In a semi-review paper, it was discussed the notion of symmetry of polyatomic systems defined as invariance under transformations, and show that this important property of atomic matter is extremely vulnerable, and may undergo internal breakdown, subject to the presence of electronic degeneracy or pseudodegeneracy. First formulated by Landau, L. in 1934, later proved and published by Jahn and Teller, this Jahn-Teller effect (JTE) underwent tremendous developments with important applications in physics, chemistry, biology, and materials science. Less attention was paid to the roots of this phenomenon and its correct interpretation in the sense of its influence on observable properties. It is shown that electronic degeneracy and its extended form, called pseudodegeneracy, are actually the only source of spontaneous symmetry breaking (SSB) in nature, including all forms of matter, beginning with elementary particles, via nuclei, atoms, molecules, and solids. Theoretically, the vulnerability of the notion of symmetry is due to the fact that, following quantum mechanics, the separation of the motion of electrons and nuclei (and, similarly, the separation of motions of elementary particles) is approximate, and hence the classical notion of polyatomic space configuration is approximate too, with SSB as one of its main violation.
在一篇半综述论文中，讨论了多原子系统的对称性概念，其定义是变换下的不变性，并指出原子物质的这一重要特性极其脆弱，可能会因电子变性或假变性的存在而发生内部崩溃。Jahn-Teller 效应（JTE）由兰道（Landau, L. ）于 1934 年首次提出，后由扬恩（Jahn）和特勒（Teller）证明并发表，它在物理学、化学、生物学和材料科学领域都有重要应用，并取得了巨大发展。人们对这一现象的根源及其对可观测特性影响的正确解释关注较少。研究表明，电子变性及其扩展形式（称为假变性）实际上是自然界自发对称性破缺（SSB）的唯一来源，包括从基本粒子开始，到原子核、分子和固体等所有形式的物质。从理论上讲，对称性概念之所以脆弱，是因为根据量子力学，电子和原子核运动的分离（同样，基本粒子运动的分离）是近似的，因此经典的多原子空间构型概念也是近似的，而自发对称性破缺（SSB）则是其主要的违背之一。
{"title":"Spontaneous symmetry breaking as a law of nature","authors":"Isaac Bersuker","doi":"10.19261/cjm.2023.1098","DOIUrl":"https://doi.org/10.19261/cjm.2023.1098","url":null,"abstract":"In a semi-review paper, it was discussed the notion of symmetry of polyatomic systems defined as invariance under transformations, and show that this important property of atomic matter is extremely vulnerable, and may undergo internal breakdown, subject to the presence of electronic degeneracy or pseudodegeneracy. First formulated by Landau, L. in 1934, later proved and published by Jahn and Teller, this Jahn-Teller effect (JTE) underwent tremendous developments with important applications in physics, chemistry, biology, and materials science. Less attention was paid to the roots of this phenomenon and its correct interpretation in the sense of its influence on observable properties. It is shown that electronic degeneracy and its extended form, called pseudodegeneracy, are actually the only source of spontaneous symmetry breaking (SSB) in nature, including all forms of matter, beginning with elementary particles, via nuclei, atoms, molecules, and solids. Theoretically, the vulnerability of the notion of symmetry is due to the fact that, following quantum mechanics, the separation of the motion of electrons and nuclei (and, similarly, the separation of motions of elementary particles) is approximate, and hence the classical notion of polyatomic space configuration is approximate too, with SSB as one of its main violation.","PeriodicalId":9922,"journal":{"name":"Chemistry Journal of Moldova","volume":"16 3","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139188061","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}
Muslim Hasan Allawi, Riyadh Almukhtar, S. Al-Humairi, A. D. Salman, Tatjana Juzsakova, Vitkor Sebestyén, Igor Cretescu
The degradation of diisopropyl methylphosphonate (DIMP) in aqueous solutions was studied using ultrasound irradiation with a fixed frequency of 26.2 kHz, following the first-order kinetic model. The study's primary goal was to determine the influence of the following experimental parameters: the pH (at different values of 2, 7 and 10), the initial concentration of DIMP (at different concentrations: 7, 14, 30, 50, 80 mg/L), the processing time (at different periods: 15, 30, 45, 60, 80, 90 min), and the concentration of the additive CCl4 (at different concentrations: 0.002, 0.004, 0.006, 0.008 mg/L). A DIMP removal efficiency of 98% from aqueous solution was obtained at pH 10 and 0.008 mg/L CCl4, after an ultrasound irradiation time of 45 min, pointing out the influence of the above-mentioned experimental parameters on the DIMP degradation process.
