Pub Date : 2021-01-01DOI: 10.31861/chem-2021-828-2
V. G. Ivanitska, Y. I. Nechesnyi, P. Fochuk
The surface quality of semiconductors has a direct impact on the performance of devices made of them. One of the stages in the semiconductor materials technology is chemical treatment of the crystal surface. Etching solutions used for this purpose often contain halogens or compounds based on them. To reduce the dissolution rate of the semiconductor during its etching, a viscous component, such as glycerol, ethylene glycol, etc., is often added to the etching compositions. The paper studied the features of chemical interaction of CdTe and Cd0,96Zn0,04Te, oriented in different crystallographic directions of iodine-containing etchants based system I2 - CH3OH. The influence of ethylene glycol on the results of chemical-dynamic and chemical-mechanical polishing of these semiconductor materials has been clarified. The concentration dependence of the rate of chemical-dynamic and chemical-mechanical polishing of CdTe (111) B, CdTe (110), Cd0,96Zn0,04Te (211) A and Cd0,96Zn0,04Te (110) surfaces was studied. It is shown that the addition of ethylene glycol to solutions of the I2 - methanol system significantly slows down the dissolution rate of both CdTe and Cd0,96Zn0,04Te samples. The addition of only 16 vol.% ethylene glycol into basic solution slows down the interaction more than two times, although a further decrease in the etching rate with increasing ethylene glycol content is not so rapid. Only solutions with an ethylene glycol content not exceeding 40% (chemical-dynamic polishing) and 50% (chemical-mechanical polishing) have polishing properties. The use of solutions with higher ethylene glycol content causes the appearance of a light blue film on their surface, which does not disappear even after careful postoperative treatment. It is shown that the surface roughness of both CdTe and Cd0,96Zn0,04Te after its chemical-mechanical polishing does not exceed 10 nm. This is a characteristic of its high quality and makes it possible to recommend ethylene glycol-modified etchants of the I2 - CH3OH system for chemical-mechanical polishing of the surface of cadmium telluride and solid solutions based on it.
{"title":"Chemical treatment of CdTe and Cd0.9Zn0.1Te surfaces with iodine-containing solutions","authors":"V. G. Ivanitska, Y. I. Nechesnyi, P. Fochuk","doi":"10.31861/chem-2021-828-2","DOIUrl":"https://doi.org/10.31861/chem-2021-828-2","url":null,"abstract":"The surface quality of semiconductors has a direct impact on the performance of devices made of them. One of the stages in the semiconductor materials technology is chemical treatment of the crystal surface. Etching solutions used for this purpose often contain halogens or compounds based on them. To reduce the dissolution rate of the semiconductor during its etching, a viscous component, such as glycerol, ethylene glycol, etc., is often added to the etching compositions. The paper studied the features of chemical interaction of CdTe and Cd0,96Zn0,04Te, oriented in different crystallographic directions of iodine-containing etchants based system I2 - CH3OH. The influence of ethylene glycol on the results of chemical-dynamic and chemical-mechanical polishing of these semiconductor materials has been clarified. The concentration dependence of the rate of chemical-dynamic and chemical-mechanical polishing of CdTe (111) B, CdTe (110), Cd0,96Zn0,04Te (211) A and Cd0,96Zn0,04Te (110) surfaces was studied. It is shown that the addition of ethylene glycol to solutions of the I2 - methanol system significantly slows down the dissolution rate of both CdTe and Cd0,96Zn0,04Te samples. The addition of only 16 vol.% ethylene glycol into basic solution slows down the interaction more than two times, although a further decrease in the etching rate with increasing ethylene glycol content is not so rapid. Only solutions with an ethylene glycol content not exceeding 40% (chemical-dynamic polishing) and 50% (chemical-mechanical polishing) have polishing properties. The use of solutions with higher ethylene glycol content causes the appearance of a light blue film on their surface, which does not disappear even after careful postoperative treatment. It is shown that the surface roughness of both CdTe and Cd0,96Zn0,04Te after its chemical-mechanical polishing does not exceed 10 nm. This is a characteristic of its high quality and makes it possible to recommend ethylene glycol-modified etchants of the I2 - CH3OH system for chemical-mechanical polishing of the surface of cadmium telluride and solid solutions based on it.","PeriodicalId":9913,"journal":{"name":"Chernivtsi University Scientific Herald. Chemistry","volume":"82 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75948169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.31861/chem-2021-828-3
A. V. Matviy, V. V. Kopach, S. M. Rusnak, O. Kopach, L. Shcherbak, P. Fochuk
The thermal properties of Cd0.80Mn0.20Te solid solutions were investigated in this article. Two methods of heat treatment were used for thermography of alloys, which allowed investigating their thermal properties. One of the methods of thermography of samples was to heat them to the maximum temperature at which they were kept for a certain time, followed by cooling of the sample. The data obtained by this type of thermography allow obtaining graphs which characterized the crystallization parameters of the melt Cd0.80Mn0.20Te. It is shown that the crystallization of the Cd0.80Mn0.20Te melt occurs without supercooling at its overheating less than 14 °С in comparison with the beginning of melting temperature, which indicates the two-phase melt. It is also shown that the crystallization rate of the Cd0.80Mn0.20Te melt increases with decreasing crystallization temperature. Thermography of alloys by the second method of heat treatment is to conduct a series of isothermal holding during heating of the samples to the maximum temperature (1150 °C). Thus, the parameters of alloy melting were investigated. It was determined that the volume fraction of solid phase in the Cd0.80Mn0.20Te melt decreases from 100% to 0% in the temperature range 1078-1095 °С. Based on the obtained data of differential thermal analyses the Cd0.80Mn0.20Te ingot was grown under controlled conditions. After cutting this crystal we can see several monocrystalline areas of different sizes. IR microscope showed that the minimum number of inclusions <7 mm in diameter distributed in different parts of the sample The value of the band gap in all samples ranges from 1.78 to 1.80 eV. The value of the resistivity of the crystal Cd0.80Mn0.20Te is 2•107 Ohm • cm at the beginning of the ingot and decreases by 2 orders of magnitude by the end of the ingot.
