Interações entre nanocristais semicondutores de CdTe e complexos polipiridínicos de rutênio (ll)
Autor(a) principal: | |
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Data de Publicação: | 2016 |
Tipo de documento: | Dissertação |
Idioma: | por |
Título da fonte: | Repositório Institucional da UFS |
Texto Completo: | https://ri.ufs.br/handle/riufs/6064 |
Resumo: | In this work Ru(II) polypyridine complexes were used as redox active molecules to study interactions with quantum dots (QDs) surface. The synthesis of cadmium telluride (CdTe) quantum dots passivated with the organic stabilizer mercaptopropionic acid (MPA) and with stabilizer mixture of MPA and L-cysteine (CYS) was carried out in aqueous solution via hydrothermal heating, and the synthesis parameters such as pH and Cd/Te/stabilizer ratio were fixed according to the literature. The colloidal dispersion was characterized by UV visible absorption spectroscopy, as well as infrared and photoluminescence. Absorption spectra were broad with a single band and the emission showed band maxima at 612 nm and 598 nm for CdTe-MPA and CdTe-MPA/CYS (labelled in this work as CdTe-CYS) respectively (indicating quantum confinement). Particle diameters were calculated using a cubic empirical formula based on the maximum absorption wavelength. Cyclic voltammetry showed the presence of anodic and cathodic peaks corresponding to redox processes of CdTe QDs. Electrochemical band gaps were estimated from the onset values of oxidation and reduction peaks, finding a correspondence with the optical band gaps estimated from absorption and emission spectra. Polypyridine ruthenium(II) complexes [Ru(bpy)3](PF6)2 and [Ru(Me-bpy)3](PF6)2 (labelled in this work as Ru-1 and Ru-2, respectively) were synthesized via hydrothermal method for 72 h at 170ºC. The solids obtained were characterized by UV visible spectroscopy and the main transitions involved in the polypyrinde complexes were observed. Fluorescence spectroscopy exhibited a band assigned to the radiative deactivation of the lowest energy excited state (3MLTC). A redox pair of the complex was observed in the cyclic voltammograms, assigned to Ru2+/Ru3+ metal center. The possibility of interactions between the quantum dots and the complexes was evaluated by electrochemical measurements. Anodic differential pulse voltammograms showed that the redox potentials of QDs were modified due to the presence of the Ru(II) polypyridine complexes onto the QD’s surfaces. Oxidation peak from QDs was shifted to more positive values while the complexes’s redox peaks shifted to less positive values, indicating that the system shows characteristics of a nanocrystal molecular conjugated. |
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Bispo, Thalita SantosGimenez, Iara de FátimaSussuchi, Eliana Midorihttp://lattes.cnpq.br/45447690953617992017-09-27T13:57:28Z2017-09-27T13:57:28Z2016-05-13BISPO, Thalita Santos. Interações entre nanocristais semicondutores de CdTe e complexos polipiridínicos de rutênio (ll). 2016. 100 f. Dissertação (Pós-Graduação em Química) - Universidade Federal de Sergipe, São Cristóvão, SE, 2016.https://ri.ufs.br/handle/riufs/6064In this work Ru(II) polypyridine complexes were used as redox active molecules to study interactions with quantum dots (QDs) surface. The synthesis of cadmium telluride (CdTe) quantum dots passivated with the organic stabilizer mercaptopropionic acid (MPA) and with stabilizer mixture of MPA and L-cysteine (CYS) was carried out in aqueous solution via hydrothermal heating, and the synthesis parameters such as pH and Cd/Te/stabilizer ratio were fixed according to the literature. The colloidal dispersion was characterized by UV visible absorption spectroscopy, as well as infrared and photoluminescence. Absorption spectra were broad with a single