{"title":"Degradation of diisopropyl methylphosphonate in aqueous solutions by ultrasonic irradiation combined with oxidation process","authors":"Muslim Hasan Allawi, Riyadh Almukhtar, S. Al-Humairi, A. D. Salman, Tatjana Juzsakova, Vitkor Sebestyén, Igor Cretescu","doi":"10.19261/cjm.2023.1019","DOIUrl":"https://doi.org/10.19261/cjm.2023.1019","url":null,"abstract":"The degradation of diisopropyl methylphosphonate (DIMP) in aqueous solutions was studied using ultrasound irradiation with a fixed frequency of 26.2 kHz, following the first-order kinetic model. The study's primary goal was to determine the influence of the following experimental parameters: the pH (at different values of 2, 7 and 10), the initial concentration of DIMP (at different concentrations: 7, 14, 30, 50, 80 mg/L), the processing time (at different periods: 15, 30, 45, 60, 80, 90 min), and the concentration of the additive CCl4 (at different concentrations: 0.002, 0.004, 0.006, 0.008 mg/L). A DIMP removal efficiency of 98% from aqueous solution was obtained at pH 10 and 0.008 mg/L CCl4, after an ultrasound irradiation time of 45 min, pointing out the influence of the above-mentioned experimental parameters on the DIMP degradation process.","PeriodicalId":9922,"journal":{"name":"Chemistry Journal of Moldova","volume":"54 6","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139190437","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}
In this work, taking the Pr(III) ion as a suitable case study, the authors test the capacity of a series of Gaussian Type Orbitals (GTOs) basis sets to account for the atomic spectra of lanthanide ions. An extended relevance of this assessment can be found in modeling the luminescence of lanthanide-based materials. It was selected the Pr(III) case because it shows a rather rich collection of experimental data, emerging from the f2 and fd configurations. The energy barycenters of spectral multiplets can be equated analytically in terms of the so-called Slater-Condon parameters. By multi-configurational ab initio procedures, with basis sets from existing GTO repositories, the calculated f→f transitions are moderately higher than the experimental values, while the relative energies of Fd states undergo both under- and over-estimation. The GTO shortcomings, that are impacting the accuracy, were debated, the critical perspective spreading the seeds of future development.
在这项工作中，作者以 Pr(III)离子为合适的研究案例，测试了一系列高斯型轨道（GTO）基础集解释镧系元素离子原子光谱的能力。在镧系元素材料的发光建模中可以发现这一评估的扩展相关性。之所以选择 Pr(III)，是因为它从 f2 和 fd 构型中收集了相当丰富的实验数据。光谱多重子的能量双中心可以通过所谓的斯莱特-康顿参数进行分析。通过多构型 ab initio 程序，利用现有 GTO 储存库中的基集，计算出的 f→f 转变值适度高于实验值，而 Fd 状态的相对能量则被低估或高估。会上还讨论了影响精度的 GTO 缺陷，并从批判的角度为未来的发展播下了种子。
{"title":"On the calculation of lanthanide systems. The spectral parameters of praseodymium trivalent ion","authors":"A. Toader, M. C. Buta, F. Cimpoesu","doi":"10.19261/cjm.2023.1146","DOIUrl":"https://doi.org/10.19261/cjm.2023.1146","url":null,"abstract":"In this work, taking the Pr(III) ion as a suitable case study, the authors test the capacity of a series of Gaussian Type Orbitals (GTOs) basis sets to account for the atomic spectra of lanthanide ions. An extended relevance of this assessment can be found in modeling the luminescence of lanthanide-based materials. It was selected the Pr(III) case because it shows a rather rich collection of experimental data, emerging from the f2 and fd configurations. The energy barycenters of spectral multiplets can be equated analytically in terms of the so-called Slater-Condon parameters. By multi-configurational ab initio procedures, with basis sets from existing GTO repositories, the calculated f→f transitions are moderately higher than the experimental values, while the relative energies of Fd states undergo both under- and over-estimation. The GTO shortcomings, that are impacting the accuracy, were debated, the critical perspective spreading the seeds of future development.","PeriodicalId":9922,"journal":{"name":"Chemistry Journal of Moldova","volume":"28 2","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139188014","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}
E. Afanasenko, I. Seifullina, E.V. Martsinko, V. Dyakonenko, S. Shishkina
Novel supramolecular cation-anionic coordination compound (HPhen)4[(μ-O){Ge2(OH) (μ-Tart)2}2]·9H2O was synthesised and characterised by the X-ray, elemental, IR- and Hirshfeld surface analysis. It was established that original synthesis method and ability of 1,10-phenanthroline to be protonated promotes the formation of [(μ-O){Ge2(OH)(μ-Tart)2}2]4- anion. In this anion, dimeric fragments are connected by a bridging oxygen atom, and the coordination polyhedra around the germanium atoms adopt a distorted trigonal bipyramidal geometry. The cations HPhen+ serve as effective building blocks, strengthening the overall structure through classical hydrogen bonding and additional π-π stacking interactions. Biological screening of (HPhen)4[(μ-O){Ge2(OH) (μ-Tart)2}2]·9H2O demonstrated its remarkable enzyme-effector and antimicrobial activity. The compounds' efficacy can be attributed to the synergistic effects of the independent cations and anions, as well as the ability of protonated 1,10-phenanthroline to inhibit metal ions in enzymes and form stacking interactions with specific protein components. These characteristics make such compounds highly effective and promising antibacterial agents that minimize the risk of developing bacterial resistance.
