Porphyrins are able to act as effective photosensitizers for oxidation due to the ability to generate reactive oxygen species under photoexitation. Various strategies for macrocycle functionalization allow us to significantly impact the photocatalytic activity of porphyrins. For instance, heterocyclic annelation with additional aromatic fragments, expanding the π-system, or the introduction of certain metal ions into the porphyrin cave can contribute to an increase in the quantum yield of singlet oxygen. It is reasonable to expect that the use of both types of modification will make it possible to obtain fundamentally new and highly efficient photocatalysts based on pyrazine-annelated metalloporphyrin. In this work, a series of novel pyrazinoporphyrinato In(III), Pd(II), Zn(II) and Mg(II) were obtained. The study of the photostability of the compounds demonstrated that In(III) and Pd(II) complexes are the most resistant to photoirradiation. Furthermore, the Pd(II) and In(III) porphyrinates demonstrated superior photocatalytic activity in the oxidation of thioanisole. Under blue-light irradiation with photocatalyst loading of 1×10⁻3 mol%, Pd(II) and In(III) complexes achieved complete conversion of the substrate to sulfoxide and the turnover number (TON) up to 100000. Remarkably, the high activity of the In(III) complex reduced the loading to 5×10⁻⁴ mol% while still achieving 100% conversion. A study of the kinetics of photooxidation of thionalizole was carried out under photocatalytic conditions. The highest oxidation rate was demonstrated by the In(III) complex, which reached 52% conversion for 3 hours, with the maximum TOF value of 17333 h^-1. The applicability of the In(III) complex as a photocatalyst for the oxidation of a series of structurally diverse organic sulfides was further studied, and 80-100% conversion was achieved for most of the substrates, which makes it a promising material for photocatalytic applications.

The work was supported by the Russian Science Foundation grant (project No. 24-73-00168).

This study reports a clean, surfactant-free synthesis of cobalt-based nanomaterials via pulsed laser ablation in liquid (PLAL) using deionized water as the ablation medium for advanced photocatalytic applications. A high-purity cobalt metal target was irradiated with a pulsed laser under controlled conditions to generate cobalt and cobalt-oxide nanoparticles directly in aqueous media, eliminating the need for chemical reducing agents, stabilizers, or post-treatment purification. The crystalline structure, phase composition, and crystallite size of the as-synthesized nanomaterials were systematically investigated using X-ray diffraction (XRD), confirming the formation of mixed metallic cobalt and cobalt oxide phases. Transmission electron microscopy (TEM) analysis revealed the successful formation of well-dispersed, predominantly nanospherical particles with a narrow size distribution in the nanometer range. The optical absorption characteristics were examined using UV–visible spectroscopy, demonstrating strong absorption in the visible region, which is highly favorable for photocatalytic activity under light irradiation. The photocatalytic performance of the synthesized cobalt-based nanomaterials was evaluated through the light-driven degradation of a model organic pollutant in aqueous solution. The nanomaterials exhibited remarkable degradation efficiency under visible-light irradiation, which can be attributed to their enhanced light-harvesting capability, high surface-to-volume ratio, and efficient charge carrier generation. The superior photocatalytic response confirms the effective role of PLAL in tailoring the structural and optical properties of cobalt-based nanomaterials. Overall, this work highlights PLAL in deionized water as a green, scalable, and environmentally benign synthesis route for producing high-purity cobalt-based photocatalysts with promising potential for wastewater remediation and environmental purification technologies.

Traditionally, pharmaceutical syntheses have relied on the use of toxic and precious metals, which poses concerns with safety and sustainability. Homogeneous photocatalysts, which use light to drive organic reactions, are offered as a solution; however, their recoverability and reuse are poor. This work reports on the development of photocatalyst-bound cotton to achieve higher reaction yields and selectivities, along with effective photocatalyst recyclability. These photocatalysts are synthesized following a two-step process: (i) a silanization reaction to covalently attach the (3-aminopropyl)triethoxysilane (APTES) linker to cotton, and (ii) a nucleophilic acyl substitution reaction between APTES-functionalized cotton and perylene-3,4,9,10-tetracarboxylic dianhydride to yield the photocatalyst-bound cotton. The lack of rigorous characterization techniques has limited the large-scale use of such heterogeneous photocatalysts. The major goal of this work is to develop a new technique to characterize the synthesized textile-bound heterogeneous photocatalysts using color shade-catalytic performance relationships. Specifically, a calibration curve relating the sample shade to the rate of photocatalytic reaction will be experimentally derived. Using spectrocolorimetry, the color of photocatalyst-bound cotton with varying photocatalyst loading was quantified. Procedures to dye cotton with photocatalysts were optimized to get evenly dyed samples, as determined by the lower standard deviation of L* values and the color intensity of the samples. Moreover, the applicability of these photocatalysts was tested in the oxidation of sulfide to sulfoxide, a functional group present in many pharmaceuticals. The progress of the reaction was monitored using thin layer chromatography (TLC) and nuclear magnetic resonance (NMR). Preliminary data accounting for several controls suggested that sulfoxide was formed only with the photocatalysts and illumination with blue light. Additionally, the recovery and reuse of these photocatalysts is under investigation. Overall, this work will serve as a foundation in the development of low-cost textile-bound photocatalysts in sustainable and efficient synthesis, which can be applied to pharmaceutical drug syntheses.

