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Adamczewska-Sowińska K, Sowiński J, Jamroz E, Bekier J. Compost from willow biomass (Salix viminalis L.) as a horticultural substrate alternative to peat in the production of vegetable transplants. Sci Rep 2022; 12:17617. [PMID: 36271107 PMCID: PMC9587216 DOI: 10.1038/s41598-022-22406-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 10/14/2022] [Indexed: 01/13/2023] Open
Abstract
Willow (Salix viminalis L.) is a species well adapted to the environment conditions of central Europe. It is mainly cultivated for energy purposes as solid fuel. In this study, an evaluation of its suitability for other purposes was made using a 4-year old short rotation coppice (SRC) willow regrowth to produce chipped biomass which was composted. Four composting methods were used: without additives (WC), with the addition of nitrogen to narrow the C:N ratio (WN), with the addition of mycelium (WPG) and with the addition of mycelium and nitrogen (WPGN). A mixture of WC and WPGN composts was also prepared at 75:25% and 50:50% by volume. Composts, different proportion (25, 50 and 75%) of peat (SM) were evaluated for suitability as a substrate for tomato and cucumber transplant production. Tomato transplants produced in the medium were prepared from mixtures of willow composts (WPGN + WC(1) and WPGN + WC(2) and these mixtures with peat (WPGN + WC(1):SM and WPGN + WC(2):SM) were characterised as having the best parameters: plant height, lateral leaf span and number of leaves. Similarly, for cucumber transplants, better growth conditions than in peat substrate were obtained in the variant WPGN + WC(1) and WPGN + WC(1):SM. The addition of nitrogen to the composted biomass positively influenced the composting process. N concentration in the substrate was too high and toxic for the growth of tomato and cucumber transplants. At the end of the tomato and cucumber experiment, the nitrate content was 1510 and 2260 mg dm-3, respectively, in the WN substrate. Similarly, the high N-NO3- content in the composted willow substrate with the addition of nitrogen and mycelium did not promote the growth of tomato and cucumber. Based on this research at least 25% of the mass of the peat can be replaced by different willow composts without having an adverse impact on seedling growth and with some of the willow compost mixtures this could be as high as 50%.
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Affiliation(s)
- Katarzyna Adamczewska-Sowińska
- grid.411200.60000 0001 0694 6014Department of Horticulture, Wroclaw University of Environmental and Life Sciences, 50-375 Wrocław, Poland
| | - Józef Sowiński
- grid.411200.60000 0001 0694 6014Institute of Agroecology and Crop Production, Wroclaw University of Environmental and Life Sciences, 50-375 Wrocław, Poland
| | - Elżbieta Jamroz
- grid.411200.60000 0001 0694 6014Institute of Soil Sciences, Plant Nutrition and Environmental Protection, Wroclaw University of Environmental and Life Sciences, 50-375 Wrocław, Poland
| | - Jakub Bekier
- grid.411200.60000 0001 0694 6014Institute of Soil Sciences, Plant Nutrition and Environmental Protection, Wroclaw University of Environmental and Life Sciences, 50-375 Wrocław, Poland
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Zhao H, Meng B, Sun G, Lin CJ, Feng X, Sommar J. Chemistry and Isotope Fractionation of Divalent Mercury during Aqueous Reduction Mediated by Selected Oxygenated Organic Ligands. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:13376-13386. [PMID: 34520177 DOI: 10.1021/acs.est.1c03171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We have investigated the chemistry and Hg isotope fractionation during the aqueous reduction of HgII by oxalic acid, p-quinone, quinol, and anthraquinone-2,6-disulfonate (AQDS), a derivate of anthraquinone (AQ) that is found in secondary organic aerosols (SOA) and building blocks of natural organic matter (NOM). Each reaction was examined for the effects of light, pH, and dissolved O2. Using an excess of ligand, UVB photolysis of HgII was seen to follow pseudo-first-order kinetics, with the highest rate of ∼10-3 s-1 observed for AQDS and oxalic acid. Mass-dependent fractionation (MDF) occurs by the normal kinetic isotope effect (KIE). Only the oxalate ion, rather than oxalic acid, is photoreactive when present in HgC2O4, which decomposes via two separate pathways distinguishable by isotope anomalies. Upon UVB photolysis, only the reduction mediated by AQDS results in a large odd number mass-independent fractionation (odd-MIF) signified by enrichment of odd isotopes in the reactant. Consistent with the rate, MDF, and odd-MIF reported for fulvic acid, our AQDS result confirms previous assumptions that quinones control HgII reduction in NOM-rich waters. Given the magnitude of odd-MIF triggered via a radical pair mechanism and the significant rate in the presence of air, reduction of HgII by photoproducts of AQDS may help explain the positive odd-MIF observed in ambient aerosols depleted of HgII.
