Macedonian Journal of Chemistry and Chemical Engineering

Impressum

2024-05-20T00:29:57-07:00

Letter from the Editor

2024-05-19T22:48:47-07:00

Letter from the Editor on the occasion of the Golden Jubilee of the Macedonian Journal of Chemistry and Chemical Engineering

Synthesis, characterisation and voltammetric study of dimethylammonium lead iodide perovskite

2024-04-03T02:57:20-07:00

In the last decade, the most investigated perovskite materials are the hybrid organic-inorganic perovskites (HOIPs) due to their optoelectronic properties and possible application in the production of photovoltaics. This interest has led to an ongoing search for new HOIP variants, alongside thorough investigations of the properties of existing HOIPs. That is why our research in the field of organic-inorganic perovskites is aimed at the synthesis, characterization, and investigation of the electrochemical properties of dimethylammonium lead iodide (DMAPbI₃) using voltammetric studies. A modified synthesis of DMAPbI₃, differing slightly from the one described in the literature, was performed by combining stoichiometric amounts of lead iodide (PbI₂) and dimethylammonium iodide (DMAI) dissolved in acetonitrile. After conducting controlled evaporation, a yellow crystalline powder of DMAPbI₃ was obtained. The identity and purity of the obtained compound were confirmed by powder X-ray diffraction (PXRD), infrared (IR) and Raman spectroscopy, and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). Investigations on the electrochemical properties of DMAPbI₃ by cyclic voltammetry were performed with dichloromethane (DCM) and tetrabutylammonium chloride (TBAC) as the electrolyte. A paraffin-impregnated graphite electrode (PIGE) was used as a working electrode, on which the perovskite microparticles were immobilized. The electrochemical activity of DMAPbI₃ is recognized through an intense, broad, and irreversible anodic peak attributed to the oxidation of the constituents to different possible products and the decomposition of the perovskite structure.

Crossroads of vibrational (infrared and Raman) spectroscopy and X-ray powder diffraction in identification and characterization of some minerals – advantages and limitations. A review

2024-03-27T03:02:21-07:00

Many analytical methods have been successfully employed for the study of minerals, in particular, vibrational infrared (FTIR) and Raman spectroscopies and X-ray powder diffraction (XRPD). The advantages of the vibrational spectroscopic techniques for identifying and characterizing minerals include: rapid and versatile use; qualitative and quantitative chemical signatures; distinctive chemical fingerprint of a material; indirect determination of the crystal features (polymorphism, isomorphism, coordination, degree of deformation of structural polyhedra); small sample quantity (area less than 1 μm² for Raman); wide coverage of 4,000 – 50 cm⁻¹ region in a single scan; in situ and direct measurements without sample preparation; nondestructive use; etc. On the other hand, XRPD is a destructive technique that, depending on the method used and the density of the material, requires from a few micrograms up to around 5 grams of sample quantity for analysis. In spite of that, it is a rapid and powerful technique used in mineral studies with relatively straightforward interpretation of the results. During the last decade, portable X-ray powder diffractometers for the nondestructive analysis of art and archeological materials have been developed along with the portable and hand-held vibrational spectroscopy instrument. Here, some advantages and limitations in the process of the complementary use of FTIR and Raman vibrational spectroscopy and XRPD for identification and characterization of minerals are outlined.

Visionary figures in the field of electrochemistry who revolutionized voltammetry