{"title":"Phase equilibria in Cd0.80Mn0.20Te solid solutions","authors":"A. V. Matviy, V. V. Kopach, S. M. Rusnak, O. Kopach, L. Shcherbak, P. Fochuk","doi":"10.31861/chem-2021-828-3","DOIUrl":"https://doi.org/10.31861/chem-2021-828-3","url":null,"abstract":"The thermal properties of Cd0.80Mn0.20Te solid solutions were investigated in this article. Two methods of heat treatment were used for thermography of alloys, which allowed investigating their thermal properties. One of the methods of thermography of samples was to heat them to the maximum temperature at which they were kept for a certain time, followed by cooling of the sample. The data obtained by this type of thermography allow obtaining graphs which characterized the crystallization parameters of the melt Cd0.80Mn0.20Te. It is shown that the crystallization of the Cd0.80Mn0.20Te melt occurs without supercooling at its overheating less than 14 °С in comparison with the beginning of melting temperature, which indicates the two-phase melt. It is also shown that the crystallization rate of the Cd0.80Mn0.20Te melt increases with decreasing crystallization temperature. Thermography of alloys by the second method of heat treatment is to conduct a series of isothermal holding during heating of the samples to the maximum temperature (1150 °C). Thus, the parameters of alloy melting were investigated. It was determined that the volume fraction of solid phase in the Cd0.80Mn0.20Te melt decreases from 100% to 0% in the temperature range 1078-1095 °С. Based on the obtained data of differential thermal analyses the Cd0.80Mn0.20Te ingot was grown under controlled conditions. After cutting this crystal we can see several monocrystalline areas of different sizes. IR microscope showed that the minimum number of inclusions <7 mm in diameter distributed in different parts of the sample The value of the band gap in all samples ranges from 1.78 to 1.80 eV. The value of the resistivity of the crystal Cd0.80Mn0.20Te is 2•107 Ohm • cm at the beginning of the ingot and decreases by 2 orders of magnitude by the end of the ingot.","PeriodicalId":9913,"journal":{"name":"Chernivtsi University Scientific Herald. Chemistry","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77715178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.31861/chem-2021-828-4
S. Boruk
It was found that the nature of the effect of mono- and disaccharides on the viscosity of aqueous solutions increases with increasing concentration. Solutions of a substance with a higher molecular weight (sucrose) have a higher viscosity than monosaccharides (glucose, fructose). Solutions of pectin in the studied concentration range (0.05 - 0.5% (wt)) have a viscosity in the range (1 - 1.5) 10-3 Pa∙s and behave like Newtonian fluids. The increase in viscosity in solutions of monosaccharide + pectin indicates a low intensity of the associative interaction of molecules in solution. It was found that the introduction of aqueous solutions of monosaccharides background concentration of pectin (C = 0.05%) can significantly bring the viscosity of monosaccharide solutions to the viscosity of disaccharide (sucrose). The composition of the complex additive monosaccharides + polysaccharide is proposed. The recommended concentration of pectin is 0.05 - 0.1%; monosaccharides 10 - 40%. The use of a complex additive (monosaccharides + polysaccharide) will provide the necessary stability of food semi-finished products.
