255875-86-6Relevant academic research and scientific papers
Evidence of a Photoinduced Electron-Transfer Mechanism in the Fluorescence Self-quenching of 2,5-Substituted Selenophenes Prepared through in Situ Reduction of Elemental Selenium in Superbasic Media
De Salles, Helena Domingues,Coelho, Felipe Lange,Paix?o, Douglas Bernardo,Barboza, Cristina Aparecida,Da Silveira Rampon, Daniel,Rodembusch, Fabiano Severo,Schneider, Paulo Henrique
, p. 10140 - 10153 (2021)
A series of new 2,5-disubstituted selenophene derivatives are described from elemental selenium and 1,3-diynes in superbasic media. The activation of elemental selenium in a KOH/DMSO system allows cyclization with conjugated diynes at room temperature. The cyclization reaction is extended to a broad range of functional groups, for which photophysics were experimentally and theoretically investigated. The selenophene derivatives present absorption maxima in the UV-A region and fluorescence emission in the violet-to-blue region. Fluorescence decay profiles were obtained showing a monoexponential decay with fast fluorescence lifetimes (～0.118 ns), as predicted by the Strickler-Berg relations. In general, in both investigations, no dependence on the solvent polarity on the absorption and emission maxima location was observed. On the other hand, solvents and substituents are shown to play a role in the fluorescence quantum yield values. In addition, a fluorescence self-quenching behavior could be observed, related to a photoinduced electron-transfer mechanism. Theoretical calculations performed at the MP2/ADC(2)/cc-pVDZ level of theory were performed in order to investigate the photophysical features of this series of selenophene derivatives.
Synthesis of diphenyl-diacetylene-based nematic liquid crystals and their high birefringence properties
Arakawa, Yuki,Nakajima, Shunpei,Ishige, Ryohei,Uchimura, Makoto,Kang, Sungmin,Konishi, Gen-Ichi,Watanabe, Junji
scheme or table, p. 8394 - 8398 (2012/07/28)
We synthesized two series of diphenyl-diacetylene (DPDA)-based materials with alkoxy and alkyl tails of length m (DPDA-OCm and DPDA-Cm, respectively), and measured their nematic-phase birefringence (Δn) as a function of wavelength and temperature. We found that Δn decreases with an increase in m, possibly by a dilution effect of the low-Δn alkyl tail. Further, of the two series, Δn was found to be relatively higher in the DPDA-OCm materials, with the highest value of 0.4 obtained for DPDA-OC1 at 550 nm at 10 °C below the isotropic-to-nematic transition temperature. Further, we observed the temperature dependence for Δn, which is proportional to the order parameter (s). From extrapolation to s = 1 (the perfect orientation state), it is speculated that the DPDA-O moiety has the potential to afford a very large Δn of 0.9. The Royal Society of Chemistry 2012.