{"title":"Selectivity, synthesis, crystal structure and biological activity of the anion-coordination phenanthrolinium tartratogermanate","authors":"E. Afanasenko, I. Seifullina, E.V. Martsinko, V. Dyakonenko, S. Shishkina","doi":"10.19261/cjm.2023.1121","DOIUrl":"https://doi.org/10.19261/cjm.2023.1121","url":null,"abstract":"Novel supramolecular cation-anionic coordination compound (HPhen)4[(μ-O){Ge2(OH) (μ-Tart)2}2]·9H2O was synthesised and characterised by the X-ray, elemental, IR- and Hirshfeld surface analysis. It was established that original synthesis method and ability of 1,10-phenanthroline to be protonated promotes the formation of [(μ-O){Ge2(OH)(μ-Tart)2}2]4- anion. In this anion, dimeric fragments are connected by a bridging oxygen atom, and the coordination polyhedra around the germanium atoms adopt a distorted trigonal bipyramidal geometry. The cations HPhen+ serve as effective building blocks, strengthening the overall structure through classical hydrogen bonding and additional π-π stacking interactions. Biological screening of (HPhen)4[(μ-O){Ge2(OH) (μ-Tart)2}2]·9H2O demonstrated its remarkable enzyme-effector and antimicrobial activity. The compounds' efficacy can be attributed to the synergistic effects of the independent cations and anions, as well as the ability of protonated 1,10-phenanthroline to inhibit metal ions in enzymes and form stacking interactions with specific protein components. These characteristics make such compounds highly effective and promising antibacterial agents that minimize the risk of developing bacterial resistance.","PeriodicalId":9922,"journal":{"name":"Chemistry Journal of Moldova","volume":"59 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139192934","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}
The aim of this research work was to evaluate the role of various fractions of humic substances (HS) in binding Al(III), Fe(III) and Cu(II) ions into complexes using gel chromatography. With an increase in HS concentration in Ukraine’s surface water bodies, the share of HS’ fraction with a molecular weight of 20–5 kDa increases from 37% to 59%. In the water bodies under study the HS’ fractions with molecular weight 20–5 kDa and < 1 kDa play a principal role in the studied metals’ migration. HS with molecular weight 20–5 kDa have been found to bind the smallest amount of Al(III), Fe(III) and Cu(II) in complexes, if the metals concentration bound by 1 mg fraction of HS with a certain molecular weight is calculated. Experimental results showed that, the investigated metal ions have the ability to bind into complexes mainly by HS with a molecular weight of >20 and <1 kDa. In the water bodies under study 1 mg of humic acids has a greater binding ability in relation to Al(III), Fe(III) and Cu(II) ions than 1 mg of fulvic acids. Fulvic acids and humic acids with a molecular weight of 20–5 kDa also have the lowest binding ability.