Harnessing the power of photocatalysis stands out as a beacon of hope in the quest for environmental restoration. Using a coprecipitation method, highly efficient Bi₂WO₆/g-C₃N₄ heterojunction photocatalysts, activated by visible light, were successfully fabricated. The Bi₂WO₆/g-C₃N₄ composite materials underwent characterisation utilising X-ray diffraction, UV-vis diffuse reflectance spectroscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy. The seamless fusion between Bi₂WO₆ and g-C₃N₄ fosters an environment where charge carriers are efficiently separated, minimising electron–hole recombination. This harmonious synergy enhances the photocatalytic prowess of the Bi₂WO₆/g-C₃N₄ composite, promising a brighter future for environmental remediation. The optical studies showed that the band gap of the composite was 2.71 eV. The parameters, such as initial dye concentration, pH and catalyst dosage, affecting photocatalytic activity were analysed and optimised. This study found that a pH of 2.5, a catalyst dosage of 30 mg, and a dye concentration of 5 ppm were the optimal parameters for this process. Under these conditions, the photocatalytic system achieved an impressive 95.649% degradation of Rhodamine B. The catalyst showed high stability up to five cycles. The kinetics of the photodegradation mechanism followed pseudo-first order. The rate constant of the composite showed that it folds greater than Bi₂WO₆, proving it to be an efficient photocatalyst.

The treatment of industrial effluents represents one of the most significant challenges in contemporary environmental engineering due to the presence of persistent organic compounds, synthetic dyes, pharmaceuticals, and endocrine disruptors that are not removed by conventional methods. Therefore, advanced oxidation processes (AOPs) are effective alternatives for the complete mineralization of recalcitrant pollutants through the generation of highly reactive species capable of degrading complex molecules into carbon dioxide, water, and inorganic salts. The objective of this work is to degrade five dyes using heterogeneous photocatalysis. The AOP study was carried out using DOE 2k and UV-Vis spectroscopic monitoring (Perkin-Elmer, Spectrum 100). The five model pollutants (AM, AT, RB, RM, and VM) (Sigma-Aldrich) were degraded under controlled conditions of pH, H₂O₂, and TiO₂. The response variables included the percentage of pollutant removal (%ERD), the apparent rate constant (kapp), and the final pH.

The optimized AOP achieved degradation efficiencies exceeding 99% for various aromatic organic compounds, demonstrating the high oxidative capacity of the generated radicals. AOPs constitute a versatile and highly efficient environmental technology capable of transforming persistent organic compounds into less toxic byproducts or completely mineralizing them. Their implementation contributes to reducing the pollutant load in effluents, promoting compliance with environmental regulations, and the reuse of treated water.

Ethidium bromide (EB) is a compound used as an intercalating agent in molecular biology for the visualization of nucleic acids in agarose gels. Its high mutagenic and carcinogenic properties, along with its potential for bioaccumulation, raise concerns regarding its release into aqueous effluents from research, diagnostic, and teaching laboratories. In this context, advanced oxidation processes (AOPs), particularly heterogeneous photocatalysis, are presented as an alternative for the complete degradation or mineralization of recalcitrant organic contaminants. In these processes, a radiation-activated semiconductor generates highly reactive radicals (•OH, •O₂⁻, h⁺) capable of breaking aromatic bonds and removing contaminants that escape conventional treatments. The objective of this protocol is to propose an experimental methodology for the removal of EB from laboratory wastewater using heterogeneous photocatalysis and to optimize operating parameters.

