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Synthesis and photophysical properties of dansyl-based polyamine ligands and their Zn(II) complexes

Parola, A. Jorge; Lima, João Carlos; Pina, Fernando; Pina, João; Melo, João Seixas de; Soriano, Conxa; García-España, Enrique; Aucejo, Ricardo; Alarcón, Javier
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
Português
Relevância na Pesquisa
36.44%
The synthesis, potentiometric studies and photophysical properties of two new polyamine ligands (L1 and L2) possessing the dansyl chromophore were studied in aqueous 0.15 M NaCl. The compounds show the absorption and emissions bands characteristic of the dansylamide fluorophore and both present intramolecular excited state proton transfer at intermediate pH ranges. One of the ligands (L2) strongly coordinates Zn(II) leading to fluorescence quenching. A model compound (L3) of the dansyl moiety was also investigated.; http://www.sciencedirect.com/science/article/B6TG5-4MB4DV1-2/1/45cafbcee9a8df7daddd765512437ca3

Nickel sorption capacity of ground xylem of Quercus ilex trees and effects of selected ligands present in the xylem sap

ARAUJO, Georgia C. L.; LEMOS, Sherlan G.; NABAIS, Cristina
Fonte: ELSEVIER GMBH, URBAN & FISCHER VERLAG Publicador: ELSEVIER GMBH, URBAN & FISCHER VERLAG
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.52%
In this work the influence of four different ligands present in the xylem sap of Quercus ilex (histidine, citric, oxalic and aspartic acids) on Ni(II) adsorption by xylem was investigated. Grinded xylem was trapped in acrylic columns and solutions of Ni(II), in the absence and presence of the four ligands prepared in KNO(3) 0-1 mol L(-1) at pH 5.5, were percolated through the column. Aliquots of solutions were recovered in the column end for Ni determination by graphite furnace atomic absorption spectrometry (GFAAS). The experimental. data to describe Ni sorption by xylem in both the presence and absence of ligands was better explained by the Freundlich isotherm model. The decreasing affinity order of ligands for Ni was: oxalic acid > citric acid > histidine > aspartic acid. On the other hand, the Ni(II) adsorption by xylem increased following the inverse sequence of ligands. Potentiometric titrations of acidic groups were carried out to elucidate the sorption site groups available in Q. ilex xylem. The potentiometric titration has shown three sorption sites: pK(a) 2.6 (57.7% of the sorption sites), related to monobasic aliphatic carboxylic acids or nitrogen aromatic bases, pK(a) 8.1 (9.6%) and pK(a) 9.9 (32.7%), related to phenolic groups. (C) 2008 Elsevier GmbH. All rights reserved.; Fundacao para a Ciencia e Tecnologia (FCT) (Portugal)[POCTI/1999/MGS/35653]

Insights into the Molecular Requirements for the Anti-obesity Activity of a Series of CB1 Ligands

WEBER, Karen C.; LIMA, Emmanuela F. de; MELLO, Paula H. de; SILVA, Alberico B. F. da; HONORIO, Kathia M.
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.44%
Two-dimensional and 3D quantitative structure-activity relationships studies were performed on a series of diarylpyridines that acts as cannabinoid receptor ligands by means of hologram quantitative structure-activity relationships and comparative molecular field analysis methods. The quantitative structure-activity relationships models were built using a data set of 52 CB1 ligands that can be used as anti-obesity agents. Significant correlation coefficients (hologram quantitative structure-activity relationships: r 2 = 0.91, q 2 = 0.78; comparative molecular field analysis: r 2 = 0.98, q 2 = 0.77) were obtained, indicating the potential of these 2D and 3D models for untested compounds. The models were then used to predict the potency of an external test set, and the predicted (calculated) values are in good agreement with the experimental results. The final quantitative structure-activity relationships models, along with the information obtained from 2D contribution maps and 3D contour maps, obtained in this study are useful tools for the design of novel CB1 ligands with improved anti-obesity potency.; FAPESP (The State of Sao Paulo Research Foundation); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); CNPq (The National Council for Scientific and Technological Development); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); CAPES (Coordination for the Improvement of High Education Personnel)...

