International Journal of Chemistry

International Journal of Chemistry | Vol. 17, No. 6, June 2026 | pp. 41–48

DOI: 10.46882/2026/IJC/000212

Article Type: Original Research Paper

Title: Thermodynamic Modeling, Kinetic Runs, and Multilayer Adsorption of Acid Yellow 17 Dye onto Modified Bentonite Clay

Names of Authors: A. D. Yusuf¹, M. A. Al-Ghamdi²*

Authors’ Affiliations:
¹Department of Industrial Chemistry, Federal University of Technology, Yola, Nigeria.
²Department of Chemistry, Qatar University, Doha, Qatar.

Abstract: The release of highly stable anionic azo dyes like Acid Yellow 17 from textile processing factories causes significant environmental and toxicity hazards in surface water channels. This study examines the adsorptive uptake performance of a surfactant-modified bentonite clay (SMB) prepared via chemical functionalization with hexadecyltrimethylammonium bromide (HDTMA-Br). The structural parameters of raw and modified clays were characterized using X-ray diffraction (XRD) and FT-IR spectroscopy. Adsorption operations were conducted via batch runs, monitoring changes in contact time, solution pH, initial dye loading concentrations, and system temperatures. The equilibrium datasets fit closely with the Freundlich isotherm model, demonstrating successful multilayer dye attachment onto the hydrophobic surfactant bilayers. Kinetic parameters matched the intra-particle diffusion expressions alongside a pseudo-second-order mechanism, showing that chemisorption reactions controlled the mass transfer rates. Thermodynamic constants showed that the adsorption process was endothermic (delta H° = 22.4 kJ/mol) and caused an increase in system randomness at the solid-solution interface (delta S° = 74.2 J/mol K). Negative values of Gibbs free energy (delta G°) spanning from -2.4 to -5.8 kJ/mol across the 298 to 328 K range confirmed process spontaneity, positioning SMB as an affordable material for industrial dye wastewater treatment.

Keywords: Bentonite clay; Surfactant modification; Acid yellow 17; Adsorption isotherm; Chemisorption; Thermodynamic parameters

Manuscript Timeline: Received: September 10, 2024; Revised: October 22, 2024; Accepted: November 15, 2024; Published: June 03, 2026.

Citation: Yusuf, A. D., & Al-Ghamdi, M. A. (2026). Thermodynamic Modeling, Kinetic Runs, and Multilayer Adsorption of Acid Yellow 17 Dye onto Modified Bentonite Clay. International Journal of Chemistry, 17(6), 41–48.

International Journal of Chemistry | Vol. 17, No. 3, March 2026 | pp. 17–24

DOI: 10.46882/2026/IJC/000209

Article Type: Original Research Paper

Title: Geochemical Speciation, Spatial Distribution, and Bioavailability of Chromium and Zinc in Urban Estuarine Sediments

Names of Authors: C. I. Obi¹, S. H. Kim²*

Authors’ Affiliations:
¹Department of Pure and Industrial Chemistry, University of Port Harcourt, Port Harcourt, Nigeria.
²Department of Chemistry, Seoul National University, Seoul, South Korea.

Abstract: Total concentrations of heavy metals are insufficient to assess ecological risk in coastal bodies because environmental mobility and bioavailability depend heavily on specific chemical binding forms. This study evaluates the total concentration and geochemical speciation fractions of chromium (Cr) and zinc (Zn) in surface sediments collected from an urban estuarine system exposed to municipal and industrial waste discharges. Quantitative analysis was performed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) following the modified BCR three-step sequential extraction procedure. The total metal concentrations followed the sequence: Zn > Cr across all sampling locations. Spatial mapping revealed significant pollutant accumulation near industrial drainage channels. Speciation patterns demonstrated that a high proportion of zinc (45.2%) was associated with the acid-soluble and exchangeable fractions, suggesting high structural instability and bioavailable risks to benthic organisms. Conversely, chromium was primarily bound within the residual and organic matrices, indicating low immediate mobility under baseline pH conditions. The Risk Assessment Code (RAC) calculated for zinc indicated a high environmental hazard rating, highlighting a strong need for local effluent regulatory frameworks.

Keywords: Estuarine sediments; Heavy metals; BCR protocol; Geochemical speciation; Bioavailability; Zinc hazard

Manuscript Timeline: Received: August 05, 2024; Revised: September 18, 2024; Accepted: October 12, 2024; Published: March 11, 2026.

Citation: Obi, C. I., & Kim, S. H. (2026). Geochemical Speciation, Spatial Distribution, and Bioavailability of Chromium and Zinc in Urban Estuarine Sediments. International Journal of Chemistry, 17(3), 17–24.

