Alexander D Roshal

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• Dr.hab., Ph.D.
• Acting Director of Research Institute of Chemistry at V. N. Karazin Kharkiv National University

he article represents a review of methods for obtaining polyhydroxy flavonols without protection of hydroxy groups, as well as syntheses using methylation, alkylation and benzylation of the initial reagents and, accordingly, demethylation, dealkylation and debenzylation of the final flavonols. It is shown that the most convenient for the synthesis...

The work is devoted to investigations of extraction methods for the isolation and accumulation of divalent and trivalent metal ions Mn2+, Ni2+, Cu2+, Zn2+, Y3+ and Ce3+ in the absence and presence of flavonol derivatives with different numbers and locations of complexation sites. Two extraction methods were used and compared: the classical LL – wat...

The study examined the interaction of a new ESIPT fluorescent probe, which is based on 4`-dodecyl¬carboxy-substituted 3-hydroxyflavone, with polyvinylpyrrolidone (PVP) at varying polymer concentrations. Through fluorimetric titration, it was determined that the probe's affinity to the polymer relies on the concentration and morphology of PVP in the...

A ruthenium nitrosyl complex of formula [RuII(fluorene(C6)CH2O-terpy)(bipy)(NO)]3+ (AC) in which fluorene(C6) is the 9,9-dihexylfluorene, terpy the 2,2’;6’,2’’-terpyridine, and bipy the 2,2’-bipyridine is presented with its related [RuII(MeO-terpy)(bipy)(NO)]3+ (C) and 9,9-dihexylfluorene...

In the previously published results, we studied the effect of flavin mononucleotide (FMN), sodium halides NaF and NaBr, iron chloride FeCl3 and aluminum chloride AlCl3 on zigzag patterns of films obtained from saline solutions of bovine serum albumin (BSA). Changes in the properties of the biopolymer and its aqueous environment in solutions were mo...

Fluorescent flavonols and their glucosylated derivatives are promising tools for studying protein structure and enzyme activity screening. The fluorescence properties of such probes are tunable by electron-withdrawing substituents in 2-aryl ring, while a role of bulky hydrophobic groups has not been examined in-depth yet. Here, we examine the appli...

A preparative approach to thiazole-containing chromone derivatives has been developed by modifying the corresponding aldehydes with their further transformation into propenone derivatives, and finally introducing them into the Algar-Flynn-Oyamada reaction. Several methods for obtaining propenones have been analyzed, and the most effective and pract...

Natural flavonoids are capable of inhibiting glucosidase activity, so they can be used for treating diabetes mellitus and hypertension. However, molecular-level details of their interactions with glucosidase enzymes remain poorly understood. This paper describes the synthesis and spectral characterization of a series of fluorescent flavonols and th...

The binding interaction of flavonols with the β-glucosidase enzyme was studied using fluorescence titration measurements and molecular docking calculations. Studied flavonols bear hydrophobic and bulky moieties at 4`-aryl ring (Fig. A), which allows tuning ligand-protein interactions. The fluorescence titration experiments revealed that flavonols 1...

The review compiles information on the spectral classification of flavonoids, the changes in their electronic structure upon complex formation, and the manifestation of these changes in the absorption and emission spectra. Part of the review is devoted to the regioselectivity of the complex formation process, including types of complexation sites,...

The paper has been devoted to the quantum-chemical prediction formation of polymer complexes based on glycidyl ethers of quercetin with some metal ions. Based on the calculated quantum chemical calculations with semi-empirical PM3 method, the heats of formation and the geometric parameters of the chelate complexes were predicted.

The relationships between the structural and aggregational state of bovine serum albumin (BSA) and the specific length and total number of zigzag pattern segments of the film textures formed upon drying biopolymer solutions with aluminum and iron chlorides have been shown. To obtain films, saline solutions of BSA were dried in a glass cuvette under...

Effect of mixed acetone/dimethyl sulfoxide solvent composition on morphology of porous epoxy polymer films obtained by chemical solution deposition method was studied. Total and surface porosity of the polymer films as well as the size of open pores were determined using FTIR spectroscopy and SEM techniques. It was revealed that the choice of the s...

