antioxidant activity at 150 μg/mL.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 703-712.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.8

Synthesis of a hybrid nanomaterial combining silver nanoparticles with water-soluble zinc phthalocyanines [ZnPc(CO2H)4(COATP)4@AgNPs]

2025-01-22T10:06:22+00:00

Phthalocyanine based hybrid nanomaterials show promises in biomedical applications. However, their lack of solubility in aqueous phase limits their development. This paper aims at bringing some answers to this problem, by reporting the synthesis of a hybrid nanomaterial consisting of new zinc phthalocyanines substituted with four carboxylic acid functions and four thiol functions, [ZnPc(CO₂H)₄(COATP)₄@AgNPs], associated with silver nanoparticles (AgNPs). The isolated hybrid species were characterized by UV-Visible, infrared (IR) and Raman spectroscopy, inductively coupled plasma atomic emission spectrometry (ICP-AES), powder X-ray diffraction (XRD), X-ray photoelectron spectrometry (XPS) and transmission electron microscopy (TEM). They show that the hybrid species consists in circa 20 nm large AgNPs with a characteristic absorption band that undergoes a bathochromic effect of about 30 nm in comparison to the parent AgNPs, in agreement with a functionalization of their surface. The XPS results give tangible proof of the establishment of an Ag-S bond, indicative of the coordination of the zinc phthalocyanine complexes to the AgNP surface via their peripheral thiol functions. With their four peripheral carboxylic acid functions, the zinc phthalocyanine complexes grafted on the AgNPs should impart a significant solubility to the hybrid system thus allowing its use in the biomedical field.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 713-729.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.9

Exploration of phthalazine bearing oxadiazolyl–triazole hybrids as selective breast cancer agents: computational docking interactions

2025-01-22T10:12:00+00:00

In this study, a series of novel phthalazine derivatives bearing 1,3,4–oxadiazolyl–1,2,3–triazole moiety were designed, synthesized, and evaluated for anticancer activity. The formation targeted compounds were conﬁrmed for their structure by means of various spectral–analytical techniques like ¹H-NMR, ¹³C-NMR, FT-IR, elemental analysis, and mass spectrum. All synthesized compounds were screened for anticancer activity against three different human breast cancer cell lines MCF-7, T-47D, and MDA-MB-231. From screening results, compound 5f exhibited the most potent anticancer activity (IC₅₀ = 10.21 ± 2.2, 7.53 ± 0.1 µM) towards T-47D, MCF-7 cell lines and 4b, 5b demonstrated the highest % growth of inhibition (61.25 ± 0.52, 62.48 ± 0.20 µg/mL) against T-47D, and MCF-7 cell lines, respectively, which is equivalent to that reported by the standard cisplatin. The docking study strongly favours compound 4d, 5a, 5e, and 5f to be a dehydrogenase type 1 complexed in breast cancer inhibitor as it displayed a similar interaction to cisplatin (3HB4). Ligand 5f exhibited amino acid interactions and having docking score –11.53 kcal/mol, respectively. The in-silico pharmacokinetics studies support the results obtained from docking and biological evaluation and displayed favourable pharmacokinetic profile for a drug to be orally available.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 731-748.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.10

Enhance food security: Sustained release of clove essential oil microcapsules

2025-01-22T10:33:05+00:00

Foodborne illnesses remain a significant concern in the realm of public health. Managing food spoilage and controlling pathogenic microorganisms rely on synthetic chemicals, regrettably accompanied by various unfavourable attributes. In response to the escalating demand for innovative and secure alternative approaches, there has been a surge in the investigation of naturally sourced agents possessing antimicrobial characteristics, among which essential oils stand out. This study focuses on improving the stability of clove essential oil (CEO), and to achieve controlled release, the CEO microcapsules are prepared by solvent evaporation method with ethyl cellulose as the wall material. The results indicated optimum technological conditions: wall material mass fraction of 3%, core wall ratio of 1.0:1.5, emulsifier mass fraction of 8% and shear rate of 14000 r/min. Under these conditions, the encapsulation efficiency is 81.28%, and the yield rate is 90.58%. The CEOM were spherical with a size of 1.43-3.92 μm and had good thermal stability. The microcapsule under 50% ethanol showed a faster release rate and significant release amount. The microencapsulation of CEO with ethyl cellulose can not only improve the stability of CEO but also realise the controlled release of CEO, which has tremendous application value in antibacterial packaging.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 749-761.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.11

