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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Zinc(II) Adsorption by Low-Carbon Shungite: The Effect of pH

Fischer, Axel R., Sgolik, Luisa, Kreller, André, Dornack, Christina 11 June 2018 (has links) (PDF)
Shungite is a carbonaceous rock which is abundant in Karelia (Russian Federation). Large deposits of shungite with low levels of carbon (approx. 10% C) are also found in Kazakhstan, where it is mined under the trade name Taurit (Koksu Mining Company). Although Taurit has been reported to be used as an adsorbent for hazardous compounds in water treatment, there is very little precise data about its adsorption capacity or the compounds adsorbed. In this study, the ability of Taurit to adsorb Zn(II) was investigated and Freundlich isotherms were determined for both distilled water and tap water. Taurit was found to have a high buffer capacity leading to pH values > 7.0 in aqueous solution. Because dissolved zinc precipitates as Zn(OH)2 under alkaline conditions, the pH must be carefully controlled and kept ≤7.0. Despite the small inner surface area (BET) of Taurit (13.4 m2 g−1), Freundlich coefficients for distilled water (Kf = 2.4, n = 4.0) and tap water (Kf = 1.5, n = 2.5) were similar to other adsorbents. Our results indicate that Taurit could provide a cheap alternative to activated carbon since both substances have a similar adsorption capacity (at least for Zn(II)).
12

Estudo da atividade antinoceptiva e anti-inflamatoria protótipos de fármacos / Study of antinoceptiva activity and anti-inflammatory farmacos prototypes

