Institute of Chemistry

Permanent URI for this communityhttps://repository.ukim.mk/handle/20.500.12188/60

Browse

Search Results

Now showing 1 - 10 of 18

Some of the metrics are blocked by your
consent settings
Lipoxygenase Inhibitory Activity and Prostate Cancer Cytotoxicity of In Situ- and In Vitro-Cultivated Balkan Endemic Sideritis scardica Griseb
(MDPI AG, 2025-10-25)
Danova, Kalina
;
;
Stoyanova, Elena
;
Alipieva, Kalina
;
Sideritis scardica Griseb., a Balkan endemic species traditionally used for respiratory conditions and wound-healing, was investigated for its 15-lipoxygenase (15-LOX) inhibitory and cytotoxic activities in relation to its phenolic composition. Aerial parts from the wild-collected and in vitro-cultivated plant were successively extracted with hexane, chloroform, and methanol and the methanol extract was further fractionated into ethyl acetate, butanol, and water fractions. This study presents the first combined evaluation of LOX inhibition and cytotoxicity against prostate cell lines WPMY-1 (normal epithelial fibroblast/myofibroblast), PC-3 (epithelial adenocarcinoma, Grade IV), and LNCaP (epithelial carcinoma) and detailed phytochemical profiles of wild-collected and in vitro-cultivated S. scardica. The phytochemical analysis revealed distinct profiles: increased LOX-inhibition activity was related to a higher phenylethanoid/flavone glycoside ratio, while PC cytotoxicity was rather related to flavone glycoside domination in the plant preparations. The cytotoxic effect of the in vitro-obtained preparations was characterized by a marked selectivity when comparing their effects on WPMY-1, PC-3 and LNCaP cells. To our knowledge, this is the first report linking phenylethanoid/flavone glycoside profiles of in situ and in vitro S. scardica plants with dual LOX-inhibitory and anti-prostate cancer activities, supporting the plant’s potential as a sustainable source of bioactive compounds.
Some of the metrics are blocked by your
consent settings
LC-HRMS and NMR study of the esterification products of ibuprofen with solketal: Formation, isolation and identification
(Society of Chemists and Technologists of Macedonia, 2025-12-24)
Jakimovska Pokupec, Viktorija
;
Popova, Milena
;
Bankova, Vassya
;
Ibuprofen is a widely used non-steroidal anti-inflammatory drug dispensed in tablets, capsules, suspensions, oral solutions, creams, and gels. Ibuprofen's poor water solubility and gastrointestinal side-effects present ongoing formulation challenges. Alcoholic excipients are often employed to enhance solubility and minimise adverse effects. Solketal (1,2-isopropylidene glycerol), a ketal produced by the condensation of glycerol with acetone, offers further versatility as an excipient due to its free hydroxyl group, which enables esterification reactions with acidic active pharmaceutical ingredients like ibuprofen. Introducing any excipient, especially in direct contact with the active pharmaceutical ingredient, necessitates careful evaluation of potential drug–excipient interactions, as these can alter the drug's physicochemical properties and impact clinical performance. Chromatographic techniques coupled with mass spectrometry and nuclear magnetic resonance spectroscopy remain essential for identifying and characterising related and degradation products in pre-formulation studies. In this study, we investigated the esterification of ibuprofen with solketal to identify possible interaction products. Two major compounds were isolated and thoroughly characterised by MS and NMR, confirming their chemical structures: 1-mono-glycerol ester of ibuprofen and ibuprofen-solketal-ester, which contained a 1,3-dioxolane ring. This finding highlights the importance of comprehensive analytical evaluation of drug–excipient interactions during formulation development, as these can affect drug stability and performance.
Some of the metrics are blocked by your
consent settings
Evaluating green and sustainable chemistry education through students’ interventions
(Society of Chemists and Technologists of Macedonia, 2025-05-28)
Nikolovski, Daniel
;
This study explores the integration of green and sustainable chemistry into educational curricula and its impact on students' knowledge, motivation, and perceptions. The research aimed to evaluate whether activities centered on green and sustainable chemistry improve students' academic performance and foster awareness of sustainability concepts. Conducted between April and June 2024 in three primary schools in N. Macedonia, the study involved 211 8th grade students, divided into a control group and an experimental group. While the control group followed standard les-sons, the experimental group participated in specific activities integrated into the topic "Introduction to Organic Chemistry." A mixed-methods approach was employed, combining quantitative tools such as