A series of amides of 1-(2-pyridyl)-5-arylpyrazole-3-carboxylic acids has been synthesized. Complexes of synthesized ligands with salts of 4f- and 5f-elements were obtained. The composition of the complexes in the gas phase, solution, and solid state has been studied. The luminescence parameters of europium complexes in solution have been determined.

В прибрежных водоемах, образовавшихся путем отделения от Белого моря в ходе послеледникового под­нятия берега, в хемоклине – градиентной зоне между аэробной и сероводородной зонами – часто наблюдается окрашенная прослойка воды с массовым развитием фототрофных микроорганизмов. Спектры пропускания солнечного света, измеренные на разных горизонтах трех стратифицированных водоемов и в прибрежной морской акватории с помощью погружаемого волоконно-оптического зонда, сопоставлены со спектрами поглощения света водой на этих же горизонтах. Для слоев с массовым развитием аноксигенных фототрофов по спектрам поглощения определены концентрации бактериохлорофиллов. Согласно полученным данным диапазоны проходящего солнечного спектра в водной толще («цветовые экологические ниши») в значительной степени зависят от растворенных в воде гуминовых веществ. Их концентрация возрастает по мере изоляции водоема от моря, из-за чего фотическая зона сужается по глубине, хемоклин оказывается ближе к поверхности и наблюдается сдвиг спектра попадающего в хемоклин света в более длинноволновую сторону. В морской бухте до хемоклина доходит в основном свет с длиной волны 524–593 нм, в морской стратифицированной лагуне преобладают длины волн 526–597 нм, в водоемах с пресным поверхностным слоем воды солнечный спектр сдвинут в красную область (573–727 нм). Показано, что «цветовые экологические ниши» в различных водоемах заняты организмами, светособирающие антенны которых адаптированы к поглощению квантов света соответствующего спектрального диапазона. Этот факт может быть использован для предсказания таксономического состава различных слоев стратифицированного водоема. In coastal water bodies formed by separation from the White Sea during the post-glacial uplift of the coast, in the chemocline (the gradient zone between the aerobic and hydrogen sulfide zones), a colored layer of water with a development of phototrophic microorganisms is often observed. The solar light transmission spectra measured at different horizons under water in three stratified water bodies in the coastal marine area using a submersible fiber optic probe are compared with the absorption spectra of light by water from the same horizons. In the layers with massive development of anoxygenic phototrophs, the concentrations of bacteriochlorophylls were determined from the absorption spectra. According to the data obtained, the ranges of the transmitted solar spectrum in the water column (“color ecological niches”) are largely determined by humic substances dissolved in water. Their concentration increases as the water body is isolated from the sea, due to which the photic zone narrows with depth, the chemocline becomes closer to the surface, and a shift towards longer wavelengths appears in the spectrum of light entering the chemocline. In the marine bay, the 520– 600 nm part of the spectrum reaches the chemocline, in the marine stratified lagoon, wavelengths of 510–6700 nm predominate, in reservoirs with a fresh surface layer of water, the solar spectrum is shifted to the red region (520–7200 nm). It is shown that "color ecological niches" in various water bodies are occupied by organisms whose light-collecting antennas are adapted to absorb light quanta of the corresponding spectral range.

In this work, three isomeric fluorinated bipyridyldicarboxamides were studied to evaluate the impact of the fluorine atom position on the structure, stability, Am(iii)/Ln(iii) separation, and photophysical properties of their complexes. The complexes of the fluorinated amides have a metal-to-ligand composition of 1 : 1, which is independent of the fluorine atom position or lanthanide metal. The bipyridyl fragments in the fluorinated complexes are flattened compared with those in unsubstituted ones. Ln-to-heteroatom distances are more affected by steric hindrance in the ligand and further by lanthanide ion radius contraction. This leads to significant effectivity of heavy lanthanide extraction compared with the light ones, particularly for 4F diamide. Fluorination leads to a slight variation in the excited triplet state of the complexes, and hence, the effectiveness of luminescence increases for Eu, Sm, and Tb complexes. Moreover, fluorination significantly affects the CIE chromaticity coordinates for the complexes. Even slight changes in the fluorinated bipyridine-derived diamide ligand structure, such as fluorine atom positioning, can substantially affect the properties of the metal complexes, with implications for selective extraction and luminescence.