Bispo Júnior, Walfrido 06 March 2013 (has links)
This work was conducted to evaluate the activity anti-inflammatory and antinocieptive two series of derivatives of N-acilidrazonas (NAH) rationally designed and synthesized by LASSBio® UFRJ. The first series consists of four compounds, being two metal complexes generated from the coordination of prototypes LASSBio-1064 and LASSBio-466 and second prototype LASSBio-1064 and LASSBio-466. The second series comprised eight derivatives, designed as structural analogues of piroxicam. Were performed nociception models of functional chemical (writhing induced by acetic acid 0.1 N, formalin test), thermal nociception (hot plate test), cell migration assay (peritonitis induced by zymosan A and / or induced by carrageenin) assay evaluation of inhibition of COX-1/COX-2. All compounds and standards were administered 40 min before starting the test (p.o) at a dose of 100 mmol / kg. In the first series, Animal constriction induced by acetic acid was inhibited by all the compounds studied, highlighting the [Zn(LASSBio-466)H2O]2 and H2LASSBio-1064 that inhibited (p˂0.01) at 82.7 % (p˂0.01) and 81.3% (p˂0.01) the number of writhes, as the standard drug (dipyrone) inhibited 77.7% (p˂0.01). In the first phase of the formalin test H2LASSBio-466 and H2LASSBio-1064 reduced the latency time to lick 53.1% (p ˂ 0.05) and 46.5% (p˂0.01), respectively. In the second phase of the test compounds H2LASSBio-1064 and [Zn(LASSBio-466)H2O]2 reduced the latency time to lick at 48.5% (p˂0.05) and 37.3% (p˂0.05), respectively. All compounds showed levels of inhibition of peritonitis induced by zymosan comparable or superior to indomethacin (drug standard). In the second series, the compounds were active in the assay of writhing induced by acetic acid highlighting the LASSBio-1638, LASSBio-1604 and LASSBio-1639 inhibited the contortions that abdmoniais in 84.0% (p˂0.01), 82.7% (p˂ 0.01) and 90.4% (p˂ 0.01), respectively, whereas piroxicam (drug standard), inhibited by 95.4% (p˂0.01) . In the formalin test, only LASSBio-1617 significantly inhibited the nociceptive activity in the first stage by 58.2% (p<0.01). In the second phase the LASSBio-1637, LASSBio-1638 inhibited the nociceptive activity in 60.0% (p<0.05) and 54.2% (p<0.05), respectively, and piroxicam inhibited 53.9 % (p<0.01). In models of acute inflammation, the compounds showed inhibitory activity against cell migration similar to or greater than the piroxicam. In the trial of carrageenan-induced acute peritonitis compounds LASSBio-1604LASSBio-1637, LASSBio-1638 and LASSBio-1639 inhibited cell migration by 74.2% (p˂ 0.01), 73.2% (p˂0.01), 77.6% (p˂ 0.01) and 81.8% (p ˂ 0.01), respectively, where as piroxicam inhibited by 25.5% (p˂0.01). The compounds LASSBio-1637, LASSBio-1638-1639 and LASSBio highlighted in the testing of acute peritonitis induced by zymosan A, inhibiting cell migration in 78.6% (p˂0.01), 81.2% (p ˂ 0.01) and 82.7% (p ˂ 0.01), showing that, in this essay, more active than piroxicam (57.3%). LASSBio-1604 and LASSBio-1617 inhibited the enzyme COX in vitro, presenting, respectively, IC50 values of 0.22 M and 0.28 M for inhibition of COX-1 and 0.24 M and 0.26 M for inhibition of COX-2. Pharmacological Evaluation results suggest that in the first series, the coordination of zinc (II) is a good strategy to improve the antinociceptive activity of the compound H2LASSBio-466 associated with inflammatory pain, and in the second series, all compounds exhibit antinociceptive and anti-inflammatory similar or superior to piroxicam. / Neste trabalho