Interações dos receptores nucleares com seus ligantes: Estudos estruturais do receptor de hormônio tireoidiano, do receptor de mineralocorticóide e do receptor ativado por proliferadores peroxissomais; Interaction of the nuclear receptors with its ligands: Structural studies of the thyroid hormone receptor, mineralocorticoid receptor and peroxisome proliferator-activated receptor

Nascimento, Alessandro Silva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 06/03/2009 Português
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Os receptores nucleares constituem uma superfamília de fatores de transcrição regulados pela interação com hormônios. Esta superfamília inclui, por exemplo, os receptores de hormônio tireoidiano, estrogênio, androgênio, glicocorticóide e mineralocorticóide. Neste trabalho, empregamos técnicas de biologia estrutura e bioinformática para estudar as interações entre alguns dos membros da família de receptores nucleares e seus respectivos ligantes. Para o receptor de hormônio tireoidiano, foi demonstrado, através da análise das estruturas cristalográficas das duas isoformas do receptor ligados aos tiromimético Triac, que os componentes entálpicos visíveis nas estruturas não explicam a seletividade do ligante. Dados de dinâmica molecular confirmaram que a seletividade do hormônio tem um importante componente entrópico. Empregando a técnica de dinâmica molecular, estudamos a ligação do receptor de mineralocorticóide humano à aldosterona, ao cortisol, à espironolactona e à cortisona e simulamos ainda o efeito da mutação S810L, conhecida por converter a atividade antagonista da cortisona e da espironolactona em agonista. A análise das simulações revelou um perfil de ligações de hidrogênio similar na ligação do receptor selvagem ao cortisol e à aldosterona. A cortisona perde...

Aplicação de complexos de CuII, NiII, ZnII e NbV com ligantes carboxilatos em banhos de eletrodeposição; Application of CuII, NiII, ZnII and NbV complexes with carboxilates ligands for electroplating baths

Silva, Mariana Beatriz dos Reis
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 23/02/2010 Português
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Complexos de coordenação de Cu(II), Ni(II), Zn(II) e Nb(V) foram obtidos com os íons acetato, citrato e oxalato como ligantes (complexos ex-situ) para serem aplicados em banhos de eletrodeposição. O objetivo é usar estes complexos como fontes de metais sem adição de aditivos os quais são os ligantes que estão coordenados. Como estudos de referência, foram investigados banhos de eletrodeposição contendo sais de sulfatos dos íons metálicos na presença de ligantes nas razões metal:ligante de 10:1 e 1:5; assim, complexos de coordenações similares podem ser gerados em solução (complexos in-situ). Os complexos ex-situ foram analisados por análise elementar, espectroscopias nas regiões do infravermelho e ultravioleta-visível e voltametria cíclica (em Pt). As eletrólises foram realizadas em substrato de aço 1020 com um ou dois complexos metálicos presentes no banho. Banhos de eletrodeposição de nióbio usando como substrato aço 1020 coberto com Cu e/ou Zn foram bem sucedidos. Os depósitos foram analisados por microscopia eletrônica de varredura (MEV), espectroscopia de dispersão de raios X (EDX), reflectância difusa, espectroscopia de difração de raios X (DRX) e por curvas de polarização anódica (estudos de corrosão). Os banhos com complexos in-situ 10:1 fomeceram depósitos com aspectos morfológicos ruins em relação aos depósitos obtidos de banhos com complexos in-situ 1:5 e ex-situ. As morfologias dos depósitos obtidos dos banhos com acetato foram dendríticos e com baixa aderência. Os depósitos dos banhos com complexos citrato e oxalato foram lisos...

