General data on features of obtaining, structure, and optical and electrical properties of chiral perovskites of different dimensional structures (0D-3D) have been analyzed and summarized. The application of chiral perovskites in optoelectronics, spintronics, and nonlinear optics is considered. An analysis of organic molecules, which are perspective for the synthesis of chiral 3D perovskites is performed. The possibility of the use of chiral dyes for improving the optical characteristics of hybrid perovskite materials is considered.

A spectrophotometric method for the quantitative determination of nitrite was developed, based on the radical nitration of indopolycarbocyanine dyes in the presence of 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO). The rate of the reaction of the studied dyes with nitrite increases with the lengthening of the polymethine chain and the presence of hydrophilic sulfo groups in the side chain of the dye. TEMPO acts as a co-reagent, significantly accelerating the reaction rate and increasing the sensitivity of nitrite determination. The proposed reaction mechanism is supported by spectrophotometric and HPLC/MS studies. For Ind2 (tetramethine indocarbocyanine cationic dye), the limit of detection for nitrite is 0.50 mu M within a linearity range of 1-13 mu M. The developed method is sensitive, with a LOD 130 times lower than the maximum contaminant level (MCL) of nitrite in drinking water (65 mu M), as specified by the WHO. The method is of low-toxicity and good selectivity, as the determination of nitrite is not significantly affected by the main components of water. The method was successfully applied for the analysis of nitrite in natural and bottled water.

Merocyanines, owing to their readily tunable electronic structure, are arguably the most versatile functional dyes, with ample opportunities for tailored design via variations of both the donor/acceptor (D/A) end groups and π-conjugated polymethine chain. A plethora of spectral properties, such as strong solvatochromism, high polarizability and hyperpolarizabilities, and sensitizing capacity, motivates extensive studies for their applications in light-converting materials for optoelectronics, nonlinear optics, optical storage, fluorescent probes, etc. Evidently, an understanding of the intrinsic structure-property relationships is a prerequisite for the successful design of functional dyes. For merocyanines, these regularities have been explored for over 70 years, but only in the past three decades have these studies expanded beyond the theory of their color and solvatochromism toward their electronic structure in the ground and excited states. This Review outlines the fundamental principles, essential for comprehension of the variable nature of merocyanines, with the main emphasis on understanding the impact of internal (chemical structure) and external (intermolecular interactions) factors on the electronic symmetry of the D-π-A chromophore. The research on the structure and properties of merocyanines in different media is reviewed in the context of interplay of the three virtual states: nonpolar polyene, ideal polymethine, and zwitterionic polyene.

By sintering ZnO powder mixed with ethylene glycol, electrodes on a glass substrate with a conductive SnO2 layer were obtained. In parallel, Ti/TiO2 electrodes were obtained by anodizing a titanium foil. Electrodes based on ZnO and TiO2 were sensitized to visible light with a cationic polymethine dye. The analysis of the photoelectrochemical characteristics of the obtained electrodes showed that the dye-sensitized ZnO films in the wavelength range of 450–650 nm have a photocurrent quantum yield two-fold higher compared with TiO2. In this way, a hybrid dye-ZnO structure sensitive to visible light was formed, which can be used for the photoelectrochemical cells for solar energy conversion, as well as for the detection of DNA and proteins in biological sensors.

Long-term operation of the supporting surfaces of large-sized parts, in particular tubular units of thermal power plants, leads to the destruction of the contact surfaces. Moisture penetrates into the formed discontinuities, and the vibrations present in the equipment in use rapidly increase the gap, reaching values of 10–15 mm. The authors of this article proposed the application of a composite layer of multimetal 1018 material without performing additional preparatory operations, ensuring the mandatory penetration of the material into the body of the supporting surface. This depth provides additional stability by maintaining boundary conditions. To determine the rational thickness of the composite layer, mathematical modeling of static loading of samples with different thicknesses in a wide range of values (from 2 mm to 12 mm) was performed. It was determined that the effective implementation of the developed technology was possible due to an increase in the load-bearing capacity of the composite material by creating additional grooves, or artificially creating grooves by welding, in the body of the part with a depth of 2.5–3 mm. The optimal excess of the composite was 1.0–1.5 mm. The proposed technology increases the stability of the composite layer up to three times and allows restoration without the use of mechanical treatment. The increase in the maximum stress values was 770 MPa, compared to the standard technology of 205 MPa.