foi realizado a avaliação da atividade antinocieptiva e anti-inflamatória de duas séries de derivados N-acilidrazonas (NAH) racionalmente planejadas e sintetizados pelo LASSBio® da UFRJ. A primeira serie é formada de 4 compostos, sendo 2 complexos metálicos gerados a partir da coordenação dos protótipos LASSBio-466 e LASSBio-1064 e 2 protótipos LASSBio-466 e LASSBio-1064. A segunda série formada por 8 derivados, desenhados como análogos estruturais do piroxicam. Foram realizados modelos funcionais de nocicepção química (contorção abdominal induzida por ácido acético 0,1N, ensaio de formalina), nocicepção térmica (ensaio da placa quente), ensaio de migração celular (peritonite induzido por zymosan A e/ou induzido por carragenina) ensaio de avaliação de inibição da COX-1/COX-2. Todos os compostos e padrões foram administrados 40 min antes do início ensaio (vo) na dose de 100 μmol/kg. Na primeira série, a constrição animal induzida por ácido acético foi inibida por todos os compostos estudados, destacando-se o [Zn(LASSBio-466)H2O]2 e H2LASSBio-1064 que inibiram (p˂0,01) em 82,7% (p˂0,01) e 81,3% (p˂0,01) o numero de contorções, enquanto o fármaco-padrão (dipirona) inibiu em 77,7% (p˂0,01). Na primeira fase do ensaio de formalina o H2LASSBio-1064 e H2LASSBio-466 reduziram o tempo de latência de lambida em 53,1% (p˂0,05) e 46,5% p˂0,01), respectivamente. Já na segunda fase do ensaio os compostos H2LASSBio-1064 e [Zn(LASSBio-466) H2O]2 reduziram o tempo de latência de lambida em em 48,5% (p˂0,05) e 37,3% (p˂0,05), respectivamente. Todos os compostos mostraram níveis de inibição da peritonite induzida por zymosan comparáveis ou superiores à indometacina (fármaco padrão). Na segunda série, os compostos mostraram-se ativas no ensaio de contorções abdominais induzida por acido acético destacando-se o LASSBio-1638, LASSBio-1639 e LASSBio-1604 que inibiram as contorções abdmoniais em 84,0% (p˂0,01), 82,7% (p˂0,01) e 90,4% (p˂0,01), respectivamente, ao passo que o piroxicam (fármaco padrão) inibiu em 95,4% (p˂0,01). No teste de formalina, apenas LASSBio-1617 inibiu significativamente a atividade nociceptiva na primeira fase em 58,2% (p <0,01). Na segunda fase o LASSBio-1637, LASSBio-1638 inibiram a atividade nociceptiva em 60,0% (p <0,05), e 54,2% (p <0,05), respectivamente, e o piroxicam inibiu em 53,9% (p <0,01). Em modelos de inflamação aguda, os compostos apresentaram atividade inibitória sobre a migração celular semelhante ou maior que o piroxicam. No ensaio de peritonite aguda induzida por carragenina os compostos LASSBio-1604, LASSBio-1637, LASSBio-1638 e LASSBio-1639 inibiram a migração celular em 74,2% (p˂0,01), 73,2% (p˂0,01), 77,6% (p˂0,01) e 81,8% (p˂0,01), respectivamente, ao passo que o piroxicam inibiu 25,5% (p˂0,01). Os compostos LASSBio-1637, LASSBio-1638 e LASSBio-1639 destacaram-se no ensaio de peritonite aguda induzida por zymosan A, inibindo a migração celular em 78,6% (p˂0,01), 81,2% (p˂0,01) e 82,7% (p˂0,01), mostrando-se, nesse ensaio, mais ativos que o piroxicam (57,3%). LASSBio-1604 e LASSBio-1617 inibiram a enzima COX in vitro, apresentando, respectivamente, valores de CI50 de 0,22 M e 0,28 M para inibição de COX-1 e 0,24 M e 0,26 M para inibição de COX-2. Os resultados da avaliação farmacológica sugerem que, na primeira série, a coordenação do zinco (II) é uma boa estratégia para melhorar a atividade antinociceptiva do composto H2LASSBio-466 associada a dor inflamatória, e na segunda série, que todos compostos apresentam atividades antinociceptiva e anti-inflamatória semelhantes ou superiores ao piroxicam.
13