Based on the preliminary results obtained, the use of advanced oxidation processes, specifically heterogeneous photocatalysis with TiO₂, is a viable method for removing ethidium bromide (EB) from laboratory wastewater. It is expected that, under optimized conditions (pH, catalyst dosage, irradiation, aeration), removal rates greater than 80% can be achieved within reasonable operating times, with kinetic constants on the scale of 10⁻³ min⁻¹. Furthermore, it is essential to consider minimizing byproducts, evaluating mineralization (TOC/COD), and transitioning to continuous or scalable systems. In this regard, the findings support the integration of this technology into biotechnological effluent treatment flows, promoting environmentally responsible management and reducing the risk associated with EB release into aquatic environments.

Keywords: Advanced oxidation processes; ethidium bromide; heterogeneous photocatalysis; contaminant degradation

The formation of 1:2 inclusion complexes between the styryl dye DASPI and cucurbit[7]uril (CB[7]) in aqueous solution leads to changes in the absorption and fluorescence spectra of the dye. While similar spectral effects were previously attributed to protonation processes [1], direct pH measurements demonstrate that the addition of CB[7] does not alter acidity under the conditions used [2]. Instead, the observed spectral transformations arise from the specific geometry of triple complexes [3]. Key spectroscopic evidence is provided by a comparative analysis with the isolated donor fragment of DASPI.

Aqueous solutions of DASPI (C = 10-5 M) were studied in the free form, in the presence of CB[7], and under acidic conditions, while the donor fragment was investigated separately to establish a reference spectrum. Absorption spectra were recorded using a Shimadzu UVmini-1240, and fluorescence spectra were recorded on a Fluorolog-3 Tau.

In the 1:2 complex, two negatively charged portals of CB[7] are located on opposite sides of the π-conjugated bridge of DASPI. This arrangement creates an electrostatic field that disrupts the intramolecular charge transfer between donor and acceptor fragments of the dye. As a result, the characteristic long-wavelength band at 450 nm, associated with charge transfer, disappears, and a new band emerges at 330 nm. This new band coincides with the absorption of the isolated donor fragment, which confirms the localization of excitation on the donor part.

Thus, the use of the donor fragment as a spectroscopic reference allowed us to directly demonstrate the mechanism of electrostatic control. The results suggest that tuning the stoichiometry of complexes with cucurbiturils may provide a powerful approach for regulating the optical properties of organic dyes, and can be potentially extended to other supramolecular platforms or sensing applications.

1. Manna A., Chakravorti S. Spectrochim. Acta A: Mol. Biomol. Spectrosc., 2015, 140, 241–247.
2. Ivanov D.A., Kolesnikova O.P., Kryukov I.V., Petrov N.Kh. High Energy Chem., 2025, 59(3), 222-226.
3. Kolesnikova, O.P.; Ivanov, D.A.; Kryukov, I.V.; Petrov, N.K. The Influence of Cucurbit[7]uril on the Photophysical Properties of Encapsulated Styryl Dye. Chem. Proc.2025, 18, 120

One of the priority areas of scientific development today is the search for new approaches to efficient and selective transformations of organic substrates. This challenge can be successfully overcome using catalytic approaches to various reactions, including oxidation reactions. Due to their broadly conjugated polyaromatic system, porphyrins possess unique optical and electronic properties upon photoexcitation, namely the ability to transfer energy and electrons to molecular oxygen, forming its reactive oxygen species (ROS). In turn, the ROS allows selective oxidation reactions to be performed under mild conditions and prevents the formation byproducts and degradation products of chemical oxidants. This is fully consistent with the principles of atom economy and green chemistry. Thus, porphyrins could be considered as promising photocatalysts for effective oxidation processes. Nevertheless, the known porphyrin-based photocatalysts require significant efforts for the optimization of their photocatalytic characteristics, including activity, photostability, and conditions of photocatalytic reactions.

In this study, we developed an approach to control the physicochemical properties of the tetrapyrroles by introducing into the axial positions of Zr and Hf(IV) porphyrinates additional coordination structures—tris-pyridinoximate complexes of Fe, Ni(II) and Co(III). Thus, new metal(IV)porphyrinate-monocapped Fe, Ni(II) and Co(III)-centered pseudoclathrochelates were prepared.