band and the emission showed band maxima at 612 nm and 598 nm for CdTe-MPA and CdTe-MPA/CYS (labelled in this work as CdTe-CYS) respectively (indicating quantum confinement). Particle diameters were calculated using a cubic empirical formula based on the maximum absorption wavelength. Cyclic voltammetry showed the presence of anodic and cathodic peaks corresponding to redox processes of CdTe QDs. Electrochemical band gaps were estimated from the onset values of oxidation and reduction peaks, finding a correspondence with the optical band gaps estimated from absorption and emission spectra. Polypyridine ruthenium(II) complexes [Ru(bpy)3](PF6)2 and [Ru(Me-bpy)3](PF6)2 (labelled in this work as Ru-1 and Ru-2, respectively) were synthesized via hydrothermal method for 72 h at 170ºC. The solids obtained were characterized by UV visible spectroscopy and the main transitions involved in the polypyrinde complexes were observed. Fluorescence spectroscopy exhibited a band assigned to the radiative deactivation of the lowest energy excited state (3MLTC). A redox pair of the complex was observed in the cyclic voltammograms, assigned to Ru2+/Ru3+ metal center. The possibility of interactions between the quantum dots and the complexes was evaluated by electrochemical measurements. Anodic differential pulse voltammograms showed that the redox potentials of QDs were modified due to the presence of the Ru(II) polypyridine complexes onto the QD’s surfaces. Oxidation peak from QDs was shifted to more positive values while the complexes’s redox peaks shifted to less positive values, indicating that the system shows characteristics of a nanocrystal molecular conjugated.Neste trabalho utilizou-se complexos polipiridínicos de Ru(II) como molécula redox ativa no estudo da interação com a superfície dos quantum dots (QDs). A síntese dos quantum dots de Telureto de Cádmio (CdTe) passivados com o estabilizante orgânico MPA (ácido mercaptopropiônico), e com a mistura de estabilizantes MPA e CYS (� – Cisteína) foi realizada em solução aquosa, via hidrotermal, e os parâmetros de síntese, como pH e relação Cd/Te/estabilizantes fixados conforme a literatura. A dispersão coloidal foi caracterizada por espectroscopia de absorção no UV Visível, no infravermelho e de emissão. Os espectros de absorção se apresentaram largos com apenas uma banda, e de emissão com máximo em 612 e 598 nm, para CdTe-MPA e CdTe-MPA/CYS (nomeado neste trabalho como CdTe- CYS), respectivamente (indicando confinamento quântico). Os diâmetros das partículas foram calculados usando-se uma fórmula empírica cúbica, a partir do comprimento de onda máximo de absorção. A voltametria cíclica mostrou a presença de picos anódicos e catódicos correspondentes a processos redox dos QDs de CdTe. Os band gaps eletroquímicos foram estimados pelos valores dos onsets e dos picos de oxidação e redução e encontrados correspondência com os band gaps ópticos estimados a partir dos espectros de absorção e emissão. Os complexos polipiridínicos de rutênio (II), [Ru(bpy)3](PF6)2 e [Ru(Me-bpy)3](PF6)2 (nomeados neste trabalho como Ru-1 e Ru-2, respectivamente), foram sintetizados através do método de síntese hidrotermal por 72 h a 170 ºC. O sólido obtido foi caracterizado por espectroscopia de absorção no UV Visível e principais transições eletrônicas envolvidas nos complexos polipiridínicos foram observadas, a espectroscopia de fluorescência exibiu a banda atribuída a desativação radiativa do estado excitado de menor energia (3TCML). Na voltametria cíclica foi observado um par redox do complexo atribuído ao centro metálico Ru(II)/(III). A possibilidade de interação entre os quantum dots de CdTe e os complexos foi avaliada por medidas eletroquímicas. Voltamogramas de pulso diferencial anódico mostraram que os potenciais redox dos QDs são modificados