“…Complexes of this type have been tagged “molecular light switches” because, although the fluorescence of these complexes in aqueous solutions is negligible, increases of greater than 10 000-fold in the presence of DNA have been observed . Complexes of dppz derivatives are also useful as components in organic light-emitting devices (OLEDs) because their emission color is largely red-shifted from their absorption wavelength. , 1 Structure of dppz, showing ring labels and IUPAC numbering (left) and the bond and angle labeling of the cis rotamer of 1 (right).…”
Section: Introductionmentioning
confidence: 99%
“…Through judicious selection of the metal ion coordinated to dppz, one can tune the nature of the lowest-energy excited state from MLCT to LC . The low orbital overlap between the dπ and ligand π* MOs results in such complexes being virtually colorless (in the absence of other chromophoric ligands) as the MLCT transition is raised in energy from the visible to the ultraviolet region and lowered in intensity …”
The ligands 11-bromodipyrido[3,2-a:2',3'-c]phenazine and ethyl dipyrido[3,2-a:2',3'-c]phenazine-11-carboxylate have been prepared and coordinated to ruthenium(II), rhenium(I), and copper(I) metal centers. The electronic effects of substitution of dipyrido[2,3-a:3',2'-c]phenazine (dppz) have been investigated by spectroscopy and electrochemistry, and some photophysical properties have been studied. The crystal structures of [Re(L)(CO)(3)Cl] (L = ethyl dipyrido[3,2-a:2',3'-c]phenazine-11-carboxylate or 11-bromodipyrido[3,2-a:2',3'-c]phenazine) are presented. Density functional theory calculations on the complexes show only small deviations in bond lengths and angles (most bonds within 0.02 Angstroms, most angles within 2 degrees) from the crystallographic data. Furthermore, the vibrational spectra of the strongest Raman and IR bands are predicted to within an average 6 cm(-1) for the complexes [Re(L)(CO)(3)Cl] and [Cu(L)(triphenylphosphine)(2)]BF(4) (in the 1000-1700 cm(-1) region). Spectroscopic and electrochemical evidence suggest that reduction of the complex causes structural changes across the entire dppz ligand. This is unusual as dppz-based ligands typically have electrochemical properties that suggest charge localization with reduction on the phenazine portion of the ligand. The excited-state lifetimes of the complexes have been measured, and they range from ca. 200 ns for the [Ru(L)(2,2'-bipyridine)(2)](PF(6))(2) complexes to over 2 mus for [Cu(11-bromodipyrido[3,2-a:2',3'-c]phenazine)(PPh(3))(2)](BF(4)) at room temperature. The emission spectra suggest that the unusually long-lived excited states of the copper complexes result from metal-to-ligand charge transfer (MLCT) transitions as they are completely quenched in methanol. Electroluminescent films may be fabricated from these compounds; they show MLCT state emission even at low doping levels [<0.1% by weight in poly(vinylcarbazole) polymer matrix].
“…Complexes of this type have been tagged “molecular light switches” because, although the fluorescence of these complexes in aqueous solutions is negligible, increases of greater than 10 000-fold in the presence of DNA have been observed . Complexes of dppz derivatives are also useful as components in organic light-emitting devices (OLEDs) because their emission color is largely red-shifted from their absorption wavelength. , 1 Structure of dppz, showing ring labels and IUPAC numbering (left) and the bond and angle labeling of the cis rotamer of 1 (right).…”
Section: Introductionmentioning
confidence: 99%
“…Through judicious selection of the metal ion coordinated to dppz, one can tune the nature of the lowest-energy excited state from MLCT to LC . The low orbital overlap between the dπ and ligand π* MOs results in such complexes being virtually colorless (in the absence of other chromophoric ligands) as the MLCT transition is raised in energy from the visible to the ultraviolet region and lowered in intensity …”
The ligands 11-bromodipyrido[3,2-a:2',3'-c]phenazine and ethyl dipyrido[3,2-a:2',3'-c]phenazine-11-carboxylate have been prepared and coordinated to ruthenium(II), rhenium(I), and copper(I) metal centers. The electronic effects of substitution of dipyrido[2,3-a:3',2'-c]phenazine (dppz) have been investigated by spectroscopy and electrochemistry, and some photophysical properties have been studied. The crystal structures of [Re(L)(CO)(3)Cl] (L = ethyl dipyrido[3,2-a:2',3'-c]phenazine-11-carboxylate or 11-bromodipyrido[3,2-a:2',3'-c]phenazine) are presented. Density functional theory calculations on the complexes show only small deviations in bond lengths and angles (most bonds within 0.02 Angstroms, most angles within 2 degrees) from the crystallographic data. Furthermore, the vibrational spectra of the strongest Raman and IR bands are predicted to within an average 6 cm(-1) for the complexes [Re(L)(CO)(3)Cl] and [Cu(L)(triphenylphosphine)(2)]BF(4) (in the 1000-1700 cm(-1) region). Spectroscopic and electrochemical evidence suggest that reduction of the complex causes structural changes across the entire dppz ligand. This is unusual as dppz-based ligands typically have electrochemical properties that suggest charge localization with reduction on the phenazine portion of the ligand. The excited-state lifetimes of the complexes have been measured, and they range from ca. 200 ns for the [Ru(L)(2,2'-bipyridine)(2)](PF(6))(2) complexes to over 2 mus for [Cu(11-bromodipyrido[3,2-a:2',3'-c]phenazine)(PPh(3))(2)](BF(4)) at room temperature. The emission spectra suggest that the unusually long-lived excited states of the copper complexes result from metal-to-ligand charge transfer (MLCT) transitions as they are completely quenched in methanol. Electroluminescent films may be fabricated from these compounds; they show MLCT state emission even at low doping levels [<0.1% by weight in poly(vinylcarbazole) polymer matrix].