Among various fluorescein dyes, nitro derivatives are less studied. At the same time, these compounds have some unusual properties. This article reports on the behavior of new dyes of this series in solution. Two compounds, 2,4,5,7,4'- and 2,4,5,7,5'-pentanitrofluoresceins, were synthesized, and their molecular structures in the solid state were ch...

Many water-soluble ionic calixarenes readily form micelle-like aggregates in aqueous solution. Presently, it is firmly proved that such aggregates tend to shift the state of the acid-base equilibrium of indicator dyes just in the same manner as cationic surfactant micelles do. In this paper, we further the corresponding studies and report the pecul...

Cross-linked polymers with chromophore fragments built-in main chains can, depending on their structure and synthesis conditions, keep during a long time the orientation of chromophores that is necessary to create new organic polymer materials demonstrating nonlinear optical properties. The present work is devoted to cross-linked polymers on the ba...

Natural and synthetic flavonols are environmentally sensitive dyes whose emission properties are highly sensitive to their immediate environment. Here we describe the synthesis and spectral properties of flavonols bearing a series of substituents in the 4‘-aryl ring. The synthesized flavonols were applied to study their capability for fluorescence...

The paper is devoted to investigation of exploitation properties of optical film materials based on cross-linked polymers containing flavonoid fragments, namely 3,7,5,3’,4’-pentahydroxyflavone (quercetin) and 3,7,5,3’,4’-pentahydroxyflavone-8-sulphonic acid (sulfoquercetin) built in the polymer chains. The influence of photoinduced destruction, fun...

The aim of the study was to assess the impact of semi-refined carrageenan (E407a) on the hydrophobic region of phospholipid bilayer in cell membranes of leukocytes exposed to the solution with high concentrations of this food additive. Materials and methods. Fluorescent probe (2-phenyl-phenanthro[9,10-d]-1,3-oxazole) was used to investigate the inf...

In recent years, the chemistry of flavonoid glycosylation has undergone significant developments. This mini-review is devoted to summarizing existing strategies and methods for glycosylation of natural and synthetic flavonoids. Herein we overviewed the reaction conditions of flavonoid glycosylation depending on the position of hydroxyl groups in a...

Objectives To estimate the state of phospholipid bilayer of rats WBCs exposed to a common food additive E407a, which is used as a thickener and emulsifier, during 4 h using a fluorescent probe − ortho-hydroxy derivative of 2,5-diaryl-1,3-oxazole. Materials and methods Steady-state fluorescence spectroscopy: a study by the environment-sensitive flu...

Aim To assess the impact of semi-refined carrageenan (E407a) on hydrophobic regions of phosphololipid bilayer in cell membranes of leukocytes collected from rats orally administered this food additive and white blood cells incubated with E407a. Methods Fluorescent probes (ortho-hydroxy derivatives of 2,5-diaryl-1,3-oxazole) were used to estimate...

Thiazole cycle is a structural element of many compounds which have potential or already proven fungicidal, bactericidal and antiviral activity. A number of compounds and materials with promising antimicrobial effects can be functionalized by introducing the thiazole component into their composition. Among them, there are photoreactive materials, c...

In this paper, we examined the fluorescent properties of 4'- and 5'-aminofluorescein, un-substituted fluorescein, and its 4'-nitro derivative in a set of solvent systems. Fluorescence lifetimes, quantum yields, time-resolved fluorescence spectra, and quantum-chemical calculations allowed clarifying the reasons of the emitting properties in this dye...

Within the course of this spectroscopic research, we revealed novel features of the protolytic behavior, which extend the knowledge of the chemistry of xanthene dyes and rationalize the utilization of these compounds. In addition to the well-known tautomerism of the molecular form, H2R, of fluorescein dyes, new aspects of tautomeric transformation...

Subject and purpose. In this paper, we studied the relationship of the structural and aggregation state of biopolymers with the quantitative characteristics of the textures of the films formed during the drying of biopolymer solutions. Methods and methodology. The structural changes of the biopolymer were determined by IR, UV and fluorescence spect...

