Journal of the Serbian Chemical Society

Synthesis and mechanism of formation of hybrid structures comprising 2-oxochromene, thiazole and hydrazilidenechromene fragments

2025-11-17T00:13:18+01:00

Molecules with a hybrid structure containing 1,3-, 1,5-dicarbonyl fragments, based on 2H-chromen-2-one, hold significant potential as biologically active substances. A direct method has been developed for the preparation of thiosemicarbazones 2-(7-(aryl)-10,10-dimethyl-6-oxo-7,9,10,11-tetrahydro-6H,8H-chromeno[4,3-b]chromen-8-ylidene)hydrazine-1-carbothioamides. Their further modification by reaction with 3-bromoacetyl-2H-chromen-2-one was carried out, involving the thioamide group to form hybrid structures comprising 2-oxochromene, thiazole and hydrazineylidenechromene fragments (yield 71–97%). It is shown that hydrazine-1-carbothioamides can be obtained from both the initial 1,5-dicarbonyl compound and the product of its intramolecular O-heterocyclization. A one-step method is preferable, because the one-step method is preferred over the more labour-intensive two-step approach (with a similar yield). A plausible reaction mechanism is presented, based on quantum chemical calculations of few possible tautomeric forms of the intermediates and the corresponding products. A comparative analysis of the ¹H NMR spectrum of the experimental sample and the spectra of several possible final products calculated by a quantum chemical method has also confirmed the chosen reaction pathway.

Georgian bentonite clay–polymer system as a carrier for volatile oil in topical applications

2025-10-22T09:37:30+02:00

This study focuses on developing a polymer–clay hybrid system using a Georgian bentonite clay (Tikha-Ascane, TA) and Carbopol (CA) as a carrier for an essential oil (EO) derived from Matricaria chamomilla L. cultivated in East Georgia. EO was extracted via hydro distillation and characterized using GC–MS and FTIR techniques. The CA–TA and CA–TA–EO formulations were evaluated for key physicochemical parameters including pH, viscosity, rheology, spreadability, compatibility, moisture loss, uniformity and stability. The EO yield was 0.3 % from air-dried plant material. The main components were bisabolol oxide A (38.2 %), α-bisabolol oxide B (12.91 %), (cis)-β-farnesene (11.8 %), α-bisabolol (8.83 %), spathulenol (2.27 %), chamazulene (1.99 %), cis-ene-yne-dicycloether (6.51 %) and β-copaene (0.38 %). These results suggest that the local chamomile chemotype is rich in bisabolol oxide A. The optimized hydrogel formulation was homogeneous, stable and demonstrated favorable rheological properties, making it suitable for topical application. Chromatographic analysis confirmed the successful incorporation of the EO into the gel, which achieved an encapsulation efficiency of 58.34 %. Overall, the study confirms the compatibility of Georgian bentonite clay with the CA polymer, forming an effective matrix for volatile oil delivery in semisolid dosage forms.

Removal of nickel(II) ions during water purification with ferrous sulfate. Part 1. Mechanism and efficiency of the process

2025-08-01T10:50:48+02:00

The purification of natural water and wastewater from nickel ions is critically important for both environmental protection and human health due to their high toxicity. This study aimed to investigate the removal of nickel ions from contaminated aqueous solutions using the coagulant FeSO₄. The results demonstrate that the removal of nickel ions via an iron(III) hydroxide precipitate, formed during coagulation at pH 7 and pH 8, can be accurately described by classical adsorption isotherms, including the Langmuir, Freundlich and Dubinin–Radushkevich models. The calculated free energy of adsorption, based on the Dubinin–Radushkevich equation, does not exceed 8 kJ mol^-1, indicating the physical nature of the adsorption process and ruling out ion-exchange interactions between nickel ions and iron(III) hydroxide. The sorption capacity of the resulting iron(III) hydroxide precipitate for nickel ions at pH 8 is 0.727 mg (mg Fe)^-1 of added Fe to the solution. At pH 7, the sorption capacity depends on the initial coagulant concentration and ranges from 0.105 to 0.730 mg (mg Fe)^-1. A comparison between the coagulants FeSO4 and the previously studied FeCl₃ reveals that FeSO₄ is more effective for nickel ion removal when the initial iron ion concentration is below 70 mg L^-1. However, at higher initial concentrations of iron, FeCl₃ demonstrates greater efficacy.

Changes in leaf epicuticular wax with age of Chenopodium album L. and Abutilon theophrasti Medik.

