Submitted by ANA KARLA PEREIRA RODRIGUES (anakarla_@hotmail.com) on 2017-07-31T14:45:43Z No. of bitstreams: 1 arquivototal.pdf: 9976488 bytes, checksum: d0e80f609f413107e918fa94fe016bad (MD5) / Made available in DSpace on 2017-07-31T14:45:43Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 9976488 bytes, checksum: d0e80f609f413107e918fa94fe016bad (MD5) Previous issue date: 2017-02-13 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / This work reports the synthesis, characterization and investigation of the luminescent properties of new lanthanide -diketonate complexes, Ln(- dic)2(NO3)L2, Ln(TTA)3L2 and Ln(DBM)3L (TPPO), where thenoyltrifluoroacetone (TTA) and dibenzoylmethane (DBM), L = triphenylphosphine oxide (TPPO), tributylphosphine oxide (TBPO), and trioctylphosphine oxide (TOPO). Eu3+ ion complexes were also synthesized with triphenylarsine oxide (TPAsO) and tricyclohexylphosphine (TCHPO) as auxiliary ligands. The complexes were characterized by complexometric titration with EDTA, CHN elemental analysis, Fourier transform infrared (FTIR) absorption spectroscopy and thermogravimetric analysis (TGA). The photoluminescent properties in the visible and near infrared (NIR) regions of the synthesized complexes were investigated from excitation, emission and luminescence decay curves. The excitation spectra are characterized by the presence of large bands associated with transitions centered on the ligands, evidencing the efficiency of the luminescence sensitization by the antenna ligands. The emission spectra in the visible region of the compounds of the Sm3+ and Eu3+ ions show narrow bands attributed to intraconfigurationtransitions and are dominated by the hypersensitive transitions (~645 nm) and (~612 nm). The values of the intensity parameters and for the complexes of Sm3+ and Eu3+ presented a good correlation, evidencing that the chemical environment influence in a similar way the spectroscopic properties of these ions. The photoluminescent properties of the Eu3+ ion complexes were investigated by the intensity parameters and , radiative and nonradiative ( and ), lifetime of the emitting state () and quantum emission efficience . The highest values of are found for Eu(-dic)2(NO3)L2 complexes, in the range of 51-86%. It was observed that the Eu(-dic)3L2 compounds exhibited shorter lifetimes, which may be related to the presence of a suppressor channel, resulting in higher values of . The intensity parameters and vary only slightly when changes occur in the number and nature of the ligands of the first coordination sphere, with parameter being more sensitive to changes in coordination geometry. The emission spectra in the NIR region of the bis- and trisdiketonate complexes of Pr3+, Nd3+, Sm3+, Er3+ and Yb3+ ions present characteristic luminescence. Changes in the nature and number of ligands coordinated to the Ln3+ ion slightly influence the spectral profiles. The results obtained for the studied systems suggest that these are potential candidates to act as Molecular Light Converting Devices. / Este trabalho reporta a síntese, caracterização e investigação das propriedades luminescentes de -dicetonatos de íons lantanídos, Ln(- dic)2(NO3)L2, Ln(TTA)3L2 e Ln(DBM)3L, em que Ln3+ = Pr3+, Nd3+, Sm3+, Eu3+, Er3+ e Yb3+, -dic = 2-tenoilltrifluoroacetona (TTA) e dibenzoilmetano (DBM), L = óxido de trifenilfosfina (TPPO), tributilfosfina (TBPO) e trioctilfosfina (TOPO). Para os compostos do íon Eu3+, foram também sintetizados os complexos com o óxido de trifenilarsina (TPAsO) e triciclohexilfosfina (TCHPO) como ligantes auxiliares. Os complexos sintetizados foram caracterizados por titulação complexométrica com EDTA, análise elementar CHN, espectroscopia de absorção na região do infravermelho com transformada de Fourier (FTIR) e análise termogravimétrica (TGA). As propriedades fotoluminescentes nas regiões do visível e infravermelho próximo (NIR) dos complexos sintetizados foram investigadas a partir dos espectros de excitação, emissão e curvas de decaimento de luminescência. Os espectros de excitação são caracterizados pela presença de bandas largas associadas às transições centradas nos ligantes , evidenciando a eficiência na sensibilização da luminescência pelos ligantes antenas. Os espectros de emissão, na região do visível, dos compostos dos íons Sm3+ e Eu3+, exibem bandas finas oriundas das transições intraconfiguracionaise são dominados pelas transições hipersensíveis (~645 nm) e (~612 nm). Os valores dos parâmetros de intensidade e dos complexos de Sm3+ e Eu3+ apresentaram uma boa correlação, evidenciando que o ambiente químico influência de maneira semelhante as propriedades espectroscópica destes íons. As propriedades fotoluminescentes dos complexos do íon Eu3+ foram investigados por meio dos parâmetros de intensidade e , taxas de radiativa e nãoradiativa ( e ), tempo de vida do estado () e, eficiência quântica de emissão ( ). Os maiores valores de são encontrados para os complexos Eu(- dic)2(NO3)L2, na faixa de 51-86%. Observou-se que os compostos Eu(-dic)3L2 exibiram tempo de vida mais curto, o que pode estar relacionado com a presença de uma canal supressor, resultando assim em maiores valores de . Os parâmetros de intensidade e , variam apenas ligeiramente quando ocorre alterações no número e na natureza dos ligantes da primeira esfera de coordenação, sendo o 2 mais sensível as alterações na geometria de coordenação. Os espectros de emissão na região do NIR dos complexos bis- e tris-dicetonatos dos íons Pr3+, Nd3+, Sm3+, Er3+ e Yb3+ apresentam luminescência característica. As alterações na natureza e número de ligantes coordenados ao íon Ln3+ influenciam ligeiramente os perfis espectrais. Os resultados obtidos para os sistemas estudados sugerem que estes são potenciais candidatos a atuarem como Dispositivos Moleculares Conversores de Luz.

In addition to the well known quantum confinement effects resulted from size and shape, interfacial bond structure is another factor, affecting the properties of the nanomaterial that is rarely studied. Inspired by the “Au-S-Au” staple motif discovered from the crystal structure of monothiol protected Au102 nanocluster (Science, 2007, 318, 430), dithiol molecules (e. g. 1, 2-dithiol, 1, 4-dithiol, etc.) with molecular structural constraint have been employed to create dithiolate protected clusters or mixed monothiolate and dithiolate protected clusters. The structure and properties of the Au clusters are expected to change due to two effects: The entropy gain of dithiol over monothiol protection and the constraint to the formation of the thiol bridging motif. DMPS (1, 2-dithiol molecule) stabilized clusters with characteristic absorption bands have been obtained, and characterized by multiple techniques. Monolayer reaction on gold core surface between the monothiol tiopronin and dithiol DMPS has been performed, and the mechanism has been probed. Mixed phenylethanethiolate and durene-dithiolate (1, 4-dithiol molecule) protected Au130 clusters with rich electrochemical features have been created, and the optical and electrochemical energetics have been successfully correlated based on core and core-ligand energy states. Furthermore, the impact of 1, 4-dithiolate-Au bonding on the near infrared luminescence has been studied.