Comprehensive analysis of indole-2-carboxylic acid as an antioxidant drug: Spectroscopic, quantum chemical, topological and molecular docking studies

2025-01-22T10:38:18+00:00

Bioactive indole-derived compounds have become increasingly important in current years owing to their wide range of biological and pharmacological uses. In this work, vibrational, electrical, physicochemical, and suppressive attributes of Indole-2-carboxylic acid (ID2CA) are predicted and analyzed. First, the molecular structure of ID2CA was refined, and its structural characteristics were computed in different environments, including polar solvents (DMSO, methanol, and water) as well as in the gas phase. A strong correlation was observed between the molecule's simulated and experimentally obtained infrared spectra. Measured UV-Visible spectra confirm the ID2CA's π→π* electronic shift, which is compatible with the computed spectra. Subsequent examination of FMO revealed intramolecular charge transfer (CT) throughout the molecule, highlighting ID2CA's bioactivity. To verify findings of the natural charge assessment and FMOs, Fukui function values were computed. ID2CA was discovered to be a significant part of the antioxidant resistance system by molecular docking studies. After performing 100 ns MD simulations and effective free energy computations with MMPBSA, durability of the best-docked protein (2C9V) was evaluated.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 763-780.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.12

Structure and magnetism of a linear tetranuclear nickel complex ligated by compartmental ligand

2025-01-22T10:43:15+00:00

A new nickel(II) complex [Ni₄L₃(acac)₂(H₂O)₂]·2DMF·Et₂O (1) (acac = acetylacetonate, and DMF = N,N′-dimethylformamide) was isolated in solid crystalline form with the reaction of nickel(II) acetylacetonate and compartmental Schiff base ligand 1,2-bis(2-hydroxy-3-methoxybenzylidene) hydrazine (H₂L). Single crystal X-ray analysis showed that the complex has a linear tetranuclear structure. In the complex, an unusual μ₃– and μ₄–bridging modes of Ligand L^2- were coexisting. Variable-temperature magnetic studies revealed that weak antiferromagnetic interaction exists between the nickel(II) ions coupling through phenoxide−O atoms and −N−N− bridging moieties.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 781-789.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.13

Magnetic properties and exchange bias behavior of poly(4-(octyloxy) phenyl-5- (thiophen-3-yl)-2-naphthoate): Insights from temperature-dependent magnetization and EPR spectroscopy

2025-01-22T10:48:26+00:00

The polymer POPTN was investigated to elucidate its magnetic and optoelectronic properties, with particular emphasis on charge carrier mobility, dichroic behaviour, and magnetic interactions. Electron paramagnetic resonance (EPR) studies confirmed delocalization over the naphthalene side chains, contributing to the observed paramagnetic behaviour at room temperature. Temperature-dependent magnetic studies revealed paramagnetic behaviour at higher temperatures transitioning to weak ferromagnetism below 10 K. Curie-Weiss analysis indicated antiferromagnetic (AFM) coupling with a paramagnetic Curie temperature (θ_P) of -203 K. Exchange bias (EB) measurements demonstrated a significant hysteresis loop shift at 2 K, diminishing with increasing temperature and vanishing near 20 K. The maximum exchange bias field (H_E) was observed to be 133 Oe at 2 K, attributed to the coexistence of ferromagnetic (FM) and AFM interactions. The interplay of AFM and FM coupling, along with π-π stacking facilitated by the naphthyl moiety, influenced the magnetic properties and anisotropy.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 791-798.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.14

Density functional theory study on the crystal structure of quercetin

2025-01-22T10:55:44+00:00

A molecular mechanics method with COMPASS and Dreiding force fields were used to predict molecular packings for quercetin (P21/c, P212121, P-1, Pbca, C2/c, Pna21, and P21). According to the minimum energy principle, the most likely crystal accumulation mode of quercetin belongs to P-1. Then, periodic band calculations were performed on the predicted crystals using the density functional theory generalized gradient approximation with revised Perdew-Burke-Ernzerhof (DFT-GGA-RPBE) functional method. LUCO (the lowest unoccupied crystal orbital) is mainly contributed by the p-state of the C atom, while HOCO (the highest occupied crystal orbital) is mainly composed of the p-states of the O atom.

Bull. Chem. Soc. Ethiop. 2025, 39(4), 799-805.

DOI: https://dx.doi.org/10.4314/bcse.v39i4.15