2024-02-28T22:31:06-08:00

Understanding energetics and electron behavior has been pivotal in elucidating numerous fundamental phenomena, including electricity, corrosion, respiration, energy generation in biological systems, intermolecular interactions within living organisms, organic synthesis, drug development, enzyme functions, and the design of biosensors, among others. As 2024 records the centennial anniversary of the completion of the first polarograph by Nobel laureate Jaroslav Heyrovský (awarded the Nobel Prize in Chemistry in 1959), it presents an opportune moment to pay tribute to several eminent electrochemists who have made significant contributions to the field of voltammetric techniques. Following our recent acknowledgment of the outstanding women who have made substantial contributions to voltammetry in a prior publication, this article aims to briefly highlight the major achievements of several distinguished male figures in the field (Jaroslav Heyrovský, Allen J. Bard, Christian Amatore, Richard Compton, Jean-Michel Savéant, Fraser Armstrong, Fritz Scholz, Joseph Wang, Milivoj Lovrić, Valentin Mirčeski, Alan M. Bond). Given that many of these remarkable personalities have contributed both as authors and referees for the Macedonian Journal of Chemistry and Chemical Engineering, this tribute serves as a fitting acknowledgment of their remarkable accomplishments on the occasion of the journal's 50th anniversary.

Label-free voltammetric screening of human blood serum

2024-03-31T22:26:56-07:00

The current study presents a comprehensive voltammetric investigation into the direct analysis of untreated human blood serum in a phosphate buffer at an unmodified, graphite electrode by means of voltammetry. By employing advanced square-wave voltammetry at an edge plane pyrolytic graphite electrode (EPPGE), the basic principles were established for developing a sensitive, fast, simple, and label-free method for the simultaneous screening of uric acid, bilirubin, and albumin analytes that are present in human blood serum and are quite essential for rapid medical diagnostics. The electrochemical protocol utilizes the specific structural patterns of the EPPGE, the inherent redox and adsorption properties of the analysed analytes, and the sensitivity and rapidity of the employed advanced voltammetric technique.

The methodology has been successfully applied for quantification of the considered analytes in a series of samples of human blood serum and was compared with the standard methods used in a clinical biochemical laboratory. This novel method represents a significant advancement towards the development of point-of-care devices aimed at swiftly and simultaneously quantifying uric acid, bilirubin, and albumin levels in human serum.

A Comment on the comments

2024-01-25T12:30:53-08:00

Commenting on the work of other authors is justified when there are serious concerns related the scientific content, and the authors do not respond with valid arguments so that such concerns cannot be addressed. It should not be used to advertise one’s own work.

Ab initio exploration of modified carbon nanotubes as potential corrosion inhibitors

2023-12-27T22:22:58-08:00

In order to develop novel unexplored potential corrosion inhibitors, covalently modified single-walled carbon nanotubes (SWCNT) via benzoic (–PhCOOH) and aniline (–PhNH₂) groups are being investigated as corrosion inhibitors for the first time. Utilizing a comprehensive approach, this study employed density functional theory (DFT), Monte Carlo (MC), and molecular dynamics simulations (MD) to assess the adsorption behavior of modified nanotubes as corrosion inhibitors on the Cu(111) surface within a simulated aqueous HCl corrosion medium. The results provided molecular information on the adsorption capability, geometry adsorption centers, and adsorption energies (E_ads) of carbon nanotubes on the surface of Cu(111). The adsorption energy values unveiled robust interactions between SWCNT–PhCOOH and SWCNT–PhNH₂inhibitors and the Cu(111) surface, suggesting a highly effective corrosion protection mechanism. The calculated E_ads values exhibited notable ranges, spanning from –260.82 to –308.18 kcal/mol for SWCNT–PhCOOH and –220.92 to –261.01 kcal/mol for SWCNT–PhNH₂ with the maximum probability values, representing the most favorable adsorption scenarios, determined to be –292.96 and –229.39 kcal/mol, respectively. A key insight from Monte Carlo simulations underscored the inherent spontaneity of the adsorption process, corroborated by the consistently negative E_ads values. These findings collectively underscore the substantial affinity of the inhibitors to the copper surface, contributing to a deeper comprehension of their corrosion inhibition capabilities.