Estudo de interação de Hg(II) com ligantes heterogêneos de ocorrência natural usando voltametria de redissolução anódica automatizada em sistema de análise por injeção sequencial; Interaction of Hg (II) with heterogeneous naturally occurring ligands studied by anodic stripping voltammetry automated by sequential injection analysis

Nascimento, Fernando Henrique do
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/05/2012 Português
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36.48%
Dentre as espécies químicas metálicas responsáveis pela contaminação do meio aquático, mercúrio e outros compostos mercuriais têm recebido atenção especial devido a sua alta toxicidade. Os ligantes de ocorrência natural formam complexos com íons de Hg2+, influenciando a sua biodisponibilidade. Em meio a esses ligantes, dá-se destaque aos ligantes heterogêneos de ocorrência natural (LHON), tais como substâncias húmicas e argilominerais, por sua elevada capacidade de adsorção/complexação com íons metálicos. Entre as técnicas existentes para a determinação de Hg(II), as voltamétricas, em especial a voltametria de redissolução anódica, ganham destaque devido as características que as tornam mais adequadas para estudos envolvendo interações entre LHON e Hg(II), tais como alta sensibilidade e mínima manipulação da amostra. Uma estratégia para se evitar os problemas causados pela passivação do eletrodo de trabalho por adsorção de matéria orgânica, bem como para se aumentar a robustez da técnica, é a mecanização da análise em sistema de análise por injeção sequencial (SIA). Baseando-se neste contexto, este trabalho teve por objetivo o desenvolvimento de um sistema SIA com detecção voltamétrica...

Aminas acíclicas como ligantes ancilares em catalisadores de rutênio para polimerização via metátese de olefinas cíclicas; Acyclic amines as ancillary ligands in ruthenium catalysts for ring opening metathesis polymerization

Silva, Tiago Breve da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/02/2012 Português
Relevância na Pesquisa
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As moléculas à base de nitrogênio, NH2Ph, NH2CH2Ph e NHnBuPh foram investigadas como ligantes ancilares nos novos complexos do tipo [RuCl2 (PPh3)2 (amina) x] para a polimerização via metátese por abertura de anel (ROMP) de norborneno (NBE), norbornadieno (NBD) e diciclopentadieno (DCPD). Os complexos foram obtidos da síntese com [RuCl2 (PPh3)3] com as respectivas moléculas. E eles foram caracterizados por análise elementar de CHN, FT-IR, RMN 31P{1H}, Espectroscopia eletrônica na região do uv-vis e voltametria cíclica. Os complexos isolados foram hexacoordenados (x = 2) com NH2Ph e NH2CH2Ph, e pentacoordenado com NHnBuPh (x = 1). Além disso, os resultados sugerem que todos os ligantes estão trans-posicionados no caso do complexo com NH2Ph (complex 1) e cis no caso do complexo com NH2CH2Ph (complex 2). O complexo com NHnBuPh ( complex 3) e sugerido estar na geometria pirâmide de base quadrada, com a amina no eixo axial. Quantitativos rendimentos foram obtidos na ROMP de NBE a 50°C com 1 por 30 min e com 2 por 5 minutos. Similar resultado foi obtido com 3 at 25°C por 5 min. O valor de Mw foram na faixa de 104 e 105 g/mol,com valores de IPD entre 1,6 e 3,5. Os valores de σc foram em torno de 0,40 a 0,52. ROMP de NBE e DCPD...

Asymmetric hydrogenation of alkenes with cationic iridium(I) complexes of 2-phosphino-1-aminoferrocene ligands

Van Belle, Lori
Fonte: Brock University Publicador: Brock University
Tipo: Electronic Thesis or Dissertation
Português
Relevância na Pesquisa
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Iridium complexes with bidentate P,N ligands represent a class of catalysts that significantly expand the application range of asymmetric hydrogenation. New substrate classes, for which there have previously been no suitable catalysts, can now be efficiently hydrogenated in high conversion and enantioselectivity. These substrates are often of synthetic importance, thus iridium catalysis represents a significant advance in the field of asymmetric catalysis. Planar chiral ferrocenyl aminophosphine ligands in which both heteroatoms were directly bound to the cyclopentadienyl ring were prepared by BF3-activated lithiationsubstitution in the presence of a chiral diamine in 49-59% yield and 75-85% enantiomeric excess. Some of these ligands were recrystallized to enantiomeric purity via ammonium fluoroborate salt formation of the phosphine sulfide. A crystal structure of one of these compounds was obtained and features an intramolecular hydrogen bond between the nitrogen, hydrogen, and sulfur atoms. Neutralization, followed by desulfurization, provided the free ligands in enantiomeric purity. Iridium complexes with these ligands were formed via reaction with [Ir(COD)Clh followed by anion exchange with NaBArF. These complexes were successfully applied in homogeneous hydrogenation of several prochiral substrates...