devido a presença dos complexos polipiridínicos de Ru(II) na superfície dos QDs. Os picos de oxidação dos QDs foram deslocados para potenciais mais positivos enquanto o pico redox dos complexos deslocou para potenciais menos positivos, indicando que o sistema exibiu características de um conjugado nanocristal-molecular.application/pdfporUniversidade Federal de SergipePós-Graduação em QuímicaUFSBrasilQuímicaSemicondutoresCompostos de telúrioCompostos de rutênioNanocompósitosEletrostáticaCristais líquidosQuantum dotsComplexos polipiridínicosInteração eletrostáticaQuantum dotsPolypyridine complexesElectrostatic interactionCIENCIAS EXATAS E DA TERRA::QUIMICAInterações entre nanocristais semicondutores de CdTe e complexos polipiridínicos de rutênio (ll)info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFSinstname:Universidade Federal de Sergipe (UFS)instacron:UFSORIGINALTHALITA_SANTOS_BISPO.pdfapplication/pdf3520885https://ri.ufs.br/jspui/bitstream/riufs/6064/1/THALITA_SANTOS_BISPO.pdfc9b32332d726e03aaa85360045b27b2dMD51TEXTTHALITA_SANTOS_BISPO.pdf.txtTHALITA_SANTOS_BISPO.pdf.txtExtracted texttext/plain170727https://ri.ufs.br/jspui/bitstream/riufs/6064/2/THALITA_SANTOS_BISPO.pdf.txt3ccf1359e8dba10567d61a71863adc1cMD52THUMBNAILTHALITA_SANTOS_BISPO.pdf.jpgTHALITA_SANTOS_BISPO.pdf.jpgGenerated Thumbnailimage/jpeg1497https://ri.ufs.br/jspui/bitstream/riufs/6064/3/THALITA_SANTOS_BISPO.pdf.jpgb62b4f45e57bb1b62474648f561d3565MD53riufs/60642017-11-27 21:48:09.206oai:ufs.br:riufs/6064Repositório InstitucionalPUBhttps://ri.ufs.br/oai/requestrepositorio@academico.ufs.bropendoar:2017-11-28T00:48:09Repositório Institucional da UFS - Universidade Federal de Sergipe (UFS)false |
dc.title.por.fl_str_mv |
Interações entre nanocristais semicondutores de CdTe e complexos polipiridínicos de rutênio (ll) |
title |
Interações entre nanocristais semicondutores de CdTe e complexos polipiridínicos de rutênio (ll) |
spellingShingle |
Interações entre nanocristais semicondutores de CdTe e complexos polipiridínicos de rutênio (ll) Bispo, Thalita Santos Química Semicondutores Compostos de telúrio Compostos de rutênio Nanocompósitos Eletrostática Cristais líquidos Quantum dots Complexos polipiridínicos Interação eletrostática Quantum dots Polypyridine complexes Electrostatic interaction CIENCIAS EXATAS E DA TERRA::QUIMICA |
title_short |
Interações entre nanocristais semicondutores de CdTe e complexos polipiridínicos de rutênio (ll) |
title_full |
Interações entre nanocristais semicondutores de CdTe e complexos polipiridínicos de rutênio (ll) |
title_fullStr |
Interações entre nanocristais semicondutores de CdTe e complexos polipiridínicos de rutênio (ll) |
title_full_unstemmed |
Interações entre nanocristais semicondutores de CdTe e complexos polipiridínicos de rutênio (ll) |
title_sort |
Interações entre nanocristais semicondutores de CdTe e complexos polipiridínicos de rutênio (ll) |
author |
Bispo, Thalita Santos |
author_facet |
Bispo, Thalita Santos |
author_role |
author |
dc.contributor.author.fl_str_mv |
Bispo, Thalita Santos |
dc.contributor.advisor1.fl_str_mv |
Gimenez, Iara de Fátima |
dc.contributor.advisor-co1.fl_str_mv |
Sussuchi, Eliana Midori |
dc.contributor.authorLattes.fl_str_mv |
http://lattes.cnpq.br/4544769095361799 |
contributor_str_mv |
Gimenez, Iara de Fátima Sussuchi, Eliana Midori |
dc.subject.por.fl_str_mv |
Química Semicondutores Compostos de telúrio Compostos de rutênio Nanocompósitos Eletrostática Cristais líquidos Quantum dots Complexos polipiridínicos Interação eletrostática Quantum dots |
topic |
Química Semicondutores Compostos de telúrio Compostos de rutênio Nanocompósitos Eletrostática Cristais líquidos Quantum dots Complexos polipiridínicos Interação eletrostática Quantum dots Polypyridine complexes Electrostatic interaction CIENCIAS EXATAS E DA TERRA::QUIMICA |