The luminescent properties of three novel water-soluble europium complexes with organic ligands based on 2,2'-bipyridyl substituted with phosphonic acids were studied in water and heavy water at temperatures from 293 to 333 K. With an increase in temperature, a decrease in the intensity of europium luminescence was observed both in water and heavy water. The luminescence intensity in the studied temperature range is well described by the van't Hoff plot for each solution. For all complexes, the luminescence lifetime in heavy water was much longer than in water due to effective quenching of the excited states by the OH oscillators of water molecules located in the first coordination sphere of the europium. The number of water molecules in the first coordination sphere of the europium at different temperatures was calculated; it did not vary with temperature. We conclude that the main mechanism of luminescence quenching is the enhanced energy back transfer from the excited state of europium to the triplet level of the ligand or the charge transfer state. The energy back transfer probability rises simultaneously with a displacement of the position of the europium ion relative to the inverse center in the complex upon solution heating.

Solutions in acetonitrile of three mixed complexes of rare-earth elements (terbium and samarium) with organic ligands with various pyridine substituents were studied in this work. The ratios of ligands and metals in the resulting complexes were determined, and the stability constants of samarium complexes were calculated using the spectrophotometric titration method. Measurements of absorption-, emission-, and excitation spectra of luminescence, luminescence kinetics of solutions of mixed complexes of rare-earth elements with an excess of metal relative to the ligand were carried out at various temperatures in the range 298–328 K. For the first time, an increase of luminescence intensity of a samarium ion in complex upon heating was observed. The dependences of the luminescence quantum yield and lifetime of mixed complexes on temperature were obtained. A thermometric parameter—the ratio of the integral luminescence intensities of samarium and terbium ions—was proposed, and the temperature sensitivity coefficient of this parameter was determined for different complexes.

In this study, we evaluated the effect of dissolved organic matter on the sorption of ciprofloxacin by magnetite silica-based nanoparticles (NPs). For this purpose, magnetite nanoparticles modified with organosilanes (tetraethox-ysilane and 3-aminopropyltriethoxysilane, MTA) were used as a model of colloidal particles and a sorbent. Analysis of the absorption spectra found that there was no interaction between antibiotic ciprofloxacin (CIP) and humic substances (HS, sodium salt of humic acids) in aquatic system at pH varied from 6 to 8. But, the behavior of CIP and HS changes dramatically upon addition of silica-coated magnetite nanoparticles. The introduction of the MTA NPs into a bicomponent system of CIP incubated with HS lead to more than twice increased CIP sorption. Results of electrokinetic measurements in terms of zeta-potentials propose the interaction mechanism into CIP-HS-NPs system. In the three-component system, the surface of MTA is completely overcharged from negative to positive, and importantly this effect is pH-dependent. The MTA zeta-potential changes from − 15 (pH 6) and − 30 mV (pH 8) to + 10 (pH 6) and + 2 (pH 8), respectively. The study provides novel scientific information as nanoparticles are increasingly produced and studied for various environmental applications, including sorption of new emerging eco-toxicants (pharmaceuticals) but the assessment of dissolved organic matter contained even in trace concentrations should not be ignored.