{"title":"The role of various fractions of humic substances from surface water in binding Al(III), Fe(III), AND Cu(II) into complexes","authors":"V. Zhezherya, Peter Linnik, R. Linnik","doi":"10.19261/cjm.2023.1091","DOIUrl":"https://doi.org/10.19261/cjm.2023.1091","url":null,"abstract":"The aim of this research work was to evaluate the role of various fractions of humic substances (HS) in binding Al(III), Fe(III) and Cu(II) ions into complexes using gel chromatography. With an increase in HS concentration in Ukraine’s surface water bodies, the share of HS’ fraction with a molecular weight of 20–5 kDa increases from 37% to 59%. In the water bodies under study the HS’ fractions with molecular weight 20–5 kDa and < 1 kDa play a principal role in the studied metals’ migration. HS with molecular weight 20–5 kDa have been found to bind the smallest amount of Al(III), Fe(III) and Cu(II) in complexes, if the metals concentration bound by 1 mg fraction of HS with a certain molecular weight is calculated. Experimental results showed that, the investigated metal ions have the ability to bind into complexes mainly by HS with a molecular weight of >20 and <1 kDa. In the water bodies under study 1 mg of humic acids has a greater binding ability in relation to Al(III), Fe(III) and Cu(II) ions than 1 mg of fulvic acids. Fulvic acids and humic acids with a molecular weight of 20–5 kDa also have the lowest binding ability.","PeriodicalId":9922,"journal":{"name":"Chemistry Journal of Moldova","volume":"20 7","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139190852","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}
P. Kuzema, Iryna Laguta, O. Stavinskaya, Viktor Anishchenko, Anastasiia Kramar, Nataliia Smirnova, T. Fesenko, Roman Ivannikov, O. Linnik
The extracts from the leaves of Deschampsia antarctica É. Desv., Camelina sativa (L.) Crantz, and Camellia japonica L. plants, as well as from defatted Camelina sativa and Silybum marianum seedcakes were investigated as potential additives for improvement of biodiesel stability against oxidation. Composition of the extracts was studied by means of HPLC, and antioxidant properties were evaluated using the Folin-Ciocalteu assay and the DPPH test. The oxidation of biodiesel was monitored during the accelerated procedure at 43C, with the changes in the acid number of biodiesel samples being the criteria of this process. In spite of significant distinctions in the content of various phenolic compounds, all the extracts were found to possess high antioxidant activity and decelerate biodiesel oxidation by 9-26%. The data did not reveal a directly proportional relationship between the antioxidants content in the extract, on the one hand, and the enhancement in biodiesel stability, on the other hand; various extracts had different influence on the behaviour of biodiesel from rape and Camelina seed oils. The results obtained are consistent with the assumption that there is no universal stabilizer for different types of biodiesel and indicate the prospects on searching for novel antioxidants of natural origin to inhibit oxidative processes.
{"title":"Antioxidant properties of some plant extracts and effect of their addition on the oxidation stability of biodiesel","authors":"P. Kuzema, Iryna Laguta, O. Stavinskaya, Viktor Anishchenko, Anastasiia Kramar, Nataliia Smirnova, T. Fesenko, Roman Ivannikov, O. Linnik","doi":"10.19261/cjm.2023.1100","DOIUrl":"https://doi.org/10.19261/cjm.2023.1100","url":null,"abstract":"The extracts from the leaves of Deschampsia antarctica É. Desv., Camelina sativa (L.) Crantz, and Camellia japonica L. plants, as well as from defatted Camelina sativa and Silybum marianum seedcakes were investigated as potential additives for improvement of biodiesel stability against oxidation. Composition of the extracts was studied by means of HPLC, and antioxidant properties were evaluated using the Folin-Ciocalteu assay and the DPPH test. The oxidation of biodiesel was monitored during the accelerated procedure at 43C, with the changes in the acid number of biodiesel samples being the criteria of this process. In spite of significant distinctions in the content of various phenolic compounds, all the extracts were found to possess high antioxidant activity and decelerate biodiesel oxidation by 9-26%. The data did not reveal a directly proportional relationship between the antioxidants content in the extract, on the one hand, and the enhancement in biodiesel stability, on the other hand; various extracts had different influence on the behaviour of biodiesel from rape and Camelina seed oils. The results obtained are consistent with the assumption that there is no universal stabilizer for different types of biodiesel and indicate the prospects on searching for novel antioxidants of natural origin to inhibit oxidative processes.","PeriodicalId":9922,"journal":{"name":"Chemistry Journal of Moldova","volume":"13 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139190225","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}
Natalia Talmaci, D. Dragancea, Elena Gorincioi, P. Bourosh, V. Kravtsov
The solid-state structure of a symmetrical carbohydrazone, namely 1,5-bis(2-hydroxy-3-methoxybenzylidene)carbonohydrazide was determined by X-ray single crystal diffraction method. Compound 1 crystallizes in the monoclinic space group P21/n with unit cell parameters a= 10.1198(6), b= 22.7847(11), c= 15.1738(10) Å, β= 100.458(6)°, Z= 4, V= 3440.6(3) Å3, R1= 0.0540. Crystal structure of 1 is defined by two crystallographic independent molecules, which are bonded via N–H···O hydrogen bond. The organic molecules are as keto tautomers with respect to the carbamide fragment, and adopt the anti conformation. 1D and 2D NMR experiments have argued on the presence of the title compound in DMSO-d6 solution mostly as keto tautomer in syn conformation, and enol-imino form when considering o-vanillin residue.
