Ni(II), Cu(II), Pd(II), and Pt(II) metal complexes have been synthesized utilizing Schiff bases, a bidentate chelating ligand based on 2-hydroxy-4-morpholinobenzaldehyde and Prontosil. Physical characteristics, micro-analytical data, and spectroscopic techniques such as 1H-NMR, FTIR, UV-Vis spectroscopy, and elemental analysis (C.H.N.S.) were used to characterize these ligands and complexes. Electronic spectra verified the octahedral geometry of the produced complexes, while the spectrum analysis verified the coordination of the Schiff base to the metal via the azo-methine nitrogen atom and the oxygen atom. Additionally, disc diffusion techniques were used to assess biological activity against both gram-positive and gram-negative bacteria. When tested against the chosen bacterial strains, the results showed that the metal complexes had stronger antibacterial action than the Schiff base ligands. To evaluate the antioxidant activity of the synthesized compounds, DPPH was used as the control, and tannic acid was used as a reference solution. Comparing these compounds to tannic acid revealed a wide range of impressive results based on their IC50 values. Furthermore, it was noted that when the concentration of the produced chemicals increases, the oxidation process becomes more intense.
In this study, complexes of Fe(III), Co(II), Cu(II), Rh(III), and Ru(III) were synthesized by coordinating to a novel azo ligand, specifically 2,2'-(4-methyl-1,2-phenylene) bis (diazine-2,1-dieyl) bis (3,5-dimethylphenol). This ligand was produced from a diazonium salt using ethanol as a reaction medium. Various techniques, including 1H and 13C-NMR, FT-IR, UV-Vis, mass spectrometry, TGA, DSC, C.H.N., conductivity, magnetic susceptibility, and metal and chlorine content. FT-IR spectroscopy was used to characterize the complexes, revealing the presence of coordination bonds and ionic coordination bonds, as well as water molecules and chlorine groups directly attached to the metal ions. Mass spectrometry confirmed the molecular weights of the prepared complexes to be in good agreement with their proposed formulas. Magnetic moment measurements revealed the paramagnetic nature of the complexes, except in a rhodium(III) complex, which was diamagnetic. All techniques indicated that the compounds adopt octahedral geometry for ruthenium, rhodium, and iron, and tetrahedral geometry for copper and cobalt. Copper, cobalt, and rhodium form binuclear structures, whereas iron and ruthenium are mononuclear. Thermogravimetric analysis confirmed structural stability up to 300 °C. In the DPPH radical-scavenging assay, the copper complex showed greater antioxidant activity than standard gallic acid; all other compounds displayed lower antioxidant capacity. KEY WORDS: Azo dye, Antioxidant, Metal ion complexes, Thermogravimetric analysis Bull. Chem. Soc. Ethiop. 2026, 40(8), 1783-1797. DOI: https://dx.doi.org/10.4314/bcse.v40i8.14
Fusarium wilt, caused by Fusarium oxysporum and Fusarium solani, poses a persistent threat to tomato production and remains difficult to manage using conventional fungicides. This study integrates chemical profiling, biological assays, and molecular docking to investigate the antifungal potential of extracellular metabolites produced by Bacillus subtilis ISMA4. Solvent extracts of dichloromethane and ethyl acetate were analyzed by GC-MS, revealing a diverse metabolite profile dominated by diketopiperazines, phenolic compounds, fatty acid derivatives, and a chlorinated piperazine. In vitro bioassays demonstrated concentration-dependent inhibition of both Fusarium species, with the ethyl acetate extract exhibiting the highest activity against F. oxysporum (42.8% inhibition at 20 mg mL-1). Key metabolites, including cyclo(L-Pro-L-Phe) and 1-(3-chlorophenyl)-2-(piperazin-1-yl)propan-1-one, showed favorable binding within or adjacent to conserved catalytic regions (Delta G =-7.5 to-8.0 kcal mol-1), suggesting interference with SDR-associated pathways linked to fungal melanin biosynthesis. Collectively, these results indicate that B. subtilis ISMA4 metabolites contribute to antifungal activity through combined physicochemical effects and targeted enzymatic interactions, highlighting SDR enzymes as plausible molecular targets for sustainable biocontrol strategies.