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Affiliation(s)
- Huifang Zhao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- School of Geography & Environmental Science, Guizhou Normal University, Guiyang 550025, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Guangyi Sun
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Che-Jen Lin
- Center for Advances in Water and Air Quality, Lamar University, Beaumont, Texas 77710, United States
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- Center for Excellence in Quaternary Science and Global Change, Chinese Academy of Sciences, Xian 710061, China
| | - Jonas Sommar
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
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Wu J, Liu Y, Zhang J, Zhou J, Liu Z, Zhang X, Qian G. A density functional theory calculation for revealing environmentally persistent free radicals generated on PbO particulate. CHEMOSPHERE 2020; 255:126910. [PMID: 32402874 DOI: 10.1016/j.chemosphere.2020.126910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 04/24/2020] [Accepted: 04/25/2020] [Indexed: 05/16/2023]
Abstract
In particulate matter, organic precursors generate environmentally persistent free radicals (EPFRs) on metal oxides and attract worldwide attentions in health risk assessment and environmental protection. For the first time, we determined characteristics and formation processes of EPFRs evolved from different organic precursors on PbO particulate. As a result, phenol resulted in phenoxyl radical at 230 °C by releasing one H atom. One Cl atom was eliminated from monochlorobenzene and 1,2-dichlorobenzene, producing phenyl and chlorobenzene radicals, respectively. The decays of these radicals had an order of chlorobenzene radical (4 d) > phenyl radical (3 d) > phenoxyl radical (2 d). Density functional theory calculations indicated that the long decay of chlorobenzene radical was contributed to the high adsorption energy of 1,2-dichlorobenzene on PbO particulate. Furthermore, chlorobenzene radical produced more reactive oxygen species than the other two radicals in oxidative-stress investigations. Therefore, 1,2-dichlorobenzene creates more persistent EPFR, which will cause more dangerous health impact. The main results of this article provide a new insight into the health risk assessment of organic and oxide-containing particulate matter.
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Affiliation(s)
- Jianzhong Wu
- MGI of Shanghai University, Xiapu Town, Xiangdong District, Pingxiang City, Jiangxi, 337022, PR China
| | - Yun Liu
- SHU Center of Green Urban Mining & Industry Ecology, School of Environmental and Chemical Engineering, Shanghai University, No. 381 Nanchen Road., Shanghai, 200444, PR China
| | - Jia Zhang
- MGI of Shanghai University, Xiapu Town, Xiangdong District, Pingxiang City, Jiangxi, 337022, PR China; SHU Center of Green Urban Mining & Industry Ecology, School of Environmental and Chemical Engineering, Shanghai University, No. 381 Nanchen Road., Shanghai, 200444, PR China.
