Chalcogen-nitrogen chemistry deals with systems in which sulfur, selenium or tellurium is linked to a nitrogen nucleus. This chemical motif is a key component of different functional systems, ranging from inorganic materials and polymers to rationally designed catalysts, to bioinspired molecules and natural enzymes. The formation of a selenium-nitrogen bond, typically occurring upon condensation of an amine and the unstable selenenic acid and often leading to intramolecular cyclizations, and its disruption, mainly promoted by thiols, are rather common events in organic Se-catalyzed processes. In nature, along the mechanistic path of glutathione peroxidase, evidence of the formation of a cyclic intermediate characterized by the presence of a Se-N bond in highly oxidizing conditions has been reported and interpreted as a strategy to protect the selenoenzyme by overoxidation. Selenium is bonded to nitrogen also in the well-known ebselen, a selenenylamide with antioxidant, antimicrobic and cytoprotective activity and its formation/disruption has a crucial role for its drug action. Focusing on examples taken from selenium organic chemistry and biochemistry, the selenium-nitrogen bond is described and its strength and reactivity are quantified using accurate computational methods applied to model molecular systems. Significant trends show up when comparing to sulfur/tellurium-nitrogen bonds, reaffirming also in this context the peculiar and valuable role of selenium in chemistry and life.

The presence of emerging contaminants (EC), such as pharmaceuticals, in aqueous media is a serious and unresolved concern. Carbamazepine (CBZ) is a highly persistent antiepileptic drug that is resistant to biodegradation. The effect of CBZ on aquatic life has been evaluated as dangerous.

The use of ZnO as a photocatalyst has been widely used for the degradation of contaminants in water due to its low toxicity, low relative cost and wide bandgap. However, the rapid recombination of photogenerated electrons and holes, which added to photocorrosion, could decrease its photocatalytic activity . Modifying ZnO with metals allows to overcome these limitations, as well as visible light absorption.

In the present work, a series of Ce-doped ZnO materials were prepared by a simple wet chemical method at pH 4 (CeZnOa) and pH 8 (CeZnOb). They were characterized by several techniques such as HRTEM, SEM, IR, Raman and photoluminesce. The analyses revealed that the presence of Ce decreases the particle size and a second phase of crystalline CeO₂ appears when the dopant is higher than 0.4 at%.

The photocatalytic activity of the materials was studied for phenol degradation, as model of organic pollutant. Then, to apply the treatment to EC, they were used to study the CBZ degradation with a visible light source.

The crystalline CeZnOb showed a good photocatalytic performance for CBZ degradation (> 50 % after 3 h of visible light irradiation). Moreover, its use decreases the photodissolution of zinc in the aqueous media with respect to the undoped one.

The aim of this work is to explore the possibility of use of layered double hydroxides (LDH) as a photocatalyst for the selective oxidation of toxic nitrogen oxides, NO and NO₂ (NO_x ), to nitrate. Recent studies suggest that layered double hydroxides could be suitable for this aim.

LDH consists of brucite-like layers, with a partial M^II/M^III substitution, which causes a positive charge in the layer. The excess of charge generated is replaced by the intercalation of anions in the interlayer space. LDHs are layered materials with general formula [M^II_1-xM^III_x(OH)₂]X^n-_x/n·nH₂O where M^II = Mg²⁺, Zn²⁺, etc; M^III = Al³⁺, Fe³⁺, etc; and X^n- an interlayer anion which could be a great variety of inorganic and organic species depending on the preparation method. Calcination at 500 ºC converts the LDHs into mixed oxides, rehydration of which restores the original LDH structure by interaction anions from aqueous solution (reconstruction).

Thus, we synthesized MgAl-CrO₄ LDH by reconstruction method, from the precursor MgAl-CO₃ with Mg/Al ratio of 3, obtained by coprecipitation method, and compared these two LDH as photocatalysts for decomposition of NO_x gases (deNO_x). Techniques such as XRD, FT-IR and UV-Vis spectroscopy have been used to characterize the samples.

Compared to the pristine LDH system, the textural characteristics, optical and electronic properties of chromium containing LDH samples exhibited a better harvesting of sunlight and the highest specific surface area (> 50 m². g^-1). In addition, the photocatalytic results showed high efficiency of LDH (60%) towards the complete oxidation of NO_x.