The optical properties of chromophoric dissolved organic matter (CDOM) of natural water have been studied by fluorescence spectroscopy and absorption spectroscopy. Samples of natural water from various depths from the meromictic lakes Trekhtzvetnoe and Elovoe were taken. The dependences of the quantum yield and the maximum of fluorescence emission on the excitation wavelength in a wide range of excitation wavelength variation (250...500 nm) for different horizons of stratified reservoirs are obtained. It is shown that the dependences of the maximum of the fluorescence emission on the excitation wavelength and the dependences of fluorescence quantum yield on the excitation wavelength in both lakes and at all depths studied are similar. On the other hand, the absolute value of the quantum yield differs in different layers of water. For example, the values of the fluorescence quantum yield took values from 1.4% to 2.4% at an excitation wavelength of 340 nm. The similar nature of the dependence of the fluorescence intensity on the excitation wavelength is explained by the common origin of DOM fluorophores in the studied horizons of stratified lakes. The different values of the fluorescence quantum yield are due to the difference in the proportion of aromatic compounds in the composition of the CDOM and are associated with differences in the hydrochemical characteristics of water at different horizons.

The composition and structure of the anoxygenic phototrophic bacterial (APB) community in the water column of meromictic Lake Bol’shie Khruslomeny during winter were investigated. The community developed at the depth of 4.25 m, and its activity in the ice-cover period was very low (6.2 µmol C L–1 day–1). The water in the zone of highest development of phototrophic bacteria was of an unusual lemon-yellow color, probably due to the production and accumulation of polysulfides. The near-bottom water was also of lemon-yellow color and was resistant to oxidation by the air oxygen. In the zone of peak APB development the content of BChl d from green-colored green sulfur bacteria was considerably higher than that of BChl e from brown-colored green sulfur bacteria: 77 and 23

Chlorosomal bacteriochlorophylls are the main photosynthetic pigments of green sulfur bacteria – anoxygenic phototrophic microorganisms. The spectral properties of chlorophylls of higher plants, algae and cyanobacteria are well studied, however, the spectral-luminescent properties of their related compounds, bacteriochlorophylls, which participate in anoxigenic photosynthesis, are practically not described in the scientific literature. The polarity of the solvent and the environment have a significant effect on the emission spectra (bacterio)chlorophylls, which is expressed in the spectral shift of the absorption and fluorescence maxima, as well as changes in the fluorescence intensity. The spectral characteristics of bacteriochlorophylls d and e were obtained in organic solvents such as acetone, methanol, ethanol and isopropanol, as well as in acetone-ethanol (7:2) and acetone-methanol (7:2) mixtures. These solvents are most often used for the extraction of bacteriochlorophylls from bacterial cells, so the work will be useful for the development of methods for the quantitative determination of chlorosomal bacteriochlorophylls in bacterial cells or in samples of natural water.

In this paper we describe the results of the influence of temperature in the range of 280–340 K on the luminescence of bimetallic Eu/Tb complexes with N-heterocyclic ligand L based on 2,2′-bipyridyldicarboxylic acid in acetonitrile. The experiments were carried out for systems with various Eu/Tb ratios. The stability of the complexes of the ligand L with metal M (Eu or Tb) was determined using spectrophotometric titration in acetonitrile solutions. The LM complexes’ stability constants were found to be typical for these systems; however, the stability of Eu complex is slightly higher than that for Tb. Along with rising temperature, we observed a decrease in Tb emission intensity and, at the same time, an enhancement in Eu luminescence. An explanation of Eu luminescence enhancement involves the appearance of charge transfer states, bands of which can be observed in the Eu luminescence excitation spectra as difference spectra measured with two close temperatures. The unusual Eu luminescence enhancement upon heating was observed for the first time for the complex with tetradentate O,N-type heterocyclic diamide ligand L, while an inverse phenomenon was observed with the Tb luminescence. The Eu luminescence enhancement was found earlier for various carboxylate complex salts, but not for heterocyclic coordination complexes. This allows the construction of a ratiometric luminescent thermometer in the range of 280–340 K using the ratio of luminescence intensities for Eu and Tb. The stability constants for the individual Eu and Tb complexes help us to understand the equilibrium in L:Tb:Eu complex system and shed light on plausible speciation in solution.