{"title":"Viscosity of aqueous solutions of mono-, di- and polysaccharides","authors":"S. Boruk","doi":"10.31861/chem-2021-828-4","DOIUrl":"https://doi.org/10.31861/chem-2021-828-4","url":null,"abstract":"It was found that the nature of the effect of mono- and disaccharides on the viscosity of aqueous solutions increases with increasing concentration. Solutions of a substance with a higher molecular weight (sucrose) have a higher viscosity than monosaccharides (glucose, fructose). Solutions of pectin in the studied concentration range (0.05 - 0.5% (wt)) have a viscosity in the range (1 - 1.5) 10-3 Pa∙s and behave like Newtonian fluids. The increase in viscosity in solutions of monosaccharide + pectin indicates a low intensity of the associative interaction of molecules in solution. It was found that the introduction of aqueous solutions of monosaccharides background concentration of pectin (C = 0.05%) can significantly bring the viscosity of monosaccharide solutions to the viscosity of disaccharide (sucrose). The composition of the complex additive monosaccharides + polysaccharide is proposed. The recommended concentration of pectin is 0.05 - 0.1%; monosaccharides 10 - 40%. The use of a complex additive (monosaccharides + polysaccharide) will provide the necessary stability of food semi-finished products.","PeriodicalId":9913,"journal":{"name":"Chernivtsi University Scientific Herald. Chemistry","volume":"104 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75973357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.31861/chem-2021-828-1
O. Tynkevych
A general review of the introduction of transition metal impurities into the structure of CdTe nanocrystals is made. The main methods of nanocomposite synthesis and the influence of synthesis conditions on the formation and properties of nanocomposites are considered. The influence of the introduction of transition metal impurities on their band structure and optical properties of CdTe nanocrystals was evaluated.
{"title":"Introduction of transition metal impurities as a method of tuning the band structure and optical properties of CdTe nanocrystals","authors":"O. Tynkevych","doi":"10.31861/chem-2021-828-1","DOIUrl":"https://doi.org/10.31861/chem-2021-828-1","url":null,"abstract":"A general review of the introduction of transition metal impurities into the structure of CdTe nanocrystals is made. The main methods of nanocomposite synthesis and the influence of synthesis conditions on the formation and properties of nanocomposites are considered. The influence of the introduction of transition metal impurities on their band structure and optical properties of CdTe nanocrystals was evaluated.","PeriodicalId":9913,"journal":{"name":"Chernivtsi University Scientific Herald. Chemistry","volume":"332 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80528935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.31861/chem-2020-827-1
N. Doskaliuk, Y. Babyuk, O. Tynkevych, A. Sachko, Y. Khalavka
Semiconductor I-III-VI nanocrystals are highly luminescent low toxic materials with direct band gap and tunable emission in visible and near infrared region which can be synthesized in aqueous media via simple procedure making them competitive object in compare with well developed and investigated II-VI quantum dots. However the nature of radiative recombination pathways definition and effect of synthesis conditions on spectral characteristics of the nanocrystals investigation remains an important task. In the present work influence of the cation precursors ratio as well as the heat treatment duration on the composition, optical properties and photostability of AgInS2 and AgInS2/ZnS nanocrystals synthesized in aqueous media have been investigated. Due to the low reactivity of indium salts in aqueous solution coused by formation of a stable complexes with stabilizer or hydroxycomplexes the nearest stoichiometric Ag1,1InSx quantum dots are formed at the initial [In]:[Ag] ratio 7:1. Under high excess of Ag formation of Ag2S/AgInS2 core/shell quantum dots confirming by presence of large 12-15 nm nanocrystals and red shift of the photoluminescence maximum with increasing [In]:[Ag] ratio from 1 to 3 (shell thickness should increase proportionally) is possible. With a further increase of the [In]:[Ag] ratio the absorption edge and the photoluminescence maximum are green shifted indicating increase of the quantum dots band energy. That can be explained by lowering of the valence band ceiling energy and rising of the conduction band bottom energy due to decrease of density of states of Ag 4d orbitals and increase of density of states of In 5s and 5p orbitals involved in the AgInS2 band gap formation. Increase of Indium content leads to significant increase of the photoluminescence intensity of AgInS2 nanocrystals eliminating nonradiative defects such as Agi. It have been shown that the ZnS shell epitaxial grow occurs due to the cation exchange between Zn2+ and In3+ and takes place only at low concentration of Zinc precursor ([Zn]:[Ag] ≤ 4). With further enhancement of the ratio the solid solution of AgInS2-ZnS is forming. To achieve the highest possible photoluminescence intensity and energy the AgInS2-ZnS nanocrystals should be heated at 950C at least for 120 minutes. It have been shown that the nearly stoichiometric Ag1,1InSx nanocrystals posess the highest photostability under UV light irradiation.
