The efficient degradation of halogenated organic compounds is a major challenge in advanced water treatment processes. This study reports the synthesis and evaluation of an asphaltene-tuned photocatalyst under two different photochemical reactors for degradation of 2,5-dichlorphenol, which is not only persistent and toxic but also declared as a pollutant of priority concern. Based on photocatalytic efficiency, graphitic carbon nitride was selected as a support material for immobilization of asphaltenes and for optimization of degradation parameters. Palladium-loaded graphitic carbon nitride (Pd/g-C₃N₄) nanocomposites were also synthesized. Photocatalytic performance of both synthesized photocatalytic materials was evaluated in two different photoreactor systems, i.e., an UV photoreactor and Xe-lamp photoreactor. Asphaltenes-tuned g-C₃N₄ exhibited significant photocatalytic activity under both irradiation sources which revealed the potential of asphaltenes as a promising and effective component of photocatalysts and highlighted the potential of transforming problematic petroleum fractions into functional materials that can be used for sustainable water treatment. The synergistic interactions between Pd nanoparticles with g-C₃N₄ matrix and effective generation of reactive species under irradiation accounts for a higher degradation rate for Pd/ g-C₃N₄ in both photoreactor systems. The comparative analysis revealed the role of loading metal on degradation kinetics. Overall, this study revealed that asphaltenes-tuned graphitic carbon nitride and palladium-loaded graphitic carbon nitride are efficient and promising photocatalysts for effective degradation and dehalogenation of halogenated phenols in diverse irradiation environments.

Bromoform (CHBr₃) is a very short-lived substance (VSLS) present in the troposphere, originating mainly from natural sources (e.g., phytoplankton and macroalgae)¹. It contributes to the formation of reactive bromine species that participate in ozone depleting and other atmospheric reactions². The aim of this work is to investigate the evolution of CHBr₃ in the presence of O₂ under UV-vis irradiation and to elucidate the mechanism involved in the photoreaction.

Different CHBr₃:O₂:Ar mixtures (1:1:400 and 1:20:400) were prepared on a vacuum line using standard manometric techniques. The mixtures were deposited on a CsI window cooled at 10 K using a pulse-deposition technique. A Xe(Hg) arc lamp was operated at 800 W. To reproduce atmospheric conditions, selected spectral intervals were used: 400≤λ≤ 800 nm for visible radiation; 350≤λ≤450 nm and 280≤λ≤320 nm, corresponding to portions of the UV-A and UV-B regions, respectively; and 200≤λ≤800 nm to include UV-C, UV-B, UV-A, and visible radiation. Complementarily, we investigated the reaction mechanism between CHBr₃ and O₂ in the gas phase using a home-built cell that allows simultaneous irradiation and FTIR acquisition.

The initial spectra of the matrix-isolated samples showed only the bands of CHBr₃. After irradiation with broadband UV-vis light and using the 350≤ λ ≤ 450 nm filter, new bands appeared in the absorption region of CO, HBr, and CO₂. These bands exhibited the same growth kinetics and increased their intensity after annealing. CO, HBr, and CO₂ were detected as photoproducts in gas phase experiments.

The structures of the possible intermolecular complexes formed among the photoproducts were theoretically simulated using the B3LYP-D3/6-311++G(d,p) approximation. At the molecular level, we detected, via FTIR-matrix isolation techniques, new complexes involving CO, HBr, and Br₂, in agreement with theoretical calculations.

(1) Villamayor et al. Nat. Clim. Chang. 13 (2023) 554–560.

(2) Tinel et al. Elem. Sci. Anthr. 11:1 (2023) 00032.

Studying the surface of heterogeneous photocatalysts has been a long-standing challenge in the catalysis community. This project investigates the effect of surface loading on the properties and performance of colloidal photocatalysts. Using detailed spectroscopic analyses, this research addresses challenges with catalysis and will help understand how surface engineering influences the properties of photocatalysts in different organic solvents. These studies will help improve the synthesis of complex organic compounds and high recovery rates for the photocatalysts used for catalyzing reactions. To synthesize our photocatalyst particles, (3-Aminopropyl)triethoxysilane (APTES) was bound to silica particles before covalently attaching the photocatalyst perylene tetracarboxylic acid dianhydride (PTCDA). The photocatalysts were characterized using several spectroscopic and chemical analyses. To assess the performance of these catalysts, the oxidation of sulfide to sulfoxide with the PTCDA-bound modified silica was tested in a photoreactor using 450 nm blue LED light over 12 hours. This reaction has wide applications in the synthesis of commercial pharmaceutical drugs, making it the best reaction to test these silica particles. The photocatalytic oxidation of sulfide was monitored by thin layer chromatography and nuclear magnetic resonance. The catalytic performance at varying photocatalyst loading on silica was tested. Analyses of these data showed a faster rate with lower photocatalyst concentration, which is the opposite of expected results. A plausible reason for this observation could be attributed to the effect of photocatalyst loading on their excited state lifetimes. Excited states of photocatalysts can be more effectively quenched at higher surface concentrations, leading to poor catalytic performance. To test this hypothesis, the surface loading–photophysical property relationships will be further assessed. Moreover, careful photochemical studies were performed to confirm that both the photocatalyst and the light illumination were required to drive sulfide oxidation. With this collected data, more experiments will be conducted to test the reproducibility of observed outcomes.