Zinc(II) Adsorption by Low-Carbon Shungite: The Effect of pH

Fischer, Axel R., Sgolik, Luisa, Kreller, André, Dornack, Christina 11 June 2018 (has links)
Shungite is a carbonaceous rock which is abundant in Karelia (Russian Federation). Large deposits of shungite with low levels of carbon (approx. 10% C) are also found in Kazakhstan, where it is mined under the trade name Taurit (Koksu Mining Company). Although Taurit has been reported to be used as an adsorbent for hazardous compounds in water treatment, there is very little precise data about its adsorption capacity or the compounds adsorbed. In this study, the ability of Taurit to adsorb Zn(II) was investigated and Freundlich isotherms were determined for both distilled water and tap water. Taurit was found to have a high buffer capacity leading to pH values > 7.0 in aqueous solution. Because dissolved zinc precipitates as Zn(OH)2 under alkaline conditions, the pH must be carefully controlled and kept ≤7.0. Despite the small inner surface area (BET) of Taurit (13.4 m2 g−1), Freundlich coefficients for distilled water (Kf = 2.4, n = 4.0) and tap water (Kf = 1.5, n = 2.5) were similar to other adsorbents. Our results indicate that Taurit could provide a cheap alternative to activated carbon since both substances have a similar adsorption capacity (at least for Zn(II)).
14

Chemistry of a new trispyrazolylborate ligand with some group 1 group 2 ions

Yaman, Gülşah 07 January 2008 (has links)
No description available.
15

Phase transformation and surface chemistry of secondary iron minerals formed from acid mine drainage

Jönsson, Jörgen January 2003 (has links)
The mining of sulphidic ore to extract metals such as zinc and copper produces huge quantities of waste material. The weathering and oxidation of the waste produces what is commonly known as Acid Mine Drainage (AMD), a dilute sulphuric acid rich in Fe(II) and heavy metals. This thesis serves to summarise five papers reporting how the precipitation of Fe(III) phases can attenuate the contamination of heavy metals by adsorption processes. Schwertmannite (Fe8O8(OH)6SO4) is a common Fe(III) mineral precipitating in AMD environments at pH 3-4. The stability and surface chemistry of this mineral was investigated. It was shown that the stability depended strongly on pH and temperature, an increase in either promoted transformation to goethite (α-FeOOH). Two pH dependent surface species of SO42- were detected with infrared (ATR-FTIR) spectroscopy. The adsorption of Cu(II), Pb(II) and Zn(II) to schwertmannite occurred at lower pH than to goethite, whereas Cd(II) adsorption occurred in a similar pH range on both schwertmannite and goethite. Extended x-ray absorption fine structure (EXAFS) spectroscopy suggests two surface species for Cu(II) and Cd(II) at the schwertmannite surface. Cu(II) adsorbs monodentately and Cd(II) bridging bidentately to adsorbed SO42-. Both metal ions also adsorb in a bridging bidentate mode to the surface hydroxyl groups. At pH 7.5 up to 2.7 μmol Cd(II) m-2 could be adsorbed to schwertmannite, indicating a large adsorption capacity for this mineral. The acid-base properties of two NOM samples were characterised and could be well described as diprotic acids below pH 6. The adsorption of NOM to schwertmannite and goethite was very similar and adsorption occured in a very wide pH range. High concentrations of NOM increased the adsorption of Cu(II) to goethite at low pH whereas a slight decrease was noted at low concentrations of NOM. No effect was detected in the schwertmannite system. The formation of Fe(III) phases from precipitation of AMD was shown to be very pH dependent. At pH 5.5 a mixture of minerals, including schwertmannite, formed whereas at pH 7 only lepidocrocite (γ-FeOOH) formed. The concentration of Zn(II) in AMD could by adsorption/coprecipitation be reduced to environmentally acceptable levels.
16

Phase transformation and surface chemistry of secondary iron minerals formed from acid mine drainage

