International Journal of Chemistry

International Journal of Chemistry | Vol. 4, No. 1, January 2013 | pp. 1–8

DOI: 10.46882/2013/IJC/000052

Article Type: Original Research Paper

Title: Phytochemical Screening, Volatile Fingerprinting, and Antiprotozoal Capacity of Crude Extracts from Carica papaya Seeds

Names of Authors: A. E. Ogunkoya¹, J. M. S. Cabral²*

Authors’ Affiliations:
¹Department of Chemistry, Ekiti State University, Ado-Ekiti, Nigeria.
²Department of Bioengineering, Instituto Superior Técnico, Lisbon, Portugal.

Abstract: Carica papaya seeds are frequently utilized in traditional tropical medicine as an anthelmintic agent, yet their volatile bioactive profiles require deep chromatographic mapping to clarify structural efficacy. This investigation reports the qualitative phytochemical screening, volatile constituent identification via Gas Chromatography-Mass Spectrometry (GC-MS), and in vitro antiprotozoal capacity of hexane, ethyl acetate, and methanol seed extracts. Qualitative testing revealed a heavy presence of alkaloids, benzyl glucosinolates, phenolics, and flavonoids concentrated within the semi-polar ethyl acetate fraction. GC-MS profiling of the ethyl acetate extract identified 15 prominent peaks, with benzyl isothiocyanate (38.42%), oleic acid (22.15%), and palmitic acid methyl ester (12.30%) emerging as the primary bioactive components. The antiprotozoal potential was evaluated in vitro utilizing susceptibility assays against Giardia lamblia trophozoites, benchmarked against metronidazole. The ethyl acetate extract displayed the highest antiprotozoal activity, yielding an IC50 value of 15.8 μg/mL, compared to 2.4 μg/mL achieved by the standard drug. A linear correlation was observed between the concentration of benzyl isothiocyanate and protozoal cell mortality, validating that thiocyanate derivatives act as the driving contributors to structural cellular disruption, lending scientific validation to traditional medical usage.

Keywords: Carica papaya; Seed extract; Gas Chromatography-Mass Spectrometry; Benzyl isothiocyanate; Antiprotozoal activity; Giardia lamblia

Manuscript Timeline: Received: July 02, 2012; Revised: August 14, 2012; Accepted: September 10, 2012; Published: January 03, 2013.

Citation: Ogunkoya, A. E., & Cabral, J. M. S. (2013). Phytochemical Screening, Volatile Fingerprinting, and Antiprotozoal Capacity of Crude Extracts from Carica papaya Seeds. International Journal of Chemistry, 4(1), 1–8.

International Journal of Chemistry | Vol. 4, No. 10, October 2013 | pp. 73–80

DOI: 10.46882/2013/IJC/000061

Article Type: Original Research Paper

Title: Synthesis, Characterization, and Photoluminescence Profiles of Novel Europium(III) Complexes with Phenanthroline Derivatives

Names of Authors: A. O. Balogun¹, L. M. Martinez²*

Authors’ Affiliations:
¹Department of Chemistry, University of Ilorin, Ilorin, Nigeria.
²Department of Physical Chemistry, National Autonomous University of Mexico, Mexico City, Mexico.

Abstract: Trivalent lanthanide coordination compounds possess intense monochromatic emissions that make them valuable components for light-emitting diodes, optical sensors, and biochemical assays. This study details the synthesis and characterization of novel europium(III) complexes using 1,10-phenanthroline and beta-diketone ligands. The newly synthesized rare-earth complexes were characterized using elemental analysis, molar conductance, Fourier-transform infrared (FT-IR) spectroscopy, and ultraviolet-visible (UV-Vis) absorption spectrophotometry. Analytical data confirmed a 1:1:3 metal-to-ligand stoichiometric configuration, corresponding to the general molecular formula [Eu(L)₃(phen)], where L represents the deprotonated beta-diketone fraction. Molar conductance measurements in acetonitrile established that the complexes are completely non-electrolytic. FT-IR spectra confirmed that both ligands coordinate to the central Eu(III) ion via the carbonyl oxygens and the azomethine nitrogen atoms. Room-temperature photoluminescence spectra exhibited highly intense, narrow emission lines characteristic of the Eu(III) ion, dominated by the electric dipole transition (⁵D₀ to ⁷F₂) at 612 nm. The high luminescence quantum yield (45.2%) and long emission lifetime (0.84 ms) indicate efficient energy transfer from the organic ligands to the central metal ion via an intramolecular antenna mechanism, presenting a robust framework for developing red-emitting materials.

Keywords: Europium complexes; Rare earth elements; Photoluminescence; Intramolecular energy transfer; Antenna effect; Coordination chemistry

Manuscript Timeline: Received: January 15, 2013; Revised: March 02, 2013; Accepted: April 10, 2013; Published: October 04, 2013.