A newly developed series of amphiphilic and cationic phthalocyanines was designed to determine how quaternization, peripheral substituents, and metal coordination govern photodynamic and sonodynamic performance. All derivatives displayed characteristic Q-band absorption between 673 and 705 nm and fluorescence quantum yields spanning Φ_f = 0.01–0.26. Quaternization markedly increased emission in Zn(II) complexes (Φ_f: 0.02 → 0.17), while reducing it in metal-free and In(III) analogues. Singlet oxygen formation was efficient across the series, with Φ_Δ = 0.63 for both InPc and QInPc and a twofold increase for ZnPc upon quaternization (Φ_Δ: 0.27 → 0.51). The unsubstituted ZnPc was used as a reference. Photodecomposition quantum yields (10⁻⁵–10⁻⁴) indicated that quaternization enhanced photostability for metal-free and Zn(II) derivatives, while minimally affecting the In(III) complex.

The quaternized phthalocyanines demonstrated high antimicrobial potency. In methicillin-resistant Staphylococcus aureus (MRSA) and ESBL-producing Escherichia coli, inactivation reached 4.6 logs, while Gram-negative strains showed 4.5-log reductions. Activity against fluconazole-resistant Candida albicans demonstrated the following: QH₂Pc, QInPc, and QZnPc achieved 3.2-log reductions.

Sonodynamic evaluation confirmed strong ROS formation. Non-quaternized sensitizers accelerated DPBF decay around 4.5-fold, with ZnPc showing the fastest kinetics (k = 0.152 min⁻¹; t₀_.₅ = 4.55 min). Quaternized derivatives remained sonodynamically active; QZnPc has the potential to generate ROS efficiently (k = 0.130 min⁻¹) and displayed improved ultrasound stability (t₀_.₅ = 59.7 min vs. 11.2 min for ZnPc).

These results establish this family of amphiphilic phthalocyanines as potent, multimodal sensitizers, capable of achieving high-log photodynamic reduction and showing potential for strong sonodynamic ROS output. Their performance, together with clear structure–property relationships, highlights their promise for next-generation antimicrobial therapy.

In this study, conjugation with human serum albumin (HSA) was explored as an alternative to micellar formulations for improving aqueous solubility and modulating the delivery profiles of chlorin-based photosensitizers (PSs) intended for photodynamic therapy (PDT).

A comparative analysis was performed for chlorin e6, HSA conjugates of chlorin derivatives and their unconjugated micellar formulations using in vitro assays on the A431 carcinoma cell line. Intracellular accumulation kinetics were quantified by flow cytometry at multiple incubation times, and photoinduced cytotoxicity was evaluated following 2 h, 4 h, and 8 h incubation in the presence and absence of a washout step.

Chlorin e6 demonstrated relatively slow intracellular uptake and correspondingly lower photoinduced cytotoxicity. In contrast, the non-conjugated PSs exhibited rapid and pronounced accumulation, accompanied by high levels of phototoxicity. HSA-conjugated PSs displayed a distinctly different uptake profile: intracellular accumulation increased gradually and continuously over time, yielding cytotoxicity values that approached those observed with unconjugated PSs at longer incubation periods. This behavior reflects the altered transport mechanisms imposed by albumin binding and suggests sustained cellular delivery rather than rapid saturation.

Micellar PS formulations showed the highest uptake rates and phototoxicity in vitro; however, their non-specific endocytic internalization may limit their biological selectivity in vivo. Although HSA conjugation resulted in comparatively slower uptake in vitro, albumin is an endogenous long-circulating carrier capable of passive tumor targeting and receptor-mediated cellular uptake, suggesting potential advantages for in vivo biodistribution, reduced systemic toxicity, and improved tumor selectivity compared to micellar systems.

These findings highlight that HSA conjugation provides a tunable delivery strategy that balances solubility enhancement and photodynamic efficacy, thereby representing a promising alternative to micellar formulations for PDT applications.

This work was carried out with the support of the Ministry of Science and Higher Education of the Russian Federation within the framework of the state assignment, research topic project № FSFZ-2025-0020.