Jönsson, Jörgen January 2003 (has links)
<p>The mining of sulphidic ore to extract metals such as zinc and copper produces huge quantities of waste material. The weathering and oxidation of the waste produces what is commonly known as Acid Mine Drainage (AMD), a dilute sulphuric acid rich in Fe(II) and heavy metals. This thesis serves to summarise five papers reporting how the precipitation of Fe(III) phases can attenuate the contamination of heavy metals by adsorption processes. </p><p>Schwertmannite (Fe8O8(OH)6SO4) is a common Fe(III) mineral precipitating in AMD environments at pH 3-4. The stability and surface chemistry of this mineral was investigated. It was shown that the stability depended strongly on pH and temperature, an increase in either promoted transformation to goethite (α-FeOOH). Two pH dependent surface species of SO42- were detected with infrared (ATR-FTIR) spectroscopy.</p><p>The adsorption of Cu(II), Pb(II) and Zn(II) to schwertmannite occurred at lower pH than to goethite, whereas Cd(II) adsorption occurred in a similar pH range on both schwertmannite and goethite. Extended x-ray absorption fine structure (EXAFS) spectroscopy suggests two surface species for Cu(II) and Cd(II) at the schwertmannite surface. Cu(II) adsorbs monodentately and Cd(II) bridging bidentately to adsorbed SO42-. Both metal ions also adsorb in a bridging bidentate mode to the surface hydroxyl groups. At pH 7.5 up to 2.7 μmol Cd(II) m-2 could be adsorbed to schwertmannite, indicating a large adsorption capacity for this mineral.</p><p>The acid-base properties of two NOM samples were characterised and could be well described as diprotic acids below pH 6. The adsorption of NOM to schwertmannite and goethite was very similar and adsorption occured in a very wide pH range.</p><p>High concentrations of NOM increased the adsorption of Cu(II) to goethite at low pH whereas a slight decrease was noted at low concentrations of NOM. No effect was detected in the schwertmannite system. </p><p>The formation of Fe(III) phases from precipitation of AMD was shown to be very pH dependent. At pH 5.5 a mixture of minerals, including schwertmannite, formed whereas at pH 7 only lepidocrocite (γ-FeOOH) formed. The concentration of Zn(II) in AMD could by adsorption/coprecipitation be reduced to environmentally acceptable levels.</p>
17

Porphyrin-based [3]- and [4]rotaxanes : towards an adaptable molecular receptor / [3]- et [4]rotaxanes à base de porphyrines : vers un récepteur moléculaire adaptable

Roche, Cécile 20 April 2012 (has links)
La synthèse et l'étude de rotaxanes et de porphyrines sont deux domaines particulièrement actifs de la recherche en chimie. Cependant, les composés combinant les propriétés intéressantes de ces deux types de structures sont plus rares. De nouveaux multi-rotaxanes à base de porphyrines, dont la préparation représente un défi synthétique, sont décrits dans cette thèse.Des porphyrines liées à deux ou quatre anneaux coordinants ont été synthétisées. Des rails moléculaires à deux chélates ont été enfilés dans les anneaux grâce à l'effet template du cuivre(I); l'introduction de bouchons a mené à la formation de rotaxanes. Dans le cas du bis-macrocycle porphyrinique, un [4]rotaxane a été obtenu. Des études de complexation hôte/invité avec des ligands azotés rigides ont montré que ce rotaxane est un récepteur moléculaire qui peut s'adapter à la taille du substrat invité en se "gonflant" ou en se "dégonflant".Dans le cas du tétra-macrocycle porphyrinique, la formation d'un [3]rotaxane d'architecture originale a étéobservée.La synthèse d'un nouveau bis-macrocycle plus rigide est en cours. Ce composé sera utilisé pour la construction d'un [4]rotaxane, qui pourrait montrer un caractère de presse moléculaire capable de modifier la conformation d'un substrat invité en le comprimant. / Rotaxanes and porphyrins are two particularly active fields of research in chemistry. However,molecules that combine the interesting properties of these types of structures are not so common. In this thesis we describe new porphyrin-based multi-rotaxanes, whose syntheses constitute interesting challenges.Porphyrins linked to two or four coordinating macrocycles were synthesised. The "gathering-andthreading" effect of copper(I) was used to thread molecular rods through the rings; the subsequent introduction of stoppers led to the formation of rotaxanes. In the case of the porphyrinic bis-macrocycle a [4]rotaxane was obtained. Host/guest complexation studies with rigid nitrogen ligands showed that the rotaxane behaves as a distensible molecular receptor that can adopt an "inflated" or "deflated" conformation and adjust its shape to the size of the guest. In the case of the porphyrinic tetra-macrocycle the formation of a [3]rotaxane of novel architecture was observed.The synthesis of a new, more rigid bis-macrocycle is in progress. This compound will be used for the construction of a [4]rotaxane that could act as a molecular press able to change the conformation of a guest substrate by compression.
18