| | - Jizhi Zhou
- MGI of Shanghai University, Xiapu Town, Xiangdong District, Pingxiang City, Jiangxi, 337022, PR China
| | - Zixing Liu
- SHU Center of Green Urban Mining & Industry Ecology, School of Environmental and Chemical Engineering, Shanghai University, No. 381 Nanchen Road., Shanghai, 200444, PR China
| | - Xing Zhang
- SHU Center of Green Urban Mining & Industry Ecology, School of Environmental and Chemical Engineering, Shanghai University, No. 381 Nanchen Road., Shanghai, 200444, PR China
| | - Guangren Qian
- MGI of Shanghai University, Xiapu Town, Xiangdong District, Pingxiang City, Jiangxi, 337022, PR China; SHU Center of Green Urban Mining & Industry Ecology, School of Environmental and Chemical Engineering, Shanghai University, No. 381 Nanchen Road., Shanghai, 200444, PR China
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Pospíšilová L, Horáková E, Fišera M, Jerzykiewicz M, Menšík L. Effect of selected organic materials on soil humic acids chemical properties. ENVIRONMENTAL RESEARCH 2020; 187:109663. [PMID: 32474305 DOI: 10.1016/j.envres.2020.109663] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 04/28/2020] [Accepted: 05/03/2020] [Indexed: 06/11/2023]
Abstract
Environmental friendly agricultural management has an urgent need for finding a sustainable strategy for the usage of different by-products from bioenergy production. These are either used as soil amendments or fertilizers. This study is aimed at evaluating if and how soil organic matter changes after the application of biochar, compost, and digestate. A pot experiment was conducted with Haplic Cambisol (low range arable soil) in Phytotron CLF PlantMaster (Wertingen, Germany). The chemical composition of isolated humic acids (HA) was determined by an inductively coupled plasma-mass spectrometer (ICP-MS). FT-IR spectroscopy and CHNS analysis were used for detailed chemical and optical characterization. Soil magnetic properties - radical concentration, g-parameters of radicals, and iron ions were evaluated by EPR spectroscopy. The results showed that amending arable soil with biochar, digestate and compost results in chemical and structural changes of humic substances. The radicals originated in biochar and digestate are built-in to the structure of the humic acid, which was confirmed by EPR g-parameter values. Despite a relatively high concentration of paramagnetic metal ions Fe and Mn the effect of semiquinone radical quenching was not observed. That suggests a conclusion that metal ions of studied amendments are binding in HA structure and did not disturb natural radical processes in the soil. It was also concluded that the effect of applied material depends mainly on its chemical properties and the soil type.
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Affiliation(s)
- Lubica Pospíšilová
- Mendel University in Brno, Faculty of AgriSciences, Department of Agrochemistry, Soil Science, Microbiology and Plant Nutrients, Zemědělská 1, 613 00, Brno, Czech Republic.
| | - Eva Horáková
- Mendel University in Brno, Faculty of AgriSciences, Department of Agrochemistry, Soil Science, Microbiology and Plant Nutrients, Zemědělská 1, 613 00, Brno, Czech Republic
| | - Miroslav Fišera
- College of Business and Hotel Management, Institute of Gastronomy, Bosonožská 9, 625 00, Brno, Czech Republic
| | - Maria Jerzykiewicz
- Wroclaw University Faculty of Chemistry, Wroclaw, F. Joliot-Curie 14, 50-383, Wrocław, Poland
| | - Ladislav Menšík
- Crop Research Institute, Division of Crop Management Systems, Drnovská 507/73, 161 06, Praha 6-Ruzyně, Czech Republic
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Boguta P, Sokołowska Z. Zinc Binding to Fulvic acids: Assessing the Impact of pH, Metal Concentrations and Chemical Properties of Fulvic Acids on the Mechanism and Stability of Formed Soluble Complexes. Molecules 2020; 25:E1297. [PMID: 32178414 PMCID: PMC7144464 DOI: 10.3390/molecules25061297] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 03/06/2020] [Accepted: 03/09/2020] [Indexed: 11/17/2022] Open
Abstract
The aim of the study was defined as a complementary analysis of molecular interactions between zinc (Zn) and fulvic acids (FAs) at a broad pH range (3-7), different metal concentrations (0-50 mg dm-3) and chemical properties of FAs and their impact on the Zn binding mechanism, stability, and efficiency. The results showed that the complexation reaction prevailed at pH 6 and 7, whereas protons exchange dominated interactions at pH 3. Stability constant of the complexes increased along with pH (logK increased from ~3.8 to 4.2). Complexation was preferred by less-humidified structures of lower molecular mass containing more oxygen groups. The number of fluorophores available for Zn(II) increased from pH 3 to 7 by ~44%. Depending on the pH, complexation involved a bidentate chelate, monodentate and bidentate bridging mode. Zn(II) binding was insufficiently modeled by the classic Stern-Volmer equation and well described by the double logarithmic equation (R > 0.94) as well as by a modified Stern-Volmer formula assuming the existence of available and unavailable fluorophore populations (R > 0.98). The fluorescence ratio of different fluorophores was proposed as an indicator of the binding affinity of various structures. A positive relationship was found between the fraction of accessible fluorophores and Zn(II) binding at pH 7 determined based on proton release (R = 0.91-0.97). The obtained results can find application in controlling the mobility and bioavailability of Zn in different conditions.