“…For this reason, the current scientific and industrial challenge is to design new ideally soluble [ 8 ] conjugated polymers with the aim of obtaining a new material having modular optoelectronic properties endowed with the desired performance, thus improving their solubility [ 9 , 10 ] in order to act as active layers in optoelectronic devices [ 11 , 12 , 13 ]. Research in these directions has been fruitful previously in polymers such as the PVK [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ] and the F8T2 [ 21 , 22 , 23 ], which have become successful in recent years thanks to their characteristic properties. To this end, considerable efforts have, therefore, been allocated to design and elaborate on this new copolymer PVK-F8T2.…”
This article is mainly a complementary study of a novel part of π-conjugated copolymers based on the poly (N-vinylcarbazole) (PVK) and poly (9,9-dioctylfluorene-co-bithiophene) (F8T2) unit based on the Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT). This study is carried out to explore the structural and optoelectronic characteristics of a new organic material named PVK-F8T2. First, the structural, optical (absorption, photoluminescence, optical transition), electronic (molecular orbital (MO), energy-level diagram) and vibratory parameters of infrared (IR) were computed and compared with experimental studies. In addition, we calculated the level energy of the excited states and their corresponding transitions. Obviously, electronic parameters such as highest occupied and lowest unoccupied molecular orbital (HOMO and LUMO), ionization potential (IP), electronic affinity (EA) and the energy band gap (Eg) were computed in order to elucidate the intramolecular charge transport and to establish the energetic diagrams of the PVK-F8T2 copolymer for different states. The results obtained looked with precision at future optoelectronic applications. From these results, we have shown that the PVK-F8T2 has significant optoelectronic properties and seems usable as an active layer in organic light-emitting diodes (OLEDs).
“…A Figura 62 apresenta a proposição do diagrama de níveis de energia com base em dados apontados na literatura, cujos estados excitados são calculados por simulação. [85] Neste diagrama é possível fazer uma analogia dos níveis HOMO e LUMO para com as espécies excitadas formadas durante o processo de eletroluminescência.…”
Section: Complexo De Térbio Disperso Em Pvkunclassified
Ao orientador e amigo prof. Fernando Josepetti Fonseca, pela oportunidade, discussões, confiança, transmissão de conhecimento e cooperação, que culminaram na possibilidade de desenvolvimento, com todas as potencialidades, deste trabalho tanto no Brasil como no exterior.Ao amigo e orientador não oficial prof. Luiz Fernando Ribeiro Pereira pelas incontáveis discussões sobre trabalho e assuntos diversos, atenção e transmissão de conhecimento, hospitalidade em Portugal sem igual e oportunidade de desenvolvimento do trabalho na Universidade de Aveiro -Departamento de Física, que contribuíram de forma fundamental na minha formação profissional e pessoal. Aos professores Adnei M. Andrade e Ely Dirani pela confiança, incentivo, direcionamento global do grupo GEM e interposições assertivas nos momentos adequados e por suas posições em prol da ciência. Agradecimento redobrado ao prof. Adnei por possibilitar a infra-estrutura necessária à pesquisa de dispositivos eletroluminescentes. Às professoras Neyde Iha e Leni Ackcelrud pela colaboração científica, discussões, disponibilização de materiais sintetizados nos laboratórios de Química da USP e Federal do Paraná, sem os quais não seria possível a concretização do presente trabalho. Aos amigos do IQUSP Otávio Patrocínio e Sérgio Mizoguchi por disponibilizar os complexos de Rutênio. Também aos colegas André Polo e Karina pelo complexo de Rênio. Meus agradecimentos aos colegas da química pela confiança, dinamismo e parceria para produção de LECs, que culminaram em ótimas publicações. Ao amigo Vitor Deichmann da UFPR pela confiança, dinamismo, vontade científica e por ser um grande colaborador através do IMMP desde o início do meu trabalho para produção de OLEDs com complexos de Terras Raras. Faço extensão dos meus agradecimentos aos colegas, também da UFPR, Jeferson Jesus, Isabel Grova e Bruno pelos polímeros disponibilizados e que foram frutos de ótimas publicações. Às colaboradoras do laboratório CICECO de Portugal Profa. Isabel Gonçalves, Susana Braga e Catarina Coelho por confiar no trabalho desenvolvido no Departamento de Física da Universidade de Aveiro e disponibilizar materiais sintetizados. Ao prof. Roberto Onmori pela transmissão de conhecimento nos primeiros passos na técnica de evaporação térmica de metais na glovebox da Escola Politécnica. Aos colegas do grupo GEM Emerson Roberto (grande amigo e companheiro de sala e de todos os anos de Doutorado), Helena Gimaiel (sempre dinâmica e com ótimas idéias), Alex Frazatti (Lekinho), Roberto Cavallari (o viajante e conhecedor de muitas línguas), Sérgio Ozaki, John Paul Lima (sempre disposto a ajudar e com muitas idéias), João Cláudio de Brito Santos (grande colaborador e amigo), Alexandre Mantovani Nardes (apesar da distância sempre presente no grupo GEM), Guilherme Braga (Mergulhão), Leonardo Paterno (grande amigo e colaborador),
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