the conceptual knowledge test and the activity perception questionnaire, alongside qualitative methods like focus groups and semi-structured inter-views. The conceptual knowledge test assessed students' academic achievements, while the activity perception questionnaire evaluated their perceptions of the activities. The results showed no significant difference in academic performance between the two groups. However, the activity perception questionnaire revealed that students in the experimental group found the activities engaging, valuable, and effective in enhancing their understanding of green and sustainable chemistry concepts. Qualitative data further indicated a preference for interactive learning methods like re-search, games, and experiments, which fostered greater motivation and collaboration among students. This study under-scores the importance of integrating green and sustainable chemistry into curricula to promote environmental awareness and sustainable practices. These findings provide insights into effective teaching strategies and support the inclusion of green and sustainable chemistry in educational policies to equip students for global environmental challenges.
Some of the metrics are blocked by your
consent settings
Molecular Hydrogen Acts as a Hydrogen Bond Proton Acceptor: From Protonated Betaine Tagging to the Weakest Hydrogen Bond
(American Chemical Society, 2024-05-23)
Achevski, Blagoj
;
Pejov, Ljupcho
In an attempt to gain further insights into the intermolecular interactions implied by Rizzo’s group’s cautionary tale related to molecular tagging in infrared multiple photon dissociation (IRMPD) spectroscopy with molecular messengers [Masson, A. et al.. J. Chem. Phys. 2015, 143, 104313], in the present study, we provide an in-depth analysis of the noncovalent interaction between the molecular hydrogen and protonated betaine molecule in the gas phase. We aim to shed some new light on the fundamental issues concerning the wide diapason of hydrogen-bonding-type intermolecular interactions, with a wide variety of proton acceptors. We demonstrate that in the course of tagging the protonated betaine with molecular hydrogen from the OH group side, it is the σ bond of molecular hydrogen that plays the role of hydrogen-bonding proton acceptor. The tagging thus induces a small yet significant red shift of the protonated betaine O−H stretching mode. We investigate the performance of a wide range of density functional theory (DFT) functionals for the calculation of anharmonic vibrational frequency shifts of the studied system, which are essential for the correct interpretation of the experimental IRMPD data. For an accurate prediction of the OH stretching frequency shifts, specifically designed functionals such as Handy’s group HCTH/407 should be applied. The empirical dispersion correction enhances the systematic overestimation of the anharmonic frequency shift, characteristic of the most widely used DFT functionals. Combining the full-wave function approach with the charge field perturbation and natural bond orbital (NBO) deletion analyses, we demonstrate that the frequency shift in the OH-tagged structure is governed by the σHH → σ*OH intermolecular charge transfer. This interaction stabilizes the OH-tagged dimer as well, in contrast to the dipole−quadrupole electrostatic interaction energy term. Topological analysis of the electron density reveals the presence of an intermolecular bond critical point with a positive value of the density Laplacian very close to the lower limit for hydrogen bonds. NCI analyses demonstrate that the OH···H2 interaction is weaker than the intramolecular CH···O one within the protonated betaine molecule, with the through of reduced density gradient appearing at less negative sign(λ2)·ρ values. Analyzing the O−H stretching vibrational potential with the second-generation absolutely localized molecular orbitals energy decomposition analysis (ALMO-EDA 2) revealed that in the case of betaineH(+) tagged from the OH group side, the permanent electrostatics (ΔEelec), polarization (ΔEpol), and charge-transfer (ΔEct) contributions to the total intermolecular interaction energy contribute favorably to the weak hydrogen bond formation and to the red shift of the fundamental O−H stretching frequency, the ΔEct contribution being the most significant in the last context. The Pauli repulsion term, on the other hand, favors an O−H stretching frequency blue shift as a consequence of the vibrational confinement effects.
Some of the metrics are blocked by your
consent settings
3D self-assembled polar vs. non-polar NiO nanoparticles nanoengineered from turbostratic Ni3(OH)4(NO3)2 and ordered β-Ni(OH)2 intermediates
(Royal Society of Chemistry, 2024-11-07)
;
Eid, Arej
;
Lari, Leonardo
;
Althumali, Ahmad
;
Šiller, Lidija