2025-07-23T14:50:43+02:00

Epicuticular wax comprises a complex mixture of diverse organic compounds. The predominant class of compounds consists of long-chain n-alkanes. Chenopodium album and Abutilon theophrasti are cosmopolitan weed species, both of economic importance due to difficulties in control, and both species produce wax on the leaf surface. This study shows that in C. album, the proportion of epicuticular waxes has higher values in the oldest leaves and lower in the youngest leaves. Conversely, in A. theophrasti, the mean wax content tended to be slightly higher in the younger upper leaves compared to the lower leaves. The proportion of waxes in leaves does not reflect the stage of development in either species. In the epicuticular wax composition of C. album leaves, alkanes and alcohols are the most abundant compounds. Conversely, in A. theophrasti leaves, alkanes, alcohols, and triterpenes dominate. Quantitative variations in leaf epicuticular waxes are influenced by leaf age.

Temporal and spatial distribution of physicochemical parameters and water quality indices in an oligotrophic dam lake: A case of Maksutlu Dam Lake, Sivas, Türkiye

2025-02-23T17:42:51+01:00

This study was conducted at three selected stations in Maksutlu Dam Lake (Şarkışla, Sivas), covering both the dry season (August 2023) and the rainy season (May 2024). Water samples were collected from the lake and a total of 18 physicochemical parameters were analyzed. The eutrophication index (EI), organic pollution index (OPI) and nutrient pollution index (NPI) values were calculated for both seasons based on the physicochemical parameters of the lake water. Additionally, a Geographic Information System (GIS) was used to show the seasonal variation in index values. Bray–Curtis and Pearson correlation analyses were applied to the physicochemical parameters of the water. As a result, it was found that both the physicochemical parameters and water quality indices of the lake exhibited seasonal variation. Phosphate pollution was detected in the lake and it was found that the lake may be oligotrophic in terms of NO₃ and Mg values. Several suggestions were also made for the sustainable management of the dam lake.

Bimetallic polyaniline/silver–palladium nanocomposite for rapid and sustainable degradation of eosin yellow dye from wastewater

2025-09-02T22:49:33+02:00

Eosin yellow (EY), a synthetic xanthene dye, is recognized for its high toxicity, posing serious threats to human health and aquatic environments. Chronic exposure to EY can result in skin irritation, respiratory disorders, and potential long-term organ damage due to its persistent and bioaccumulative nature. In this study, a polyaniline-based silver–palladium nanocomposite (PANI/Ag–Pd) was synthesized via the co-precipitation method and employed as an efficient nanocatalyst for the degradation of EY dye. The structural, morphological and elemental properties of the synthesized nanocomposite were characterized using UV–Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The UV–Vis and FTIR analyses confirmed the formation of the PANI/Ag–Pd nanocomposite with a notable red shift, indicating electronic interaction among the constituents. SEM images demonstrated the successful incorporation of Ag and Pd nanoparticles into the PANI matrix, while EDX confirmed the elemental composition. The nanocomposite exhibited remarkable photocatalytic performance under microwave irradiation, achieving up to 96.63 % degradation of EY dye. This study highlights the potential of PANI/Ag–Pd nanocomposites as a promising nanocatalyst for water purification. These findings contribute to the development of polymer-stabilized nanomaterials as effective candidates for the remediation of dye-contaminated wastewater.

Theoretical and experimental prediction of corrosion inhibition efficiency of isatin and its derivatives by DFT calculations and weight loss method – A comparative study

2025-08-19T17:06:53+02:00

The corrosion inhibition performance of isatin and its N1/C5 substituted derivatives were analyzed by DFT calculation (B3LYP, 6311g, dp) in gas phase and solvation method with the help of Gaussian 09W and Gaussian 16. The calculated quantum chemical parameters such as E_LUMO, E_HOMO, ionization potential (I), electron affinity (A), electronegativity (χ), band gap energy (ΔE), softness (σ), hardness (η) and electrophilicity (ω), proved that isatin and its derivatives have the tendency to donate the electrons to the surface of metal ion on adsorption. The number of electron transfer (∆N) from isatin and its derivatives to iron metal was calculated theoretically and was in following order IX>III>VII>IV>II>V>I>VIII>VI. The experimental studies reveal the same order of inhibition as in theoretical studies. Mulliken’s charge distribution analysis of the same compounds indicates the high negative magnitude on N1 atom. The negative magnitude of N1 atom was altered by substitution in N1 and C-5 position of isatin, which was identified theoretically. Fukui local parameters were also calculated and used in the prediction of the compounds local selectivity.