The effect of localized surface plasmon resonance (LSPR) of a system consisting of a highly dipolar merocyanine dye and a silver nanoparticle (NP) was studied experimentally and theoretically. A theoretical model for estimating the fluorescence quantum yield (φfl) using quantum chemical calculations of intramolecular and intermolecular electronic transition rate constants was developed. Calculations show that the main deactivation channels of the lowest excited singlet state of the studied merocyanines are internal conversion (kIC(S1 → S0)) and fluorescence (kr(S1 → S0)). The intersystem-crossing transition has a low probability due to the large energy difference between the singlet and triplet levels. In the presence of plasmonic NPs, the fluorescence quantum yield is increased by a factor of two according to both experiment and computations. The calculated values of φfl, when considering changes in kr(S1 → S0) and the energy-transfer rate constant (ktransfer) from the dye to the NP was also twice as large at distances of 6-8 nm between the NP and the dye molecule. We also found that the LSPR effect can be increased or decreased depending on the value of the dielectric constant (εm) of the environment.

This paper presents new research results aimed at ensuring reliability and durability of equipment due to its diagnostics including monitoring and recording parameters changes of bearing units technical conditions determined before the moment of equipment shutdown, dismantling and fault detection of units as well as development of new methods for their restoration. As a method of operability recovery of unique bearing units a progressive approach is offered based on use of composite material 'Multimetal Stahl 1018'. A new field of application of composite material 'Multimetal Stahl 1018' to create temporary bearing sliding support instead of failed unique design construction with rolling bearings is described. Successful operation of majority of industrial equipment units restored using composite materials evidences broad prospects for solving various repair tasks mechanics of repair industries face including protection of foundations from destruction during vibration loads.

The series of 4,40-substituted 3-hydroxyethyl-pentaza-1,4-dienes were synthesized in the reaction of aromatic diazonium salts with an ethanol amine. Photolysis of pentaza-1,4-dienes was investigated by means of UV/Vis spectroscopy. Electron donating methyl and methoxy substituents were found to increase photosensitivity whereas electron withdrawing chloro-substituents cause higher photolytic stability. 3-hydroxyethyl-pentaza-1,4-dienes as a radical polymerization initiator has been successfully investigated in 10% methyl methacrylate solution in DMF. Gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) were used for obtained polymers characteristics evaluation. The highest values of PMMA Mn and D can be obtained in the case of chloro-substituted derivative. The holograms of a plane wavefront were recorded in media based on obtained PMMA doped by azo-dye by a 532 nm laser in a.1-lm-thick sample. The diffraction efficiency values for parallel polarized acting light increased in Cl -> Me -> OMe series. [GRAPHICS] .

It is shown that new benzo[cd]indole-based heptamethinecyanines (HMCs) have an ultrashort lifetime τ of the photoexcited state and a high intensity of light absorption in the generation range of practically important neodymium lasers. The electronic structure and types of electronic transitions in HMCs are analyzed by the DFT and TD-DFT methods. The influence of vibronic and intermolecular interactions on τ is considered. The advantages of HMCs for passive mode locking of lasers over known dyes with ultrashort τ are demonstrated. The advantages of HMCs to implement passive mode locking of lasers over known dyes with ultrashort τ are demonstrated.

Merocyanines, thanks to their easily adjustable electronic structure, appear to be the most versatile and promising functional dyes. Their D-π-A framework offers ample opportunities for custom design through variations in both donor/acceptor end-groups and the π-conjugated polymethine chain, and leads to a broad range of practical properties, including noticeable solvatochromism, high polarizability/hyperpolarizabilities, and the ability to sensitize various physicochemical processes. Accordingly, merocyanines are applied and extensively studied in various fields, such as light-converting materials for optoelectronics, nonlinear optics, optical storage, solar cells, fluorescent probes, and antitumor agents in photodynamic therapy. This review encompasses both classical and novel more important publications on the structure-property relationships in merocyanines, with particular emphasis on the results by A.  I. Kiprianov and his followers in Institute of Organic Chemistry in Kyiv, Ukraine.

In recent years, polymer materials with various adhesive compounds based on epoxy resins, polyesters, polyurethanes, polyacrylics, and others enriched with fine-dispersed metallic and other fillers have found wide application in various industrial sectors for equipment repair. These composite repair materials have excellent adhesive properties when applied to metal surfaces, and when combined with their high strength and the ability to transition from a plastic to a solid state without shrinkage in a short period of time, they provide a broad range of applications in solving repair problems. A technology for restoring the original dimensions of equipment parts using composite materials has been developed, eliminating the need for welding and milling. Numerous industrial tests have shown that composite materials allow solving a range of serious repair problems in rolling production, particularly on heavily loaded sheet rolling stands and blooming mills when restoring worn contact surfaces of this equipment. An original technology for the application of composite materials was developed at the Pryazovskyi State Technical University (Mariupol, Ukraine), which allowed for a unique repair operation at one of the metallurgical plants, involving the installation of a new blooming mill housing onto old worn plates with wear of up to 7 mm at certain points. These composite repair materials have excellent adhesion properties when applied to metal surfaces, which, in combination with their high strength and the ability to transition from a plastic to a solid state without shrinkage in a short period of time, provide a wide range of applications in solving repair problems. Additionally, there are cases of damage to certain types of machinery that are either impossible to repair using traditional methods or require significant material and time investments for restoration

Different approaches to the development of promising photosensitizers based on polymethine dyes (PD) for photodynamic therapy are systematized, summarized, and analyzed. PD of the near-IR spectral range has drawn special attention. The influence of a heavy atom (chalcogens, halogens, and noble metals), the chromophore interaction, electron transfer, and free radicals on the singlet oxygen generation by PD is discussed. The PD photodynamic activity mechanisms under hypoxia conditions are considered. The PD structural modifications that ensure their targeted delivery to cancer cells are analyzed.

