Journal of the Serbian Chemical Society

Fabrication of visible-light photoactive TiO2/BiVO4 composite for photocatalytic degradation of ciprofloxacin

2025-11-04T22:13:09+01:00

Pure BiVO₄ and three TiO₂/BiVO₄ composite photocatalysts with Bi³⁺:Ti⁴⁺ mole ratios of 1:1, 2:1 and 4:1 were readily synthesized, for the first time, using a one-pot hydrothermal procedure for the photodegradation of ciprofloxacin. Conducting the hydrothermal reaction in a basic medium yielded single-phase scheelite monoclinic polymorphic BiVO₄ (ms-BiVO₄) in the composite samples. Microstructural analysis showed spherical TiO₂ nanoparticles with an average grain size of 120 nm embedded on the surface of BiVO₄ nanoplates. The optimized composite exhibited a ciprofloxacin photodegradation reaction rate constant about 3.8 times higher than that of the pure BiVO4 sample. This significant enhancement is attributed to the formation of a TiO₂/BiVO₄ heterojunction, which promotes efficient charge separation. This research expands the knowledge on designing of BiVO₄-rich composites (with Bi³⁺:Ti⁴⁺ mole ratio ≥ 1:1) via heterogeneous junction engineering to enhance photocatalytic activity beyond that of pure BiVO₄. The research also provided a perspective on using the BiVO₄-rich composites as effective photocatalysts for degradation of antibiotics in aqueous media under visible-light irradiation.

Adsorption of copper ions onto acid-modified Aframomum africanum shell: Isotherm and kinetic studies

2025-12-18T10:55:58+01:00

In this work, copper ions were successfully removed from aqueous solution using the acid-modified Aframomum africanum shell (MAAS) as an adsorbent. The adsorbent was characterized using Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM). The A. africanum shells were also characterized before and after acid modification to determine their pH at the point of zero charge (pH_PZC). MAAS was found to have a pH_PZC value of 4.77. In batch experiments, the adsorption capacity of MAAS was investigated as a function of solution pH, adsorbent dosage, contact time, initial copper ion concentration and agitation speed. The results revealed that at a solution pH of 9, an adsorbent dosage of 5 g/L, a contact time of 30 min, an initial Cu(II) ion concentration of 50 mg/L and at an agitation speed of 250 rpm, the maximum Cu(II) ion adsorption capacity of MAAS was 31.25 mg/g. The adsorption kinetic data and isotherm data were also studied to find the suitable models of Cu(II) removal. The kinetic data and the isotherm data of Cu(II) removal by MAAS were found to follow the pseudo-second order kinetics model (R² = 0.999) and the Langmuir isotherm model (R² = 0.990), respectively. Therefore, the outcome suggested that A. africanum shells can be utilized as an economical and efficient adsorbent for the removal of Cu(II) from aqueous solution.

Epoxy- and cyclopropane-functional copolymers: Synthesis, thermal properties and photocrosslinking behavior

2026-04-09T09:58:10+02:00

Copolymers bearing both epoxy and cyclopropane groups were synthesized by free-radical copolymerization of glycidyl 2-(4-vinylphenyl)cyclopropanecarboxylate (GVPCC) with methyl methacrylate (MMA) using AIBN at 343 K, in bulk and in benzene under inert atmosphere. Copolymer compositions were determined by spectroscopy and copolymerization parameters were evaluated by the Fineman–Ross method. The reactivity ratios were r₁(GVPCC) = 0.68±0.05 and r₂(MMA) = 0.51±0.07; their product (r₁r₂ = 0.35) indicates random copolymerization with a tendency toward alternation. Alfrey–Price parameters (Q₁ = 0.96, e₁ = −0.63; Q₂ = 0.74, e₂ = 0.40) confirm strong comonomer interactions and pronounced polar effects. For a 50/50 copolymer, the intrinsic viscosity was 0.66 dL g^-1 (benzene, 25 °C). Thermogravimetric analysis showed composition-dependent stability with T₅ 250–320 °C, increasing with GVPCC content, alongside improved adhesion (up to 5.6 MPa) and Vicat softening temperature (121 °C). UV irradiation produced efficient crosslinking and negative-tone photoresist behavior (resolution with depth of penetration, D_p 0.25–0.35 μm; critical exposure energy, Ec, 14.5–16.4 mJ cm^-2; sensitivity, S, 61–69 cm² J^-1), demonstrating potential for UV-patternable microfabrication materials.