Identification and specificity studies of small-molecule ligands for SH3 protein domains

Inglis, S.; Stojkoski, C.; Branson, K.; Cawthray, J.; Fritz, D.; Wiadrowski, E.; Pyke, S.; Booker, G.
Fonte: Amer Chemical Soc Publicador: Amer Chemical Soc
Tipo: Artigo de Revista Científica
Publicado em //2004 Português
Relevância na Pesquisa
36.48%
The Src Homology 3 (SH3) domains are small protein-protein interaction domains that bind proline-rich sequences and mediate a wide range of cell-signaling and other important biological processes. Since deregulated signaling pathways form the basis of many human diseases, the SH3 domains have been attractive targets for novel therapeutics. High-affinity ligands for SH3 domains have been designed; however, these have all been peptide-based and no examples of entirely nonpeptide SH3 ligands have previously been reported. Using the mouse Tec Kinase SH3 domain as a model system for structure-based ligand design, we have identified several simple heterocyclic compounds that selectively bind to the Tec SH3 domain. Using a combination of nuclear magnetic resonance chemical shift perturbation, structure-activity relationships, and site-directed mutagenesis, the binding of these compounds at the proline-rich peptide-binding site has been characterized. The most potent of these, 2-aminoquinoline, bound with Kd = 125 μM and was able to compete for binding with a proline-rich peptide. Synthesis of 6-substitued-2-aminoquinolines resulted in ligands with up to 6-fold improved affinity over 2-aminoquinoline and enhanced specificity for the Tec SH3 domain. Therefore...

Development of small-molecule ligands for SH3 protein domains.

Inglis, Steven Robert
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado Formato: 450061 bytes; 2711228 bytes; 1708026 bytes; 1188101 bytes; application/pdf; application/pdf; application/pdf; application/pdf
Publicado em //2005 Português
Relevância na Pesquisa
36.48%
Src Homology 3 (SH3) domains are small protein- protein interaction domains that bind to proline-rich peptides, mediating a range of important biological processes. Because the deregulation of events involving SH3 domains forms the basis of many human diseases, the SH3 domains are appealing targets for the development of potential therapeutics. Previously in the field, no examples of entirely small-molecule ligands for the SH3 domains have been identified. However, in our research group, we have discovered a class of heterocyclic compounds that bind to the Tec SH3 domain at conserved residues in the proline-rich peptide binding site, with weak to moderate affinity. The highest affinity of these was 2- aminoquinoline (Kd = 125 mM). In this thesis, a range of approaches are described, that were intended to contribute towards development of higher affinity small-molecule ligands for the Tec SH3 domain. Preliminary experiments, involving testing a variety of compounds structurally related to 2- aminoquinoline, provided new structure activity information, and led to a better understanding of the 2-aminoquinoline/SH3 domain binding event. The major component of this thesis is a thorough investigation into the synthesis of a range of 2- aminoquinoline derivatives. N-Substituted- 2-aminoquinolines were synthesised...

Autoimmune regulator deficiency results in decreased expression of CCR4 and CCR7 ligands and in delayed migration of CD4⁺ Thymocytes; Autoimmune regulator deficiency results in decreased expression of CCR4 and CCR7 ligands and in delayed migration of CD4(+) thymocytes

