Bulletin of the Chemical Society of Ethiopia

Spectrophotometric determination of procaine hydrochloride using oxidative coupling and cloud point extraction

2024-10-25T07:52:04+00:00

A method with rapid, sensitive, accurate, and selective for estimation of local anesthetic procaine hydrochloride (PRO.HCl) is crucial, due to its bad damage to health if administrated excessively. In this work two spectrophotometric methods oxidative coupling and cloud point extraction (CPE) were utilized for determination of PRO.HCl in its standard state and pharmaceutical preparations. Method A, based on the oxidative coupling reaction using sodium hypochlorite as an oxidant and 2,5-dimethylphenol as coupling agent. The blue colored product has high absorption at 600 nm. Method B based on the CPE relying on the previous reaction, with addition of Triton X-114, after extracting the colored product, it was measured at 630 nm. Beer’s law of both methods are linear in the concentration ranges 2.50-50 µg/mL (method A) and 1.25-3.75 µg/mL (method B). The molar absorptivity coefficients of methods (A) and (B) are 4.01 x 10³ and 1.34 x 10⁴ L/mol.cm, respectively. For (method A) limit of detection and limit of quantification were calculated and found that 0.26 µg/mL and 0.87 µg/mL, respectively, while for (method B) were found to be 0.16 and 0.54 µg/mL, respectively. Both methods (A and B) are applied to evaluate PRO.HCl in pharmaceutical preparations (injection).

KEY WORDS: Cloud point extraction, 2,5-Dimethylphenol reagent, Odxiative-coupling, Procaine-hydrochloride, Spectrophotometry, Triton X-114.

Bull. Chem. Soc. Ethiop. 2025, 39(1), 1-13.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.1

Synthesis, characterization, biological activity, DFT and Hirshfeld surface studies of Pd(II) and Pt(II)-1-cyclohexyl-3-phenylthiourea and amine ligands

2024-10-25T07:58:56+00:00

A series of mixed ligand complexes of Pd(II) and Pt(II) of 1-cyclohexyl-3-phenylthiourea and diamine ligands {2,2'-bipyridyl (Bipy) and 1,10-phenanthroline (Phen)} were prepared and characterized by FT-IR, NMR spectroscopy, molar conductivity. Density functional theory (DFT) calculations and biological activity were carried out on the prepared complexes. In vitro antimicrobial activity was investigated against three pathogenic bacteria (Staphylococcus aureus, Bacillus cereus and Escherichia coli). The most active compound 6 was found more active than free ligand and other complexes. The crystal structure of the free ligand was determined by X-ray diffraction (XRD) analysis. Hirshfeld surface analysis was executed for the free ligand by finding and exploring the interatomic contacts that are important considering the supramolecular assembly of the crystal. The mechanical stability or response is prophesied by voids analysis. The supramolecular assembly is significantly uncovered by intermolecular interaction energies calculations performed at of the B3LYP/6-31G(d,p) electron density level.

KEY WORDS: Thiourea, Diamine, Crystal structure, DFT, Hirshfeld surface

Bull. Chem. Soc. Ethiop. 2025, 39(1), 15-27.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.2

Facile synthesis of ZnO/RGO/Fe2O3 using macroalgae Caulerpa taxifolia as green reductor and its application as malachite green removal

2024-10-25T08:05:18+00:00

This study presents the synthesis of a novel ZnO/rGO/Fe₂O₃ composite using Caulerpa taxifolia as a green reductant for the effective removal of Malachite Green from aqueous solutions. Characterization techniques, including FTIR, SEM, and XRD, confirmed the successful incorporation of ZnO and Fe₂O₃ onto the rGO matrix, enhancing its adsorption properties. The composite achieved an exceptional maximum adsorption capacity of 454.5 mg/g at pH 9, significantly outperforming rGO alone and other adsorbents. The adsorption kinetics followed a pseudo-second-order model, indicating chemisorption as the dominant mechanism, with a high correlation coefficient (R² = 0.999). The adsorption isotherms were best described by the Langmuir model, suggesting monolayer adsorption. Thermodynamic parameters revealed that the process was spontaneous and exothermic, with a Gibbs free energy (ΔGo) of -10.93 kJ/mol at 25 °C. The composite's high adsorption capacity, rapid kinetics, and favorable thermodynamics highlight its potential as an efficient and sustainable adsorbent for dye removal. This research offers a promising approach to water treatment, aligning with environmentally friendly practices and providing a viable solution for mitigating water pollution caused by organic dyes.

