Fluorenone

About: Fluorenone is a research topic. Over the lifetime, 1067 publications have been published within this topic receiving 17162 citations. The topic is also known as: Diphenylene ketone & 9-Oxofluorene.

Effect of meta-linkages on the photoluminescence and electroluminescence properties of light-emitting polyfluorene alternating copolymers

Abstract: Alternating copolymers poly[9,9-dihexylfluorene-alt-(1,3-phenylene)x(1,4-phenylene)1−x] (x = 0, 0.05, 0.1, 0.25, 0.5, 0.75, 1.0) were prepared, and the absorption spectra showed the expected hypsochromic shift with increasing meta linkages. In the solution photoluminescence (PL) emission spectra, all but the all-meta polymer (x = 1) showed a spectrum similar to the all-para polymer, indicating rapid intrachain energy transfer to para-linked segments. Similar spectra were observed from thin films in which inter-chain energy transfer is also available. Annealing of the thin films in air above the Tg of the polymer for several hours led to an increase in long wavelength emission, but the increase was smaller for the polymers containing more meta linkages. IR experiments confirmed the formation of fluorenone defects during the annealing process. For those polymers with high meta-linkage incorporation (i.e. 75% and 100% meta) the long wavelength emission is suppressed. This suggests that when the conjugation length of the polymer is reduced then energy transfer to fluorenone defects is less likely, due to lower exciton delocalisation and mobility. The long wavelength emission was more prominent in the electroluminescence (EL) spectra of devices prepared from the polymer, and, while initially less intense in the high meta linkages polymers, became dominant even for the all-meta linked polymer after a few minutes of operation. In summary, the meta linkages had a beneficial effect in suppressing the undesirable long wavelength emission in both the PL and EL output.

A ketone/alcohol polymer for cycle of electrolytic hydrogen-fixing with water and releasing under mild conditions.

Abstract: Finding a safe and efficient carrier of hydrogen is a major challenge. Recently, hydrogenated organic compounds have been studied as hydrogen storage materials because of their ability to stably and reversibly store hydrogen by forming chemical bonds; however, these compounds often suffer from safety issues and are usually hydrogenated with hydrogen at high pressure and/or temperature. Here we present a ketone (fluorenone) polymer that can be moulded as a plastic sheet and fixes hydrogen via a simple electrolytic hydrogenation at -1.5 V (versus Ag/AgCl) in water at room temperature. The hydrogenated alcohol derivative (the fluorenol polymer) reversibly releases hydrogen by heating (80 °C) in the presence of an aqueous iridium catalyst. Both the use of a ketone polymer and the efficient hydrogen fixing with water as a proton source are completely different from other (de)hydrogenated compounds and hydrogenation processes. The easy handling and mouldable polymers could suggest a pocketable hydrogen carrier.

Reaction mechanisms for the hydrothermal oxidation of petroleum derived aromatic and aliphatic hydrocarbons

Abstract: The oxidative decomposition patterns of some aromatic and aliphatic hydrocarbons, which are components of crude and refined oil, have been studied in sub-critical and supercritical water conditions. The compounds include biphenyl, fluorene, hexadecane and eicosane. These compounds were oxidized in deionized water with hydrogen peroxide at temperatures of 300, 350, 370 and 380 °C, and at corresponding pressures of 10.5, 17.0, 21.0 and 22.5 MPa, respectively, using a batch stainless steel reactor. In one set of experiments, the reactions were stopped and quenched once the specified temperatures were reached. In another set of experiments, the reactions were held for a period of 1 h each at the designated temperatures. Results showed that the aromatic hydrocarbons were much more resistant to hydrothermal oxidation that the aliphatic ones. Fluorene was however more reactive than biphenyl as it was easily oxidized to 9-Fluorenone, which was the major intermediate compound found. The fluorenone produced xanthone via epoxidation, while loss of CO gave biphenyl. Further oxidation produced compounds similar to those found during the oxidation of biphenyl itself. These compounds were mainly phenol, benzofuran, dibenzofuran, hydroxybiphenyls, acetophenone, benzaldehyde and benzoic acid. More complex decomposition patterns were observed for hexadecane and eicosane, involving both gas-phase and liquid-phase mechanisms. The major intermediate compounds were ketones and carboxylic acids, with small amounts of aldehydes. All the ketones bore their functional groups on carbon no. 2, indicating that they were formed by the oxidation of their corresponding 1-alkenes. Finally, the configuration of the reaction vessel was found to have affected the decomposition of these hydrocarbons especially the aliphatics.