dc.subject.eng.fl_str_mv |
Polypyridine complexes Electrostatic interaction |
dc.subject.cnpq.fl_str_mv |
CIENCIAS EXATAS E DA TERRA::QUIMICA |
description |
In this work Ru(II) polypyridine complexes were used as redox active molecules to study interactions with quantum dots (QDs) surface. The synthesis of cadmium telluride (CdTe) quantum dots passivated with the organic stabilizer mercaptopropionic acid (MPA) and with stabilizer mixture of MPA and L-cysteine (CYS) was carried out in aqueous solution via hydrothermal heating, and the synthesis parameters such as pH and Cd/Te/stabilizer ratio were fixed according to the literature. The colloidal dispersion was characterized by UV visible absorption spectroscopy, as well as infrared and photoluminescence. Absorption spectra were broad with a single band and the emission showed band maxima at 612 nm and 598 nm for CdTe-MPA and CdTe-MPA/CYS (labelled in this work as CdTe-CYS) respectively (indicating quantum confinement). Particle diameters were calculated using a cubic empirical formula based on the maximum absorption wavelength. Cyclic voltammetry showed the presence of anodic and cathodic peaks corresponding to redox processes of CdTe QDs. Electrochemical band gaps were estimated from the onset values of oxidation and reduction peaks, finding a correspondence with the optical band gaps estimated from absorption and emission spectra. Polypyridine ruthenium(II) complexes [Ru(bpy)3](PF6)2 and [Ru(Me-bpy)3](PF6)2 (labelled in this work as Ru-1 and Ru-2, respectively) were synthesized via hydrothermal method for 72 h at 170ºC. The solids obtained were characterized by UV visible spectroscopy and the main transitions involved in the polypyrinde complexes were observed. Fluorescence spectroscopy exhibited a band assigned to the radiative deactivation of the lowest energy excited state (3MLTC). A redox pair of the complex was observed in the cyclic voltammograms, assigned to Ru2+/Ru3+ metal center. The possibility of interactions between the quantum dots and the complexes was evaluated by electrochemical measurements. Anodic differential pulse voltammograms showed that the redox potentials of QDs were modified due to the presence of the Ru(II) polypyridine complexes onto the QD’s surfaces. Oxidation peak from QDs was shifted to more positive values while the complexes’s redox peaks shifted to less positive values, indicating that the system shows characteristics of a nanocrystal molecular conjugated. |
publishDate |
2016 |
dc.date.issued.fl_str_mv |
2016-05-13 |
dc.date.accessioned.fl_str_mv |
2017-09-27T13:57:28Z |
dc.date.available.fl_str_mv |
2017-09-27T13:57:28Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/masterThesis |
format |
masterThesis |
status_str |
publishedVersion |
dc.identifier.citation.fl_str_mv |
BISPO, Thalita Santos. Interações entre nanocristais semicondutores de CdTe e complexos polipiridínicos de rutênio (ll). 2016. 100 f. Dissertação (Pós-Graduação em Química) - Universidade Federal de Sergipe, São Cristóvão, SE, 2016. |
dc.identifier.uri.fl_str_mv |
https://ri.ufs.br/handle/riufs/6064 |
identifier_str_mv |
BISPO, Thalita Santos. Interações entre nanocristais semicondutores de CdTe e complexos polipiridínicos de rutênio (ll). 2016. 100 f. Dissertação (Pós-Graduação em Química) - Universidade Federal de Sergipe, São Cristóvão, SE, 2016. |
url |
https://ri.ufs.br/handle/riufs/6064 |
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por |
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Universidade Federal de Sergipe |
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Pós-Graduação em Química |
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UFS |
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Brasil |
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