KEY WORDS: Reduced graphene oxide, Water treatment, Caulerpa taxifolia, Isothermal and kinetic studies, Malachite Green

Bull. Chem. Soc. Ethiop. 2025, 39(1), 29-47.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.3

Synthesis and structural studies on zinc(II) macrocyclic and hetrocyclic complexes derived from schiff base and mixed ligands of 1,4-dihydroquinoxaline-2,3-dione, orthophenylene diamine and hydroquinone

2024-10-25T08:43:35+00:00

In this study two new zinc(II) complexes involving oxygen and nitrogen donor sequences derived from 1,4-dihydroquinoxaline-2,3-dione (QXD), o-phenylenediamine (OPD) and hydroquinone (HQ) were synthesized through a template procedure. The structural elucidation of these complexes was carried out using measurement of molar conductance in 1x10^-3 M solution of DMSO and various spectral techniques; ¹H and ¹³C NMR, FT-IR, UV-VIS and AAS. The results showed that the zinc(II) ion coordinates with the Schiff base ligands in octahedral geometry, leading to the formation of stable macrocyclic and heterocyclic structures. The cyclic ligand (L) was found to coordinate as NNNN donor, through four imine nitrogen atoms which were formed up on condensation of the –NH₂ groups on o-phenylenediamine with C=O group on quinoxaline dione in a 2:2 mole ratio, in the presence of one mole equivalent of ZnCl₂ in ethanol medium. It also indicates the formation of a new mixed ligand zinc(II) complex with an OO OO O O coordination around zinc(II). The study contributes to the understanding of the coordination chemistry of zinc(II) with Schiff bases and provides insights into the development of novel zinc-based complex compounds.

KEY WORDS: Macrocyclic and mixed ligand, 1,4-Dihydroquinoxaline-2,3-dione, o-Phenylenediamine, Hydroquinone

Bull. Chem. Soc. Ethiop. 2025, 39(1), 49-64.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.4

Divalent transition metal complexes with mixed of β-enaminone and N,O-donor ligands: synthesis, characterization and biological assessment

2024-10-25T08:49:15+00:00

This study extensively describes the synthesizing and characterizing of new β-enaminone complexes derived from dimedone and amines coordinated with transition metals Fe(II), Co(II), Ni(II), and Cu(II), also two ligand's metformin (Met) and 8-hydroxyquinoline (8-hq). These were determined via FT-IR, ¹H-NMR, electron and mass spectroscopy, molar electrical conductivity, thermal analysis (TGA, DTA and DSC) and characterized by metal content determination (%), magnetic susceptibility and elemental analysis (C.H.N.) and SEM technique. The measurements indicate that the complexes have six coordination numbers, where the β-enaminone is coordinated as tetradentate ligand through the two nitrogen atoms and the two oxygen atoms beside metformin is coordinated through the two nitrogen atoms and 8-hydroxyquinoline is coordinated by oxygen and nitrogen atoms as bidentate ligands. The conductance suggests that all complexes have electrolytic behavior, being conductive in a ratio of (1:2). SEM results revealed the presence of nanostructures on sample surfaces. The biological activity of the prepared ligands and complexes are studied in different concentrations for four types of bacteria Staphylococcus aureus has (+G) and Escherichia coli, Pseudomonas aeruginosa, Klebsiella have (-G), well as, the influence of the fungus. The ligands have disparate effectiveness while complexes have high effectiveness inhibiting the bacteria and fungus.