Laan, M.; Kisand, K.; Kont, V.; Moll, K.; Tserel, L.; Scott, H.; Peterson, P.
Fonte: Amer Assoc Immunologists Publicador: Amer Assoc Immunologists
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
Relevância na Pesquisa
36.57%
Autoimmune regulator (Aire) has been viewed as a central player in the induction of tolerance. This study examines whether Aire can modulate the production of the thymic chemokines involved in corticomedullary migration and thus play a role in intrathymic thymocyte migration and maturation. Aire deficiency resulted in reduced gene expression and protein levels of the CCR4 and CCR7 ligands in whole thymi of mice, as determined by quantitative PCR analysis and ELISA. The expression of the CCR4 ligands coincided with Aire expression in the CD80(high) medullary thymic epithelial cells, whereas the expression of the CCR7 ligands was detected in other cell populations. Also, the expression pattern of the CCR4 and CCR7 ligands follows that of Aire during postnatal but not during embryonic development. In vitro, overexpression of Aire resulted in an up-regulation of selected CCR4 and CCR7 ligands, which induced selective migration of double-positive and single-positive CD4(+) cells. In vivo, Aire deficiency resulted in a diminished emigration of mature CD4(+) T cells from the thymi of 5-day-old mice. In conclusion, Aire regulates the production of CCR4 and CCR7 ligands in medullary thymic epithelial cells and alters the coordinated maturation and migration of thymocytes. These results suggest a novel mechanism behind the Aire-dependent induction of central tolerance.; Martti Laan...

Synthesis and coordination chemistry of polypyridyl amide ligands.

Abdul Kadir, Maisara
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2012 Português
Relevância na Pesquisa
36.7%
This thesis provides an account of the synthesis and study of fifteen amide-containing polypyridyl ligands, eleven of which are new compounds. These ligands all possess at least one amide moiety, potentially capable of anion binding and one or more pendant pyridyl donor groups as the metal coordinating sites. A further evolution over previously reported compounds is that a majority of the amide compounds incorporate a pre-organised amide component that will constitute the anion binding region. The alkyl and phenyl spacers were utilised to confer flexibility to these compounds and to extend the spacing between the anion binding moiety and the pendant metal complexing groups. The compounds investigated in this work are divided into three categories; (i) unsymmetrical monoamide ligands that possess one amide functional group, one ester protected carboxylate and one external donor pyridyl moiety; (ii) symmetrical flexible amide ligands that possess two or more internal amide groups and two external pyridyl metal coordinating sites, and; (iii) symmetrical amide bridging ligands that incorporate two di-2-pyridylmethylamine chelating motifs. The coordination chemistry and metallo-supramolecular chemistry of these ligands was investigated with a range of late transition metals including cadmium(II)...

Charakterisierung von MHC-I-Liganden zum Einsatz in der patienten-individuellen Immuntherapie des Nierenzellkarzinoms; Characterization of MHC-I-Ligands for patient-individual immunotherapy of renal cell carcinoma (RCC)

Krämer, Björn
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
Relevância na Pesquisa
36.48%
Das Nierenzellkarzinom (RCC) stellt durch seine weitgehende Resistenz gegenüber Strahlen- und Chemotherapie und seine oftmals späte Entdeckung einen therapeutisch schwer zu beeinflussenden Tumor dar. Schwerpunkt dieser Arbeit ist die Isolierung und Identifizierung möglicher Tumor-assoziierter Peptide aus Nierenzellkarzinomen zum Einsatz in der Patienten-individuellen Immuntherapie. Darüberhinaus wurde ein quantitatives ELISA-Verfahren zur Quantifizierung von MHC-I-Molekülen in Tumorlysaten etabliert und mit quantitativen Untersuchungen aus Western-Blot und Edman-Abbau verglichen. Im Rahmen dieser Arbeit gelang es mit Hilfe eines kombinierten Ansatzes aus massenspektrometrischer Analyse und Genexpressionsuntersuchung, aus über 350 gefundenen HLA-Liganden eine Reihe neuer, Tumor-assoziierter Peptide aus dem RCC zu identifizieren. Erstmals konnten dabei auch weit über 100 Peptide aus einer einzelnen Tumorprobe identifiziert werden. So kamen neu identifizierte Liganden aus RGS5, IGFBP3, USH1C und ADFP in der Vakzinierung von RCC-Patienten zum Einsatz. Darüberhinaus gelang der Nachweis des ersten natürlich vorkommenden Liganden aus MAGED4 im RCC. Das etablierte ELISA-Verfahren zeigte Übereinstimmung hinsichtlich quantitativer Tendenzen gegenüber Western-Blot und Edman-Abbau und stellte sich zur Messung von Lysaten als günstige Ergänzung heraus. Keines der quantitativen Verfahren vermag bislang absolut verlässliche Messwerte zu erzeugen...

