Synthesis and photophysical characterization of novel triphenylamine-benzimidazole derivatives

Research on organic luminescent materials has been intensely pursued due to their importance in technological applications related to signaling, fluorescent biosensory/chemosensory materials, molecular switches and organic light emitting diodes (OLEDs). Organic fluorophores such as triphenylamine and benzimidazole derivatives have attracted a particular attention owing to their high emission efficiency being widely used as electron transporters and emitting layers for OLEDs.1 Recently, we have been investigating the potential of heterocyclic systems bearing functionalized (benz)imidazole derivatives exhibiting high thermal stability, interesting emissive and chemosensory properties.2 In this communication we report the synthesis and photophysical characterization of triphenylamine-benzimidazoles (compounds 1a-d) which were synthesized by a one step reaction through the Na2S2O4 reduction of several commercially available o-nitroanilines in the presence of triphenylamine aldehyde in DMSO at 120 °C. Compounds 1a-d bear different functionalization at position 5 of the benzimidazole with electron-donor or acceptor groups (Figure 1). A comprehensive spectral and photophysical investigation of these compounds including absorption, fluorescence and triplet-triplet absorption spectra, together with quantum yields of fluorescence, internal conversion, intersystem crossing and singlet oxygen and rate constants for the radiative and radiationless processes has been undertaken in solution at room temperature. It is shown that compounds 1a-d exhibit high fluorescence quantum yields (0.70-0.78). Additionally, a comparison between the optical and photophysical properties of 1a-d will be also presented and discussed.Fundação para a Ciência e a Tecnologia (FCT

Fluorescence Enhancement of the Water- Soluble Poly{1,4-phenylene-[9,9-bis- (4-phenoxybutylsulfonate)]fluorene-2,7-diyl} Copolymer in n-Dodecylpentaoxyethylene Glycol Ether Micelles

http://dx.doi.org/10.1021/ma048780

Emerging and under-recognized Chagas cardiomyopathy in non-endemic countries

Due to recent population emigration movements, an epidemic of Chagas disease is currently menacing most developed countries. The authors report the case of a 53-year-old Brazilian woman living in Europe for the last 10 years who developed heart failure symptoms, having a previous symptomatic sinus node disease with a pacemaker implant at age of 40 years. The diagnosis was based on serology and myocardial biopsy and the patient was treated with nifurtimox. The authors emphasize the need of a high level of suspicion in patients with suggestive epidemiology and the need of populational screening of specific high risk groups. New treatment options are also discussed

Relatório de gestão 2001-2004.

Embrapa Informática Agropecuária. Pesquisa e Desenvolvimento. Ações gerenciais estratégicas. Transferência de tecnologia e comunicação empresarial. Gestão Institucional. Prêmios recebidos. Infra-estrutura física. Gestão de Recursos Financeiros. Gestão de Recursos Humanos.bitstream/CNPTIA/10727/1/doc51.pdfAcesso em: 29 maio 2008

The influence of the relative position of the thiophene and pyrrole rings in donor-acceptor thienylpyrrolyl benzothiazole derivatives. A photophysical and theoretical investigation

A detailed spectroscopic and photophysical study has been carried out on a series of heterocyclic compounds -known to display nonlinear optical properties- consisting on one electron donating thienylpyrrolyl π-conjugated system functionalized with an electron acceptor benzothiazole moiety. The absorption, emission and triplet-triplet absorption together with all relevant quantum yields (fluorescence, intersystem crossing and internal conversion), excited state lifetimes and the overall set of deactivation rate constants (kF, kIC and kISC) were obtained in solution at room (293 K) and low (77 K) temperature. The optimized ground-state molecular geometries for the compounds together with the prediction of the lowest vertical one-electron excitation energy and the relevant molecular orbital contours for the compounds were also determined using the density functional theory (DFT) at the B3LYP/3 21G* level. The experimental results showed that the photophysical properties are influenced by the relative position of the pyrrole and thiophene relative to the benzothiazole groups.Fundação para a Ciência e a Tecnologia (FCT