The increase in the production and application of engineered nanomaterials, including nanoparticles (NPs), leads to their discharge into the environment, where they can interact with coexisting antibiotics from wastewater, causing a complicated joint effect on organisms that need to be studied. Herein, a typical engineered nanomaterial, silica-magnetite NPs modified with tetraethoxysilane and 3-aminopropyltriethoxysilane (MTA-NPs, 1-2 g/L), and common antibiotic ciprofloxacin (CIP, 0-5 mg/L) were selected as the analytes. Their joint toxicity to a model of ciliates infusoria, Paramecium caudatum was specifically investigated. The impact of CIP, MTA-NPs, and humic acids (HA) was tracked for 24 h, individually and collectively, on the mortality of infusoria. The addition of MTA-NPs and HA at the studied concentrations leads to 40% mortality of organisms. The combined presence of the MTA-NPs at a concentration of 1.5-2 mg/L and HA at a concentration of 20-45 mg/L has a multiplier effect and allows to reduce the mortality rate of ciliates > 30% due to the enhanced removal of CIP. That finding demonstrated a clearly detoxifying role of dissolved organic matter (here, humic substances) in case of complex water pollution where pharmaceuticals and nanomaterials are presented.

Along the shoreline of the White Sea, due to the post-glacial uplift of the coast, some water bodies with stable stratification have been formed. They have been classified as meromictic as they are at different stages of isolation from the Sea. As separation progresses, significant changes occur in the water column, including the composition of chromophoric dissolved organic matter (CDOM) and the structure of the aquatic microbial community. In this work, we searched for optical proxies of euxinia (anoxic conditions with accumulated hydrogen sulfide) in the water column of the meromictic lagoon on Zeleny Cape. The lagoon is separated from the White Sea basin by a shallow threshold that completely isolates the lagoon during low tide, but marine water enters the lagoon during high tide. The ecosystem in the lagoon is characterized by the marine salinity of water and a high organic matter content in the bottom water and sediments. In this study, spectral methods were used to obtain the depth distribution of CDOM, chlorophyll, and bacteriochlorophyll in the lagoon with strong water stratification and euxinic conditions in the bottom water. The measured optical CDOM characteristics were compared with hydrochemical data (water salinity, Eh, pH, dissolved oxygen), phytoplankton (oxygenic phototrophs), and green sulfur bacteria (anoxygenic phototrophs) distribution along the water column. The spectroscopic methods showed to have the advantages of not requiring water sample pre-treatment and allowing rapid sensing of CDOM and photosynthetic pigments at each horizon.

Исследована зависимость от температуры спектрально-люминесцентных характеристик комплексов редкоземельных элементов (РЗЭ) с N-гетероциклическим лигандом на основе 2,2'-бипиридилдикарбоксамида при одновременном присутствии двух излучающих центров (европий + тербий). Измерения проводились в физиологическом диапазоне температур (20-60oС). Растворы лиганда, гексагидрата нитрата европия и пентагидрата нитрата тербия в ацетонитриле (концентрации 3·10-5 mol/l) смешивались в соотношении 1 : 1 : 1. Для того, чтобы выявить особенности энергетических переходов в таких соединениях, полученные результаты сравнивались с аналогичными результатами для растворов комплекса европия или тербия с тем же лигандом. Для исследуемых соединений получены времена жизни ионов европия и тербия в растворах при различных температурах. Получены зависимости квантового выхода люминесценции соединений от температуры. Рассчитаны отношения интегральных интенсивностей люминесценции ионов европия и тербия в зависимости от температуры. Обнаружено, что время жизни люминесценции ионов европия и тербия в растворе на длинах волн регистрации европия и тербия (615 и 545 nm) не зависит от порядка смешивания лиганда, европия и тербия. Также по экспериментальным данным сделан вывод, что время жизни люминесценции не меняется в диапазоне температур от 20 до 60oС. Ключевые слова: люминесценция, органические лиганды, европий, тербий, лантаноиды, сенсор температуры.