It was shown that this functionalization of porphyrinates was shown to significantly increase photostability and the photocatalytic activity of the macrocycles in oxidation compared to their precursors. Irradiation with low-power light (LED lamp, 3W, 410-510 nm) in most cases resulted in complete conversion of thioanisole as model organic sulfide while maintaining >99% selectivity of the formation of the target sulfoxide. This type of photocatalyst has demonstrated high applicability for the oxidation of a series of aryl alkyl and alkyl alkyl sulfides with various substituents at extremely low catalyst loading (0.02 mol%).

This work was supported by the Russian Science Foundation grant (project No. 24-23-00323).

Silicon carbide/polystyrene (SiC/PS) nanocomposites with 1–10 wt% SiC were synthesized to investigate how structural, optical, and interfacial properties govern light-induced behavior relevant to photocatalysis and photochemical processes. SEM and XRD measurements confirmed that micron-scale, highly crystalline β-SiC is successfully incorporated into the amorphous PS matrix, with progressively intensified SiC reflections as loading increases. Williamson–Hall analysis showed that the 7 wt% composite exhibits the largest crystallite size (≈30.23 nm) and minimal microstrain, suggesting reduced lattice distortion and more efficient pathways for charge separation at polymer–ceramic interfaces. UV–Vis spectroscopy demonstrated that SiC concentrations of 1–5 wt% sharpen the absorption edge and increase the direct band gap from 3.91 to 4.22 eV and the indirect band gap from 2.91 to 3.82 eV. This band-edge modulation indicates suppression of defect-assisted transitions and improved generation of photo-excited carriers under UV illumination—properties essential for photocatalytic activity. At higher loadings (≥7 wt%), strong absorption and scattering prevent reliable gap extraction, pointing to intense photon attenuation within the composite. FTIR analysis revealed preserved PS vibrational signatures together with progressively strengthened SiC-related modes (Si–O–C at 1100–1150 cm⁻¹, Si–C/Si–C–O at 800–600 cm⁻¹, and a ~910 cm⁻¹ surface phonon), confirming physical rather than covalent interactions and indicating increased exposure of optically active SiC surface sites. Dielectric spectroscopy showed a systematic rise in ε′ and ε″ with increasing filler concentration due to Maxwell–Wagner–Sillars interfacial polarization, highlighting enhanced charge accumulation and migration under alternating fields. These results establish a direct correlation between SiC loading, photon absorption behavior, and interface-driven charge dynamics, identifying 3–5 wt% as optimal for UV-activated photochemical applications and 7 wt% as the most structurally stable composition.

Porphyrins constitute a versatile platform for designing photocatalysts, and the growing interest in photocatalysis for organic synthesis and sustainable technologies underscores the need for strategies that improve their efficiency. The synthesis of the target pyrazinoporphyrins was carried out following previously developed methodologies, which involve the reduction of 2-nitro-3-aminoporphyrin to the corresponding 2,3-diamino derivative followed by condensation with aromatic carbonyl compounds. A synthetic approach enabling the introduction of phosphoryl groups on the periphery of diaryl-substituted and phenanthrene-appended pyrazinoporphyrins was established via phosphorylation of brominated precursors. This strategy afforded a series of photoactive compounds, including the free bases and the Zn(II) and In(III) complexes bearing various meso-substituents.

To assess the effect of these structural modifications on the stability of pyrazinoporphyrins, the kinetics of photodegradation were analyzed. The introduction of diethylphosphoryl groups was found to markedly enhance photostability. Indium(III) complexation further decreased the photodegradation rate by nearly 20-fold, whereas zinc(II) coordination had the opposite effect.

The introduction of phosphoryl substituents and indium(III) ions into the macrocycle also resulted in a systematic enhancement in photocatalytic activity in the photooxidation of thioanisole. At 0.0005 mol% loading, functionalized free bases and In(III) complexes achieved 78–100% conversion, whereas non-functionalized pyrazinoporphyrins produced only 66–72% even at higher loadings (0.001 mol%).

Kinetics studies of thioanisole photooxidation in acetic acid revealed that in both series of pyrazinoporphyrins, the In(III) complexes outperform the corresponding free bases. At the lowest tested loading (0.00001 mol%), an exceptional TON of 9900000 and a TOF of 309000 h^-1 were obtained, highlighting the outstanding catalytic performance of these systems. The high efficiency of the catalysts was further demonstrated in the selective oxidation of a wide range of sulfides. Overall, the new photosensitizers outperformed previously reported porphyrin systems.

This work was supported by the Russian Science Foundation (grant № 24-73-00168).