Citation: Balogun, A. O., & Martinez, L. M. (2013). Synthesis, Characterization, and Photoluminescence Profiles of Novel Europium(III) Complexes with Phenanthroline Derivatives. International Journal of Chemistry, 4(10), 73–80.

International Journal of Chemistry | Vol. 4, No. 11, November 2013 | pp. 81–88

DOI: 10.46882/2013/IJC/000062

Article Type: Original Research Paper

Title: Adsorptive Sequestration of Nickel(II) Ions from Industrial Effluents Using Sulfonated Tea Waste Matrices

Names of Authors: E. N. Chidi¹, J. P. van der Berg²*

Authors’ Affiliations:
¹Department of Pure and Industrial Chemistry, Nnamdi Azikiwe University, Awka, Nigeria.
²Department of Chemical Engineering, Delft University of Technology, Delft, Netherlands.

Abstract: The contamination of aquatic networks by toxic industrial nickel residues presents persistent public health and ecological hazards due to its bioaccumulative nature. This research examines the adsorptive performance of chemically modified black tea waste prepared via sulfonation with concentrated sulfuric acid for the removal of Ni(II) ions from aqueous systems. Structural configurations and morphology changes were monitored using scanning electron microscopy (SEM) and FT-IR spectroscopy, which confirmed the successful introduction of sulfonic acid (-SO₃H) active functional groups onto the biomass surface. Batch extraction experiments evaluated parameters of solution pH, contact time, adsorbent dosage, and initial metal concentrations. Maximum Ni(II) removal was achieved at an optimum pH of 6.0, with an equilibrium contact period of 90 minutes. Equilibrium data matched the Langmuir isotherm expressions perfectly, indicating a maximum monolayer adsorption capacity of 52.64 mg/g at 298 K. Sorption kinetics conformed to the pseudo-second-order model with high correlation coefficients (R² > 0.998), proving that chemical ion exchange reactions governed the phase transfer process. Thermodynamic parameters confirmed that the sorption mechanism was spontaneous (delta G° = -4.25 kJ/mol) and endothermic, establishing sulfonated tea waste as an affordable material for metal recovery.

Keywords: Tea waste; Chemical modification; Sulfonation; Nickel removal; Adsorption kinetics; Chemisorption

Manuscript Timeline: Received: February 02, 2013; Revised: March 18, 2013; Accepted: April 22, 2013; Published: November 08, 2013.

Citation: Chidi, E. N., & van der Berg., J. P. (2013). Adsorptive Sequestration of Nickel(II) Ions from Industrial Effluents Using Sulfonated Tea Waste Matrices. International Journal of Chemistry, 4(11), 81–88.

International Journal of Chemistry | Vol. 4, No. 4, April 2013 | pp. 25–32

DOI: 10.46882/2013/IJC/000055

Article Type: Original Research Paper

Title: Spatial Analysis, Speciation, and Bioavailability of Mercury Contamination in Well Water Networks near Landfills

Names of Authors: T. H. Awotunde¹, L. A. Rossi²*

Authors’ Affiliations:
¹Department of Chemistry, Federal University of Agriculture, Abeokuta, Nigeria.
²Department of Environmental Chemistry, University of São Paulo, São Paulo, Brazil.

Abstract: Municipal landfill leachate containment failures result in toxic heavy metal migrations into shallow groundwater aquifers, creating chronic ingestion risks. This study monitors the spatial variations, chemical speciation, and bioavailability indices of toxic mercury (Hg) compounds across twenty household well water sources positioned around a major urban dumpsite. Water monitoring was carried out over consecutive wet and dry cycles. Total mercury levels and organic methylmercury fractions were quantified utilizing cold vapor atomic fluorescence spectrometry (CV-AFS). Total mercury concentrations ranged from 0.45 to 4.85 μg/L, with 35% of monitored groundwater sites surpassing the strict WHO drinkable contaminant threshold of 6.0 μg/L. Speciation analysis showed that inorganic Hg(II) was the dominant species, though methylmercury accounted for up to 12.5% of total burden profiles at down-gradient coordinates. Seasonal mapping confirmed elevated total mercury mobilization during the rainy period, indicating rain-induced plume leaching. Chronic Daily Intake (CDI) projections and Hazard Quotient (HQ) risk parameters for child consumption cohorts surpassed 2.5 near historical waste dump boundaries, emphasizing an immediate public healthcare concern and a need for local membrane filtration arrays.

Keywords: Groundwater pollution; Mercury speciation; Methylmercury; Atomic fluorescence spectrometry; Landfill leachate; Hazard quotient

Manuscript Timeline: Received: August 14, 2012; Revised: September 25, 2012; Accepted: October 15, 2012; Published: April 05, 2013.