Nowadays, efforts to develop novel light harvesters with high activity, stability and economy of precious metals it is fundamental in the field of photocatalysis. In this regard, coupling a low bad gap of p-type CuO with a high reactive n-type HLaTa₂O₇ protonated layered perovkite, is expected to produce enhanced charge carrier lifetime with beneficial impact on the photocatalytic activity. Therefore, a novel lamellar architecture was fabricated, via successive intercalation of n-butylamine followed by slowly introduction of smaller Cu²⁺ cations using HLaTa₂O₇ as host matrix to yield Cu²⁺/CuxLaTa₂O₇ layered compound. According to XRD data, the peak corresponding to (001) diffraction line of HLaTa₂O₇ host material was changed depending on the guest molecule in the interlayer (i.e. n-butylamine, copper). H₂-TPR results of the fabricated Cu-based perovskite indicated the co-existence of both Cu²⁺ reduced in two steps on HLaTa₂O₇ surface and [Cu²⁺(amine)^-]⁺ between host interlayers. A correlation between H₂-TPR experiments and EDX analysis shows that 26 % Cu²⁺ was incorporated in between interlayer galleries of HLaTa₂O₇. The beneficial role of copper addition demonstrates increasing of the specific surface area up to 4.1 m²/g compared to unmodified host compound. The photocatalytic degradation of phenol under simulated solar light irradiation has been used to assess the activity of modified layered perovskites. Our finding strongly support Cu-based layered perovskite as a promising candidate for depollution reactions.

Single-molecule fluorescence spectroscopy was used to study the behavior of a 2-hydroxy substituted nile red (NR-OH) dye in silica films incorporating amine gradients. These amine gradients were made by the vapor-phase deposition of 3-aminopropyltrimethoxysilane (3-APTMOS) onto microporous silica base layers in a humidity-controlled chamber. Water contact angle and ellipsometry measurements were used to confirm the formation of amine gradients. X-ray photoelectron spectroscopy (XPS) measurement of the nitrogen content of the gradient films showed that there was a gradual decrease in the amine content of the gradient films away from the 3-APTMOS reservoir. Bulk fluorescence studies of the dye in basic media of varying strengths showed that there is a hypsochromic shift in the emission maxima of the spectra with increasing basicity. Two-color fluorescence videos acquired along the gradients showed that the fluorescence of the dye was more intense in the 580/40 nm channel (where the deprotonated form of the dye is more prevalent) than the 640/40 nm channel at the high amine end of the films. With decrease in the amine content of the films, the fluorescence of the 580/40 nm channel decreases relative to the 640/40 nm channel. This study can aid in understanding the nature of active sites of bifunctional catalysts for an aldol condensation reaction carried out at the single molecule level.

UV irradiation is an essential factor in natural and artificial climate in modern environmental conditions, which has a constant effect on living systems.

Trypsin («MP biomedicals»), collagenase, ficin, papain and bromelain («Sigma-Aldrich») were the objects of this study. The substrate for hydrolysis was BSA («Sigma-Aldrich»), the carriers for immobilization were chitosans (< 100, 200 and 350 kDa) and chitosan succinate («Bioprogress»). The protease immobilization was carried out by the adsorption. The determination of the protein amount in samples and their catalytic activity was carried out by the modified Lowry method. UV irradiation of proteases was performed using doses 151–6040 J/m².

By the degree of photosensitivity, hydrolases can be arranged in the following row: collagenase → bromelain → ficin → papain → trypsin. Immobilization on a chitosan leads to an increase in the UV stability of heterogeneous biocatalysts compared to free enzymes. Photoprotective effect of the chitosan may be due to the following reasons: enzyme interact with the chitosan to form photo resistant complexes; сhitosan screen active free-radicals, preventing the photooxidation of a certain number of amino acids, including the active centers of the studied enzymes under the influence of UV irradiation.

This work was financially supported in the form of a grant from the President of the Russian Federation for state support to young Russian scientists - doctors of sciences (MD-1982.2020.4. Agreement 075-15-2020-325).

Nowadays, it is greatly concerning the harmful effects provoked over the environment and citizens by the urban pollution of NOx (NO + NO₂) gases. With the aim to remediate this problem, photocatalytic Layered Double Hydroxides (LDH) have been applied recently to remove these pollutants (De-NOx action) directly from the air. In this work, Ni²⁺Ti⁺⁴ -LDH with the interlayer anion carbonate have been synthesized by the coprecipitation method (NiTi-LDH). In addition to this preparation procedure, a treatment, AMOST (Aqueous Miscible Organic Solvent Treatment) has been applied to the samples in order to increase its surface area and particle dispersion (NiTi-AM samples). Moreover, two Ni/Ti ratios have been prepared to examine its effect on the De-NOx performance. The samples were characterized in order to study its structure, porosity, morphology, and optical properties. The obtained results showed that the NiTi-AM chemical structure did not change after the AMOST, but they showed a high increase of the delamination degree, leading to high specific surface area values. The photocatalytic De-NOx performance increases in those samples with higher amount of Ti (Ni/Ti = 2/1) and those subjected to the AMOST process. This process had more effect on the Ni/Ti = 3/1 ratio samples exhibiting improved photoactivity (≈ 10 %) compared to those samples prepared by conventional method. The enhanced De-NOx performance was associated to the higher number of LDH nanosheets, which increases the number of actives sites accessible to the reactant molecules.