Experimental biological studies of novel tetradentate hydrazone Cu(II) complexes for potential applications in medicinal chemistry

2024-02-26T23:45:57-08:00

A series of mononuclear Cu(II) complexes were synthesized using a potential tetradentate hydrazone ligand obtained from the reaction between phenylhydrazine groups and 2,5-thiophenedicarboxaldehyde. The structures of ligands and complexes were elucidated through various spectroscopic techniques, confirming their composition. All complexes were found to adopt four-coordinated geometries, indicating the formation of stable structures. Spectroscopic analysis revealed that the hydrazone ligand coordinated with the Cu(II) metal ions as a dibasic tetradentate ligand by utilizing the phenolic oxygen and azomethine nitrogen atoms. The binding affinity of the complexes with calf thymus DNA (CT-DNA) was investigated using absorption and viscosity measurements, demonstrating their interaction through the intercalation mode. The binding studies showed that the Cu(II) complexes exhibited varying degrees of binding affinity, with Cu(L⁴) demonstrating the highest affinity, followed by Cu(L¹), Cu(L²), and Cu(L³). Moreover, the DNA fragmentation properties of the Cu(II) complexes were evaluated, suggesting their potential utilization in pharmaceutical applications. The obtained results highlight the significance of these novel complexes in the field of medicinal chemistry.

Phenolic fingerprint of Macedonian propolis

2024-04-17T22:45:24-07:00

Propolis is a chemically complex resinous material collected by honeybees (Apis mellifera) from tree buds and resins, comprising plant exudates, secreted substances from bee metabolism, pollen and waxes. Its chemical composition depends strongly on the plant sources available around the beehive, which have a direct impact оn the quality and bioactivity of the propolis.

In this study, the composition of phenolic compounds in 13 Macedonian propolis extracts was investigated by HPLC-DAD-ESI-MS/MS. Overall, the UV spectra, the MS and MS/MS data allowed the identification of 36 compounds.

The major constituents of propolis were phenolic acids (caffeic and coumaric) and their esters (methyl, (iso)prenyl, benzyl, phenylethyl, cinnamyl), flavonols (quercetin, kaemferol), flavones (chrysin, apigenin, acacetin), flavanonols (pinobanksin) flavanones (pinocembrin naringenin, hesperetin, pinostrobin) and their methylated/esterified derivatives.

The results reveal that Macedonian propolis contains a diversity of phenolic compounds confirming that it is a poplar type of propolis with higher phenolic content (ranging from 43.75–637.94 mg/g) than reported in previous studies in the region and beyond in Europe (< 80 mg/g). This suggests the potential significance of Macedonian propolis as a valuable source of bioactive compounds with health benefits as well as for unlocking its economic potential for industry and beekeepers.

Regulation of carbohydrate metabolism and insulin secretion in diabetic rats following treatment with Hypericum perforatum L. hairy root aqueous methanol extract

2024-05-15T03:22:27-07:00

Hairy root (HR) cultures of Hypericum perforatum L. have shown promise in controlling hyperglycemia, regulating blood lipid and enzyme profiles, and improving metabolic function in vivo. These benefits are mainly attributed to the phenolic acids, flavonoids, and xanthones present in HR extracts. However, the specific mechanism underlying these effects remains unclear. This study was performed to elucidate the biochemical and molecular mechanisms driving HR the antihyperglycemic and antidiabetic effects of HR extracts.

HR extract (200 mg/kg body weight) was administered daily for 14 days to healthy rats and rats with streptozotocin-induced diabetes, with glibenclamide serving as a positive control. The phenolic composition of the HR extracts was confirmed through high-performance liquid chromatography/diode array detection/electrospray ionization mass spectrometry (HPLC/DAD/ESI-MSⁿ ) analysis.

The results showed that HR extract treatment increased the plasma insulin level and pancreatic poly (adenosine diphosphate-ribose) polymerase (PARP) activity in diabetic rats, thus normalizing blood glucose levels. Additionally, it reduced the activity of gluconeogenic enzymes, increased the activity of glycolytic enzymes, and normalized the glycogen content in the liver. HR extract-treated rats also exhibited increased hepatic adenosine monophosphate-activated protein kinase (AMPK) mRNA expression and a decreased protein kinase Cε (PKCε) concentration.