{"title":"Influence of the cationic composition on the optical properties and photostability of AgInS2 and AgInS2/ZnS quantum dots","authors":"N. Doskaliuk, Y. Babyuk, O. Tynkevych, A. Sachko, Y. Khalavka","doi":"10.31861/chem-2020-827-1","DOIUrl":"https://doi.org/10.31861/chem-2020-827-1","url":null,"abstract":"Semiconductor I-III-VI nanocrystals are highly luminescent low toxic materials with direct band gap and tunable emission in visible and near infrared region which can be synthesized in aqueous media via simple procedure making them competitive object in compare with well developed and investigated II-VI quantum dots. However the nature of radiative recombination pathways definition and effect of synthesis conditions on spectral characteristics of the nanocrystals investigation remains an important task. In the present work influence of the cation precursors ratio as well as the heat treatment duration on the composition, optical properties and photostability of AgInS2 and AgInS2/ZnS nanocrystals synthesized in aqueous media have been investigated. Due to the low reactivity of indium salts in aqueous solution coused by formation of a stable complexes with stabilizer or hydroxycomplexes the nearest stoichiometric Ag1,1InSx quantum dots are formed at the initial [In]:[Ag] ratio 7:1. Under high excess of Ag formation of Ag2S/AgInS2 core/shell quantum dots confirming by presence of large 12-15 nm nanocrystals and red shift of the photoluminescence maximum with increasing [In]:[Ag] ratio from 1 to 3 (shell thickness should increase proportionally) is possible. With a further increase of the [In]:[Ag] ratio the absorption edge and the photoluminescence maximum are green shifted indicating increase of the quantum dots band energy. That can be explained by lowering of the valence band ceiling energy and rising of the conduction band bottom energy due to decrease of density of states of Ag 4d orbitals and increase of density of states of In 5s and 5p orbitals involved in the AgInS2 band gap formation. Increase of Indium content leads to significant increase of the photoluminescence intensity of AgInS2 nanocrystals eliminating nonradiative defects such as Agi. It have been shown that the ZnS shell epitaxial grow occurs due to the cation exchange between Zn2+ and In3+ and takes place only at low concentration of Zinc precursor ([Zn]:[Ag] ≤ 4). With further enhancement of the ratio the solid solution of AgInS2-ZnS is forming. To achieve the highest possible photoluminescence intensity and energy the AgInS2-ZnS nanocrystals should be heated at 950C at least for 120 minutes. It have been shown that the nearly stoichiometric Ag1,1InSx nanocrystals posess the highest photostability under UV light irradiation.","PeriodicalId":9913,"journal":{"name":"Chernivtsi University Scientific Herald. Chemistry","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87253690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.31861/chem-2019-818-05
I. Kobasa, M. M. Vorobet’s, O. Sema
The results of the spectral, electrochemical and energy characteristics of symmetric cationic polymethine dye 2 - [(1E) -1,3,5-hexatrienyl -] - 1- (phenylmethyl)-benzindolium boron fluoride (D) indicate the possibility of its use as an effective titanium(IV) sensitizer oxide. Comparison of the absorption spectra of the dye solution and the reflectance spectra of the D/TiO2 heterostructures showed that the deposition of the dye on the TiO2 surface leads to bathochrome and hypochromic shifts of the absorption bands, the value of which depends on the content of this component in the heterostructure (HS). The obtained changes in the spectra of heterostructures indicate the possibility of formation of both J- and H-aggregates. Cyclic voltammetry determines the oxidation and reduction potentials of the investigated polymethine dye and calculates their redox potentials in the excited state. They have been found to be sufficient for sensitization by electron transfer to the TiO2 conduction band. The photocatalytic activity of HS D/TiO2 in the model reaction of methylene blue reduction depending on irradiation conditions and dye concentration has been determined. It is shown that, when irradiated with D/TiO2 heterostructures with light with λ <400 nm, their photocatalytic activity decreases with increasing dye content in the whole concentration range of the studied concentrations. When irradiated with heterostructures by light absorbed by the dye (λ = 872 nm), the photocatalytic activity increases to a maximum value at a concentration of the dye equal to 0,20 mg/g, and then decreases with increasing concentration. The energy of possible electronic processes caused by the action of light absorbed by a semiconductor and a dye-sensitizer is considered. The possibility of using created heterostructures as functional materials with a given level of photocatalytic activity and extended range of light sensitivity is shown.