Investigação comparativa da liberação controlada de CO e NO por carboxilatos trinucleares de rutênio contendo ligantes pi-receptor e sigma-doador; Comparative investigation of the controlled release of CO and NO by ruthenium trinuclear carboxylates containing pi-receptor ligands and sigma-donor

Silva, Camila Fontes Neves da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 23/02/2015 Português
Relevância na Pesquisa
36.52%
Neste trabalho foram realizadas as sínteses e caracterizações dos precursores (1) [Ru3O(CH3COO)6(CH3OH)3]CH3COO, (2) [Ru3O(CH3COO)6(CO)(CH3OH)2] (3) [Ru3O(CH3COO)6(4-acpy)2(H2O)]PF6, (4) [Ru3O(CH3COO)6(4-tbpy)2(H2O)]PF6 e dos complexos inéditos (5) [Ru3O(CH3COO)6(4-acpy)2(CO)], (6) [Ru3O(CH3COO)6(4-tbpy)2(CO)], (7) [Ru3O(CH3COO)6(4-acpy)2(NO)]PF6, (8) [Ru3O(CH3COO)6(4-tbpy)2(NO)]PF6. Os complexos foram caracterizados por espectroscopia na região do UV-Vis e do infravermelho, espectroscopia de ressonância magnética nuclear (RMN), voltametria cíclica e análise elementar. Por meio dos resultados obtidos nas técnicas de caracterização, foi possível confirmar a estrutura proposta inicialmente para os complexos e também para os precursores. Além disso, também foi possível observar a influência dos ligantes, -receptor e -doador na estrutura dos mesmos. Por meio da técnica de espectroscopia de infravermelho analisou-se principalmente estiramentos dos ligantes CO nos complexos 5 e 6 e do NO nos complexos 7 e 8. Nos estudos de RMN observou-se as características diamagnéticas dos complexos 5 e 6, e no caso dos complexos 7 e 8 foi possível confirmar que há uma forte interação entre o elétron desemparelhado na unidade [Ru3O]+ e do ligante NO0. Os ensaios eletroquímicos de voltametria cíclica mostraram a influência dos ligantes CO e NO na comunicação eletrônica da unidade [Ru3O].Os complexos com ligantes CO e NO foram irradiados com laser em 377 nm e 660 nm em soluções de acetonitrila e tampão fosfato pH 7...

The Synthesis and Coordination Chemistry of Two Families of Polydentate Ligands - Exploring Their Potential for the Preparation of Molecule-Based Magnets

ZARRABI, NILOOFAR
Fonte: Brock University Publicador: Brock University
Português
Relevância na Pesquisa
36.62%
The synthesis and studies of two classes of poly dentate ligands are presented as two projects. In project 1, four new carboxamide ligands have been synthesised via the condensation of 2,2',6,6'-tetrachloroformyl-4,4'-bipyridine or 2,6-dichloroformyl pyridine together with heterocyclic amines containing pyridine or pyrazole substituents. The coordination chemistry of these ligands has been investigated and studies have shown that with a Cu(II) salt, two carboxamide ligands LJ and L2 afford large clusters with stoichiometries [Cu8(L1)4Cl16].CHCl3.5H2O.7CH3OH (I) and [Cu9(L2)6Cl6].CH3OH.5H2O.(C2H5)3N (II) respectively. [molecular diagram availabel in pdf]. X-ray diffraction studies of cluster (I) reveal that it has approximate S4 symmetry and is comprised of four ligands and eight copper (II) centers. Here, coordination takes place via amide 0 atoms, and pyrazole nitrogens. This complex is the first reported example of an octanuclear copper cluster with a saddle-shaped structure. The second cluster comprises nine copper ions that are arranged in a cyclic array. Each ligand coordinates three copper centers and each copper ion shares two ligands to connect six ligands with nine copper ions. The amide nitrogens are completely deprotonated and both amide Nand 0 atoms coordinate the metal centres. The cluster has three-fold symmetry. There are six chloride ions...