To examine the scope of the abnormal aryl strengthening effect (an increase in the extraction of metal ions when an aromatic substituent is introduced into the amide group) on f-metal extraction, a series of tetradentate diamide-type extragents bearing electron-withdrawing pyridine rings in amide moieties of the molecules were tested. The solvent extraction of Am(III)/Eu(III) pairs was investigated under various conditions, the solution chemistry of the lanthanide-extragents systems was studied, and the bonding constants were calculated for complexes of Eu(III) and Tb(III) ions with diamides. The photophysical properties of chemically synthesized ligand/metal (LM) complexes with various LM compositions were additionally studied in depth. The replacement of a phenyl ring by a pyridine one led to a critical reduction in metal affinity, showing the major contribution of electronic nature to the abnormal aryl strengthening effect. However, the pyridine group in the amide side chain provided additional coordination positions for metal ion binding; corresponding complexes with LM2 composition were detected in the system and their stability was calculated. Due to the low stability of the corresponding LM2 complexes, chemical synthesis of the complexes led to the formation of only one metal-containing species with LM composition. The luminescence spectra of europium and terbium complexes of the LM composition were studied. Differences were discovered in the luminescence excitation spectra of europium and terbium complexes with the same ligand. The luminescence quantum yields and luminescence lifetimes of solutions of europium and terbium complexes were determined.

Optical characteristics of water in stratified lakes can be used to study the pigment composition of various groups of photosynthetic organisms, its depth distribution and changes in different seasons. In the Arctic zone it is especially important to explore the evolution of natural water bodies under the influence of climate change and urbanization processes. Several water bodies on the coast of the Kandalaksha Bay of the White Sea are known as being at different stage of isolation from the Sea. In some of them the colored water layers in their chemocline zone resulted from the massive development of anoxygenic phototrophic bacteria were observed. The most numerous inhabitants of the chemocline zone are green sulfur bacteria. Besides green sulfur bacteria and purple sulfur bacteria, there were found cyanobacteria above and inside the chemocline zone. To access the pigment concentration, we measured fluorescence spectra of acetone extractions prepared from water sampled from various depths within chemocline of the lake Trekhtzvetnoe in March 2021. To increase the sensitivity of fluorescence measurements to certain pigments we acquired synchronous spectra of luminescence spectrometer performing scanning with a constant wavelength offset of 30 nm. This paper presents for the first time depth distribution of photosynthetic pigments BChl d (from green sulfur bacteria) accompanied with phycobilins (from cyanobacteria) derived from synchronous fluorescence spectra of acetone extractions prepared from water from various depths. This type of spectral measurements allowed us to receive depth distribution of cyanobacteria within the bacterial plate of green sulfur bacteria with very high depth resolution.

An important characteristic of a natural water body is the distribution of pigment composition of different groups of photosynthesizing organisms over depth and its variations in different seasons. Optical methods are widely used to monitor the concentrations of chlorophylls in algae or cyanobacteria in aqueous ecosystems, but they have very limited application in monitoring the bacteriochlorophyll (BChl) concentration in phototrophic bacteria. The paper describes comprehensively three new methods of quantitative analysis of the photosynthetic pigment of BChl d of green sulfur bacteria using spectral measurements in both initial samples of natural water (absorption spectra), and in pigment extracts in organic solvents (absorption and fluorescence spectra). A comparative analysis of the results from different methods is carried out using, as an example, natural water from the chemocline region in Lake Trekhtzvetnoe, one of the meromictic water bodies in the Kandalaksha Bay in the White Sea. Conclusions are drawn about the applicability conditions of different methods, their advantages and limitations. All three methods suggested have been proven to be efficient using, as an example, samples of natural water with BChl concentrations differing by orders of magnitude, from 5 to 5000 mg/m(3).