{"title":"Photocatalytic reduction of methylene blue by the heterostructure of Titanium (IV) oxide and symmetric cationic polymethine dye","authors":"I. Kobasa, M. M. Vorobet’s, O. Sema","doi":"10.31861/chem-2019-818-05","DOIUrl":"https://doi.org/10.31861/chem-2019-818-05","url":null,"abstract":"The results of the spectral, electrochemical and energy characteristics of symmetric cationic polymethine dye 2 - [(1E) -1,3,5-hexatrienyl -] - 1- (phenylmethyl)-benzindolium boron fluoride (D) indicate the possibility of its use as an effective titanium(IV) sensitizer oxide. Comparison of the absorption spectra of the dye solution and the reflectance spectra of the D/TiO2 heterostructures showed that the deposition of the dye on the TiO2 surface leads to bathochrome and hypochromic shifts of the absorption bands, the value of which depends on the content of this component in the heterostructure (HS). The obtained changes in the spectra of heterostructures indicate the possibility of formation of both J- and H-aggregates. Cyclic voltammetry determines the oxidation and reduction potentials of the investigated polymethine dye and calculates their redox potentials in the excited state. They have been found to be sufficient for sensitization by electron transfer to the TiO2 conduction band. The photocatalytic activity of HS D/TiO2 in the model reaction of methylene blue reduction depending on irradiation conditions and dye concentration has been determined. It is shown that, when irradiated with D/TiO2 heterostructures with light with λ <400 nm, their photocatalytic activity decreases with increasing dye content in the whole concentration range of the studied concentrations. When irradiated with heterostructures by light absorbed by the dye (λ = 872 nm), the photocatalytic activity increases to a maximum value at a concentration of the dye equal to 0,20 mg/g, and then decreases with increasing concentration. The energy of possible electronic processes caused by the action of light absorbed by a semiconductor and a dye-sensitizer is considered. The possibility of using created heterostructures as functional materials with a given level of photocatalytic activity and extended range of light sensitivity is shown.","PeriodicalId":9913,"journal":{"name":"Chernivtsi University Scientific Herald. Chemistry","volume":"51 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80991512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.31861/chem-2019-818-09
I. Kobasa, M. M. Vorobet’s, O. Sema, Yu. V. Kropelnytska
The influence of the structure of a number of merocyanine dyes (D), which differ in the length of the polyethylene chain on one vinyl group, on their spectral, electrochemical and energy characteristics is established. Cyclic voltammetry determines their oxidation and reduction potentials. The values of the HOMO and LUMO energy levels of the studied dyes from spectral and electrochemical data were calculated. It is shown that the obtained values of the potentials of the energy levels of the dyes differ little (the energy difference ranges from 0,22–0,53 eV). The possibility of using merocyanins as sensitizers of titanium(IV) oxide and the creation of photosensitive heterostructures has been made. In order to investigate the possibility of using the merocyanin dyes under study as TiO2 sensitizers, the energy of the «semiconductor – dye – reagents» systems was considered. For this purpose, we compared the redox characteristics of merocyanine dyes with the electrophysical parameters of titanium(IV) oxide, as well as the redox characteristics of the reaction participants. It is established that in such systems the processes of photon transfer of the electron from the dye to the semiconductor are necessary for sensitization, and the regeneration of the original form of the sensitizers by the action of the reducing agent on the cation radicals formed is thermodynamically allowed. The conclusion about the possibility of using the studied merocyanines as effective sensitizers was confirmed by the results of the study of the photocatalytic activity of D/TiO2 heterostructures in the reaction of methylene blue formaldehyde recovery under different irradiation conditions and at different dye concentrations. The explanation for the found laws is offered. Scientific approaches to the production of new photosensitive systems with an expanded range of photosensitivity and a given level of photocatalytic activity have been developed.
{"title":"New light-sensitive materials based on TiO2 and merocianin polymetine dye","authors":"I. Kobasa, M. M. Vorobet’s, O. Sema, Yu. V. Kropelnytska","doi":"10.31861/chem-2019-818-09","DOIUrl":"https://doi.org/10.31861/chem-2019-818-09","url":null,"abstract":"The influence of the structure of a number of merocyanine dyes (D), which differ in the length of the polyethylene chain on one vinyl group, on their spectral, electrochemical and energy characteristics is established. Cyclic voltammetry determines their oxidation and reduction potentials. The values of the HOMO and LUMO energy levels of the studied dyes from spectral and electrochemical data were calculated. It is shown that the obtained values of the potentials of the energy levels of the dyes differ little (the energy difference ranges from 0,22–0,53 eV). The possibility of using merocyanins as sensitizers of titanium(IV) oxide and the creation of photosensitive heterostructures has been made. In order to investigate the possibility of using the merocyanin dyes under study as TiO2 sensitizers, the energy of the «semiconductor – dye – reagents» systems was considered. For this purpose, we compared the redox characteristics of merocyanine dyes with the electrophysical parameters of titanium(IV) oxide, as well as the redox characteristics of the reaction participants. It is established that in such systems the processes of photon transfer of the electron from the dye to the semiconductor are necessary for sensitization, and the regeneration of the