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Affiliation(s)
- Patrycja Boguta
- Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland;
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Durak R, Bednarski W, Formela-Luboińska M, Woźniak A, Borowiak-Sobkowiak B, Durak T, Dembczyński R, Morkunas I. Defense responses of Thuja orientalis to infestation of anholocyclic species aphid Cinara tujafilina. JOURNAL OF PLANT PHYSIOLOGY 2019; 232:160-170. [PMID: 30537603 DOI: 10.1016/j.jplph.2018.11.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Revised: 11/18/2018] [Accepted: 11/19/2018] [Indexed: 05/20/2023]
Abstract
The aim of this study was to determine an interdependence between generation of semiquinone radicals, superoxide anion (O2-), manganese ions (Mn2+) and phenolic content in leaves of Thuja orientalis in response to infestation by varying populations of Cinara tujafilina, i.e. 40 or 80 aphids per plant. Also, superoxide dismutase (SOD) and β-d-glucosidase activities in leaves of T. orientalis in a defense response to C. tujafilina was recorded. Analyses of electron paramagnetic resonance (EPR) showed generally a higher concentration of semiquinone radicals with g-values of 2.0051 ± 0.0005 and 20032 ± 0.0005 after C. tujafilina infestation in leaves in comparison to the control. Up to 48 h post-infestation in leaves infested by 80 aphids the level of semiquinone radicals was significantly higher than in the control, while in leaves infested by 40 aphids the highest concentrations of these radicals were recorded at later time points (i.e. at 72 and 96 hpi). In parallel, the highest total generation of O2- and low activity of SOD were recorded in 24-h leaves infested by 80 aphids. Additionally, analysis of confocal images showed that the strongest yellow fluorescence indicating O2- generation was detected in epidermal cells of leaves up to 48 hpi. Significant reduction of Mn2+ ions detected by EPR spectroscopy in relation to the control was observed in 4-w leaves infested by 80 and 40 aphids and in 48-h leaves infested by 40 aphids. Phenolic contents in leaves infested by 80 and 40 aphids at all time points were higher than in the control. The greatest β-d-glucosidase activity and phenolic contents were recorded at 96 h of feeding. These results indicate that the perception of C. tujafilina infestation by T. orientalis leaves induces a specified sequence of defense mechanisms in the course of time.
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Affiliation(s)
- Roma Durak
- Department of Experimental Zoology, University of Rzeszów, Pigonia 1, 35-310, Rzeszów, Poland
| | - Waldemar Bednarski
- Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznań, Poland
| | - Magda Formela-Luboińska
- Department of Plant Physiology, Poznań University of Life Sciences, Wołyńska 35, 60-637 Poznań, Poland
| | - Agnieszka Woźniak
- Department of Plant Physiology, Poznań University of Life Sciences, Wołyńska 35, 60-637 Poznań, Poland
| | - Beata Borowiak-Sobkowiak
- Department of Entomology and Environmental Protection, Poznań University of Life Sciences, Dąbrowskiego 159, 60-594 Poznań, Poland
| | - Tomasz Durak
- Department of Plant Physiology and Ecology, University of Rzeszów, Rejtana 16c, 35-959, Rzeszów, Poland
| | - Radosław Dembczyński
- Department of Biotechnology and Food Microbiology, Poznań University of Life Sciences, Wojska Polskiego 48, 60-627 Poznan, Poland
| | - Iwona Morkunas
- Department of Plant Physiology, Poznań University of Life Sciences, Wołyńska 35, 60-637 Poznań, Poland.
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Ćwieląg-Piasecka I, Witwicki M, Jerzykiewicz M, Jezierska J. Can Carbamates Undergo Radical Oxidation in the Soil Environment? A Case Study on Carbaryl and Carbofuran. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:14124-14134. [PMID: 29171253 DOI: 10.1021/acs.est.7b03386] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Radical oxidation of carbamate insecticides, namely carbaryl and carbofuran, was investigated with spectroscopic (electron paramagnetic resonance [EPR] and UV-vis) and theoretical (density functional theory [DFT] and ab initio orbital-optimized spin-component scaled MP2 [OO-SCS-MP2]) methods. The two carbamates were subjected to reaction with •OH, persistent DPPH• and galvinoxyl radical, as well as indigenous radicals of humic acids. The influence of fulvic acids on carbamate oxidation was also tested. The results obtained with EPR and UV-vis spectroscopy indicate that carbamates can undergo direct reactions with various radical species, oxidizing themselves into radicals in the process. Hence, they are prone to participate in the prolongation step of the radical chain reactions occurring in the soil environment. Theoretical calculations revealed that from the thermodynamic point of view hydrogen atom transfer is the preferred mechanism in the reactions of the two carbamates with the radicals. The activity of carbofuran was determined experimentally (using pseudo-first-order kinetics) and theoretically to be noticeably higher in comparison with carbaryl and comparable with gallic acid. The findings of this study suggest that the radicals present in soil can play an important role in natural remediation mechanisms of carbamates.