International Journal of Chemistry | Vol. 17, No. 5, May 2026 | pp. 33–40

DOI: 10.46882/2026/IJC/000211

Article Type: Original Research Paper

Title: Synthesis, Computational Modeling, and Enzymatic Inhibition Screening of Novel N-Substituted Glutarimide Derivatives

Names of Authors: O. M. Kolawole¹, E. R. Watson²*

Authors’ Affiliations:
¹Department of Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria.
²Department of Chemistry, University of Cambridge, Cambridge, United Kingdom.

Abstract: Inhibiting alpha-glucosidase represents a critical therapeutic target for managing postprandial hyperglycemia in type 2 diabetes mellitus. In this work, five novel N-substituted glutarimide derivatives were synthesized via the condensation of glutaric anhydride with various substituted aniline compounds in the presence of catalytic glacial acetic acid. The molecular frameworks of the synthesized targets were verified using elemental analysis, FT-IR, and ¹H-NMR spectroscopy. In vitro alpha-glucosidase enzyme inhibition assays revealed that compound 3c, bearing a p-nitro substituent, possessed the highest inhibitory potency, showing an IC50 value of 12.4 μM, compared to the acarbose clinical standard (IC50 = 38.2 μM). To investigate specific binding configurations, in silico molecular docking simulations were run inside the catalytic domain of alpha-glucosidase using AutoDock Vina software. The computational docking models demonstrated that the glutarimide carbonyl forms stable hydrogen bonds with Asp214 and Arg315 residues. The aromatic ring extensions fit well into the hydrophobic pocket, engaging in significant pi-pi stacking interactions with Phe178. These structural contacts stabilize the ligand-protein topology, explaining the sub-micromolar inhibition constants and presenting a potential scaffold for further antidiabetic drug design.

Keywords: Glutarimide; Chemical synthesis; Alpha-glucosidase; Enzyme inhibition; Molecular docking; Antidiabetic drug design

Manuscript Timeline: Received: September 02, 2024; Revised: October 12, 2024; Accepted: November 05, 2024; Published: May 04, 2026.

Citation: Kolawole, O. M., & Watson, E. R. (2026). Synthesis, Computational Modeling, and Enzymatic Inhibition Screening of Novel N-Substituted Glutarimide Derivatives. International Journal of Chemistry, 17(5), 33–40.

International Journal of Chemistry | Vol. 17, No. 8, August 2026 | pp. 65–72

DOI: 10.46882/2026/IJC/000215

Article Type: Original Research Paper

Title: Asymmetric Synthesis and Molecular Docking of Novel Chiral Oxazoline Ligands for Catalytic Carbon-Carbon Bond Formations

Names of Authors: E. R. Hoffmann¹, J. C. Smith²*

Authors’ Affiliations:
¹Department of Organic Chemistry, Heidelberg University, Heidelberg, Germany.
²Department of Chemistry, Yale University, New Haven, Connecticut, United States of America.

Abstract: The design of highly stereoselective chiral ligands remains a critical frontier in modern synthetic organic chemistry for constructing complex pharmaceutical intermediates. This study details the asymmetric synthesis of a new series of C2-symmetric bis(oxazoline) ligands derived from readily available L-amino acids. The chemical architectures of the synthesized ligands were verified using high-resolution mass spectrometry (HRMS), Fourier-transform infrared (FT-IR) spectroscopy, and multi-nuclear magnetic resonance (¹H-NMR and ¹³C-NMR) spectroscopy. Optical rotation tracking confirmed high enantiomeric purity. The coordination chemistry of these ligands was evaluated by preparing copper(II) complexes in situ, which were then deployed as catalysts in asymmetric Diels-Alder reactions. Enantiomeric excesses (ee) up to 96.5% were achieved under optimized conditions at 243 K. To explore the mechanistic pathways and structural parameters governing the stereochemical outcomes, in silico molecular docking simulations and density functional theory (DFT) computations were executed using the B3LYP functional. The computational models demonstrated that the bulky tert-butyl substituents on the oxazoline rings create a highly constrained chiral pocket, shielding one face of the coordinated dienophile. This steric framework forces the incoming diene to attack exclusively from the less hindered re-face, explaining the exceptional enantioselectivity and providing a reliable scaffold for targeted catalyst optimization.

Keywords: Asymmetric synthesis; Chiral ligands; Bis(oxazoline); Diels-Alder reaction; Molecular docking; Density functional theory

Manuscript Timeline: Received: February 12, 2025; Revised: April 18, 2025; Accepted: May 20, 2025; Published: August 03, 2026.

Citation: Hoffmann, E. R., & Smith, J. C. (2026). Asymmetric Synthesis and Molecular Docking of Novel Chiral Oxazoline Ligands for Catalytic Carbon-Carbon Bond Formations. International Journal of Chemistry, 17(8), 65–72.