original form of the sensitizers by the action of the reducing agent on the cation radicals formed is thermodynamically allowed. The conclusion about the possibility of using the studied merocyanines as effective sensitizers was confirmed by the results of the study of the photocatalytic activity of D/TiO2 heterostructures in the reaction of methylene blue formaldehyde recovery under different irradiation conditions and at different dye concentrations. The explanation for the found laws is offered. Scientific approaches to the production of new photosensitive systems with an expanded range of photosensitivity and a given level of photocatalytic activity have been developed.","PeriodicalId":9913,"journal":{"name":"Chernivtsi University Scientific Herald. Chemistry","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90307820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.31861/chem-2019-819-09
S. Drapak, A. Ivanova-Tolpintseva, Y. Khalavka
Nowadays, one of the most relevant areas of modern materials science is the science of nanoparticles and nanomaterials, as well as nanotechnology. Composition, size and shape of nanomaterials at the nanoscale determines its electronic, optical, magnetic, catalytic, etc. properties. Due to the unique optical and catalytic properties, noble metals nanoparticles (silver and gold ones) today are one of the most intensively studied types of nanoobjects. The properties of silver and gold nanoparticles are extremely important and promising for technological use in such areas as electronics, optics, solar energy, information storage, communications, biomedicine, environmental research and others. A number of promising applications of noble metal nanoparticles are due to the effect of localized surface plasmon resonance, which consists in the collective oscillation of conduction electrons relatively to the ions in metallic crystal lattice bounded by the nanoparticle surface at the resonant excitation frequency. The dimensional dependence of the basic physical and chemical properties of nanoparticles makes specific demands on the synthesis, which should provide the necessary particles’ diameter and size distribution, the possibility of surface functionalization, particles’ stability in the manufacturing process, subsequent storage and operation for its further practical application. Existing methods for obtaining noble metals nanoparticles, including physical, thermal, chemical, photochemical, electrochemical, etc. do not provide the required reproducibility or are too expensive for mass use. In addition, most currently known methods allow to obtain metal nanoparticles only with a wide distribution of shapes and sizes. Careful control of the reaction parameters, such as time, process temperature, stirring rate, concentration of reactans and stabilizing additives, allows to narrow the size distribution of nanoparticles, but not always to the desired limits. According to recent studies, monodisperse colloidal solutions of noble metals nanoparticles can be obtained by excitation of plasmon-stimulated reactions in the reaction mixture. This review, based on a rage of experimental studies, demonstrates how light can be used to control the processes of growth, shape and size of noble metals nanoparticles, and to convert heterogeneous populations of metal nanoparticles into populations with high monodispersity. The manifestation of localized surface plasmons in the optical spectra of metal nanoparticles of different sizes and shapes was also considered. In addition, there were also discussed photophysical processes, associated with the excitation of localized surface plasmon resonance in metal nanoparticles, which allow to control chemical reactions at the nanoscale, namely the photothermal effect; concentration of light near the surface of nanoparticles, which leads to an increase in the electromagnetic field and the intensity of the photon flux for molecules n
{"title":"Photostimulated Synthesis of Noble Metals Nanoparticles","authors":"S. Drapak, A. Ivanova-Tolpintseva, Y. Khalavka","doi":"10.31861/chem-2019-819-09","DOIUrl":"https://doi.org/10.31861/chem-2019-819-09","url":null,"abstract":"Nowadays, one of the most relevant areas of modern materials science is the science of nanoparticles and nanomaterials, as well as nanotechnology. Composition, size and shape of nanomaterials at the nanoscale determines its electronic, optical, magnetic, catalytic, etc. properties. Due to the unique optical and catalytic properties, noble metals nanoparticles (silver and gold ones) today are one of the most intensively studied types of nanoobjects. The properties of silver and gold nanoparticles are extremely important and promising for technological use in such areas as electronics, optics, solar energy, information storage, communications, biomedicine, environmental research and others. A number of promising applications of noble metal nanoparticles are due to the effect of localized surface plasmon resonance, which consists in the collective oscillation of conduction electrons relatively to the ions in metallic crystal lattice bounded by the nanoparticle surface at the resonant excitation frequency. The dimensional dependence of the basic physical and chemical properties of nanoparticles makes specific demands on the synthesis, which should provide the necessary particles’ diameter and size distribution, the possibility of surface functionalization, particles’ stability in the manufacturing process, subsequent storage and operation for its further practical application. Existing methods for obtaining noble metals nanoparticles, including physical, thermal, chemical, photochemical, electrochemical, etc. do not provide the required reproducibility or are too expensive for mass use. In addition, most currently known methods allow to obtain metal nanoparticles only with a wide distribution of shapes and sizes. Careful control of the reaction parameters, such as time, process temperature, stirring