{"title":"Crystal structure and NMR spectroscopic characterization of 1,5-bis(2-hydroxy-3-methoxybenzylidene)carbonohydrazide","authors":"Natalia Talmaci, D. Dragancea, Elena Gorincioi, P. Bourosh, V. Kravtsov","doi":"10.19261/cjm.2023.1074","DOIUrl":"https://doi.org/10.19261/cjm.2023.1074","url":null,"abstract":"The solid-state structure of a symmetrical carbohydrazone, namely 1,5-bis(2-hydroxy-3-methoxybenzylidene)carbonohydrazide was determined by X-ray single crystal diffraction method. Compound 1 crystallizes in the monoclinic space group P21/n with unit cell parameters a= 10.1198(6), b= 22.7847(11), c= 15.1738(10) Å, β= 100.458(6)°, Z= 4, V= 3440.6(3) Å3, R1= 0.0540. Crystal structure of 1 is defined by two crystallographic independent molecules, which are bonded via N–H···O hydrogen bond. The organic molecules are as keto tautomers with respect to the carbamide fragment, and adopt the anti conformation. 1D and 2D NMR experiments have argued on the presence of the title compound in DMSO-d6 solution mostly as keto tautomer in syn conformation, and enol-imino form when considering o-vanillin residue.","PeriodicalId":9922,"journal":{"name":"Chemistry Journal of Moldova","volume":"40 3","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139188811","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}
The reaction mechanism of several Williamson‟s ether syntheses have been studied using density functional theory with triple-ζ basis sets. These computations show that the synthesis of geometrically-strained epoxide from deprotonated halohydrins is due to the combined effects of favourable solvation of the products, higher bond enthalpy of C-O bonds vs. C-Cl bonds and increased vibrational entropy of the epoxide vs. the original halohydrin. Examination of the pathways leading to the formation of larger cyclic ethers revealed that the experimentally-observed preference for the formation of five-atom rings over six-atom-rings is due to the preference of the intervening methylene groups for staggered conformations, which entails that the alkyl carbon in the reactant state leading to the six-atom cyclic ether is initially not properly aligned with the attacking alkoxide. Study of the competing elimination reactions further shows that during the synthesis of five-atom cyclic ethers the competing elimination reaction is strongly disfavoured due to steric effects. The temperature dependence of both reactions favours elimination over SN2 as temperature rises, though only when the alkoxide and the halogen moieties are not part of the same carbon chain.
{"title":"Computational insights into the spontaneity of epoxide formation from halohydrins and other mechanistic details of Williamson’s ether synthesis","authors":"Pedro J. Silva","doi":"10.19261/cjm.2023.1083","DOIUrl":"https://doi.org/10.19261/cjm.2023.1083","url":null,"abstract":"The reaction mechanism of several Williamson‟s ether syntheses have been studied using density functional theory with triple-ζ basis sets. These computations show that the synthesis of geometrically-strained epoxide from deprotonated halohydrins is due to the combined effects of favourable solvation of the products, higher bond enthalpy of C-O bonds vs. C-Cl bonds and increased vibrational entropy of the epoxide vs. the original halohydrin. Examination of the pathways leading to the formation of larger cyclic ethers revealed that the experimentally-observed preference for the formation of five-atom rings over six-atom-rings is due to the preference of the intervening methylene groups for staggered conformations, which entails that the alkyl carbon in the reactant state leading to the six-atom cyclic ether is initially not properly aligned with the attacking alkoxide. Study of the competing elimination reactions further shows that during the synthesis of five-atom cyclic ethers the competing elimination reaction is strongly disfavoured due to steric effects. The temperature dependence of both reactions favours elimination over SN2 as temperature rises, though only when the alkoxide and the halogen moieties are not part of the same carbon chain.","PeriodicalId":9922,"journal":{"name":"Chemistry Journal of Moldova","volume":"11 7","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139193967","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}
In this paper the process of reagent desalination of mineralized mine waters was studied. The peculiarity of mine waters in many regions of Ukraine is that, along with hardness ions, they also contain sulphates in fairly high concentrations. Therefore, the task of desalination of mineralized waters consists in effective removal of sulphates along with softening of the solution. For effective purification of water from sulphates and hardness ions, 5/6 aluminum hydroxychloride (Al2(OH)5Cl) and sodium tetrahydroxoaluminate (Na[Al(OH)4]) were used during liming. A significant increase in efficiency of the treatment process was achieved when the solution was acidified with carbon dioxide after treatment with reagents. The directions of processing of the formed sediments as part of building materials have been determined. Complex processing of the generated waste in the process of water treatment allows creating a low-waste technology for the purification of mineralized water.