Avaliação da concentração de metais pesados (Zn, Cd, Pb e Cu) em água de chuva visando sua aplicação como fonte alternativa de água potável na cidade de Juiz de Fora/MG

Cerqueira, Marcos Rodrigues Facchini 02 March 2012 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-07-07T12:40:57Z No. of bitstreams: 1 marcosrodriguesfacchinicerqueira.pdf: 4104766 bytes, checksum: a30bb0a2c3edae3f0d744732482aa070 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-08T13:31:42Z (GMT) No. of bitstreams: 1 marcosrodriguesfacchinicerqueira.pdf: 4104766 bytes, checksum: a30bb0a2c3edae3f0d744732482aa070 (MD5) / Made available in DSpace on 2016-07-08T13:31:42Z (GMT). No. of bitstreams: 1 marcosrodriguesfacchinicerqueira.pdf: 4104766 bytes, checksum: a30bb0a2c3edae3f0d744732482aa070 (MD5) Previous issue date: 2012-03-02 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Muitas pessoas sofrem da falta crônica de água potável para necessidades pessoais e, nesse contexto, a água de chuva surge como uma possível fonte alternativa. Em cima disso, foi proposto um método simples e efetivo para a determinação de cobre(II), cádmio(II), zinco(II) e chumbo(II) em 64 amostras de água de chuva de Juiz de Fora/MG/Brasil utilizando a técnica de redissolução potenciométrica. Um potenciostato μ-AUTOLAB foi utilizado para a aquisição dos dados e a célula eletroquímica consistia de um eletrodo de trabalho de carbono vítreo modificado com filme de mercúrio, um eletrodo de Ag/AgCl(sat) como eletrodo de referência e um de eletrodo de platina como eletrodo auxiliar. Foi realizada uma avaliação do pH do meio variando de 0-3 para uma determinação simultânea de Cd, Pb e Cu e de 0-6 para a determinação de Zn. Um Planejamento Estrela 22 foi realizado para a otimização das condições eletroquímicas das determinações. Para as determinações de Cd, Pb e Cu foram estudados níveis entre -1,06 e -0,64 V para o potencial de deposição (Ed), com tempo de deposição (td) entre 239 s e 662 s. Para a determinação de Zn os níveis estudados para o Ed foram entre -1,70 V e -1,10 V, com td entre 239 s e 662 s. A condição ótima encontrada para o pH do meio foi de pH = 4 para a determinação de Zn e um pH = 0 para a determinação de Cd, Pb e Cu. De acordo com as superfícies de resposta obtidas, foi estipulado para a determinação de Zn um Ed = -1,40 V e um td = 300 s e para a determinação de Cd, Pb e Cu um Ed = -1,00 V e um td = 300 s. Foram construídas curvas analíticas para verificar a linearidade do método. Os limites de detecção e quantificação foram de 1,26 e 3,83 μg L-1 para Zn, 0,38 e 1,26 μg L-1 para Cd, 0,41 e 1,36 μg L-1 para Pb e 0,96 e 3,20 μg L-1 para Cu, respectivamente. O método mostrou valores de recuperação entre 86 e 113%. As amostras de água de chuva também foram analisadas por espectroscopia de absorção atômica em forno de grafite (GFAAS), como método de referência, demonstrando uma boa correlação entre os resultados. Foram encontrados valores entre 3,93 e 13,8 μg L-1 de Zn, 3,11 e 7,51 μg L-1 de Cu, enquanto que nenhuma concentração significativa foi observada para Pb e Cd. Conforme os valores estipulados na Portaria nº 2914, de 12 de dezembro de 2011, do Ministério da Saúde, a água de chuva da região de Juiz de Fora pode ser considerada como potável com relação os parâmetros avaliados. / Many people suffer from a chronicle lack of potable water for their personal needs and, in this context, the rainwater arises as a possible alternative source. Upon this, an effective and simple method to determine copper(II), cadmium(II), zinc(II) and lead(II) in 64 rainwater samples from Juiz de Fora/MG/Brazil, using potentiometric stripping analysis (PSA), is proposed. A μ-AUTOLAB potentiostat was used for data acquisition and the electrochemical cell consisted of a working glassy carbon electrode modified with a thin mercury film, an Ag/AgCl(sat) as reference electrode and a platinum as auxiliary electrode. The pH of the medium was evaluated in the range of 0-3 for the simultaneous determination of Cd, Pb and Cu, and in the range of 0-6 for Zn. A 22 Star Design was run to optimize the analytical conditions. For Cd, Pb and Cu determination the studied levels for deposition potential (Ed) were between -1.06 V and -0.64 V, with deposition time (td) between 239 s and 662 s. For Zn determination the studied levels for Ed were between -1.70 V and -1.10 V, with td between 239 s and 662 s. The optimum medium pH conditions found were of pH = 4 for Zn determination and pH = 0 for Cd, Pb and Cu determination. According to the obtained response surfaces it was stipulated for Zn determination a Ed = -1.40 V and a td = 300 s and for Cu, Pb and Cd determination a Ed = -1.00 V and a td = 300 s. Analytical curves were constructed to verify the method linearity. The detection and quantification limits were of 1.26 and 3.83 μg L-1 for Zn, 0.378 and 1.26 μg L-1 for Cd, 0.407 and 1.36 μg L-1 for Pb and 0.960 and 3.20 μg L-1 for Cu, respectively. The method showed recovery values between 86 and 113%. The rainwater samples were also analyzed by graphite furnace atomic absorption spectrometry (GFAAS), as reference method, showing a good correlation between the results. Values between 3.93 and 13.8 μg L-1 of Zn, 3.11 and 7.51 μg L-1 of Cu were found, while no significant concentrations of Pb and Cd were found. According to the stipulated values on Portaria nº 2914, of december 12 of 2011, from Ministério da Saúde, the Juiz de Fora region rainwater can be considered potable, with respect to the evaluated parameters.
19