In order to evaluate spectral and nonlinear optical (NLO) properties of polymers and polymer composites containing natural hydroxyflavones as chain fragments or dopants, a theoretical analysis of absorption spectra of flavones, as well as calculations of values of their first hyperpolarizabilities and bond length alternation coefficients (BLA), wer...

1 In this work polymer nonlinear optical (NLO) materials in the form of thin films based on 3,7,3 ' ,4 '-tetrahydroxyflavone and diglycidyl ether of bisphenol A were obtained and investigated. It was found that the influence of the chromophore concentration on values of the macroscopic NLO susceptibilities (χ (2) of doped polymer films has extreme...

Recently, a photochemical stability of polymer nonlinear optical (NLO) materials is not sufficiently studying. Meanwhile, when using polymer NLO materials in optics and optoelectronics, this factor can substantially limit the utilization time of such materials [1]. The purpose of this work was to investigate the photochemical stability of thin poly...

This article is devoted to spectral properties of non-associated 16,17-dihydroxy- and dialkyloxy violanthrones, in order to study the relationship between the nature of alkoxy substituents and the UV/Vis absorption/emission characteristics of these dyes. Solvatochromic and solvatofluorochromic effects of the violanthrone derivatives are investigate...

The article describes investigations of 2'-hydroxychalcone and its three derivatives bearing differently sized alkyloxy groups at position 4'. The compounds are investigated from the point of view of crystal structure, electronic absorption, fluorescence features in solutions and crystals using X-ray diffraction and electronic spectroscopy methods,...

. Synthesis of glycidyl ethers of quercetin and studies of their structure have been carried out. The X-ray studies of glycidyl ethers of quercetin were performed using by the Debye-Sherrer method. The XRD data are in good correlation with the results of thermophysical studies and analysis by the scanning electron microscopy method, which was carri...

Formation of patterns on the surface of dried films of saline biopolymer solutions is influenced by many factors, including particle size and structure. Proteins may be modified under the influence of ionizing radiation. By irradiating protein solutions with gamma rays, it is possible to affect the formation of zigzag (Z) structures on the film sur...

Structural parameters and optical anisotropy relaxation dynamics of cross-linked polymers obtained from 7,4'-diglycidyl-, 7,3',4'-triglycidyl- and 3,7,3',4'-tetraglycidyl ethers of quercetin (3,5,7,3',4'-pentahydroxyflavone) are investigated. Values of effective cross-linked density and molecular weight between the cross-linked units, as well as dy...

The component composition of molecular layers of dicarbocyanine dyes of cationic type on glass is determined by the absorption spectroscopy methods. For symmetric and asymmetric molecules the component composition depends on the chemical structure of a molecule and its interaction with the substrate, which are responsible for the electron density d...

Optical properties and morphology of polymer films based on diglycidyl ether of bis-phenol A and on natural compound 3,5,7,30,40epentahydroxyflavone (quercetin) using UV-vis spectroscopy, scanning electron microscopy and powder X-ray diffraction methods have been investigated. The influence of ordering degree of the polymers, flexibility of their c...

The review focuses on the investigations of molecular systems in which double intramolecular proton transfer can occur. Spe≿ific attention is paid to the transformations and deactivation processes in the electronically excited state of such compounds as well as their spectral, mainly fluorescent features. For each group of compounds thermodynamics,...

Among the vast set of fluorescein derivatives, the double charged R²⁻ anions of aminofluoresceins are known to exhibit only low quantum yields of fluorescence, φ. The φ value becomes as high as that of the fluorescein dianion when the lone electron pair of the amino group is involved in a covalent bond. According to Munkholm et al (1990 J. Am. Chem...

Cross-linked polymers on the basis of di-, tri and tetraglycidyl ethers of quercetin (3,3′,4′,5,7-pentahydroxyflavone) were synthesized, and then, poled in electrical field of corona discharge. Investigations of structural, thermal and optical parameters of the polymer films were carried out. It was found that the polymers obtained from di- and tri...

