International Journal of Chemistry

International Journal of Chemistry | Vol. 7, No. 4, April 2016 | pp. 25–32

DOI: 10.46882/2016/IJC/000091

Article Type: Original Research Paper

Title: Green synthesis of Platinum Nanoparticles Using Aqueous Bark Extract of Prunus africana and Their Heterogeneous Catalytic Efficiency

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 platinum 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 platinum nanoparticles (PtNPs) utilizing the aqueous bark extract of Prunus africana 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 platinum chloride precursor band over 60 minutes. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses showed highly spherical nanoparticles with an average particle diameter of 14 nm. X-ray diffraction (XRD) patterns confirmed the face-centered cubic crystalline structure of the biosynthesized metallic platinum. Fourier-transform infrared (FT-IR) spectroscopy indicated that water-soluble biomolecules, primarily pentacyclic triterpenes and phytosterols within the bark matrix, were responsible for capping and protecting the PtNPs against structural agglomeration. The catalytic efficiency of the synthesized PtNPs was evaluated by tracking the reduction of eosin Y dye by sodium borohydride (NaBH₄) in an aqueous system. In the absence of a catalyst, the reaction proceeded slowly, but the introduction of PtNPs accelerated the degradation process, achieving 97.4% decolorization within 10 minutes. The dye degradation kinetics conformed strictly to the pseudo-first-order kinetic model with a rate constant of 0.284 min⁻¹, indicating excellent catalytic potential for chemical waste neutralization.

Keywords: Platinum nanoparticles; Green synthesis; Prunus africana; Biosynthesis; Heterogeneous catalysis; Eosin Y degradation

Manuscript Timeline: Received: October 12, 2015; Revised: November 24, 2015; Accepted: December 18, 2015; Published: April 02, 2016.

Citation: Musa, S. I., & Al-Jubouri, K. A. (2016). Green synthesis of Platinum Nanoparticles Using Aqueous Bark Extract of Prunus africana and Their Heterogeneous Catalytic Efficiency. International Journal of Chemistry, 7(4), 25–32.

International Journal of Chemistry | Vol. 7, No. 1, January 2016 | pp. 1–8

DOI: 10.46882/2016/IJC/000088

Article Type: Original Research Paper

Title: Development and Validation of a Spectrophotometric Method for Quantitative Determination of Norfloxacin in Pharmaceutical Tablets

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 norfloxacin in tablet dosage forms. The analytical procedure relied on the reaction of norfloxacin with 2,4-dinitrophenylhydrazine in an acidic medium, generating a highly stable yellow-colored hydrazone derivative monitored spectrophotometrically at its absorption maximum of 420 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 norfloxacin 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; Norfloxacin; Chemical derivation; Method validation; Pharmaceuticals; Quality control

Manuscript Timeline: Received: May 02, 2015; Revised: June 15, 2015; Accepted: July 20, 2015; Published: January 03, 2016.

Citation: Effiong, E. O., & Cardoso, J. M. S. (2016). Development and Validation of a Spectrophotometric Method for Quantitative Determination of Norfloxacin in Pharmaceutical Tablets. International Journal of Chemistry, 7(1), 1–8.

International Journal of Chemistry | Vol. 7, No. 3, March 2016 | pp. 17–24

DOI: 10.46882/2016/IJC/000090

Article Type: Original Research Paper

Title: Thermodynamic Modeling, Kinetic Runs, and Multilayer Adsorption of Malachite Green Dye onto Modified Montmorillonite 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 cationic triphenylmethane dyes like Malachite Green 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 montmorillonite clay (SMM) 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 SMM as an affordable material for industrial dye wastewater treatment.

Keywords: Montmorillonite clay; Surfactant modification; Malachite green; Adsorption isotherm; Chemisorption; Thermodynamic parameters

Manuscript Timeline: Received: July 20, 2015; Revised: August 28, 2015; Accepted: September 15, 2015; Published: March 04, 2016.

Citation: Yusuf, A. D., & Al-Ghamdi, M. A. (2016). Thermodynamic Modeling, Kinetic Runs, and Multilayer Adsorption of Malachite Green Dye onto Modified Montmorillonite Clay. International Journal of Chemistry, 7(3), 17–24.

International Journal of Chemistry | Vol. 7, No. 2, February 2016 | pp. 9–16

DOI: 10.46882/2016/IJC/000089

Article Type: Original Research Paper

Title: Synthesis, Computational Modeling, and Enzymatic Inhibition Screening of Novel Coumarin-Linked Hydrazone 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 Oxford, 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 coumarin-linked hydrazone derivatives were synthesized via the condensation of 3-acetylcoumarin with various substituted benzohydrazides 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 coumarin lactone 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: Coumarin; Hydrazones; Alpha-glucosidase; Enzyme inhibition; Molecular docking; Antidiabetic drug design

Manuscript Timeline: Received: June 12, 2015; Revised: July 25, 2015; Accepted: August 18, 2015; Published: February 06, 2016.