Kompleksi nekih prelaznih metala sa Šifovim bazama aminogvanidina / Some transition metal complexes with Schiff bases of aminoguanidine

Radanović Mirjana 29 October 2015 (has links)
<p>&nbsp;&nbsp; U ovoj doktorskoj disertaciji opisane su sinteze novih kompleksa prelaznih metala sa piridoksiliden-&nbsp; (PLAG), odnosno saliciliden-aminogvanidinom (SALAG). Dobijeni<br />kompleksi su okarakterisani elementalnom analizom, IR spektrima, konduktometrijskim i magnetnim merenjima, a većina i rendgenskom<br />strukturnom analizom. Osim toga, dobijene su i nove forme ovih &Scaron;ifovih baza, i to u vidu monokristala, čime su omogućena ispitivanja njihovih&nbsp; molekulskih i kristalnih struktura, kao i uporedna analiza sa koordinovanim ligandima.<br />&nbsp; &nbsp; Sa PLAG je sintetisano 7 novi&nbsp; kompleksa Cu(II), a pored toga po prvi put su<br />izolovani mono i bis(ligand) kompleksi Fe(III) i Co(III), mono(ligand) kompleksi&nbsp; V(V), kao&nbsp; i jedan kompleks Zn(II) u kojem ovaj potencijalno tridentatni&nbsp;<em> ONN&nbsp;</em> ligand,&nbsp; u<br />monoprotonovanoj formi,&nbsp; ima ulogu kontra-jona. Sa stanovi&scaron;ta geometrije zajedničko za izolovane komplekse Cu(II) i V(V) je da imaju kvadratno-piramidalnu strukturu, sa izuzetkom jednog kvadratno-planarnog kompleksa Cu(II), dok je u kompleksima Fe(III) i Co(III) nađeno očekivano oktaedarsko okruženje centralnog<br />jona. Pored ovih, sintetisano je i pet novih kompleksa sa SALAG, od kojih su dva<br />kompleksa Cu(II) i kompleks V(V) okarakterisani rendgenskom strukturnom<br />analizom, dok je mikrokristalnim bis(ligand) kompleksima Co(III) i Ni(III) na osnovu<br />fizičko-hemijskih karakteristika predložena odgovarajuća struktura.<br />&nbsp;&nbsp; Zajedničko za obe opisane &Scaron;ifove baze je da se koordinuju na&nbsp;<em> ONN&nbsp; </em>tridentatni način, i to preko atoma kiseonika deprotonovane fenolne grupe i atoma azota azometinske i imino grupe AG fragmeta. Posebno je nagla&scaron;eno da su&nbsp; sa<br />PLAG izolovana dva dimerna kompleksa Cu(II) u kojima je po prvi put nađena tetradentatna koordinacija ovog&nbsp; liganda, u koju je dodatno uključen atom kiseonika hidroksimetil-grupe PL-ostatka. Za razliku od SALAG, koji je u izolovanim kompleksima koordinovan isključivo kao monoanjon, nastao deprotonacijom fenolne<br />OH-grupe, za PLAG je osim ove, potvđena koordinacija u neutralnoj, zwitter-jonskoj, ali i dvostruko deprotonovanoj formi. Zwitter-jonska forma liganda nastaje migracijom atoma vodonika sa fenolnog hidroksila na piridinski atom azota PL-ostatka, dok deprotonacijom piridinskog ili hidrazinskog atoma azota, odnosno oba pomenuta atoma nastaju monoanjon i dianjon helatnog liganda, respektivno.<br />&nbsp;&nbsp; Na kraju, urađena su&nbsp; i ispitivanja antimikrobne aktivnosti odabranih jedinjenja<br />prema predstavnicima grampozitivnih i gramnegativnih bakterija, kao i dve kulture<br />kvasca. Tom prilikom nije utvrđena nikakva inhibitorna aktivnost&nbsp;&nbsp; prema primenjenim<br />bakterijskim sojevima, dok su u slučaju kvasaca izvesno mikrobicidno dejstvo pokazali samo kompleksi Cu(II).</p> / <p>This PhD thesis describes the syntheses of some new transition metal complexes with&nbsp; pyridoxilidene-&nbsp; (PLAG) and salicylideneaminoguanidine (SALAG). Obtained&nbsp; complexes are characterized by&nbsp;&nbsp; elemental analysis, IR&nbsp; spectroscopy,&nbsp; conductometric and magnetic measurements. Besides, the structural analysis of majority of the obtained complexes was performed. Some new forms of these Schiff&nbsp; bases are synthesized in form of single crystals, which made their X-ray analysis as well as comparison with coordinated forms possible.</p><p>With PLAG, 7 new Cu(II) complexes were obtained and for the first time mono and bis(ligand) complexes of Fe(III) and Co(III) as well&nbsp; mono(ligand)&nbsp; complexes&nbsp; of V(V) were isolated. Furthermore,&nbsp; the structure of Zn(II) complex in which PLAG in its monocationic form has a role of counter ion is presented. With the exception of one Cu(II) complex, all reported Cu(II) and V(V) complexes have a square-pyramidal geometry, whilst&nbsp; Fe(III)&nbsp; and Co(III)&nbsp; are situated in octahedral surroundings. Also, five new complexes of Cu(II), Co(III), Ni(II) and V(V) with SALAG were synthesized. In both&nbsp; Cu(II) complexes and V(V) complex the expected coordination mode and geometry were confirmed by X-ray analysis, while octahedral structure of bis(ligand) complexes with Co(III) and Ni(II) was proposed based on results of physico-chemical&nbsp; characterization.</p><p>Both PLAG and SALAG coordinate the metal ion in tridentate&nbsp; ONN&nbsp; manner, through the oxygen atom of deprotonated phenolic group and nitrogen atoms&nbsp; of azomethine and imino groups of AG moiety. It is also emphasized that in two dimeric Cu(II) complexes with PLAG tetradentate coordination mode was found, in which the oxygen atom of hydroxymethyl group of PL residue was additionally involved. Unlike SALAG, which is coordinated as monoanion in all of the examined complexes, PLAG can have one of three degrees of deprotonation. Zwitter-ion of PLAG is formed by migration of H-atom from phenolic oxygen to pyridine nitrogen, while the deprotonation of pyridine or/and hydrazine nitrogen, makes it mono-and dianion, respectively.</p><p>Also, microbiological tests on the selected compounds were preformed. Namely, antimicrobial activity of these compounds against some gram-positive and gram-negative bacteria, as well as some yeast cultures was examined and none of the samples showed antimicrobial activity against bacteria, whilst only Cu(II) complexes showed certain inhibitory effect against yeasts.</p>
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Σύμπλοκες ενώσεις του ψευδαργύρου με υποκατεστημένα βενζοτριαζόλια ως υποκαταστάτες : σύνθεση, χαρακτηρισμός και συσχέτισή τους με την αναστολή της διάβρωσης του μετάλλου / Complexes of zinc with substituted benzotriazoles as ligands : synthesis, characterization and their relevance to the corrosion inhibition of the metal

