Íons lantanídeos(III) sensibilizados por éteres coroa como precursores de complexos luminescentes bimetálicos heterolépticos com metais do bloco d: síntese, caracterização e avaliação das propriedades ópticas
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2020-02-14
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Universidade Estadual Paulista (Unesp)
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Neste trabalho foi desenvolvida a síntese, etapa a etapa, e caracterização, estrutural e óptica, de um sistema heterobimetálico contendo Eu3+ coordenado ao éter coroa 18coroa-6 (18C6) em associação ao Ni2+ coordenado à -dicetona dibenzoilmetano desprotonada (dbm), para avaliar sua aplicabilidade em dispositivos ópticos conversores de luz. O ligante 2,2’–bipirimidina (bpm) em ponte foi utilizado para unir os dois complexos e a formação do bimetálico. O éter coroa e os ligantes N-N doadores tiveram a função de diminuir a probabilidade de coordenação de moléculas de água (supressoras de luminescência) ao centro emissor e atuar como sensibilizadores, respectivamente. Complexos isoestruturais contendo Gd3+ também foram sintetizados para a determinação dos estados tripletos dos ligantes em todos os sistemas. Paralelamente, desenvolveu-se uma rota de síntese de um novo ligante da classe dos éteres coroa, o dibenzo-18coroa-4, DB18C4, que devido à demora no aperfeiçoamento das etapas envolvidas, não pôde ser testado na produção dos complexos. Todos os complexos sintetizados, contendo o éter coroa 18C6, foram caracterizados via FTIR, UV-Vis, titulação complexométrica, análise térmica, espectrometria de massas e espectroscopia de luminescência. Já o novo ligante sintetizado, DB18C4, foi caracterizado por FTIR, UV-Vis, espectrometria de massas, RMN de 1H, 13C, e HH COSY, análise elementar e teve sua estrutura determinada por difração de raios X de monocristal. Dados de FTIR confirmaram a formação dos compostos e a partir da análise térmica e da espectrometria de massas foi possível propor as estequiometrias mais prováveis, sendo elas: [EuCl3(18C6)(H2O)3], [EuCl(18C6)(bpm)2(H2O)]Cl2◦H2O, e [Eu(18C6)(EtOH)(-bpm)2(Ni(dbm)2)2]Cl3. Todos os complexos sintetizados são emissores desde o laranja até o vermelho, com elevada pureza de cor. Essa emissão, característica de Eu3+, só foi possível devido à sensibilização do íon emissor pelos ligantes N-N doadores, uma vez que o complexo de európio(III) precursor exibiu resposta luminescente muito baixa, quando comparado aos demais. E no complexo bimetálico constatou-se um ligeiro abaixamento do estado tripleto dos ligantes atribuído ao acoplamento spin-orbita do níquel(II). Devido a elevada pureza de cor, os complexos foram considerados promissores para aplicações em dispositivos moleculares conversores de luz. Já o novo ligante, o qual foi sintetizado com sucesso e teve sua estrutura elucidada pelo conjunto de técnicas utilizadas, abre perspectivas futuras na produção de novos complexos mais eficientes, já que provavelmente atuará também como sensibilizador na esfera de coordenação de Eu3+.