A surfactant-free ammonia and carbamide precursor-modulated engineering of self-assembled flowerlike 3D NiO nanostructures based on ordered β-Ni(OH)2 and turbostratic Ni3(OH)4(NO3)2 nanoplate structured intermediates is reported. By employing complementary structural and spectroscopic techniques, fundamental insights into structural and chemical transformations from intermediates to NiO nanoparticles (NPs) are provided. FTIR, Raman and DSC analyses show that the transformation of intermediates to NiO NPs involves subsequent loss of NO3− and OH− species through a double-step phase transformation at 306 and 326 °C corresponding to the loss of free interlayer ions and H2O species, respectively, followed by the loss of chemically bonded OH− and NO3− ions. Transformation to NiO NPs via the ammonia route proceeds as single-phase transition, accompanied with a loss of OH− species at 298 °C. The full transformation to NiO NPs of both intermediates is achieved at 350 °C through annealing in the air atmosphere. Ammonia-derived NPs maintain nanoflower morphology by self-assembling into nanoplates, which is enabled by H2O-mediated adhesion on the NiO NPs’ {100} neutral surfaces. Structural transformations of turbostratic Ni3(OH)4(NO3)2 nanoplates result in the formation of NiO NPs dominantly shaped by inert polar OH-terminated (111) atomic planes, leading to the loss of the initial self assembled 3D structure. DFT calculations support these observations, confirming that H2O adsorbs dissociatively on polar {111} surfaces, while only physisorption is energetically feasible on {100} surfaces. NiO NPs obtained via two different routes have overall different properties: carbamide-derived NPs are 3 times larger (15.5 vs. 5.4 nm), possess a larger band gap (3.6 vs. 3.2 eV) and are more Ni deficient. The intensity ratio of surface optical (SO) modes to transversal and longitudinal optical modes is ∼40 times higher in the NiO NPs obtained from β-Ni(OH)2 compared to Ni3(OH)4(NO3)2-derived NPs. The SO phonon lifetime is an order of magnitude shorter in NiO obtained from β-Ni(OH)2, reflecting a much smaller NP size. The choice of a precursor defines the size, morphology, crystallographic surface orientations and band gap of the NiO NPs, with Ni deficiency providing pathways for utilizing them as p-type materials, allowing for the precise nanoengineering of polar and neutral surface-dominated NiO NPs, which is of exceptional importance for use in catalysis.
Some of the metrics are blocked by your
consent settings
Facile Synthesis of Cu<sub>x</sub>S Electrocatalysts for CO<sub>2</sub> Conversion into Formate and Study of Relations Between Cu and S with the Selectivity
(Wiley, 2024-10-25)
Stojkovikj, Sasho
;
El‐Nagar, Gumaa A.
;
Gupta, Siddharth
;
;
Koleva, Violeta
<jats:title>Abstract</jats:title><jats:p>The conversion of CO<jats:sub>2</jats:sub> into formate (HCOO<jats:sup>−</jats:sup>), a techno‐economically feasible product, can be achieved using earth‐abundant Cu<jats:sub>x</jats:sub>S electrocatalysts, but questions remain regarding how catalyst structure, composition, and reaction environment influence product selectivity. A novel synthesis method based on electrodeposition of Cu foam and its subsequent sulfidation via immersion in sulfur saturated toluene solution resulted in Cu<jats:sub>x</jats:sub>S foams. Catalytic activity studies found that HCOO<jats:sup>−</jats:sup> selectivity is dependent on electrochemical activation at higher overpotentials. To understand the effects of activation, determine the active forms of the catalysts, and identify the role of sulfur, the electrodes are carefully characterized as well as gaseous and sulfur dissolved in electrolyte. This included study of the effects of intentional addition of solution sulfur species, identification of the sulfur loss, determination of the electrode composition and relating sulfur speciation to observed product selectivity. It is found that residual sulfur stabilizes Cu<jats:sup>+</jats:sup> during electrolysis at potentials favoring HCOO<jats:sup>−</jats:sup> production, in contrast to pristine Cu that undergoes complete reduction and shows poor HCOO<jats:sup>−</jats:sup> selectivity. Sulfur in both the catalyst and dissolved in electrolyte are of dynamic nature, and surface residues of SO<jats:sub>4</jats:sub><jats:sup>2−</jats:sup> species are identified in all activated catalysts which correspond with enhanced HCOO<jats:sup>−</jats:sup> production.</jats:p>
Some of the metrics are blocked by your
consent settings
Establishment, evaluation, and application of a gas chromatography–mass spectrometry method for quantification of volatile organic compounds in ambient air using anisole as an internal standard
(SHTM, UKIM, 2024)
Sofronievska, Ivona
;
;
;
Some of the metrics are blocked by your
consent settings
Crystal structure and spectroscopic determination of the phase transitions in methylammonium and formamidinium bismuth iodide perovskites