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Affiliation(s)
- Irmina Ćwieląg-Piasecka
- Institute of Soil Science and Environmental Protection, Wroclaw University of Environmental and Life Sciences , Grunwaldzka 53 St., Wroclaw, Poland
| | - Maciej Witwicki
- Faculty of Chemistry, Wroclaw University , 14 F. Joliot-Curie St., 50-383 Wroclaw, Poland
| | - Maria Jerzykiewicz
- Faculty of Chemistry, Wroclaw University , 14 F. Joliot-Curie St., 50-383 Wroclaw, Poland
| | - Julia Jezierska
- Faculty of Chemistry, Wroclaw University , 14 F. Joliot-Curie St., 50-383 Wroclaw, Poland
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Tadini AM, Nicolodelli G, Mounier S, Montes CR, Milori DMBP. The importance of humin in soil characterisation: A study on Amazonian soils using different fluorescence techniques. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 537:152-158. [PMID: 26282749 DOI: 10.1016/j.scitotenv.2015.07.125] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 07/24/2015] [Accepted: 07/25/2015] [Indexed: 06/04/2023]
Abstract
Soil organic matter (SOM) is a complex mixture of molecules with different physicochemical properties, with humic substances (HS) being the main component as it represents around 20-50% of SOM structure. Soil of the Amazon region is considered one of the larger carbon pools of the world; thus, studies of the humic fractions are important for understanding the dynamics of organic matter (OM) in these soils. The aim of this study was to use laser-induced fluorescence spectroscopy (LIFS) and a combination of excitation-emission matrix (EEM) fluorescence with Parallel Factor Analysis (CP/PARAFAC) to assess the characteristics of humin (HU) extracted from Amazonian soils. The results obtained using LIFS showed that there was an increasing gradient of humification degree with depth, the deeper horizon presenting a higher amount of aromatic groups in the structure of HU. From the EEM, the contribution of two fluorophores with similar behaviour in the structures of HU and whole soil was assessed. Additionally, the results showed that the HU fraction might represent a larger fraction of SOM than previously thought: about 80-93% of some Amazon soils. Therefore, HU is an important humic fraction, thus indicating its role in environmental analysis, mainly in soil analysis.
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Affiliation(s)
- Amanda Maria Tadini
- Embrapa Agricultural Instrumentation, São Carlos, SP, Brazil; Institute of Chemistry of São Carlos, University of São Paulo, São Carlos, SP, Brazil.
| | | | - Stephane Mounier
- Laboratoire PROTEE, EA3819, Université de Toulon, CS 60584, 83041 Toulon CEDEX 9, France
| | - Célia Regina Montes
- Centro de Energia Nuclear na Agricultura and NUPEGEL, University of São Paulo, Piracicaba, SP, Brazil
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Jerzykiewicz M, Witwicki M, Jezierska J. pH-dependent formation of Hg(II)-semiquinone complexes from natural phenols. CHEMOSPHERE 2015; 138:233-238. [PMID: 26086808 DOI: 10.1016/j.chemosphere.2015.06.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 04/20/2015] [Accepted: 06/02/2015] [Indexed: 06/04/2023]
Abstract
The ability of various natural phenols to form Hg(II)-semiquinone complexes was tested in the pH range of 2.8-12. EPR experiments performed at 9.6 and 34 GHz (the X- and Q-band, respectively) revealed that the complexes formed at low and high pH values exhibit a significant dissimilarity between their g-matrices (g-tensors), strongly suggesting that the complexes differ structurally. Our previous investigation on the low pH complex (Chemosphere 2015, 119, 479-484) had shown the Hg(II) ion to be tetracoordinated by two ligands, one of the ligands being monoprotonated with the unpaired electron mainly located on it. In order to reveal the molecular structure of the high pH form a DFT-based theoretical analysis was carried out in this work. For all the optimized model structures the g-matrices were computed and compared with their experimental counterparts. Good agreement was observed only if the geometry of the model Hg(II) complex was planar and the coordination sphere was composed of one fully deprotonated radical ligand and hydroxyl anions.