This day, there is a growing interest in searching for new, effective, and alternative naturally occurring insecticidal agents from botanical sources using a slow-release mechanism of the active ingredients. Accordingly, Echinops kebericho Mesfin (E. kebericho) root is traditionally used as a fumigant to repel insects. In this study, methanol extracts (ME) and essential oils (EO) of this plant were successfully extracted and formulated using modified and unmodified kaolinite clay as supporting material. Moreover, the essential oil was analyzed by gas chromatography-mass spectrometry (GC-MS). Dehydrocostus lactone (25.09%), quinolin-5(6H)-one-7,8-dihydro-2-hydroxy-4,7,7-trimethyl-(10.71%), and modephene (9.07%) were the first three major constituents. The unformulated essential oil and the methanol extracts were tested for insecticidal activities on the Sitophilus zeamais, and the result evidenced that the essential oil was more active within short exposure periods. Finally, the formulation efficacy, stability, and residual effect of the kaolinite-supported essential oil were tested, and the result showed an improvement in its insecticidal activities over longer periods with high persistence and stability effects. The results confirm that the roots of E. kebericho EO/ME-modified kaolinite formulations can be used as the best options to synthetic insecticides for stored sorghum protection. KEY WORDS: Echinops kebericho Mesfin, Crude extract, Essential oil, Modified kaolinite clay, Insecticidal formulation, Stored sorghum Bull. Chem. Soc. Ethiop. 2026, 40(9), 2005-2021. DOI: https://dx.doi.org/10.4314/bcse.v40i9.13
In this study, seven novel hybrid derivatives were synthesized from sulfadoxine and ambroxol. All derivatives were characterized by spectroscopic techniques, including Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (¹H-NMR), and carbon-13 magnetic resonance (¹³C-NMR). The anticancer activity of five derivatives (compounds 2, 3, 4, 5, and 8) was evaluated against prostate cancer (PC-3) cells using the MTT assay. Compound 3 exhibited the most potent activity with an IC₅₀ of 24.9 µM/mL, followed by compound 4 (IC₅₀ = 28.4 µM), compound 8 (IC₅₀ = 50.6 µM), compound 2 (IC₅₀ = 64.6 µM), and compound 5 (IC₅₀ = 101.6 µM). On normal human dermal fibroblasts (HDF), the IC₅₀ values ranged from 65.9 to 328.7 µM, indicating acceptable selectivity. The electron-withdrawing trifluoromethyl (-CF₃) and bromine substituents enhanced anticancer activity, while the larger oxazepane ring system (compound 5) reduced potency. This synthetic approach offers a promising strategy for developing new anti-prostate-cancer agents. KEY WORDS: Sulfadoxine, Ambroxol, Hybrid derivatives, Prostate cancer, MTT cell viability assay Bull. Chem. Soc. Ethiop. 2026, 40(9), 1961-1974. DOI: https://dx.doi.org/10.4314/bcse.v40i9.10
Charge-transfer (CT) reactions have attracted significant research interest due to their potential for developing novel CT materials with unique properties that are valuable in both fundamental research and materials science. This study examines the physical properties and optical band gaps of new CT complexes synthesized via interactions between two organic donors: carbonyldiimidazole (D1) and hydroxybenzotriazole (D2), and the acceptor 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ). Solid DDQ-D1 and DDQ-D2 complexes were prepared using two methods: liquid-liquid and solid-solid techniques, depending on the initial states of the reactants. The liquid-liquid method involved dissolving both components in a solvent, mixing their solutions in a specific ratio, evaporating the solvent, and isolating/purifying the resulting complex. The solid-solid method entailed grinding the components together to promote direct complex formation through intimate contact. Both approaches yielded the same 1:1 CT complexes between DDQ and each donor. The formation of these complexes is an exothermic, spontaneous process, as confirmed by elemental analysis, UV-Vis and FT-IR spectroscopy (which exhibited a characteristic n→π* transition, and physical parameters calculated using established equations. KEY WORDS: Charge-transfer reaction, DDQ acceptor, Organic donors, Physical parameters Bull. Chem. Soc. Ethiop. 2026, 40(9), 1809-1825. DOI: https://dx.doi.org/10.4314/bcse.v40i9.1
The present study investigated the phytochemical constituents of Euphorbia abyssinica Gmel. The crude 80% ethanol extract was partitioned between EtOAc and water, and the EtOAc fraction was subjected to chromatographic fractionation, yielding twelve compounds: one sterol ((3-sitosterol, 1); one sterol-glucoside (sitosterol-3-O-(3-D-glucoside, 2); four triterpenes (glutinol, 3; epifriedelanol, 7; taraxerol, 8; friedelin, 9); three ellagic acid derivatives (3,3 ',4-tri-O-methylellagic acid, 4; 3,4,3 '-tri-O-methylellagic acid-4 '-rutinoside, 5; 3,4,3 '-tri-O-methylellagic acid-4 '-glucopyranoside, 12); one flavonoid glycoside (quercetin-3-O-L-rhamnoside, 6); and two coumarins (scoparone, 10; scopoletin, 11). Compounds 1-9 were previously reported from E. abyssinica, while scoparone (10) and scopoletin (11) were isolated and characterized for the first time. Additionally, 3,4,3 '-tri-O-methylellagic acid-4 '-glucopyranoside (12) is reported for the first time from this species. GC-MS analysis of the petroleum ether fraction revealed Kaur-16-ene (24.82%), 9-Tricosene, (Z)-(12.84%), Hexacosane (11.51%), Nonadecane (7.96%), 10-Heneicosene (6.67%), 9-Nonadecene (5.72%), and Pentadecanal (4.65%) as major components. These findings highlight the chemical diversity of E. abyssinica and provide a basis for future pharmacological investigations.