{"title":"Low waste technology for mine waters treatment using lime and aluminum coagulants","authors":"I. Trus, V. Halysh, M. Tverdokhlib, M. Gomelya","doi":"10.19261/cjm.2023.1063","DOIUrl":"https://doi.org/10.19261/cjm.2023.1063","url":null,"abstract":"In this paper the process of reagent desalination of mineralized mine waters was studied. The peculiarity of mine waters in many regions of Ukraine is that, along with hardness ions, they also contain sulphates in fairly high concentrations. Therefore, the task of desalination of mineralized waters consists in effective removal of sulphates along with softening of the solution. For effective purification of water from sulphates and hardness ions, 5/6 aluminum hydroxychloride (Al2(OH)5Cl) and sodium tetrahydroxoaluminate (Na[Al(OH)4]) were used during liming. A significant increase in efficiency of the treatment process was achieved when the solution was acidified with carbon dioxide after treatment with reagents. The directions of processing of the formed sediments as part of building materials have been determined. Complex processing of the generated waste in the process of water treatment allows creating a low-waste technology for the purification of mineralized water.","PeriodicalId":9922,"journal":{"name":"Chemistry Journal of Moldova","volume":"40 1-2","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139195073","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}
The in vivo experiments show that the adenosylcobalamin cofactor in glutamate mutase and methylmalonyl-CoA mutase processes lose its dimethylbenzimidazole axial ligand before starting the enzymatic processes. Complete active space self-consistent field geometry optimization of the vitamin B12 active forms plus substrates joint models have been performed. These joint models include the adenosylcobalamin cofactor, the carboxyl negative ion model of the studied processes’ active substrates, and the histidine molecule. Partial electronic density is transferred from the highest occupied substrate molecular orbitals to the lowest unoccupied antibonding molecular orbitals, which consist of corrin ring and dimethylbenzimidazole ligand common molecular orbitals during the multi-configurational self-consistent field molecular orbital mixing process. As a result, the Co-N axial bond is permanently elongated during the complete active space self-consistent field geometry optimization until its complete rupture and until the removal of the dimethylbenzimidazole ligand from the central cobalt atom and the corrin ring is complete. The Co-N bond cleavage in the adenosylcobalamin cofactors in the studied processes is running as no energy barrier process under the influence of their active substrates and histidine molecule.
{"title":"The Co-N bond cleavage in the adenosyncobalamin cofactor in advance to glutamate mutase and methylmalonyl-CoA mutase processes","authors":"Tudor Spataru","doi":"10.19261/cjm.2023.1087","DOIUrl":"https://doi.org/10.19261/cjm.2023.1087","url":null,"abstract":"The in vivo experiments show that the adenosylcobalamin cofactor in glutamate mutase and methylmalonyl-CoA mutase processes lose its dimethylbenzimidazole axial ligand before starting the enzymatic processes. Complete active space self-consistent field geometry optimization of the vitamin B12 active forms plus substrates joint models have been performed. These joint models include the adenosylcobalamin cofactor, the carboxyl negative ion model of the studied processes’ active substrates, and the histidine molecule. Partial electronic density is transferred from the highest occupied substrate molecular orbitals to the lowest unoccupied antibonding molecular orbitals, which consist of corrin ring and dimethylbenzimidazole ligand common molecular orbitals during the multi-configurational self-consistent field molecular orbital mixing process. As a result, the Co-N axial bond is permanently elongated during the complete active space self-consistent field geometry optimization until its complete rupture and until the removal of the dimethylbenzimidazole ligand from the central cobalt atom and the corrin ring is complete. The Co-N bond cleavage in the adenosylcobalamin cofactors in the studied processes is running as no energy barrier process under the influence of their active substrates and histidine molecule.","PeriodicalId":9922,"journal":{"name":"Chemistry Journal of Moldova","volume":"18 3-4","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139191311","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：