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Affiliation(s)
- Maria Jerzykiewicz
- Faculty of Chemistry, Wroclaw University, Joliot-Curie 14, 50-383 Wroclaw, Poland.
| | - Maciej Witwicki
- Faculty of Chemistry, Wroclaw University, Joliot-Curie 14, 50-383 Wroclaw, Poland.
| | - Julia Jezierska
- Faculty of Chemistry, Wroclaw University, Joliot-Curie 14, 50-383 Wroclaw, Poland
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Witwicki M. Theoretical Characterisation of Phosphinyl Radicals and Their Magnetic Properties: g Matrix. Chemphyschem 2015; 16:1912-25. [PMID: 25873130 DOI: 10.1002/cphc.201500121] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Indexed: 11/11/2022]
Abstract
The g matrices (g tensors) of various phosphinyl radicals (R2 P(.) ) were calculated using the DFT and multireference configuration interaction (MRCI) methods. The g matrices were distinctly dependent on the molecular structure of the radical. To thoroughly examine this dependence, the contributions from individual atoms and excited states were calculated. The former revealed the gain from the phosphorus atom to be preeminent unless PO or PS bonds are present in the radical molecule. The contributions owing to excited states arising from electronic transitions between doubly occupied molecular orbitals and the SOMO were clearly positive, as in the case of semiquinone and niroxide radicals. The transitions from the phosphorus lone pair were of paramount importance. Surprisingly, unlike for semiquinones and nitroxides, a significant negative contribution was observed from excitations from the SOMO to unoccupied molecular orbitals. For radicals with PO bonds, this contribution to the g2 component was dominant.
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Affiliation(s)
- Maciej Witwicki
- Faculty of Chemistry, Wroclaw University, 14 F. Joliot-Curie St., Wroclaw 50-283 (Poland).
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Witwicki M, Jerzykiewicz M, Ozarowski A. Understanding natural semiquinone radicals--multifrequency EPR and relativistic DFT studies of the structure of Hg(II) complexes. CHEMOSPHERE 2015; 119:479-484. [PMID: 25108678 DOI: 10.1016/j.chemosphere.2014.07.047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 07/17/2014] [Accepted: 07/19/2014] [Indexed: 06/03/2023]
Abstract
Multifrequency EPR spectroscopy and DFT calculations were used to investigate Hg(II) complexes with semiquinone radical ligands formed in a direct reaction between the metal ions and tannic acid (a polyphenol closely related to tannins). Because of the intricate structure of tannic acid a vast array of substituted phenolic compounds were tested to find a structural model mimicking its ability to react with Hg(II) ions. The components of the g matrix (the g tensor) determined from the high field (208 GHz) EPR spectra of the Hg(II) complexes with the radical ligands derived from tannic acid and from the model compounds were analogous, indicating a similar coordination mode in all the studied Hg(II) complexes. Since catechol (1,2-dihydroxybenzene) was the simplest compound undergoing the reaction with Hg(II) it was selected for DFT studies which were aimed at providing an insight into the structural properties of the investigated complexes. Various coordination numbers and different conformations and protonation states of the ligands were included in the theoretical analyses. g Matrices were computed for all the DFT optimized geometries. A good agreement between the theoretical and experimental values was observed only for the model with the Hg(II) ion tetracoordinated by two ligands, one of the ligands being monoprotonated with the unpaired electron mainly localized on it.
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Affiliation(s)
- Maciej Witwicki
- Faculty of Chemistry, Wroclaw University, Joliot-Curie 14, 50-383 Wroclaw, Poland.
| | - Maria Jerzykiewicz
- Faculty of Chemistry, Wroclaw University, Joliot-Curie 14, 50-383 Wroclaw, Poland.
| | - Andrzej Ozarowski
- National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, United States.
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Witwicki M, Jezierska J. DFT insight into o-semiquinone radicals and Ca2+ ion interaction: structure, g tensor, and stability. Theor Chem Acc 2013. [DOI: 10.1007/s00214-013-1383-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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