International Journal of Chemistry | Vol. 17, No. 4, April 2026 | pp. 25–32

DOI: 10.46882/2026/IJC/000210

Article Type: Original Research Paper

Title: Development and Validation of a Spectrophotometric Method for Quantitative Determination of Ofloxacin in Dosage Forms

Names of Authors: E. O. Effiong¹, J. M. S. Cardoso²*

Authors’ Affiliations:
¹Department of Chemistry, University of Uyo, Uyo, Nigeria.
²Department of Pharmacy, University of Coimbra, Coimbra, Portugal.

Abstract: Developing rapid, low-cost analytical protocols is essential for routine quality monitoring and the detection of substandard antibiotic formulations in clinical testing laboratories. This paper describes the development and validation of a simple UV-Vis spectrophotometric method for the quantification of offloxacin in commercial tablet dosage forms. The analytical procedure relied on the reaction of offloxacin with iron(III) chloride in an acidic medium, generating a highly stable yellow-colored complex monitored spectrophotometrically at its absorption maximum of 385 nm. Method validation parameters followed the International Council for Harmonisation (ICH) guidelines. Excellent linearity was established over a concentration range of 2.0 to 25.0 mg/L with a correlation coefficient (R²) of 0.999. The limit of detection (LOD) and limit of quantification (LOQ) were determined to be 0.08 mg/L and 0.24 mg/L, respectively. Precision assessments yielded relative standard deviations (RSD) below 1.8%. The validated method was successfully applied to screen five commercial brands of offloxacin tablets, producing recovery percentages between 98.6% and 101.4% with no interference from common tablet excipients, making it suitable for routine quality control setups.

Keywords: UV-Vis spectrophotometry; Offloxacin; Complexation; Method validation; Pharmaceuticals; Quality control

Manuscript Timeline: Received: August 14, 2024; Revised: September 25, 2024; Accepted: October 15, 2024; Published: April 02, 2026.

Citation: Effiong, E. O., & Cardoso, J. M. S. (2026). Development and Validation of a Spectrophotometric Method for Quantitative Determination of Ofloxacin in Dosage Forms. International Journal of Chemistry, 17(4), 25–32.

International Journal of Chemistry | Vol. 17, No. 7, July 2026 | pp. 49–56

DOI: 10.46882/2026/IJC/000213

Article Type: Original Research Paper

Title: Green Synthesis of Silver-Copper Core-Shell Nanoparticles Using Extract of Podocarpus gracilior and Their Catalytic Efficiencies

Names of Authors: S. I. Musa¹, K. A. Al-Jubouri²*

Authors’ Affiliations:
¹Department of Chemistry, University of Jos, Jos, Nigeria.
²Department of Chemistry, University of Baghdad, Baghdad, Iraq.

Abstract: The biological synthesis of bimetallic noble metal nanoparticles using medicinal plant extracts offers an eco-friendly and economically sustainable alternative to traditional chemical reduction protocols. This study details the green synthesis of stable copper-silver (Cu-Ag) core-shell nanoparticles utilizing the aqueous leaf extract of Podocarpus gracilior as both a reducing and stabilizing agent. The bioreduction process was monitored via UV-Vis spectrophotometry, which revealed the gradual decay and disappearance of the metal precursor bands over 60 minutes. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses showed highly spherical nanoparticles with an average particle diameter of 16 nm. X-ray diffraction (XRD) patterns confirmed the shell crystalline structure of the biosynthesized bimetallic system. Fourier-transform infrared (FT-IR) spectroscopy indicated that water-soluble biomolecules, primarily flavonoids and terpenoids within the leaf matrix, were responsible for capping and protecting the nanoparticles against structural agglomeration. The catalytic efficiency of the synthesized Cu-Ag nanoparticles was evaluated by tracking the reduction of rhodamine B dye by sodium borohydride (NaBH₄) in an aqueous system. In the absence of a catalyst, the reaction proceeded slowly, but the introduction of bimetallic nanoparticles accelerated the degradation process, achieving 97.4% decolorization within 10 minutes, outperforming monometallic controls.

Keywords: Bimetallic nanoparticles; Green synthesis; Podocarpus gracilior; Core-shell structure; Heterogeneous catalysis; Rhodamine B degradation

Manuscript Timeline: Received: October 12, 2024; Revised: November 24, 2024; Accepted: December 18, 2024; Published: July 08, 2026.

Citation: Musa, S. I., & Al-Jubouri, K. A. (2025). Green Synthesis of Silver-Copper Core-Shell Nanoparticles Using Extract of Podocarpus gracilior and Their Catalytic Efficiencies. International Journal of Chemistry, 17(7), 49–56.