In this study, the synthesis, step by step, and structural and optical characterization of a heterobimetallic system containing Eu3+ coordinated to the ether crown 18crown-6 (18C6) in association with Ni2+ coordinated to deprotonated dibenzoylmethane (dbm) were developed, to evaluate their applicability in light converting optical devices. The bridged 2,2'-bipyrimidine (bpm) ligand was used to join the two complexes and bimetallic formation. The crown ether and the donor N-N ligands had the function of decreasing the probability of coordination of water molecules (luminescent quenchers) to the emitting center and acting as sensitizers, respectively. Isostructural complexes containing Gd3+ were also synthesized for the determination of ligand triplet states in all systems. At the same time, a synthetic route for a new crown ether ligand, dibenzo-18crown-4, DB18C4, was developed which, due to the delay in the improvement of the involved steps, could not be tested in the production of the complexes. All synthesized complexes containing 18C6 crown ether were characterized via FTIR, UV-Vis, complexometric titration, thermal analysis, mass spectrometry and luminescence spectroscopy. The new synthesized ligand, DB18C4, was characterized by FTIR, UV-Vis, mass spectrometry, 1H, 13C NMR, and HH COSY, elemental analysis and its structure was determined by single crystal X-ray diffraction. FTIR data confirmed the formation of the compounds and from thermal analysis and mass spectrometry it was possible to propose the most probable stoichiometry, as follows: [EuCl3(18C6)(H2O)3], [EuCl(18C6)(bpm)2(H2O)]Cl2◦H2O, and [Eu(18C6)(EtOH)(-bpm)2(Ni(dbm)2)2]Cl3. All synthesized complexes emit from orange to red with high color purity. This emission, characteristic of Eu3+, was only possible due to the sensitization of the emitting ion by the donor N-N ligands, since the precursor europium(III) complex exhibited very low luminescent response when compared to the others. And in the bimetallic complex there was a slight lowering of the triplet state of the ligands attributed to the spin-orbit coupling caused by nickel(II). Due to the high color purity, the complexes were considered promising for applications in molecular light-converting devices. The new ligand, which was successfully synthesized and its structure elucidated by the set of techniques used, opens future perspectives in the production of new more efficient complexes, since it will probably also act as a sensitizer in the Eu3+ coordination sphere.
In this study, the synthesis, step by step, and structural and optical characterization of a heterobimetallic system containing Eu3+ coordinated to the ether crown 18crown-6 (18C6) in association with Ni2+ coordinated to deprotonated dibenzoylmethane (dbm) were developed, to evaluate their applicability in light converting optical devices. The bridged 2,2'-bipyrimidine (bpm) ligand was used to join the two complexes and bimetallic formation. The crown ether and the donor N-N ligands had the function of decreasing the probability of coordination of water molecules (luminescent quenchers) to the emitting center and acting as sensitizers, respectively. Isostructural complexes containing Gd3+ were also synthesized for the determination of ligand triplet states in all systems. At the same time, a synthetic route for a new crown ether ligand, dibenzo-18crown-4, DB18C4, was developed which, due to the delay in the improvement of the involved steps, could not be tested in the production of the complexes. All synthesized complexes containing 18C6 crown ether were characterized via FTIR, UV-Vis, complexometric titration, thermal analysis, mass spectrometry and luminescence spectroscopy. The new synthesized ligand, DB18C4, was characterized by FTIR, UV-Vis, mass spectrometry, 1H, 13C NMR, and HH COSY, elemental analysis and its structure was determined by single crystal X-ray diffraction. FTIR data confirmed the formation of the compounds and from thermal analysis and mass spectrometry it was possible to propose the most probable stoichiometry, as follows: [EuCl3(18C6)(H2O)3], [EuCl(18C6)(bpm)2(H2O)]Cl2◦H2O, and [Eu(18C6)(EtOH)(-bpm)2(Ni(dbm)2)2]Cl3. All synthesized complexes emit from orange to red with high color purity. This emission, characteristic of Eu3+, was only possible due to the sensitization of the emitting ion by the donor N-N ligands, since the precursor europium(III) complex exhibited very low luminescent response when compared to the others. And in the bimetallic complex there was a slight lowering of the triplet state of the ligands attributed to the spin-orbit coupling caused by nickel(II). Due to the high color purity, the complexes were considered promising for applications in molecular light-converting devices. The new ligand, which was successfully synthesized and its structure elucidated by the set of techniques used, opens future perspectives in the production of new more efficient complexes, since it will probably also act as a sensitizer in the Eu3+ coordination sphere.
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Európio, Níquel, Luminescência, Éteres Coroa, Beta-dicetonas