A new nano-Cu(II) complex has been synthesized from a Schiff base derivative ligand. FT-IR and UV-Visible instrumental analysis, atomic flame absorption, LC-mass procedures, and molar conductivity tests were employed for the determination of complex identification, which indicated the octahedral geometrical structure with chemical formula [Cu(C18H16N4O3S)2(H2O)2]. Then it was converted to nanoparticles by the Ultrasonic (Hielscher) technique, which was measured by the FSEM technique. The images show that the synthesized complex consists of spherical or quasi-spherical particles. The primary particle size lies in the nano-scale range of ~50–70 nm. The results provided reflect the nanostructured nature. Then, the biological activity of the synthesized ligand and complex against four kinds of bacteria and one type of fungi has been evaluated by the agar well diffusion method. And the results were that the ligand and the nano copper complex provided substantial resistance, measured by inhibition zone, against Klebsiella spp. 9mm,10 mm, respectively. Candida albicans fungi both showed the same results as 9 mm, and the Staphylococcus aureus strain showed the same results as 12 mm, but the ligand and the nano-Cu complex failed to inhibit Escherichia coli. On the other hand, the ligand does not inhibit Staphylococcus epidermidis, while the nano-copper complex shows 12 mm inhibition zone effect. KEY WORDS: Nano-complex of copper(II), 6-Oxopyrimidin-1(6H)-yl)imino) ligand, Ultrasonic technique of complexes, Copper complexes, Heterocyclic ligand Bull. Chem. Soc. Ethiop. 2026, 40(8), 1651-1663. DOI: https://dx.doi.org/10.4314/bcse.v40i8.5
In this study, a series of novel Schiff base ligands (2-7) were synthesized through the condensation of a 2-aminothiazole derivative (1) with various substituted benzaldehydes (R=H, OCH3, 3,4-diOH, 2,4-diCl, 4-N,N-dimethylamine, 4-NO2). The chemical structures of the synthesized ligands were rigorously confirmed using elemental analysis (CHNS) and spectroscopic techniques, including FT-IR, ¹H-NMR, and ¹³C-NMR. Subsequently, a new series of transition metal complexes (8-19) was prepared and characterized via metal content determination, electronic spectra, FT-IR, magnetic susceptibility, and molar conductance measurements.The analytical data revealed that the complexes are monomeric with a 1:2 (metal:ligand) stoichiometry, adopting a high-spin octahedral geometry. Spectroscopic evidence confirmed that the ligands act as bidentate chelators, coordinating through the azomethine nitrogen (HC=N) and the thiazole ring nitrogen. The novelty of this work lies in the strategic design of these heterocyclic frameworks to enhance biological efficacy. All synthesized compounds were screened for their antibacterial activity, where the metal complexes exhibited superior inhibitory effects compared to the free ligands. Furthermore, molecular docking studies were conducted to provide theoretical insights into the binding affinities and interaction modes with bacterial target proteins, correlating well with the experimental in-vitro results. KEY WORDS: Schiff base, 2-aminothiazole, Transition metal complexes, Biological activity, Molecular docking, Cobalt(II) and Nickel(II) Bull. Chem. Soc. Ethiop. 2026, 40(9), 1827-1841. DOI: https://dx.doi.org/10.4314/bcse.v40i9.2
A novel ILVO4/SiO2-supported ionic liquid was fabricated and applied as a green and efficient catalyst in the oxidative desulfurization of model oil with H2O2 oxidant. As a heterogeneous catalyst, ILVO4/SiO2 demonstrated excellent catalytic performance for the oxidative desulfurization; the sulfur removal rate of DBT, 4,6-DMDBT, and BT can reach up to 99.5%, 98.4%, and 96.4%, respectively. Additionally, ILVO4/SiO2 could serve as a durable and recoverable heterogeneous catalyst for the oxidative desulfurization, which could be used for five cycles without significant loss of catalytic activity. This study offers novel insights for the development and design of green catalysts for oxidative desulfurization. KEY WORDS: Supported ionic liquid, Oxidation desulfurization, H2O2, High efficiency, Sustainability Bull. Chem. Soc. Ethiop. 2026, 40(8), 1597-1607. DOI: https://dx.doi.org/10.4314/bcse.v40i8.1