In conclusion, HR extract demonstrated insulinotropic effects and effectively regulated hepatic carbohydrate metabolism in diabetic rats by modulating AMPK expression and the PKCε concentration. These findings suggest the potential use of HR extract as an herbal medicine for diabetes treatment and a source of antidiabetic drug development.

Мultivariate analysis for rapid screening and prediction of solid-state compatibility in pharmaceutical preformulation studies-paving the road for machine learning

2024-02-26T01:13:31-08:00

Multivariate analysis models were developed to evaluate the results obtained from a compatibility study designed for ibuprofen with a large group of different types of excipients, as a possible approach for rapid screening of the incompatibility between the active pharmaceutical ingredient (API) and excipients. The solid-state characterization of the binary mixtures was performed by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) using SIMCA^® software were applied for evaluation of the experimentally obtained results. The optimal PCA model for the FTIR spectra explains 96.2 % of the variations in the dataset with good statistical indicators (R²X = 0.960, Q² = 0.900), which was also the case for the PCA model for the DSC curves (R²X = 0.981, Q² = 0.866). The applied PLS-DA models have shown similar behaviour to the PCA. Moreover, the main spectral variations in the FTIR spectra and the thermal events in the DSC data were attributed the highest variable importance for the projection (VIP) scores in the corresponding VIP plots, confirming the model capability for predicting ibuprofen interactions. Furthermore, the prediction power of the optimal models for FTIR and DSC experimental data was evaluated by the root mean square error of prediction (RMSEP) of 0.10 and 0.16, respectively. The obtained results demonstrated the potential of multivariate statistical analysis as a machine learning-based technique for screening and prediction of ibuprofen-excipients solid-state compatibility in the preformulation phase of the pharmaceutical development of dosage forms.

Smart textiles: Paving the way to sustainability

2024-01-29T01:32:56-08:00

As an emerging technology, smart textiles can bring solutions to many problems, but also create new ones, especially related to their disposal and their impact on the environment. That is why it is important to address this problem at this stage of technological development when smart textiles have not yet pervaded the mass markets. In this article, first, an attempt is made to understand the chronological development of smart textiles: the reasons for a weak breakthrough in the commercial markets throughout the decades, starting from the 1990s until today, but also the emergence of new driving forces that should inevitably lead to a bright future for smart textiles. In addition, we explore the contemporary possibilities for sustainable materials, manufacturing techniques, and end-of-life solutions for developing sustainable smart textiles based on a broad literature review, online sources, and a questionnaire survey among textile experts. Finally, an overview of the latest developments related to the standardization of smart textiles is given. This research was spurred by participation in CONTEXT COST Action (CA17107 - European Network to connect research and innovation efforts on advanced Smart Textiles).

Comparative physicochemical investigation of the inclusion compounds of cyclodextrins with arginine and histidine stereoisomers

2023-12-27T04:09:41-08:00

The inclusion complexes of α-, β-cyclodextrin and 2-hydroxypropyl-α-cyclodextrin with two amino acid stereoisomers (L-, D-arginine and L-, D-histidine) were studied by using differential scanning calorimetry, thermogravimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy methods. The solid inclusion compounds were prepared in a 1:1 molar ratio of the host and guest using the co-precipitation method. The pH measurements and structural visualization of complexes were carried out. The obtained results proved the formation of the complexes and revealed that the size and the symmetry of the cyclodextrin (CD) and also the structure and flexibility of the amino acid molecule had a significant influence on the complexation interaction. The correlation of the experimental data shows that βCD has a preference to form more stable complexes with levogir isomers of amino acid than αCD and 2-hydroxypropyl-α-cyclodextrin. The complexation of the amino acids isomers was accomplished by partial inclusion of the guest molecule in the CD cavity, and it was observed that CDs could better discriminate between histidine isomers than between arginine isomers.