Comprehensive spectral investigations of 3,7-dihydroxyflavone and its two derivatives, which each contain a methyl-blocked hydroxyl group, reveal complex radiation absorption in the 300-450 nm range and emission in the 370-650 nm range. The absorption and fluorescence characteristics of these compounds depend on the pH/H0 of the water:methanol medi...

A novel fluorescent probe, based on the excited-state intramolecular proton transfer (ESIPT) phenomenon, for evaluation of β-glucosidase activity was designed. The synthesis of the probe was optimized. The conditions for the monitoring of enzymatic cleavage of the probe were developed and discussed from the point of view of reaction kinetics and si...

Synthesis of glycidyl ethers of quercetin and studies of their structure and spectral properties have been carried out. Using FTIR spectroscopy, 1H and HSQC NMR spectroscopy, mass spectrometry and quantum chemical simulations, it was shown that glycidation of 7-hydroxy and 4′-hydroxy groups primarily takes place, and then, the sequential glycidatio...

The formation of the textures on the surface of the films from the solutions of bovine serum albumin (BSA) with sodium halides (NaF, NaCl, and NaBr) of various concentrations was studied. The formation of symmetric zigzag textures on the surface of BSA films (Cryst Eng 3:173-194, 2000) in the presence of sodium halides depends on the conformational...

In an attempt to create a flavone derivative able to take part in Excited State Intramolecular Double Proton Transfer (ESIDPT), we synthesized two carbonyl derivatives of 3,7-dihydroxyflavone, both containing two different proton-transfer sites as well as related carbonyl derivatives of 3-hydroxyflavone and 7-hydroxyflavone. All the examined hydrox...

Three derivatives of 7-hydroxy-2-phenyl-4H-chromen-4-one (7-hydroxyflavone), containing chloro, methoxy, and dimethylamino substituents at position 4', were synthesized and investigated from the view of their ground and electronically excited state behavior. Spectral and fluorescent properties in a wide range of pH/H0, thermodynamics of the ground...

Реферат: Спосіб визначення гідрогелю в біологічних тканинах належить до медицини та біології і може бути використаний для люмінесцентного визначення областей локалізації та реологічного стану гідрогельних біоструктурних матеріалів, у тому числі хірургічних імплантатів, а також оцінки ефективності доставки лікарських препаратів гідрогельними носіям...

Computational methods were used to calculate the crystal lattice energy reflecting global interactions, predominantly long-range electrostatic interactions between ions, as well as the energy of selected specific local C–H···O, C–H···π and π···π interactions found in synthesized 7-(diethylamino)-2-(2-oxo-2H-chromen-3-yl)chromenium perchlorate, the...

The absorption and photoluminescence spectra of the solutions and crystals of ADP in the presence of dopant molecules (pH 3.5) and/or anion (pH 5.2) of salicylic acid and Tl+ cation are studied. Dissociation of salicylic acid at the first stage is accompanied with the formation of salicylate complexes with thallium phototautomer. It is shown that t...

Second-order nonlinear optical (NLO) properties and temporary stability of epoxy polymers based on diglycidyl ether of bisphenol A (DGEBA) both doped with p-nitroaniline (p-NA) and functionalised linear polymer DGEBA with p-NA moieties (attached to the bearing main chain) in the main chain (DGEBA-p-NA) have been investigated. Second-order polarizab...

New chiral compounds of the steroid type, namely, 3-alkanoyl-and 3-alkyl derivatives of 16-arylidene estrone, were synthesized and exhibited high helical twisting power (HTP) in nematic liquid crystals E63 and LC-1289. The peculiarities of the molecular structure of chiral compounds (CCs) and their high degree of chirality were discussed. Quite sma...

The paper deals with the spectral properties of dyes with interfragmental charge transfer, in particular, derivatives of 2-(3-coumaroyl)benzopyrylium (CBP) perchlorates. The positions of long-wavelength absorption and emission bands, quantum yields, and lifetimes of fluorescence were measured, mostly in aprotic solvents. Regression analysis of the...