. This study presents a sustainable and efficient synthesis of novel 2-amino-3,5-dicyanopyridine derivatives 4a-h via a one-pot, three-component reaction catalyzed by Fe2NiO4 nanoparticles (Fe2NiO4-NPs) under microwave irradiation. This green protocol offers high yields (90-94%), short reaction times (10-15 minutes), and facile catalyst recovery. All synthesized compounds were evaluated for their antimicrobial properties. The results indicated that compounds 4d and 4e exhibited significant activities against Gram-positive (84-92% efficacy compared to Penicillin G) and Gram-negative bacteria (74-86% efficacy compared to Ciprofloxacin). Furthermore, compounds 4c and 4e showed promising antifungal potential (70-75%, efficacy relative to ketoconazole). Molecular docking studies against the E. coli FabH enzyme identified 4d and 4h as the most potent binders.
A series of new bis-hydrazinyl phenylthiazole derivatives (5a–5e) were synthesized through a reaction of substituted bis(oxy) dibenzaldehyde compounds (3a-3e), thiosemicarbazide and bromophenacylbromide to investigate their structural features and biological activities. The intermediates of the bis-thiosemicarbazones (4a-4e) were then cyclized to give the desired thiazole derivatives. The synthesized products had their structures validated by FT-IR, ¹H-NMR, 13C-NMR, DEPT-135, UV-Vis, and Mass spectrometry and all of the mentioned tools confirmed the structure of the synthesized compounds and their purity. To determine the biological properties of these drugs, the well diffusion test was performed to determine the antimicrobial activity of these drugs against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. Also, the DPPH (2, 2-diphenyl-1-picrylhydrazyl) assay was used to determine their antioxidant activity. Molecular docking studies were carried out to supplement the results of the experiment using Pim-1 kinase (PDB ID: 2OBJ) as the target receptor target molecules. KEY WORDS: Bis-thiazole, Schiff base, Stepwise, One pot, Biological activity, Molecular docking Bull. Chem. Soc. Ethiop. 2026, 40(8), 1621-1638. DOI: https://dx.doi.org/10.4314/bcse.v40i8.3
The present work outlines the synthetic approach and subsequent characterization of a new 1-phenoxy-2-propyl xanthate ligand (1-Pho-2-PrXant) and its corresponding divalent transition metal complexes, [M(1-Pho-2-PrXant)2], where M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), or Zn(II). The structures and physicochemical properties of these compounds were elucidated through a comprehensive suite of analytical methods, including AA, FT-IR, 1H/13C-NMR, and UV-visible spectroscopy, alongside magnetic properties and conductive behavior analyses. Data from the electronic spectra and magnetic moments strongly corroborate a tetrahedral coordination geometry for all complexes. In biological assays, the metal complexes displayed enhanced antibacterial potency compared to the uncomplexed ligand. To complement the observed results, Density Functional Theory (DFT) calculations utilizing the GGA-PBE functional were employed to determine optimized geometries, electronic structures, and thermodynamic properties. The theoretical findings correlated well with the experimental observations, confirming the proposed structures. These results highlight the potential of these novel xanthate complexes for development in various technological applications.
The purpose of this study is to determine the influence of the moisture content of leaves on the yield of essential oil, composition, and antimicrobial activity of Melaleuca leucadendra leaves grown in Songkhla Province, Thailand. The study addresses (1) how the oil yield was influenced by the length of drying process; (2) chemical profile, and (3) antibacterial and antifungal activities of the oils. Fresh leaves resulted in a better oil yield (21 mL) than those that had been sun-dried (7 mL), an indication of loss of volatile compounds because of the over-drying. Thirty compounds were found with GC-MS analysis, including bioactive sesquiterpenes and hydrocarbons. The essential oil was highly antimicrobial, especially against Staphylococcus aureus and Bacillus cereus (Zone of Inhibition = 12.5 mg/mL), and possessed fungistatic activity against Mucor sp., Aspergillus niger, and Candida albicans. Such revelations highlight the practicality of moisture control during post-harvest processing and the structural foundation on which M. leucadendra oil has been used in natural antimicrobial applications.