rate, concentration of reactans and stabilizing additives, allows to narrow the size distribution of nanoparticles, but not always to the desired limits. According to recent studies, monodisperse colloidal solutions of noble metals nanoparticles can be obtained by excitation of plasmon-stimulated reactions in the reaction mixture. This review, based on a rage of experimental studies, demonstrates how light can be used to control the processes of growth, shape and size of noble metals nanoparticles, and to convert heterogeneous populations of metal nanoparticles into populations with high monodispersity. The manifestation of localized surface plasmons in the optical spectra of metal nanoparticles of different sizes and shapes was also considered. In addition, there were also discussed photophysical processes, associated with the excitation of localized surface plasmon resonance in metal nanoparticles, which allow to control chemical reactions at the nanoscale, namely the photothermal effect; concentration of light near the surface of nanoparticles, which leads to an increase in the electromagnetic field and the intensity of the photon flux for molecules n","PeriodicalId":9913,"journal":{"name":"Chernivtsi University Scientific Herald. Chemistry","volume":"9 4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80630715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.31861/chem-2019-819-01
О. Kapush, I. O. Mazarchuk, L. І. Trіshchuk, V. Y. Morozovska, S. Boruk, S. Budzulyak, D. Korbutyak, B. N. Kulchitsky, O. Kosinov, Rashad Gabil Abaszade
The physicochemical properties of low-dimensional structures based on CdTe obtained are investigated by the method of colloidal synthesis. The analysis of the optical absorption spectra and the luminescence intensity of the CdTe colloidal NCs showed that the nature of the dispersion medium significantly affects their optical properties. The optical absorption spectra of the CdTe NK fractions obtained by dissolving the flocs in deionized water and in deionized water with the addition of NaOH have been shown to have the same character. However, the addition of NaOH results in a shift of the absorption maximum by 8-12 nm into the longwave region. This suggested that the addition of NaOH to the colloidal solution of NK CdTe during sedimentation deposition leads to the aggregation of cadmium telluride particles. The addition of NaOH results in the quenching of photoluminescence. It can be assumed that during the sedimentation deposition there is a leaching of THC to a critical concentration, therefore, due to insufficient stabilization of the surface of the NC CdTe, a rapid aggregation of particles occurs and a loss of sedimentation stability of the solution is observed, which causes the PL quenching. The analysis of the optical absorption and photoluminescence spectra of the fractions of the colloidal solution of NC CdTe obtained by using DMF as a dispersion medium during the sedimentation deposition leads to the conclusion that the nature of the dispersion medium significantly affects the optical properties of CdTe NC. The maxima of the OP spectra corresponding to the first exciton transition of all fractions are shifted to the longwave region and change their shape compared to the corresponding spectra for the aqueous fractions. In this case, the PL intensity of the first and second fractions of CdTe NC in DMF is approximately 100 ppm. exceeds the PL intensity of the aqueous fractions, which can be explained by the fact that DMF, unlike deionized water, does not wash out THC from the surface of the CdTe NC.
{"title":"Influence of the nature of the dispersion medium on the optical properties of CdTe nanocrystals during sedimentation deposition","authors":"О. Kapush, I. O. Mazarchuk, L. І. Trіshchuk, V. Y. Morozovska, S. Boruk, S. Budzulyak, D. Korbutyak, B. N. Kulchitsky, O. Kosinov, Rashad Gabil Abaszade","doi":"10.31861/chem-2019-819-01","DOIUrl":"https://doi.org/10.31861/chem-2019-819-01","url":null,"abstract":"The physicochemical properties of low-dimensional structures based on CdTe obtained are investigated by the method of colloidal synthesis. The analysis of the optical absorption spectra and the luminescence intensity of the CdTe colloidal NCs showed that the nature of the dispersion medium significantly affects their optical properties. The optical absorption spectra of the CdTe NK fractions obtained by dissolving the flocs in deionized water and in deionized water with the addition of NaOH have been shown to have the same character. However, the addition of NaOH results in a shift of the absorption maximum by 8-12 nm into the longwave region. This suggested that the addition of NaOH to the colloidal solution of NK CdTe during sedimentation deposition leads to the aggregation of cadmium telluride particles. The addition of NaOH results in the quenching of photoluminescence. It can be assumed that during the sedimentation deposition there is a leaching of THC to a critical concentration, therefore, due to insufficient stabilization of the surface of the NC CdTe, a rapid aggregation of particles occurs and a loss of sedimentation stability of the solution is observed, which causes the PL quenching. The analysis of the optical absorption and photoluminescence spectra of the fractions of the colloidal solution of NC CdTe obtained by using DMF as a dispersion medium during the sedimentation deposition leads to the conclusion that the nature of the dispersion medium significantly affects the optical properties of CdTe NC. The maxima of the OP spectra corresponding to the first exciton transition of all fractions are shifted to the longwave region and change their shape compared to the corresponding spectra for the aqueous fractions. In this case, the PL intensity of the first and second fractions of CdTe NC in DMF is approximately 100 ppm. exceeds the PL intensity of the aqueous fractions, which can be explained by the fact that DMF, unlike deionized water, does not wash out THC from the surface of the CdTe NC.","PeriodicalId":9913,"journal":{"name":"Chernivtsi University Scientific Herald. Chemistry","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85005281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.31861/chem-2019-819-06