Dependence of rheological and diffusion properties of gels on their composition as well as desorption of active components from the resulted implants in biological objects have been studied. The work has been performed in vitro using step-wise extraction of polypeptides form the heart of newborn piglets and also in vivo by implanting the «gel-extr...

Quantum chemistry studies of various tautomeric/rotameric forms of the furanyl analogues of acetyl dihydroxychalcone (FC) and dihydroxydichalcone (FDC) have shown that the thermodynamically most stable molecules are planar. In the crystalline solid phase, both molecules are more (FDC) or less (FC) non-planar. Two relatively strong intramolecular H-...

Spectral and acid-base properties of 7-hydroxyflavone (7HF) in the ground and excited states were investigated with a purpose to enable reasonable application of this dye and its derivatives as fluorescent probes. Analysis of solvatochromic and solvatofluorochromic ability of 7HF in 20 solvents, investigations of 7HF spectral properties in the froz...

The spectral characteristics and structure of 2-(3-coumaroyl)benzopyrylium cations and also of their nucleophilic complexes with acetonitrile molecules were investigated by DFT and TD DFT methods. It was shown that the investigated cations in the ground state are characterized by the presence of two conformers differing in the distribution of the p...

Quantum-chemical modeling of the geometry and electronic structure of the ground state and the lowest excited states of various multiplicity was undertaken for the photochromic compound 1,3,3-tri-methyl-1',2'-diphenylspiro[indoline-2,7'-furo[3,2-f]chromene], which belongs to the spiropyran class. After analysis of the localization of electronic exc...

This work is devoted to improving the understanding of Algar–Flynn–Oyamada reaction mechanism and the analysis of factors that affect the formation of flavonols. The calculation of thermodynamic parameters for the key reaction steps pointed to a mechanism involving chalcone epoxides as intermediates. A correlation was identified between the nucleop...

54) СПОСІБ ОТРИМАННЯ ІМПЛАНТА З ПРОЛОНГОВАНИМ ЗВІЛЬНЕННЯМ БІОЛОГІЧНО АКТИВНИХ ПЕПТИДНИХ КОМПОНЕНТІВ (57) Реферат: Спосіб отримання імпланта з пролонгованим звільненням біологічно активних пептидних компонентів полягає у створенні композиції шляхом введення біологічно активних компонентів пептидного походження до біодеградуючої полімерної основи. Як...

Research is devoted to using chemical markers for studying and description of ecosystems. Photosynthetic pigments – carotenoids and chlorophylls, and soil polymers – humic, fulvic acids and their salts, were used as chemical markers. Correlations between concentrations of these markers in samples and parameters of “total nitrogen” and ash were stud...

Primitive soils of the Mount Demaria (Graham Land, Antarctic Peninsula): morphology, mineral composition, vertical distribution. A.D. Roshal, A.P. Krasnopiorova, I.V. Dykyy, Z.A. Sizova, G.D. Yukhno, D.V. Shmyrov, Yu.G. Gamulya, A.Yu. Utevsky Abstract. The research is devoted to primitive soils of West Antarctica (Graham Land, Antarctic Peninsula)....

The electronic structure of 2-(3-coumaroyl)-benzopyrylium perchlorate (CBP) and its di-substituted derivatives has been investigated; the experimental and theoretical analysis of spectral properties of these compounds in various media has been carried out. It was found that spectral behavior of CBP and its derivatives depend on two solvent properti...

Absorption and emission spectroscopic investigations and computational predictions have shown that neutral molecules of flavonols and diflavonols can exist in the ground and excited states in one or two tautomeric forms stabilized by intramolecular (in aprotic media) or intermolecular (with solvent molecule(s), in protic media) hydrogen bonds. Elec...

The relationship between the spectral properties and interfragmental charge transfer (ICT) upon excitation, relaxation and excited state deactivation of 2-(3-coumaroyl)-benzopyrylium perchlorates has been analyzed. It was found that the positions of emission bands and rate constants of radiationless deactivation linearly correlate with ICT upon exc...