Citation: Awotunde, T. H., & Rossi, L. A. (2013). Spatial Analysis, Speciation, and Bioavailability of Mercury Contamination in Well Water Networks near Landfills. International Journal of Chemistry, 4(4), 25–32.

International Journal of Chemistry | Vol. 4, No. 9, September 2013 | pp. 65–72

DOI: 10.46882/2013/IJC/000060

Article Type: Original Research Paper

Title: Synthesis, Characterization, and Antifungal Activity of Novel Chloroquine-Based Transition Metal Complexes

Names of Authors: A. A. Yusuf¹, P. K. Mukherjee²*

Authors’ Affiliations:
¹Department of Chemistry, Ahmadu Bello University, Zaria, Nigeria.
²Department of Pharmaceutical Technology, Jadavpur University, Kolkata, India.

Abstract: The persistent emergence of drug resistance profiles among pathogenic fungal strains requires the structural modification of classic quinoline scaffolds via coordination to transition metal ions to boost clinical performance. This research outlines the synthesis, structural characterization, and in vitro antifungal testing of novel copper(II), nickel(II), and cobalt(II) complexes coordinated with chloroquine diphosphate ligands. The synthesized coordination compounds were profiled utilizing elemental analysis, molar conductance measurements, magnetic susceptibility, and FT-IR spectroscopy. Analytical metrics established a 1:1 metal-to-ligand stoichiometric coordination pattern for all complexes, corresponding to a general structural configuration of [M(CQ)Cl₂], where CQ represents the chloroquine base molecule. Molar conductance tests in DMSO indicated a non-electrolytic nature. FT-IR spectra confirmed that chloroquine acts as a bidentate ligand, binding to the metal centers via the quinoline ring nitrogen and the secondary aliphatic amine nitrogen atoms. In vitro antifungal evaluation was conducted against Candida albicans and Aspergillus niger isolates via the disk diffusion test. The copper(II)-chloroquine complex demonstrated a two-fold increase in mycelial growth inhibition compared to standalone uncoordinated chloroquine, which is explained via cell permeability and chelation principles.

Keywords: Chloroquine; Metal complexes; Antifungal activity; FT-IR spectroscopy; Candida albicans; Chelation theory

Manuscript Timeline: Received: October 20, 2012; Revised: November 28, 2012; Accepted: January 05, 2013; Published: September 10, 2013.

Citation: Yusuf, A. A., & Mukherjee, P. K. (2013). Synthesis, Characterization, and Antifungal Activity of Novel Chloroquine-Based Transition Metal Complexes. International Journal of Chemistry, 4(9), 65–72.

International Journal of Chemistry | Vol. 4, No. 6, June 2013 | pp. 41–48

DOI: 10.46882/2013/IJC/000057

Article Type: Original Research Paper

Title: Mechanochemical Properties and Microstructural Framework of Fly Ash Based Geopolymer Concrete Containing Slag Additives

Names of Authors: T. S. Ani¹, M. F. Montemor²*

Authors’ Affiliations:
¹Department of Electronic and Chemical Engineering, Enugu State University of Science and Technology, Enugu, Nigeria.
²Department of Chemical Engineering, Instituto Superior Técnico, Lisbon, Portugal.

Abstract: The replacement of conventional cement with fly ash-based geopolymer binders helps lower industrial greenhouse gas footprints, though curing parameters require mechanical optimization via supplementary calcium sources. This research tracks the structural development and mechanical profiles of binary geopolymer cements synthesized from class F fly ash integrated with ground granulated blast furnace slag (GGBS) at replacement levels from 0% to 40%. Alkaline activation was executed utilizing structural mixtures of sodium silicate and 12 M sodium hydroxide solutions. Hardening kinetics and microstructural phases were analyzed using X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, and Scanning Electron Microscopy (SEM). FT-IR spectra demonstrated the formation of a rigid aluminosilicate network, indicated by the prominent framework stretching bands at 995 cm⁻¹. Compressive strength experiments showed that concrete cubes prepared with 30% GGBS substitution reached a maximum compressive value of 52.4 MPa after 28 days of curing at room temperature, outperforming pure fly ash controls. SEM characterization revealed a highly dense matrix featuring co-existing sodium aluminosilicate gel (N-A-S-H) and calcium silicate hydrate (C-S-H) gel structures, which significantly reduces structural porosity.

Keywords: Geopolymer; Fly ash; Ground granulated blast furnace slag; Compressive strength; Microstructure; C-S-H gel

Manuscript Timeline: Received: September 10, 2012; Revised: October 22, 2012; Accepted: November 15, 2012; Published: June 08, 2013.

Citation: Ani, T. S., & Montemor, M. F. (2013). Mechanochemical Properties and Microstructural Framework of Fly Ash Based Geopolymer Concrete Containing Slag Additives. International Journal of Chemistry, 4(6), 41–48.