KEY WORDS: Mixed ligand systems, Dimedone, β-Enaminone ligands, Transition metals, Biological application

Bull. Chem. Soc. Ethiop. 2025, 39(1), 65-78.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.5

Spectroscopic and biological studies of Pd(II) complexes of 5-(p-tolyl)-1,3,4-oxadiazole-2-thiol

2024-10-25T08:52:31+00:00

Reactions of Na₂PdCl₄ with two equivalents of 5-(p-tolyl)-1,3,4-oxadiazole-2-thiol (MoxSH), afford complex of the type [Pd(MoxS)₂] (1). Further reaction with equivalent mole of diphosphine ligand {Ph₂P(CH₂)_nPPh₂} ( where n = 1 dppm, 2 dppe, 3 dppp, 4 dppb, (CH₂)_n = dppf ) or two equivalents of triphenyl phosphine or triphenyl phosphine sulfide affords mixed-ligand complexes of the type [Pd(MoxS)₂(Ph₂P(CH₂)_nPPh₂)] (2-6), [Pd(MoxS)₂(PPh₃)₂] (7) and [Pd(MoxS)₂(SPPh₃)₂](8). The prepared complexes were characterized using different physical and spectroscopic methods. The results indicated that the MoxS ligand behave as coordinate in a anion monodentate fashion sulfur atom to give a square planer around the metal ion. Preliminary anti-bacterial activity has been assessed against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis bacteria. The prepared complexes show good activity in compared with standard drug. [Pd(MoxS)₂(dppf)] (6) displays good activity (18, 22 and 20 mm) against certain tested microbes Escherichia coli, Staphylococcus aureus and Bacillus subtilis, respectively.

KEY WORDS: Complexes, Palladium, Thione, Anti-bacteria, Phosphine

Bull. Chem. Soc. Ethiop. 2025, 39(1), 79-90.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.6

Biological activity of azo quinoline dye and its palladium(II) complex

2024-10-25T09:03:12+00:00

Azo dye derived from 8-hydroxyquinoline and 3-aminopyridine namely (E)-5-(pyridin-3-yldiazenyl)quinolin-8-ol (PQ8OL) and its palladium complex were prepared and was characterized by H-NMR, UV-Vis, and mass spectroscopies. The value of conductivity indicates that the palladium complex is non-ionic. The structure of PQ8OL dye has been solved from powder X-Ray by using Material Studio. The structure has been indicated to hydrazone form of PQ8OL dye. The PQ8OL has coordinated via nitrogen and oxygen atoms of quinoline. The UV-Vis transitions indicated that the palladium complex is square planer. The palladium complex appeared biological activity more than PQ8OL ligand. The prepared compounds appeared potential biological activity in the range of 0.6-2.0 mm against Staphylococcus aureus and E. coli bacteria. The PQ8OL ligand and its palladium complex showed potential inhibition where the inhibition was 1.0 and 6.0 mm for PQ8OL ligand and palladium complex respectively against Staphylococcus aureus. The inhibition for E. coli, by the ligand and its palladium complex was 2.0, and 7.0 mm, respectively.

KEY WORDS: Biological activity, Palladium(II) complex, Quinoline, Crystal, Pyridine

Bull. Chem. Soc. Ethiop. 2025, 39(1), 91-100.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.7

Synthesis, characterization, and antioxidant activity of novel diorganotin(IV) complexes derived from Ibuprofen-5-aminosalicylic acid ligand

2024-10-25T09:14:32+00:00

This study focuses on the preparations of a new ligand prepared by the condensation reaction between two substances ibuprofen and 5-aminosalicylic acid, and complexes of di organotin(IV) salts were prepared using this produced ligand to yield the appropriate complexes. The generated compounds were identified using FTIR and elemental analysis, in addition (tin, proton and carbon) magnetic resonance (¹¹⁹Sn,¹H, and ¹³C, NMR). Octahedral geometry was suggested for the synthesized complexes based on the observations of the spectra. Two techniques were used to examine the antioxidant activity of the compounds: DPPH and CUPRAC. Because the tin element was present, the resultant complexes exhibited a higher rate of inhibition than the ligand. Di-methyltin-di-IAS also showed a greater effect as antioxidants than the other compounds.