The interaction between beta-cyclodextrin (β-CD) and the merocyanine form of 4-[(2E)-1,1-dimethyl-2-({[(1Z)-2-oxo-1,2-dihydronaphthalen-1-ylidene]amino}methylidene)-1H,2H,3H-benzo[e]indol-3-yl]butane-1-sulfonic acid (MC) was investigated to elucidate host–guest complexation dynamics and stability, in order to develop applications such as photoswitches for imaging and therapy. These applications are possible due to MC’s absorption changes upon isomerization; therefore, the β-CD environment can provide a consistent, water-compatible platform and potentially targetable coatings. β-CD is a cyclic oligosaccharide that is well known for its ability to form "inclusion complexes" with other molecules, changing the properties of the guest molecule upon binding. Spironaphthoxazines belong to the class of organic photochromic compounds. In this work, MC’s Open Photomerocyanine form was used in the investigations and complex formation. Aqueous solutions of MC in the presence and absence of β-CD were irradiated at the corresponding wavelength, and their spectroscopic behavior was analyzed. Binding constants were calculated, and the continuous variation method (Job’s plot) demonstrated that stoichiometries other than 1:1 were present. Not only were 2:1 and 3:1 complexes observed, but many other possible intermediate stoichiometries (e.g., between 1:1 and 3:1) may also be present in the solution. Dynamic light scattering measurements were used to characterize the β-CD/MC nanoparticles. The thermal behavior of the complexes was investigated using solution calorimetry. Docking studies combined with DFT calculations were done to evaluate the stability of β-CD/MC complexes with different stoichiometries. Interestingly, the 2:1 complex shows a slightly higher stability compared to the 1:1 and 3:1 complexes, aligning well with experimental findings. The results have shown that the inclusion of MC within the β-CD cavity influences the rate and direction of isomerization between different MC forms, also affecting MC solubility and stability. The interaction between MC and β-CD can be used for further applications to create controlled optical switches that respond to external stimuli like light, temperature, or pH.

PDT is known as a non-invasive technique for the treatment of tumors of epithelial tissues. One of the main directions in the development of PDT methods is to increase their cytotoxicity. For this purpose, a combined therapy strategy is being implemented, which consists of the simultaneous use of a photosensitizer and cytotoxic agent [1]. Doxorubicin is one of the most commonly used chemotherapeutic agents. In order to reduce its off-target toxicity and implement the principle of combination therapy, guided delivery systems need to be developed [2]. Light is a convenient external stimulus, and conjugates of therapeutic agents through photocleavable linkers have been shown to be effective for combined PDT [3].

In our work, we obtained a conjugate of the derivative of natural chlorin, anthracycline antibiotic doxorubicin and a photocleavable linker. The mechanism of photochemical destruction was studied both experimentally using light irradiation, UV-Vis spectrophotometry, and fluorescence spectroscopy, as well as computationally using density functional theory (DFT) calculations. We conducted biological tests on a human breast cancer cell line MCF-7 and tried to interpret the results obtained in vitro using in silico docking methods.

The work was carried out with the support of the Ministry of Science and Higher Education of the Russian Federation within the framework of the state assignment, research topic project № FSFZ-2025-0020.

1) Grin, Mikhail, et al. "Advantages of combined photodynamic therapy in the treatment of oncological diseases." Biophysical Reviews 14.4 (2022): 941-963.

2) Chen, Pinggui, et al. "Porphyrin-based covalent organic frameworks as doxorubicin delivery system for chemo-photodynamic synergistic therapy of tumors." Photodiagnosis and Photodynamic Therapy 46 (2024): 104063.

3) Johan, Audrey Nathania, and Yi Li. "Development of photoremovable linkers as a novel strategy to improve the pharmacokinetics of drug conjugates and their potential application in antibody–drug conjugates for cancer therapy." Pharmaceuticals 15.6 (2022): 655.

The global rise in energy demand and the continuous increase in atmospheric CO₂ emissions have underscored the urgent need to develop cleaner and more sustainable energy technologies. Among the different strategies under study, photocatalytic hydrogen production is especially attractive, as it enables the conversion of solar energy into a carbon-free fuel. Titanium dioxide (TiO₂) is one of the most widely investigated photocatalysts owing to its stability, low cost, and non-toxicity. However, its practical efficiency remains limited by rapid electron–hole recombination and weak absorption in the visible region. In this work, we synthesized novel TiO₂-based composites modified with ferroelectric BST perovskites (Ba_1-xSr_xTiO₃), conductive MXene (Ti₃C₂T_x), and metallic co-catalysts (Ni/Cu). The samples were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy (PL), and Brunauer–Emmett–Teller (BET) surface area analysis to evaluate their structural, optical, and morphological properties. Photocatalytic tests revealed a clear enhancement in hydrogen photoproduction. While pure TiO₂ generated around 0.5 mmol h^-1 ·g_cat^-1, the best-performing TiO₂/BST/MXene/Cu composite reached values equal to ~60 mmol ·h^-1 ·g_cat^-1. This improvement can be attributed to the synergistic contribution of each component. BST helps to separate charges more efficiently thanks to the internal electric field within its ferroelectric structure, which reduces the chance of electron–hole recombination. At the same time, MXenes act as highly conductive pathways, facilitating efficient electron transfer to the metal co-catalyst sites. As a result, charge recombination is suppressed, leading to a significant increase in hydrogen evolution activity. Overall, the obtained results demonstrate that combining TiO₂ with BST, MXene, and Cu metal co-catalysts is a highly effective strategy for enhancing photocatalytic performance and supports the development of renewable hydrogen technologies.