O. Perepelytsya, I. Yaremiy, K. P. Kupchanko, N. Panasenko, M. Bratenko, M. Vovk
An effective preparative method of synthesis of a series of new (pyrazole-4-il)methylenethiazolidine structures has been elaborated. The structures are functionalized in the 3rd position by the carboxylate or carboxyle group and in the 3rd and 5th positions of the thiazolidine cycle – by the oxo-, thio- or iminogroups. The method involves condensation of 4-formylpyrazole-3-carbonic acids and their ethyl esters with a series of the substituted thiazolidines: 1,3-thiazolidine-2,4-dione, 4-thioxo-1,3-thiazolidine-2-one, 2-thioxo-1,3-thiazolidine-4-one and 2-imino-1,3-thiazolidine-4-one. A group of 112 white adult nonlinear rats of both genders was used to investigate the hypoglycemic activity of the synthesized compounds. Pioglitazonum (5-{4-[2-(5-ethylpyridine-2-il)etoxy]benzyl}thiazolidine-2,4-dione, M=246) was used as a reference medicine in the standard dosage of 0.0214 mmole/kg. All compounds were administered intragastrically on an empty stomach using a non-traumatic catheter as a 3 % starch suspension while same dosage of the neutral suspension (without any acting medicine) was administered to the animals of the control group. Possible hypoglycemic activity of the compounds was evaluated by the changes in glucose concentration in blood measured before and 2, 4, 6, 8 and 10 hours after the single administration of a compound. An express glucometer “One Touch Select Simple” was employed for the above tests. Then all the data were processed by MS Excel. As seen from the results of the biochemical investigations, a clear hypoglycemic activity has been registered for the compounds mentioned in this work. Five of ten products have ensured a prolonged effect embracing the entire duration of the experiment. 1-methyl-4[(4-oxo-2-thiooxo-1,3-thiazolidine-5-iliden)methyl]-1H-pyrazole-3-carbonic acid caused the deepest decrease in the glucose content (2.0 units or 30.4 %) while in case of the reference medicine it was only 1.35 units (23.9 %). Some dependence between the compound structure and its pharmaceutical activity was also found. The most prolonged and steady hypoglycemic activity was registered for (pyrazole-4-il)methylethiazolidines with methyl group as a substitute in the 1st position and carboxylic group – in the 3rd position. Additional introduction of the methyl and carboxylate groups into pyrazolic scaffold results in a prolonged and deeper hypoglycemic effect leading to the 1.4 times lesser drop in glucose concentration as compared to that after administration of the reference medicine.
{"title":"Synthesis and hypoglycemic activity of derivatives of 4-((1,3-thiazolydine-5-yliden)methy)pyrazole-3-carbonic acid and its esters","authors":"O. Perepelytsya, I. Yaremiy, K. P. Kupchanko, N. Panasenko, M. Bratenko, M. Vovk","doi":"10.31861/chem-2019-819-06","DOIUrl":"https://doi.org/10.31861/chem-2019-819-06","url":null,"abstract":"An effective preparative method of synthesis of a series of new (pyrazole-4-il)methylenethiazolidine structures has been elaborated. The structures are functionalized in the 3rd position by the carboxylate or carboxyle group and in the 3rd and 5th positions of the thiazolidine cycle – by the oxo-, thio- or iminogroups. The method involves condensation of 4-formylpyrazole-3-carbonic acids and their ethyl esters with a series of the substituted thiazolidines: 1,3-thiazolidine-2,4-dione, 4-thioxo-1,3-thiazolidine-2-one, 2-thioxo-1,3-thiazolidine-4-one and 2-imino-1,3-thiazolidine-4-one. A group of 112 white adult nonlinear rats of both genders was used to investigate the hypoglycemic activity of the synthesized compounds. Pioglitazonum (5-{4-[2-(5-ethylpyridine-2-il)etoxy]benzyl}thiazolidine-2,4-dione, M=246) was used as a reference medicine in the standard dosage of 0.0214 mmole/kg. All compounds were administered intragastrically on an empty stomach using a non-traumatic catheter as a 3 % starch suspension while same dosage of the neutral suspension (without any acting medicine) was administered to the animals of the control group. Possible hypoglycemic activity of the compounds was evaluated by the changes in glucose concentration in blood measured before and 2, 4, 6, 8 and 10 hours after the single administration of a compound. An express glucometer “One Touch Select Simple” was employed for the above tests. Then all the data were processed by MS Excel. As seen from the results of the biochemical investigations, a clear hypoglycemic activity has been registered for the compounds mentioned in this work. Five of ten products have ensured a prolonged effect embracing the entire duration of the experiment. 1-methyl-4[(4-oxo-2-thiooxo-1,3-thiazolidine-5-iliden)methyl]-1H-pyrazole-3-carbonic acid caused the deepest decrease in the glucose content (2.0 units or 30.4 %) while in case of the reference medicine it was only 1.35 units (23.9 %). Some dependence between the compound structure and its pharmaceutical activity was also found. The most prolonged and steady hypoglycemic activity was registered for (pyrazole-4-il)methylethiazolidines with methyl group as a substitute in the 1st position and carboxylic group – in the 3rd position. Additional introduction of the methyl and carboxylate groups into pyrazolic scaffold results in a prolonged and deeper hypoglycemic effect leading to the 1.4 times lesser drop in glucose concentration as compared to that after administration of the reference medicine.","PeriodicalId":9913,"journal":{"name":"Chernivtsi University Scientific Herald. Chemistry","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79562824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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