KEY WORDS: Diorganotin(IV), Antioxidant activity, Ligand (IAS), DPPH method, CUPRAC method

Bull. Chem. Soc. Ethiop. 2025, 39(1), 101-110.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.8

Synthesis, and spectroscopic characterizations of gold(III) complexes containing nitrogen-heterocycle based pyridine derivatives as a biomolecular chelates

2024-10-25T09:17:53+00:00

Three gold(III) nanostructured complexes of nicotinamide (nta), picolinic acid (pica), and isonicotinic acid (inta) were synthesized by the reacted of AuCl₃ salt with nta, pica, and inta with 1:2 stoichiometry in the alcoholic medium. The solid products obtained were formulated by comparing experimental and calculated data for microanalytical (C, H, N) and metal. Both produce 1:2 compounds with metal ions. The prepared complexes were characterized by different physico-spectroscopic techniques. The FTIR, and ¹H NMR spectral analysis, morphological analysis (scanning electron microscopy SEM, transmittance TEM, and X-ray powder diffraction XRD) of these complexes have been discussed. The conductive behavior of the complexes indicates that all of them behave as electrolytic behavior. The mononuclear gold(III) complexes have formulated as [Au(nta)₂(Cl)₂].Cl, [Au(pica)₂].Cl and [Au(inta)₂].Cl. The shifts of the ν(N–H) amino, ν(C=N) pyridine, and ν(C=O) carboxylic stretches have been monitored to find out the donor sites of the ligands. According to the experimental data, the three complexes can be characterized in the solid state as mononuclear, with a four-coordinate stereochemistry.

KEY WORDS: Gold complex, Nicotinamide, Picolinic acid, Isonicotinic acid, Nanostructure, Spectroscopic

Bull. Chem. Soc. Ethiop. 2025, 39(1), 111-121.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.9

The applications of nanocatalysts in the synthesis of heterocyclic compounds

2024-10-25T09:20:42+00:00

Nanocatalysts in heterocyclic synthesis are a very important direction in producing eco-friendly compounds. These catalysts can be reused up to six times without losing their quantity and efficiency. Most of these nanocatalysts are cheap, available, economical and safe for the environment. In this review, I focused on the synthesis of furans, pyrans, chromenes and thiazoles from nanocatalysts. For example, pyranopyrazoles 8a-c were synthesized by the multicomponent reactions between aldehydes 4a-c, malononitrile (5), ethyl acetoacetate (6) and hydrazine hydrate (7) using titanium dioxide as a nanocatalyst.

KEY WORDS: Heterocyclic, Chromenes, Nanocatalysts, Eco-friendly compounds

Bull. Chem. Soc. Ethiop. 2025, 39(1), 123-129.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.10

Chemoselective metal free deallylation of α-allyl-phenyl-carboxylic esters under reduction condition

2024-10-25T09:23:40+00:00

A simple and efficient method for chemoselective deallylation of –COO-allyl group in presence of C-allyl group has been developed. C-allyl cleavage of α-methylene compounds was successfully completed by refluxing with excess sodium borohydride in methanol. The reagent's stability, ready availability and ease of handling encourage its usage for deallylation.

KEY WORDS: C-allyl cleavage, Sodium borohydride, Chemoselectivity, Reduction

Bull. Chem. Soc. Ethiop. 2025, 39(1), 131-139.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.11

Preparation of flower-like hierarchical structure SnO2/g-C3N4 and its ethanol gas-sensitive properties

2024-10-25T09:26:57+00:00

The flower-like hierarchical structured SnO₂/g-C₃N₄ nanocomposites were successfully prepared by one-step hydrothermal method with high-temperature calcination. The structure and morphology of the synthesized samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and N₂ adsorption-desorption. The gas-sensitive performance of the pure SnO₂ and SnO₂/g-C₃N₄ sensors were investigated and compared towards ethanol gas. The results showed that the response of the SnO₂/g-C₃N₄ composites to 100 ppm ethanol gas at 200 °C was 18.88, which was 2.09 times that of pure SnO₂, with response and recovery time of 2 s and 13 s. In addition, the gas sensor has excellent selectivity for ethanol gas, good repeatability, and long-term stability. These gas-sensitive properties of the flower-like graded structure SnO₂/g-C₃N₄ to ethanol gas are attributed to the materials which have unique graded structure and n-n heterojunction.