Citation: Kolawole, O. M., & Watson, E. R. (2016). Synthesis, Computational Modeling, and Enzymatic Inhibition Screening of Novel Coumarin-Linked Hydrazone Derivatives. International Journal of Chemistry, 7(2), 9–16.

International Journal of Chemistry | Vol. 6, No. 4, April 2015 | pp. 25–32

DOI: 10.46882/2015/IJC/000079

Article Type: Original Research Paper

Title: Ultrasonic Speeds, Excess Volumetric Quantities, and Intermolecular Hydrogen Bond Strengths of Binary Fluids of N-Methylformamide with Diols

Names of Authors: E. C. Chiemeka¹, M. A. K. Al-Saeed²*

Authors’ Affiliations:
¹Department of Chemistry, Federal University of Technology, Owerri, Nigeria.
²Department of Chemistry, University of Khartoum, Khartoum, Sudan.

Abstract: Investigating ultrasonic velocities and excess thermodynamic parameters across multi-component fluid systems provides valuable foundational insights into industrial solvent behaviors and intermolecular hydrogen bonding configurations. This study presents the experimental determination of ultrasonic speed (u), density (rho), and dynamic viscosity (eta) for binary liquid mixtures of N-methylformamide (NMF) with ethylene glycol, diethylene glycol, and triethylene glycol over the complete composition range at temperatures of 298.15 K, 308.15 K, and 318.15 K under atmospheric pressure. From these basic data, excess molar volumes (V^E) and excess isentropic compressibilities (kappa_s^E) were calculated. The resulting datasets were successfully fitted to the Redlich-Kister polynomial expression to compute binary interaction coefficients and standard standard deviations. All investigated liquid mixtures exhibited highly negative excess molar volumes (V^E) and negative excess isentropic compressibilities (kappa_s^E) across all composition bounds. These strong negative deviations confirm dense interstitial molecular packing and intense intermolecular hydrogen bonding networks between the amidic carbonyl of NMF and the terminal hydroxyl protons of the diols, which decrease in intensity as thermal energy increases.

Keywords: Ultrasonic speed; Excess molar volume; Isentropic compressibility; N-methylformamide; Redlich-Kister equation; Hydrogen bonding

Manuscript Timeline: Received: May 11, 2014; Revised: June 22, 2014; Accepted: July 18, 2014; Published: April 02, 2015.

Citation: Chiemeka, E. C., & Al-Saeed, M. A. K. (2015). Ultrasonic Speeds, Excess Volumetric Quantities, and Intermolecular Hydrogen Bond Strengths of Binary Fluids of N-Methylformamide with Diols. International Journal of Chemistry, 6(4), 25–32.

International Journal of Chemistry | Vol. 6, No. 3, March 2015 | pp. 17–24

DOI: 10.46882/2015/IJC/000078

Article Type: Original Research Paper

Title: Electrochemical Properties and Capacitive Performance of Polypyrrole-Manganese Dioxide Composite Electrodes for Supercapacitors

Names of Authors: U. B. Aliyu¹, K. N. S. Tan²*

Authors’ Affiliations:
¹Department of Chemistry, Ahmadu Bello University, Zaria, Nigeria.
²Department of Chemistry, National University of Singapore, Singapore.

Abstract: The fabrication of hybrid electrochemical capacitors requires electrode configurations that successfully merge high pseudocapacitive charge transfer with structural network longevity. This research outlines the synthesis and supercapacitive performance of polypyrrole-manganese dioxide (PPy-MnO₂) nanocomposites prepared via the in situ chemical oxidative polymerization of pyrrole monomers in the presence of hydrothermally prepared MnO₂ nanorods. The microstructural morphology and chemical networks of the composite films were analyzed using field emission scanning electron microscopy (FESEM), FT-IR, and Raman spectroscopy. FESEM images confirmed the uniform encapsulation of a thin amorphous PPy layer around the highly crystalline MnO₂ nanorods. Electrochemical characterization was carried out in a three-electrode system using a 1.0 M Na₂SO₄ electrolyte via cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) cycles. The optimized PPy-MnO₂ composite electrode delivered a maximum specific capacitance of 435 F/g at a current density of 1.0 A/g, outperforming standalone pure polypyrrole (210 F/g). Electrochemical impedance spectroscopy (EIS) data showed a low internal charge-transfer resistance of 0.42 ohms, and cyclic evaluations proved that the electrode retained 88.4% of its capacitance after 2000 continuous cycles.

Keywords: Polypyrrole; Manganese dioxide; Nanocomposites; Supercapacitors; Cyclic voltammetry; Specific capacitance

Manuscript Timeline: Received: May 02, 2014; Revised: June 15, 2014; Accepted: July 12, 2014; Published: March 04, 2015.

Citation: Aliyu, U. B., & Tan, K. N. S. (2015). Electrochemical Properties and Capacitive Performance of Polypyrrole-Manganese Dioxide Composite Electrodes for Supercapacitors. International Journal of Chemistry, 6(3), 17–24.