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.

Carbon-hydrogen bond functionalization approach for the synthesis of fluorenones and ortho-arylated benzonitriles.

Abstract: A sequence consisting of palladium-catalyzed benzamide ortho-arylation/reaction with (CF3CO)2O was developed allowing a convenient one-pot synthesis of ortho-arylated benzonitriles and fluorenone derivatives. The outcome of this transformation is dependent on the amide N-alkyl substituent. Dehydration of ortho-arylated N-cyclohexyl-benzamides by (CF3CO)2O results in efficient production of benzonitriles. In contrast, o-arylated N-propylbenzamides are converted to fluorenone derivatives.

Fast and Slow Time Regimes of Fluorescence Quenching in Conjugated Polyfluorene−Fluorenone Random Copolymers: The Role of Exciton Hopping and Dexter Transfer along the Polymer Backbone

Abstract: The luminescence decay kinetics of polyfluorene copolymers containing fluorenone units randomly distributed along the polymer chain have been studied by steady-state and time-resolved fluorescence techniques in toluene solution. The typical green emission from polyfluorenes containing 9-fluorenone moieties is only observed if the 9-fluorenone group is covalently attached to the polymer. Small-angle neutron scattering (SANS) measurements indicate that, independent of the 9-fluorenone fraction, all the studied copolymers adopt an open wormlike conformation. This prevalent 1-dimensional arrangement confirms that the green emission observed with polyfluorenes is not the result of excimer formation in the typical sandwich-like conformation. Analysis of time-resolved fluorescence decays by the maximum entropy method (MEM) collected at the polyfluorene emission (415 nm) and by global analysis of decays collected at 415 and 580 nm (the 9-fluorenone defect emission wavelength) clearly indicates two different time regimes in the population of the fluorenone defect: one occurring in the time interval of 10 to 30 ps and a second one occurring in the time range from 70 to 200 ps. While the slower process shows a linear dependence with the 9-fluorenone fraction, compatible with a hopping migration process along the polymer chain, the faster process does not show such a dependence and instead suggests a short-range Dexter mechanism. These findings are in agreement with our previous work where the presence of a faster component was suggested.

Fluorenone core donor–acceptor–donor π-conjugated molecules end-capped with dendritic oligo(thiophene)s: synthesis, liquid crystalline behaviour, and photovoltaic applications

Abstract: We have synthesized a new series of donor–acceptor–donor (D–A–D) π-conjugated molecules, consisting of fluorenone core end-capped with dendritic oligo(thiophene)s of increasing generation (abbreviated as FG0, FG1, and FG2). In view of the application of these new organic semiconductors in photovoltaic devices, we have explored their spectroscopic, redox, and structural properties. The thermal behaviour of the new organic semiconductors was investigated by differential scanning calorimetry and polarized-light optical microscopy. Liquid crystalline behaviour has been found in the case of FG1, corresponding to a smectic ordering with a triclinic symmetry (Smobl) upon heating, as confirmed by variable temperature small-angle X-ray diffraction studies. In order to evaluate their photovoltaic performances, devices with an active area of 0.28 cm2 were fabricated. Under AM1.5 simulated sunlight (100 mW cm−2) conditions, a device containing FG1/[70]PCBM blends showed a power conversion efficiency of ca. 0.8%.

Population and decay of keto states in conjugated polymers

Abstract: Using time-resolved and steady-state photoluminescence techniques, fluorene/fluorenone copolymers have been studied to investigate the role of keto defects in degraded polyfluorene. Keto sites can be populated via migration from polyfluorene singlets, thereby quenching the polyfluorene fluorescence, and via direct photon absorption. In the former case, the migration process dominates all thermal and interchain variability in the efficiency of quenching. No annihilation process of fluorenone triplets and no interchain processes such as excimer formation participate in the defect emission itself.