A new series of 4,6-diarylpyrimidin-2(1H)-one derivatives (1A-6A) was synthesized through an efficient one-pot, three-component reaction and proceeds via a Biginelli-like cyclocondensation mechanism. The method employs 2-aminoacetophenones, aryl aldehydes, and urea in the presence of barium hydroxide [Ba(OH)₂] as a catalyst to furnish the desired compounds in high yields and short reaction duration. This method offers a direct and atom-economical route to obtain structurally diverse pyrimidinone scaffolds. The structures of all the products were fully elucidated by IR, 1H-NMR, 13C-NMR, and mass spectrometry, confirming their purity and identity. The biological screening revealed that several of the derivatives synthesized (1A-6A) exhibited potent antimicrobial activity with inhibitory activity higher than that of standard antibiotics. Compound 6A showed the highest activity, while compounds 3A and 4A showed high antibacterial and antifungal activity, and compound 5A showed moderate antibacterial activity. Compound 1A demonstrated the lowest antimicrobial activity. The hemocompatibility assays further depicted the compounds to be biocompatible, emphasizing the compounds as promising bioinspired therapeutic agents. This study highlights a facile synthetic approach to the synthesis of novel pyrimidinones with possible biomedical applications. Molecular docking studies were used to investigate the binding conformations of the new pyrimidinones to the active sites of protein 3FYV. KEY WORDS: One-pot synthesis, Multicomponent reaction, 4,6-Diarylpyrimidin-2(1H)-ones, Antimicrobial activity, Hemocompatibility, Molecular docking Bull. Chem. Soc. Ethiop. 2026, 40(8), 1665-1678. DOI: https://dx.doi.org/10.4314/bcse.v40i8.6
. In this work, 1,3-thiazole/phenolic derivatives 4a-d were prepared via a multicomponent reaction of 3-bromo-4-hydroxybenzaldehyde (1), thiosemicarbazide (2), and some derivatives of phenacyl bromide 3a-d under microwave irradiation. These compounds were evaluated for their antibacterial activity against S. aureus, B. cereus, P. aeruginosa, and E. coli. It was found that most of the 1,3-thiazole/phenolic hybrids exhibited excellent antibacterial potential towards all bacterial species. In particular, the compound 4c was the most active candidate towards S. aureus and P. aeruginosa, with activity indices of 92.30% and 88.88%, respectively. Moreover, the antioxidant activity of thiazole derivatives 4a-d was investigated, and the obtained outcomes revealed that compound 4d showed the highest antioxidant activity (IC50 = 56.35 & micro;M), which was similar to the antioxidant effect of ascorbic acid (IC50 = 57.70 & micro;M). Furthermore, a docking study was carried out within E. coli gyrase B for the most potent compounds 4c and 4d. Docking results revealed that candidates 4c and 4d displayed favorable binding within the active site with binding energy scores equal to -8.54 and -8.73 kcal/ mol, respectively. Furthermore, an ADMET study was conducted for compounds 4c and 4d. The outcomes indicated that these constructed compounds might serve as lead candidates for antibiotic development.