Introduction. Perovskite KTaO₃ is regarded as a promising photocatalyst owing to its high stability and structural adaptability to substitution. The possibility of substituting oxygen with nitrogen or sulfur in its lattice allows the band gap to be reduced and the material response in the visible region of the spectrum to be enhanced. In this work, the oxysulfide perovskite KTaO_3-xS_x is presented, and the effect of sulfur content on its structure and photocatalytic properties under solar-light irradiation is investigated.

Materials and Methods. KTaO_3-xS_x powders were obtained in two steps: KTaO₃ was first synthesised via a solid-state reaction between K₂CO₃ and Ta₂O₅ at 800 °C for 8 h, and then KTaO₃ was treated at 600 °C in an H₂S atmosphere. The sulfur content was determined by means of EDS, and changes in the crystal structure were monitored via XRD. The photocatalytic activity of KTaO_3-xS_x particles was evaluated from the degradation of rhodamine B (RhB), and the contribution of different catalytically active species to the photocatalytic process was assessed by means of scavenger experiments.

Results. Oxysulfide perovskites KTaO_3-xS_x with sulfur contents of 1.8, 4.2 and 7.4 at.% were obtained. The samples are single-phase, and the KTaO₃ structure is preserved over the entire sulfur-doping range studied. The KTaO_2,79S_0,21 sample (4.2 at.% S) exhibits the highest photocatalytic activity under solar-light irradiation: in RhB degradation, its activity is 2.25 times higher than that of pristine KTaO₃, with superoxide anion O₂•⁻ being the main active species.

Conclusions. It is shown that sulfurization of KTaO₃ in H₂S vapor enables controlled formation of the oxysulfide perovskite KTaO_3-xS_x. Sulfur doping increases the photocatalytic activity by more than a factor of two: the composition containing 4.2 at.% S exhibits an activity of 12.5 mg·g^-1·h^-1 in RhB degradation under solar-light irradiation.

This work was supported by the Russian Science Foundation (25-19-00458).

Photocatalytic nitrate (NO₃¯) reduction represents a novel and transformative technology that has the potential to produce harmless gaseous byproducts. The photocatalytic denitrification process is frequently accompanied by the creation of undesirable nitrite (NO₂¯) or ammonium (NH₄⁺), resulting in poor selectivity for dinitrogen (N₂). The catalytic reduction of NO₃¯ ions utilizing bimetallic catalysts necessitates the presence of a noble metal, alongside a promoting transition metal. The transition metal facilitates the reduction of NO₃¯ to NO₂¯ ions through a redox mechanism, which subsequently results in its oxidation. Furthermore, the noble metal's function is to maintain the transition metal in its lower oxidation states via hydrogen spillover. Among oxide photocatalysts, titanium dioxide (TiO₂) has found significant application in photocatalysis and the cleanup of environmental contaminants.

In this report, we present the deposition of platinum (Pt), cobalt (Co), and nickel (Ni) onto the surface of TiO₂ powder through a successive impregnation method. The influence of non-noble metal incorporation over Pt-TiO₂ catalyst was studied by means of powder X-ray diffraction (XRD), diffuse reflectance UV-Vis, and temperature programmed reduction in hydrogen (H₂-TPR) analyses and photoluminescence spectroscopy (PL). The initial activity evaluation focused on the catalytic reduction of NO₃¯ with H₂. The following stage involved the evaluation of the photocatalytic activity of the catalysts by monitoring the reduction of NO₃¯ under the illumination of a UV lamp. A primary goal is to assess these materials for their optimal selectivity in generating benign end products (such as N₂). In the tests conducted under UV light irradiation, the selectivity toward N₂ was around 68%, which is approximately 1.5 times greater than the values obtained during denitrification without light exposure. A preliminary test for water splitting using the Pt-Ni/TiO₂ sample yielded hydrogen. It is hypothesized that hydrogen is generated, yet it is utilized in the process of nitrate photoreduction.