Frequent use of pharmaceuticals and their improper disposal increasingly contribute to environmental pollution. Ibuprofen, a commonly used nonsteroidal anti-inflammatory drug, is usually not completely removed in the wastewater treatment process. To address this problem, we attempted to use photocatalysis to develop a new effective method for water remediation.

For this purpose, copper(II) phthalocyanine (CuPc) and zinc(II) phthalocyanine (ZnPc) were deposited on titanium dioxide nanoparticles (5 and 15 nm), yielding two types of photocatalytic material: CuPc@TiO₂, ZnPc@TiO₂. Briefly, TiO₂ nanoparticles were suspended in a Pc solution in dichloromethane. The mixture was left overnight stirring, the solvent was evaporated and the resulting solid dried at room temperature.

The photocatalytic experiment was carried out in a reactor composed of three vessels containing aqueous ibuprofen solution (10 mg/L) and the photocatalytic material. The mixtures were stirred and irradiated with three UV lamps (λ = 365 nm), positioned on a circular line. Samples were taken at -0.5, 0, 0.5, 1, 2, 4, and 6 h after the irradiation started. The concentration of ibuprofen was determined using HPLC-MS/MS.

Ibuprofen was photocatalytically degraded according to the first-order kinetics. When using CuPc@TiO₂, nearly 90% of ibuprofen content was removed from the solution after six hours of the experiment.

This study was supported by the National Science Centre, Poland under grant number 2016/21/B/NZ9/00783.

Various mesoporous molecular sites, such as SBA, have been synthesized using self-assembly of surfactants, with low and / or high molecular weight copolymers. Mesoporous molecular sieves such as SBA-3 can be synthesized at room temperature under acidic conditions. The method is similar to that of SBA-15, except for the template, which may be a low molecular weight quaternary alkylammonium salt. For this reason, the development of this material is interesting for applications in catalysis and redox deposition of metals on a nano-metric scale. Also, various catalysts have been applied for the oxidation of organic compounds in water, including the organic dyes. Nile Blue is a fluorescent dye, used in various bio-applications and it is considered a contaminant in water.

In this study, catalysts obtained by immobilisation of transitional metals on SBA-3 mesoporous silica were used to oxidize the Nile Blue from wastewater. The obtained silica support and catalysts were characterized by SEM, TG, UV-VIS, FTIR, BET surface area and pore size distribution measurements.

The oxidation was carried out in a batch reactor at room temperature and pressure. The de-colourization experiments were monitored by UV-VIS spectrophotometry. The oxidation reactions followed the first order kinetics. The catalysts could be recovered and reused.

The Nile Blue from wastewater can be oxidized by catalysts obtained by impregnation of transitional metals on SBA-3 suport, the oxidation products being less harmful for the environment and for the aquatic systems.

We developed a novel synthetic methodology for the chemo regio and stereoselective selenomethoxylation of olefins and the selenium mediated cyclofunctionalization of alkenols and alkenoic acids promoted by low-energy blue-led light. The electrophilic species is generated, in situ, starting from diphenyl diselenide according to a self-catalyzed photoredox processes that use atmospheric oxygen as additional oxidant. From a mechanicistic point of view it can be envisioned that the photoactivated homolytic cleavage of Se – Se bond affords a phenylselenenyl radical that can be oxidized by a molecule of oxygen leading the formation of a superoxide anion and the electrophilic selenium species PhSe+ that reacts with C-C double bound affording the formation of a seleniranium ion intermediate able to react regio and stereospecifically with external and internal nucleophiles. Furthermore, the photocatalytically formed PhSe^. radical can react directly with the unsaturated substrates affording a radical selenium containing intermediate that can react with oxygenated nucleophile affording the desired products and a molecule of selenol that is in turn oxidized to diselenide by the atmospheric oxygen. Investigation focused on prove the mechanism and investigate the stereoselectivity also in the presence of preformed chiral centers will be reported and discussed. In our opinion this reaction that can be performed without additives, without external oxidants (apart naturally present oxygen) and without a workup is currently the greener way to perform electrophilic selenenylation reactions in good yield and high selectivity. The use of Santi's reagent (PhSeZnCl) and 1,1'-diselanediylbis(naphthalen-2-ol) as selenium sources will be reported and discussed.