(Elsevier, 2024-06-24)
Understanding of the structural properties of hybrid organic–inorganic perovskites (HOIPs) and their behavior is crucial for their use as photovoltaics and for the design and assembly of solar cells. As part of this work, a detailed study was conducted to further understand bismuth iodide perovskites, with a specific focus on the phase transitions of methylammonium and formamidinium analogs. A detailed analysis of the temperature-dependent IR spectra was also performed in order to analyze the structural changes that occur. The presence of five phases in the methylammonium bismuth iodide (MABiI) and four phases in formamidinium bismuth iodide (FABiI) were determined. An additional confirmation of the reported results was obtained from the differential scanning calorimetry. The ambiguities concerning the crystal structure of FABiI were resolved based on the results by X- ray powder diffraction (XRPD)
Some of the metrics are blocked by your
consent settings
Integrating ethics and democratic principles in chemistry education: a case study
(Walter de Gruyter GmbH, 2024-10-09)
<jats:title>Abstract</jats:title> <jats:p>This study presents a novel approach to integrating ethics and core values into chemistry education through the module “Culture of Democracy Through the Didactics of Chemistry.” Developed as part of a broader initiative aimed at educating future teachers for democracy and human rights, this module explores the ethical dimensions of chemical knowledge and its social and environmental impact. Utilizing the Council of Europe’s Reference Framework of Competences for Democratic Culture, it introduces pre-service teachers to concepts such as responsibility, human dignity, and the rule of law. The module involved six pre-service teachers and two schoolteacher-mentors. Key activities included student-led discussions, such as exploring personal responsibility and moral dilemmas in chemistry, exemplified by the Heinz dilemma, and engaging in discourse on the possibility of breaking a law for morally justifiable reasons to comprehend the delicate balance between legal duties and moral responsibilities. Through reflective exercises and collaborative learning, pre-service teachers engage critically with the ethical implications of their future profession. Initial feedback highlights the value of integrating ethical discussions into chemistry education, fostering deeper reflection and a sense of responsibility among pre-service teachers. The study provides a valuable framework for educators integrating ethics into science curricula, fostering responsible chemistry practice aligned with social values.</jats:p>
Some of the metrics are blocked by your
consent settings
A Rising Tide Lifts All Boats? The Model of Differentiation As a Tool for Diversity in Science toward Social Inclusion
(American Chemical Society (ACS), 2024-02-13)
Kieferle, Sarah
;
Devetak, Iztok
;
Essex, Jane
;
Hayes, Sarah
;
Approaches for inclusive science teaching currently tend to focus on only one dimension of diversity at a time. This neglects the fact that diversity is multidimensional in nature, and the consideration of only one dimension of diversity can yield inclusive practices with limited scope. Therefore, the goal of the project “Diversity in Science toward Social Inclusion Non-formal Education in Science for Students’ Diversity” (DiSSI) is to promote inclusive teaching practices for dealing with several dimensions of diversity simultaneously for non-formal education. Researchers from Ireland, Germany, the United Kingdom, Slovenia, and North Macedonia are developing a teaching approach that considers the needs of (i) students with a low socioeconomic status, (ii) students of ethnic minorities or with cultural backgrounds that differ from those of the mainstream culture, (iii) students with different linguistic skills, and (iv) gifted students. For this purpose, the Pedagogical Model of Differentiation was developed. In addition, the approaches of inquiry-based learning, context-based learning, game-based learning, and cooperative learning were reviewed in regard to their suitability for inclusive learning settings for non-formal science education. Conclusions were drawn about the mentioned dimensions of diversity. An innovative combination of pedagogical approaches that benefits all learners and thus is truly inclusive is presented. The teaching is inclusive in the sense that it allows for cooperative learning while simultaneously supporting the learning progress of the four differentiated groups of students. Thus, in this paper, the model of differentiation is presented and explained, and a summary of the approaches is discussed, which are applicable for inclusive teaching.

Institute of Chemistry

Browse

Filters

Settings

Sort By

Results per page

Search Results