KEY WORDS: Hierarchical structure, SnO₂/g-C₃N₄, Gas sensing property

Bull. Chem. Soc. Ethiop. 2025, 39(1), 141-152.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.12

Effect of (Zr, Ta) doping on electronic and magnetic properties of zinc-blende MgTe DMS compound: AB-initio approach

2024-10-25T09:30:09+00:00

This study utilizes density functional theory (DFT) and the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) to explore the effects of zirconium (Zr) and tantalum (Ta) doping on the electronic and magnetic properties of zinc-blende MgTe. The electronic configurations of Mg_1-x(TM)_xTe (TM = Zr, Ta) were analyzed, revealing that Zr induces magnetic behavior with near-total spin polarization, while Ta doping leads to metallic behavior with partial polarization. The variations in magnetic moments are largely determined by impurity concentrations, with ferromagnetic stability in both systems driven by a double exchange interaction mechanism. Additionally, Curie temperatures exceeding room temperature were observed for specific doping concentrations. These results suggest significant potential for MgTe-based materials in spintronic applications. The findings further illustrate that Zr-doped alloys display half-metallicity, making them especially promising for future spintronics device development.

KEY WORDS: DMS, KKR-CPA, Polarization, Metallic behavior, Curie temperature, Double exchange, Spintronic

Bull. Chem. Soc. Ethiop. 2025, 39(1), 153-164.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.13

Thermodynamic study of pyridoxine in different solvents and temperatures: DFT study

2024-10-25T09:43:18+00:00

The equivalent conductivities (Λ) of B₆ vitamin (pyridoxine) in H_շՕ and MeOH were measured at different temperatures between 293 to 313 K, as well as in mixtures of H₂O and MeOH at percentages of 10, 20, 30, 40, and, 50% MeOH at 310 K. All the practical results were mathematically processed using the Lee Wheaton equation, which is applied to the derived conductivity of electrolytes with a similar composition (1:1). This equation calculates various conductivity components, including the equivalent conductance at infinite dilution (Λₒ), the ionic conductivity, the distance between ions (R), and also the constant of ionic aggregation (K_a) at best-fit values of (ϬΛ). The values of these parameters differed from one solvent to another depending on the molecular interactions in the solution and the physical properties of the solvents, such as viscosity and dielectric constant. Finally, thermodynamic quantities for the ion association reaction (ΔG°, ΔH°, and ΔS°) were also studied. Density functional theory (DFT) calculations (B3LYP/6-31G (d,p)) were employed to analyze vitamin B₆ in the gas phase and diverse solvents. Three different continuum methods, namely AM1, PM3, and HF, were utilized, followed by DFT. The final method was utilized to explore the effects on its characteristics.

KEY WORDS: Electrical conductivity, Lee-Wheaton equation, Theoretical chemistry, DFT.

Bull. Chem. Soc. Ethiop. 2025, 39(1), 165-176.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.14

Electrical conductance study of Schiff base in different solvents and temperatures: DFT calculation

2024-10-25T09:46:31+00:00

The electrical conductivities of the N-(2-chlorobenzylidene)benzylamine (NCB) as Schiff bases (SB) compound in water and methanol were studied in different temperatures, the mixtures of methanol and water studied in various percentages of methanol at 298 K. Initially, the relationship between equivalent conductivity and the square root of molar concentration was plotted to find electrolyte types using Kohlrausch equations. The plot indicates that NCB was weakly associated with water, methanol, and mixtures. Lee-Wheaton equation treated the experimental results of symmetrical electrolytes (1:1) to calculate the conductivity confines: equivalent conductance at infinite dilution Λₒ, association constant KA, and the main distance between ions in solution (R) at best-fit values of (ϬΛ). Thermodynamic quantities for the ion association reaction (∆G^o, ∆H^o and ∆S^o) have been measured. Also, the theoretical calculation was used to optimize the energy of the molecule in the gas phase then measured many descriptors by using (AM1, PM3) then DFT. In addition, recalculated the optimization energy in water, and methanol. After theoretical calculation and analysis, it was found that the Λₒ value is related to the molecular volume of the system (molecules assembled in the solvent). As the molecular volume increases, the Λₒ value decreases due to association.

KEY WORDS: Schiff bases, Electrical conductivities, Lee-Wheaton equation, Thermodynamic parameter, DFT

Bull. Chem. Soc. Ethiop. 2025, 39(1), 177-187.

DOI: https://dx.doi.org/10.4314/bcse.v39i1.15