Energetic networks of lone pair–π interactions in phycobiliprotein interfaces: Structural organization, geometry and cooperative stabilization

2026-03-30T11:27:11+02:00

Lone pair–π interactions represent an underexplored class of noncovalent forces in protein architecture, despite their fundamental electronic significance. Here, we present a comprehensive computational and bioinformatics analysis of lone pair–π interactions at phycobiliprotein interfaces based on 20 high-resolution X-ray crystal structures. Using defined geometric criteria and ab initio quantum-chemical calculations at the LMP2/cc-pVTZ++ level on reduced molecular models, we systematically characterized their distribution, geometry, topology and energetic contributions. We identified 2,245 lone pair–π interactions, revealing a highly non-random and chemically selective interaction landscape dominated by oxygen-based lone pair donors and aromatic π acceptors, particularly Tyr and Phe. Geometric analysis showed strong distance and angular preferences, consistent with directional donor–acceptor orbital interactions rather than nonspecific packing effects. Energy calculations revealed a structured interaction potential surface, with stabilizing energies clustering in the −0.1 to −5.0 kJ mol^-1 range within defined geometric domains. Network analysis further demonstrated that more than half of the interactions participate in cooperative, furcated lone pair–π motifs, generating interfacial stabilization through multivalent interaction networks. Collectively, these results establish lone pair–π interactions as geometry-encoded, energetically selective and cooperatively organized stabilizing elements that contribute to interfacial specificity, structural precision and quaternary structure stability in phycobiliprotein assemblies.

Hydrothermal synthesis of VO2(B) and its phase transformation to VO2(M): Investigating metal–insulator transition behavior

2026-03-09T09:13:29+01:00

In this study, VO₂(B) nanostructures were synthesized via a stabilizer-free hydrothermal route and successfully converted to VO₂(M) at 350 °C in just 30 min. This process offers a reduced thermal budget compared to established protocols, which generally require temperatures above 400 °C and durations exceeding 1 h. The resulting urchin-like VO₂ nanostructures were characterized using a variety of techniques such as XRD, Raman spectroscopy, SEM and DSC to investigate their structural evolution, surface morphology and metal–insulator transition characteristics. The experimental results reveal that VO₂(B) predominantly transforms to VO₂(M) upon annealing at 350 °C, with minor secondary oxide phases. Furthermore, the annealing at 450 °C led to the complete phase transformation of VO₂ to V₂O₅, indicating the sensitivity of VO₂ to annealing temperature. The results show that the insulator-to-metal transition temperature to be ~65 °C, which is lower than that of bulk VO₂ (~68 °C), indicating modified transition behavior in the nanostructured samples. These results demonstrate that hydrothermally synthesized VO₂(B) can be converted to predominantly VO₂(M) by annealing at 350 °C for 30 min, enabling the observation of a reversible metal–insulator transition near 65 °C.

Embracing green chromatography principles in perindopril, amlodipine and indapamide drug mixture analysis using β-cyclodextrin modified mobile phase

2026-01-08T13:33:55+01:00

Raising the level of environmental awareness in the field of liquid chromatography is considered indispensable while the use of β-cyclodextrin, as additive, in a mobile phase is promising strategy in this regard. This study presents a method development in line with ICH Q14 regulatory requirements for introducing sustainability and method life-cycle management to separate components of a cardiovascular multi-drug tablet formulation. At the beginning, the analytical method target profile was defined, separation of perindopril, amlodipine, and indapamide in a shortest possible analytical run time. Following risk analysis pointed out that the mobile phase constituents represent the critical method parameters affecting the chromatographic analyses. Design of experiments methodology and desirability function calculation was employed to simultaneously optimize the levels of concentration of β-cyclodextrin solution, pH value and acetonitrile content in the mobile phase investigated in the ranges 5–15 mM, 4.0–6.0 and 20–30 vol. %, respectively. The optimal chromatographic conditions consisted of 10 mM β-cyclodextrin (pH 5.4) and acetonitrile in the volume ratio 70:30, 2 mL min^-1 flow rate, RP-18e column kept at 25 °C, 215 nm detection wavelength, and 10 μL injection volume. The eco-friendliness of the method was assessed using the AGREE tool indicating a green and sustainable method was successfully developed.

December Armageddon: Biothermodynamic analysis of rhinoviruses based on the calculation of Gibbs energy change of antigen–receptor binding and biosynthesis of rhinovirus particles

2026-03-26T15:06:01+01:00

The subject of this research is a battle that is repeated every year and spreads epidemically across different territories, causing a large number of infected cases and casualties. Infections with rhinovirus are well known to the biomedical sciences. However, for a deeper understanding of the causes of rhinovirus disease and virus-host interaction (infection) it is necessary to understand them from the perspective of chemistry and biothermodynamics. This paper presents the empirical formulas, the driving forces of rhinovirus-host interactions, as well as a mechanistic model of virus-host interactions at the cell membrane and in the cytoplasm. Based on the described data, conclusions are presented about why 50 % of infections of the upper respiratory tract are caused by rhinoviruses. For the first time, the changes in Gibbs energies of biosynthesis of virus particles of rhinoviruses A2, B3 and C15, as well as change in Gibbs energy of binding of rhinovirus A2 are presented, which are needed to understand the lifecycle of rhinoviruses.