LUMINESCENT TRANSITION METAL COMPLEXES OF 2-(2’-PYRIDYL)BENZIMIDAZOLYL AND 2-(2’-PYRIDYL)INDOLYL BASED LIGANDS AND THEIR APPLICATIONS

McCormick, Theresa
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 8117821 bytes; application/pdf
Português
Relevância na Pesquisa
36.64%
The objective of this thesis is to examine the photophysical and structural properties of Cu(I) complexes of 2-(2’-pyridyl)benzimidazolyl based ligands and Cu(I), Pd(II) and Pt(II) complexes of 2-(2’-pyridyl)indolyl based ligands, for possible use as phosphorescent emitters in OLEDs. The discovery of the atropisomeric 3,3’-bis(2-(2’-pyridyl)indolyl based ligands led to the examination of C-C coupling reactions and the investigation of the new chiral ligands with transition metal ions. Cu(I) complexes of 2-(2’pyridyl)benzimidazolyl-benzene with varying phosphine ligands were prepared. The structures were studied with X-ray crystallography and NMR. Experimental and computational results established that steric and electronic properties of the phosphine ligands influence the photophysical properties of the Cu(I) complexes. Polynuclear Cu(I) complexes with 2-(2’-pyridyl)benzimidazolyl based ligands and two PPh3 ancillary ligands were synthesized, the photoluminescent and electroluminescent properties were examined. A series of 2-(2’-pyridyl)indolyl based ligands; 2-(2’-pyridyl)indolyl-benzene (pib), 1,4-bis[2-(2’-pyridyl)indolyl]benzene (bib) and 1,3,5-tris[2-(2’-pyridyl)indolyl]benzene) (tib) and the corresponding C-C coupled dimers bis[3...

Inorganic self-assembly through sequential complexation in the formation of bimetallic and trimetallic architectures from multisite ligands based on 5,5'-disubstituted 2,2'-bipyridines

Machado,Vanderlei G.; Mangrich,Antonio S.; Lehn,Jean-Marie
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2003 Português
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Two multisite 5,5'-disubstituted 2,2'-bipyridine ligands containing N-methyl hydroxamic acids as substituents [5,5'-bis(N-methylhydroxamic)-2,2'-bipyridine (4) and 5-methyl-5'-(N-methylhydroxamic)-2,2-bipyridine (10)] were synthesized. These ligands were used in order to illustrate the strategy of self-assembly through sequential complexation. According to this concept, the first metal added organizes the ligands disposed in 5,5'-positions to accomodate the second metal ion that is sequentially added. Thus, addition of Fe2+ to a solution of 4 led to a Fe2+-tris(bipyridine) complex. Addition of Fe3+ to this solution yielded a trimetallic architecture, which was characterized. Ligand 10 yielded a mixture of bimetallic architectures through complexation with Fe2+ followed by Fe3+ ions. However, if the order of metal addition is changed, only one bimetallic complex is obtained. This is due to the fact that the first metal ion added (Fe3+) acts as a template, organizing the bipyridine ligands and preforming an adequate cavity for the Fe2+ ion.

Ligandos multivalentes con residuos de tioazúcares. Síntesis y actividad biológica; Multivalent ligands bearing thiosugars. Synthesis and biological activity

Cagnoni, Alejandro J.
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2013 Português
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Las interacciones específicas entre hidratos de carbono y proteínas regulan una gran diversidad de fenómenos biológicos, puesto que desencadenan numerosos procesos de transferencia de información. Para lograr interacciones de alta afinidad, la Naturaleza ha diseñado biomoléculas que presentan múltiples copias de un determinado residuo oligosacarídico, que actúa como elemento de reconocimiento de una proteína. Esto conlleva al efecto cluster glicosídico o efecto multivalente, en el cual la afinidad del proceso global resulta mucho mayor que la simple suma de las interacciones individuales. Asimismo, estas interacciones entre ligandos multivalentes y sus proteínas receptoras (en la mayoría de los casos, lectinas) conducen a redes entrecruzadas que desencadenan procesos biológicos específicos. En búsqueda de compuestos de alta afinidad por lectinas que pudieran interferir con este tipo de procesos, y que además resultaran estables en medios biológicos sin sufrir degradación por glicosidasas endógenas, se planteó como objetivo principal de este trabajo de tesis la síntesis de ligandos multivalentes con unidades de tioazúcares específicamente diseñados para estudiar fenómenos biológicos regulados por lectinas. Estos ligandos se diseñaron para ser resistentes a la degradación enzimática...