Eco-friendly nanocomposites composed of chitosan, montmorillonite, polyaniline-anthranilic acid, and silver chloride (CS-MMT/PAAN/Ag@AgCl) were developed to serve as multifunctional platforms for controlled release and antimicrobial application. The nanocomposite was synthesized via ion-exchange intercalation of chitosan into montmorillonite (MMT) layers, followed by in-situ copolymerization of aniline and anthranilic acid using ferric chloride as an oxidant. Subsequently, silver nitrate was reduced with sodium borohydride to form silver chloride (Ag@AgCl) nanoparticles within the composite. The incorporation of chitosan effectively prevented copolymer aggregation, while the antimicrobial properties of silver chloride helped overcome limitations associated with MMT as a controlled release agent. Structural and morphological characterization was performed using FTIR, XRD, TGA, and TEM analysis. The nanocomposites were evaluated as a carrier for an azine-based thiosemicarbazide, with the loading behavior monitored by UV spectroscopy and modeled using Langmuir and the Freundlich isotherm. Additionally, the antibacterial activity of CS-MMT/PAAN/Ag@AgCl was evaluated to investigate the effect of MMT on the antimicrobial performance of this nanocomposite. KEY WORDS: Nanohybrid, Controlled release, Copolymer, Montmorillonite, Biological activity, Antimicrobial Bull. Chem. Soc. Ethiop. 2026, 40(8), 1733-1749. DOI: https://dx.doi.org/10.4314/bcse.v40i8.11
. Aphids, which have an extremely short life cycle, a high reproductive rate, and an efficient dispersal strategy, represent one of the most serious threats in crop production and are responsible for huge economic losses annually. The use of familiar insecticides was limited due to the development of resistance in pest populations, attributed to frequent applications of those agrochemicals over the years. Therefore, it is an important and challenging task for chemists to develop potent insecticidal agents with novel modes of action. Accordingly, our group is interested in synthesizing the title compounds and evaluating their insecticidal activity towards Bemisia tabaci (whitefly) insects. Ten pyridine derivatives and twenty-two thienopyridines containing mainly the ethyl nicotinate scaffold as a substructure were prepared in our laboratory. Most of them were evaluated for their insecticidal activity towards the nymphs and adult females of Bemisia tabaci (whitefly) insects by using the leaf dipping technique. Elemental and spectral analyses confirmed the structures of all compounds. Compounds 4-23 were evaluated as insecticidal agents against nymphs and adult females of Bemisia tabaci (whitefly) insects, and promising results were obtained. The ethyl nicotinates 6 exhibited the highest toxicity with an LC50 of 0.189 mg/L, which is the closest to the activity of acetamiprid (LC50: 0.161 mg/L), followed by that of 13 (LC50: 0.235 mg/L), while compound 16 (LC50: 0.808 mg/L) was the lowest active compound.
Recently, diabetes mellitus and Alzheimer’s disease have emerged as major chronic diseases and represent a significant public health challenge. Accordingly, this manuscript aims to synthesize new isatin-triazole-pyrazole hybrids 6a-d and confirm their chemical structures via spectroscopy (1H and 13C-NMR). In addition, the in vitro pharmacological potential of 6a-d as potential anti-diabetic and anti-Alzheimer agents was studied. The study also includes computational prediction and analysis of physicochemical properties, lipophilicity, drug-likeness, ADME properties (absorption, distribution, metabolism, and excretion), organ toxicity, and toxicity endpoint properties of 6a-d. In the future, the results of this manuscript will be the preliminary step for the modification and optimization of the chemical structure of the target compounds, in addition to more advanced in vitro and in vivo studies with the purpose of discovering new drugs to address chronic diseases. KEY WORDS: Isatin-pyrazole derivatives, Isatin-triazole derivative, Diabetes mellitus, Molecular hybridization, Physicochemical properties, Computational toxicity assessments Bull. Chem. Soc. Ethiop. 2026, 40(8), 1691-1706. DOI: https://dx.doi.org/10.4314/bcse.v40i8.8
A series of cationic iridium(III) complexes of general formula [Ir(2,4′-bpy)₂(N^N)]PF₆, where N^N corresponds to N-methyl-, N, N-dimethyl-, and N-phenyl-o-phenylenediamine (complexes 1-3), were synthesized and fully characterized by high-resolution mass spectrometry and multinuclear NMR spectroscopy. Their photophysical properties were investigated using UV-Vis and emission spectroscopy, supported by density functional theory (DFT) calculations. This study examined a systematic replacement of diimine ancillary ligands with σ-donor diamine ligands, introducing substituents of increasing hydrophobic character, and the influence of electronic donation and intermolecular π-stacking on the excited-state properties. DFT results indicate that the weak electron-donating nature of the diamine ligands enhances the contribution of the cyclometallated ligand to the LUMO, modifying the emission character. All complexes exhibit blue emission centered at 372, 442, and 418 nm for 1–3, respectively. While elongated Ir–N bond distances correlate with low quantum yields for 1 and 2, complex 3 displays an improved quantum yield (20 %), attributed to increased hydrophobicity and stabilizing π-stacking interactions. These results highlight the critical role of hydrophobic and π-stacking effects in modulating the emission behavior of diamine-based iridium complexes. KEY WORDS: Photophysical properties, Density functional theory, Iridium complexes, Diamine ancillary ligands Bull. Chem. Soc. Ethiop. 2026, 40(8), 1679-1690. DOI: https://dx.doi.org/10.4314/bcse.v40i8.7