The paper provides information about the XXIX Coastal Conference, held in Kaliningrad in April 2022. The thematic directions of reports, round tables are reflected, statistical data are given on the number of speeches (232), on participating organizations (38) and cities (13). Additional events held within the framework of the conference (sessions, lectures, competitions, excursions) are described. The text is accompanied by illustrative materials – color photographs of participants taken directly during the conference. The decision of the conference notes that the practical development of new sections of the coasts, the construction of modern infrastructure facilities and the existing natural trends lead to increased coastal erosion in almost all coastal regions of Russia; that there is an urgent need to apply unified observation methods, division of work into research and monitoring and an interdisciplinary approach to jointly take into account physical, chemical and biological aspects (especially for coastal waters with limited or periodic connection with the marine area), that pollution by anthropogenic debris continues to grow, while the pollution pattern is extremely heterogeneous, and information on pollution by anthropogenic debris and microplastics of the marine environment and coasts of the Russian Federation is extremely fragmented. The conference recommends the introduction of amendments and additions to the federal and regional legislation on the regulation of the activities of nature users in the coastal zone, as well as the inventory of the natural resource potential of coastal territories and adjacent water areas with the compilation of a Coastal Registry for coastal ecosocio-economic systems of the Russian Federation. The participants highly appreciated the existing experience and results of coastal protection activities in the Kaliningrad Oblast, and also emphasized the lack of attention of the coastal community to the problems of inland waters (for example, the shores of Lake Baikal). Proposals on the venues of the conference in 2024 (Moscow) and 2026 (Lake Baikal) were announced.

The absorption and luminescence spectra and the luminescence decay kinetics of uranyl ions (UO22+) in the presence of organic reagents based on 2,2'-bipyridyldicarboxamides with various substituents have been studied. The quantum yields and luminescence lifetimes of uranyl nitrate hexahydrate and uranyl complexes with organic ligands in acetonitrile solutions have been determined. The mechanism of energy transfer in uranyl complexes is proposed.

Hybrid donor extractants are a promising class of compounds for the separation of trivalent actinides and lanthanides. In this paper, we present a new ligand from the bipyridyl-dicarboxylic acid diamide family—N,N’-diethyl-N,N’-bis(2,4,5-trimethylphenyl)-[2,2’-bipyridine]-6,6’-dicarboxamide. The synthesis of N-ethyl-2,4,5-trimethylaniline from pseudocumene by selective acetylation is presented. The target ligand was obtained using this aminylene. Chemical synthesis of its complexes with Ln(NO3)3 and their spectroscopic analysis showed that the structure of the complexes is near to the corresponding structures of well-known di-methylated dianilides. A series of studies on the photophysical, complexing, and extraction properties of this ligand and its complexes were carried out. It was shown that the extraction system based on this ligand can selectively isolate americium from the solution of high-level waste imitator.

Fungal contamination of aquatic environments can lead to an adverse impact on the environment and human health. (1) The search for fast, inexpensive and appropriate methods for detection of fungi is very moving rapidly due to their significant impact on ecosystem functions and human health. (2) We focused on examination of fluorescence proxies able to distinguish chromophoric matter occurring in different fungi. Spectroscopic studies were performed on five strains of filamentous fungi: Trichoderma harzianum, Fusarium solani, Alternaria alternata, Cladosporium cladosporioides and Aspergillus terreus. (3) The results showed that most of the fungal autofluorescence was emitted by amino acids, melanin-like compounds, NAD(P)H and flavins. The spectra of five fungal species cultivated as planktonic or surface-associated forms turned out to be different. Protein fluorescence can be used to detect general microbial contamination. Presence of excitation wavelength dependent mode and the “blue shift” of fluorescence (emission bands 400–500 nm) can be suggested as specific feature of fluorescence of fungal melanin-containing samples. (4) The determination based on fluorescence spectra obtained at a certain excitation/emission wavelengths pair and at whole excitation-emission matrices (EEMs) coupled to principal component analysis (PCA) algorithms as a tool of improving detection capabilities can be suggested to enable fast and inexpensive monitoring of fungal contamination of aquatic environments.