Dioxygen activation by low valent cobalt complexes supported by ferrocenyl-substituted, redox active hydrotris(pyrazolyl)borate ligands

Sirianni, Eric R.
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
Português
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Theopold, Klaus H.; The successful synthesis and structural characterization of a new family of second and third generation ferrocenyl-substituted tris(pyrazolyl)borate ligands was achieved. These ligands employ ferrocenyl (Fc) moieties for increased C-H bond strengths as well as maintaining the steric demands necessary to remain "tetrahedral enforcers". The thallium(I) salts of the TP Fc* (1 ) and TpFc,Me* (2 ) ligands were isolated as N-confused asymmetric isomers. However, Tp Fc,iPr Tl (3 ) was isolated as the symmetric ligand as a dimer with an apparent Tl - Tl interaction. Cyclic voltammetry of 1, 2 , and 3 revealed single, reversible, three electron redox processes which suggests a lack of electronic communication between the ferrocenyl moieties when bound to a hydrotris(pyrazolyl)borate ligand. Conversely, TpCF3,Fc Tl (4 ) displays an irreversible redox process that is accompanied by decomposition during the oxidation wave of the CV. Thallium salts 1 and 2 undergo borotropic rearrangements to form the symmetric TpFc Tl (7 ) and Tp Fc,Me Tl (8 ), respectively. These ligands react with CoX 2 (X: Cl, I) to form their symmetric TpCoX complexes. Salt metathesis of 3 with CoI2 led to the isolation of TpFc,iPr CoI (13 ) as the only observable product. However...

Contribution of KIR (killer immunoglobulin-like receptor) genes, HLA class I ligands, and KIR/HLA class I ligand combinations on the genetic predisposition to celiac disease and coexisting celiac disease and type 1 diabetes mellitus

Akar,H. Haluk; Patiroglu,Turkan; Sevinc,Eylem; Aslan,Duran; Okdemir,Deniz; Kurtoglu,Selim
Fonte: Revista Española de Enfermedades Digestivas Publicador: Revista Española de Enfermedades Digestivas
Tipo: info:eu-repo/semantics/article; journal article; info:eu-repo/semantics/publishedVersion Formato: text/html; application/pdf
Publicado em 01/09/2015 Português
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Backgound and aim: There are some common genetic features between celiac disease (CD) and diabetes mellitus type 1 (DM). However, the genetic risk factors have not been fully clarified for CD and the co-occurrence of CD and DM. KIR (killer immunoglobulin-like receptor) genes regulate the cytolitic activity of NK-cells and T lymphocytes. The aim of this study is to evaluate the contribution of KIR genes, KIR ligands, and combinations of KIR/KIR ligands on the genetic predisposition to CD and co-occurrence of CD and DM. Material and methods: Forty six patients with CD (n = 46), 20 patients with CD+DM (n = 20), and 60 healthy controls (n = 60) were included in this study. KIR genes and KIR ligands were investigated with PCR-ssOP and PCR-ssP in all subjects, respectively. Results: This study showed that while the telomeric KIR genes (2DS5 and 3DS1), and combinations of 3DS1+HLA-BBw4-Thr- and 3DS1+HLA-BBw4-Iso- (p < 0.001, p < 0.001, p < 0.001, and p < 0.001, respectively) were observed more frequently in patients with CD than in controls, the 2DS5, 3DS1 KIR genes, C1 ligand, and combinations of 3DS1+HLA-BBw4-Thr- and 3DS1+HLA-BBw4-Iso- (p = 0.002, p = 0.004, p = 0.036, p < 0.001, and p = 0.007, respectively) were observed more frequently in patients with CD+DM than in controls. Conclusions: The results of this study indicated that some KIR genes...