Sensing of toxic and heavy metals is of great importance for protecting environment and health monitoring. Here we demonstrate an improved fluorescent probe operating in the near-infrared (NIR). The probe represents a NIR tricarbocyanine dye with 2,2′-dipicolylamine meso-group which is able to chelate zinc, cobalt and palladium ions. We show that the probe operation via monitoring of the anti-Stokes photoluminescence provides much better sensitivity of the probe compared to its Stokes photoluminescence. Particularly, it is shown that the anti-Stokes photoluminescence increases by more than an order of magnitude and can reveal additional features of the dye-metal complex not observed via the Stokes emission.

The earlier described organic coordination polymer [Zn3(HCit)2(H2O)2]n (HCit is citric acid) (I) formed completely by the biocompatible components is synthesized under hydrothermal conditions. The selection of the hydrothermal synthesis conditions makes it possible to obtain the polymer as high-quality single crystals and perform a detailed analysis of the electron density distribution function recovered using the data of a high-resolution X-ray diffraction experiment. This study is the second example of such investigations for the biocompatible metal−organic framework.

Spectral and nonlinear optical properties of the new tricarbocyanine dyes, derivatives of the benzo[cd]indole, which absorb efficiently in the region 1.05-1.08 mu m, have been investigated. Based on these compounds, the liquid (ethanol solutions) and polymer (in a form of triplexes, where dye-doped polyurethane films are placed between two optical glass substrates) passive Q-switches for the neodymium lasers have been developed. The modulation depth of 100% at the generation of the ultrashort pulse (USP) trains has been obtained. The high-stable regime of passive mode-locking has been realized; it is characterized with the 100% probability appearance of a single pulse in an axial period with average durability 25-30 ps and energy 1-2 mJ, depending on the dye structure. Advantages of the new Q-switches over the corresponding an-alogues, based on organic dyes, nanotubes, graphene, inorganic semiconductors and mirrors (SESAM), LiF:F-2(-) and Cr4+:YAG, have been demonstrated.

The influence of plasmonic effect of Ag nanoparticles (NPs) on singlet-singlet (S–S) and triplet-singlet (T–S) energy transfer in the same donor–acceptor pair of organic molecules was studied. It was established that a 7-fold increase in the fluorescence and phosphorescence intensity of the energy donor (Rose bengal) and a 4-fold increase in the fluorescence intensity of the acceptor (polymethine dye) are observed on silver island films. The changes are associated with an increase in the emission rate of dye molecules, as evidenced by a decrease in the lifetime of their luminescence in the presence of Ag NPs. An increase in the efficiency of both types of energy transfer was recorded in the plasmon field of Ag NPs. The plasmon effect has almost the same influence on both S–S and T–S energy transfer. Estimation of the energy transfer rates using of the model of electric dipole interaction showed a good correlation between the experimental and calculated data for the S–S energy transfer.

We have made a selection of the leading structures among cationic polymethine dyes with different structures of terminal heterocyclic groups and polymethine chains for passive Q-switch of a diodepumped solid-state neodymium laser. Such dyes have a maximum absorption in the region of 1060 nm and a minimum absorption in the region of 810 nm. It was found that the 4-((E)-2-((E)-2-chl oro-3-(2-(2,6-diphenyl-4H-thiopyran-4-ylidene)ethylidene)cyclohex-1-en-1-yl)vinyl)-2,6-diphenylthio pyrylium tetrafluoroborate dye most closely matches these characteristics. The nature of its longwavelength and higher electronic transitions was interpreted based on quantum-chemical calculations by the DFT/B3LYP/6-31G (d, p) method and TDDFT taking into account the polarity of the medium by the PCM method. The use of this dye as a laser Q-switch made it possible for the first time to obtain passive mode locking in diode-pumped neodymium lasers. Copyright (c) 2022 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the EastWest Chemistry Conference 2021.

The possibility of target control of the electro-optical properties of polymethacrylate with covalently bound azobenzene chromophores in a side chain by introducing metal ions capable of chromophore coordination, acceptor substituents that change the dipole moment of an azobenzene fragment, and organic dyes that expand the range of light absorption of azobenzene chromophore were considered. The mechanism of action of these factors was analyzed.