Μπαρούνη, Ελευθερία 15 February 2012 (has links)
Η προστασία των μετάλλων με δραστικές ενώσεις που έχουν τη δυαντότητα σχηματισμού επιφανειακών ενώσεων εντάξεως είναι ένας κλάδος της Χημείας και της Επιστήμης των Υλικών μεγάλης επιστημονικής, αρχαιολογικής και τεχνολογικής σημασίας. Οι αντιδιαβρωτικές ιδιότητες του βενζοτριαζολίου και μικρού αριθμού υποκατεστημένων βενζοτριαζολίων για ορισμένα μέταλλα, ειδικά του χαλκού και των κραμάτων του, έχουν προσελκύσει το ενδιαφέρον για τη χημεία ένταξης του βενζοτριαζολίου και της συζυγούς του βάσεως, του βενζοτριαζολάτο ανιόντος. Έχουμε ξεκινήσει ένα ανόργανο μοντέλο προσέγγισης της παρεμπόδισης της διάβρωσης του Zn με βενζοτριαζόλια. Στην παρούσα εργασία έχουμε μελετήσει λεπτομερώς τη χημεία ένταξης του 1-μεθυλοβενζοτριαζολίου (Mebta) με Zn(II). Παρασκευάσθηκαν τα νέα σύμπλοκα [ZnCl2(Mebta)2](1), [ZnBr2 (Mebta)2](2), [ZnI2(Mebta)2](3), τετ-[Zn(ΝΟ3)2(Mebta)2](4), οκτ-[Zn(ΝΟ3)2(Mebta)2] (5), [Zn(Mebta)4](ClO4)2(6), [Zn(Mebta)4](PF6)2(7) και [Zn3(Ο2CPh)6(Mebta)2](8). Οι μοριακές και κρυσταλλικές δομές των συμπλόκων έχουν προσδιορισθεί με κρυσταλλογραφία ακτίνων-Χ μονοκρυστάλλου. Η γεωμετρία ένταξης του ZnΙΙ στα 1-4, 6 και 7 είναι τετραεδρική, ενώ στο σύμπλοκο 5 το μεταλλοϊόν έχει παραμορφωμένη οκταεδρική στερεοχημεία. Τα μεταλλικά κέντρα στο 8 υιοθετούν τετραεδρικές και οκταεδρικές γεωμετρίες. Το Mebta συμπεριφέρεται στα σύμπλοκα ως μονοδοντικός υποκαταστάτης με το άτομο δότης να είναι το άζωτο της θέσης 3 του αζολικού δακτυλίου. Τα σύμπλοκα χαρακτηρίσθηκαν με φασματοσκοπία IR. Τα δεδομένα συσχετίζονται με τον τρόπο ένταξης των υποκαταστατών και τις γνωστές δομές. Επίσης αναλύεται η τεχνολογική σημασία των αποτελεσμάτων μας. Φαίνεται ότι τα Ν-υποκατεστημένα βενζοτριαζόλια με ομάδες που δεν περιέχουν άτομα δότες δεν μπορεί να οδηγήσουν σε αποτελεσματικούς παρεμποδιστές της διάβρωσης εξ’αιτίας της αδυνμίας αυτών των μορίων να σχηματίζουν πολυμερικά είδη. / Protection of metals with reactive compounds capable of forming surface-phase coordination compounds is an area of chemistry and materials science which is of considerable scientific, archaeological and technological importance. The anticorrosion properties of benzotriazole and few substituted benzotriazoles towards certain metals, particularly copper and its alloys, have focused interest on the coordination chemistry of the parent molecule and its conjugate base, the benzotriazolate anion An inorganic model approach to the corrosion inhibition of Zn by benzotriazoles has been initiated. The coordination chemistry of 1-methylbenzotriazole (Mebta) with Zn(II) has been studied in detail. The new complexes [ZnCl2(Mebta)2](1), [ZnBr2 (Mebta)2](2), [ZnI2(Mebta)2](3), tet-[Zn(ΝΟ3)2(Mebta)2](4), οkt-[Zn(ΝΟ3)2(Mebta)2](5), [Zn(Mebta)4](ClO4)2(6), [Zn(Mebta)4](PF6)2(7) and [Zn3(Ο2CPh)6(Mebta)2](8) have been prepared. Their molecular and crystal structures have been determined by single crystal, X-ray crystallography. The coordination geometry of ZnII in 1-4, 6 and 7 is tetrahedral, while complex 5 has a distorted octahedral stereochemistry. The metal sites in 8 adopt both tetrahedral and octahedral geometries. Mebta behaves as a monodentate ligand in the complexes; the donor atom is nitrogen of the position 3 of the azole ring. The complexes were characterized by IR spectroscopy; the data are discussed in terms of the coordination modes of the ligands and known structures. The technological relevance of our results is also discussed. It seems that benzotriazole N-substitution with groups containing no donor atoms cannot lead to effective corrosion inhibitors due to the inability of these molecules to form polymeric species.

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