Dependence between structures of R-oxyflavones and their spectral and basic properties has been investigated. It was found that pKa of flavones, depending on positions of hydroxy and methoxy groups, increases by 6-8 orders of magnitude upon excitation and reaches 3.7-6.6 units. Due to high pKa* value carbonyl group can serve as a proton acceptor in...

In the title compound, C16H12O4, the substituent benzene ring and meth­oxy group are twisted relative to the 4H-chromene skeleton by 24.1 (1) and 61.3 (1)°, respectively. In the crystal, mol­ecules are connected by classical O—H⋯O and weak C—H⋯O hydrogen bonds, forming chains parallel to [201]. The 4H-chromene ring systems of adjacent mol­ecules ar...

We have shown the high efficiency of using podand complexes (open-chain analogs of crown-ethers) for the inhibition of corrosion of structural iron alloys in neutral aqueous solutions. We have proposed a mechanism for the control of the rate of spontaneous electrode processes on steel by complexes of zinc with modified podands.

In the crystal structure of the title compound, C15H11FO2, mol­ecules form inversion dimers through pairs of weak C—H⋯O hydrogen bonds. Dimers oriented in parallel, linked by C—H⋯π contacts, are arranged in columns along the b axis. The fluoro­phenyl ring and the benzene ring of the 2H-chromen-4(3H)-one unit are inclined to one another by 70.41 (16...

The dehydrational self-organization of DNA with Na + and Ag + ions and silver nanoparticles has been studied. It has been shown that the character of the formation of dendritic textures (the size of the area occupied on the film surface) is governed by the conformational state of DNA.

A.D.Roshal, T.V.Shkand, N.A.Chizh, V.O.Cheranovsky, A.N.Kalinkevich, B.P.SandomirskyResearch of polypeptide extraction dynamics of alginate hydrogelsAlginate gels can be used as a source of high biological activity polypep-tides for treatment of cardiovascular pathologies. The investigations of the extraction dynamics of polypeptides from gels cont...

ADP–NH4Sal hybrid crystals are grown from aqueous solutions. The influence of the acidity of the mixed solution on the conditions of co-crystallization of the components is studied. The spectral and scintillation characteristics are determined. Co-crystallization of ammonium salicylate (NH4Sal) and ammonium dihydrogen phosphate (ADP, NH4H2PO4) is s...

Spectral properties of cinnamoyl pyrone (CP) and its derivatives were studied in water-alcohol and water solutions within a wide pH/H(0) range. It was found that the most of CP may exist in neutral, anionic and cationic forms, except for alkylamino substituted CP, which can also form dications. The constants characterizing equilibria between all th...

The micellization of asymmetric diblock copolymers (DBC) MePEG-b-PAAm formed by monomethoxy-poly(ethylene)oxide (MePEG) and polyacrylamide (PAAm) has been studied in water, a water/alcohol mixture, and a NaCl solution. The effect of added NaCl on the critical micellization concentration of DBC water solutions was examined. The interaction between D...

10-Methyl-9-(phenoxycarbonyl)acridinium trifluoromethanesulfonates bearing alkyl substituents at the benzene ring were synthesized, purified, and identified. In the reaction with OOH(-) in basic aqueous media, the cations of the compounds investigated were converted to electronically excited 10-methyl-9-acridinone, whose relaxation was accompanied...

In the title compound, C16H12O4, the benzene ring is twisted at an angle of 12.3 (1)° relative to the 4H-chromene skeleton, and an intramolecular O—H⋯O hydrogen bond occurs. The meth­oxy group is almost coplanar with the benzene ring [1.5 (1)°]. In the crystal, inversely oriented mol­ecules are arranged in double (A, A′) columns, along the b axis,...

The presented work is devoted to investigations of the relationship between spectral properties, photo stability and excited-state kinetic characteristics of cinnamoyl pyrone (CP) derivatives and photochemical/photophysical processes taking place in their excited molecules. The obtained results permit to obtain a general scheme of photophysical and...