Showing papers on "Fluorenone published in 2005"
TL;DR: Purely organic and catalytic systems of anthraquinones and N-hydroxyphthalimide efficiently promote oxygenation of hydrocarbons with dioxygen under mild conditions, e.g., fluorene can be converted completely to fluorenone with 85% yield at 80 degrees C.
129 citations
TL;DR: Studies of the photophysical properties of OFnK in solution and thin film by steady-state and time-resolved fluorescence spectroscopic measurements suggest efficient funneling of excitation energy from the photoexcited fluorene segments to the low-energy fluorenone sites by both intra- and intermolecular hopping events whereby they give rise to green emission.
Abstract: Oligofluorenes (a trimer, pentamer, and heptamer) with one fluorenone unit in the center (OFnK: n=3, 5, or 7) were synthesized and used as models to understand the origin of the low-energy emission band in the photoluminescence and electroluminescence spectra of some polyfluorenes. All compounds form glasses with T(g) at 30 degrees C (OF3 K), 50 degrees C (OF5 K) and 57 degrees C (OF7 K). Oligomers OF5 K and OF7 K exhibit smectic liquid crystal phases that undergo transition to isotropic melts at 107 and 205 degrees C, respectively. Oligomer OF5 K could be obtained in form of single crystals. The X-ray structure analysis revealed the helical nature of the molecule and a helix reversal defect located at the central fluorenone unit. The packing pattern precludes formation of excimers. Electrochemical properties were investigated by cyclic voltammetry. The ionization potential (I(p)) and electron affinity (E(a)) were calculated from these data. Studies of the photophysical properties of OFnK in solution and thin film by steady-state and time-resolved fluorescence spectroscopic measurements suggest efficient funneling of excitation energy from the photoexcited fluorene segments to the low-energy fluorenone sites by both intra- and intermolecular hopping events whereby they give rise to green emission. Intermolecular energy transfer was investigated by using a model system composed of a highly defect free polyfluorene PF2/6 doped by OFnK. Forster-type energy transfer takes place from PF2/6 to OFnK. The energy-transfer efficiency increases predictably with increasing concentration of OFnK.
101 citations
TL;DR: In this paper, a comparison of the features of the steady-state fluorescence spectra of fluorenone in various kinds of media demonstrates that two spectroscopically distinct forms of fluornone in the S 1 state, namely the non-hydrogen-bonded (or free) molecule as well as the hydrogen-bunded complex, are responsible for the dual-fluorescence behavior of fluorescence behavior of normal alcoholic solvents at room temperature (298 K).
Abstract: Steady-state fluorescence and time-resolved absorption measurements in pico- and femtosecond time domain have been used to investigate the dynamics of hydrogen bond in the excited singlet (S 1 ) state of fluorenone in alcoholic solvents. A comparison of the features of the steady-state fluorescence spectra of fluorenone in various kinds of media demonstrates that two spectroscopically distinct forms of fluorenone in the S 1 state, namely the non-hydrogen-bonded (or free) molecule as well as the hydrogen-bonded complex, are responsible for the dual-fluorescence behavior of fluorenone in solutions of normal alcoholic solvents at room temperature (298 K). However, in 2,2,2-trifluoroethanol (TFE), a strong hydrogen bond donating solvent, emission from only the hydrogen-bonded complex is observed. Significant differences have also been observed in the temporal evolution of the absorption spectroscopic properties of the S 1 state of fluorenone in protic and aprotic solvents following photoexcitation using 400 nm laser pulses. An ultrafast component representing the solvent-induced vibrational energy relaxation (VER) process has been associated with the dynamics of the S 1 state of fluorenone in all kinds of solvents. However, in protic solvents, in addition to the VER process, further evolution of the spectroscopic and dynamical properties of the S 1 state have been observed because of repositioning of the hydrogen bonds around the carbonyl group. In normal alcohols, two different kinds of hydrogen-bonded complex of the fluorenone-alcohol system with different orientations of the hydrogen bond with respect to the carbonyl group and the molecular plane of fluorenone have been predicted. On the other hand, in TFE, formation of only one kind of hydrogen-bonded complex has been observed. These observations have been supported by theoretical calculations of the geometries of the hydrogen-bonded complexes in the ground and the excited states of fluorenone. Linear correlation between the lifetimes of the equilibration process occurring because of repositioning of the hydrogen bonds and Debye or longitudinal relaxation times of the normal alcoholic solvents establish the fact that, in weakly hydrogen bond donating solvents, the hydrogen bond dynamics can be described as merely a solvation process. Whereas, in TFE, hydrogen bond dynamics is better described by a process of conversion between two distinct excited states, namely, the non-hydrogen-bonded form and the hydrogen-bonded complex.
101 citations
TL;DR: In dialkyl-substituted PFs that is hydrogen-free at the 9'-position of the fluorene, blue emission with very weak green emission is observed from end-capped polydioctylfluorene (PFO) for both photoluminescence and electroluminescent spectra, while the low-energy green emission at 507 nm is very pronounced only in uncapped PFO (P FOun).
Abstract: Green emission in polyfluorenes (PFs) has been attributed to aggregation or excimer emission, but recently it was reassigned as an on-chain fluorenone defect. We show here that, in dialkyl-substituted PFs that is hydrogen-free at the 9‘-position of the fluorene, blue emission with very weak green emission is observed from end-capped polydioctylfluorene (PFO) for both photoluminescence and electroluminescence spectra, while the low-energy green emission at 507 nm is very pronounced only in uncapped PFO (PFOun). The facts that there is no detectable infrared absorption at around 1721 cm-1 due to >CO stretching vibration in PFOun and no charge-trapping occurring in the light-emitting device from PFOun are in contrast with those found in the literature-reported copolymers with fluorenone units, which have detectable infrared absorption at 1721 cm-1 and charge-trapping in devices. We found that this green emission at around 507 nm originates from the end-group-enhanced aggregation by use of UV−vis absorption, ...
81 citations
TL;DR: In this paper, the external power conversion efficiencies and the external quantum efficiency of the various TVF-, PTVF-, and PDOBTF-based photovoltaic cells have been determined.
Abstract: Oligomers and regioregular copolymers based on fluorenone subunits are synthesized and used in bulk-heterojunction photovoltaic cells. These are 2,7-bis(5-[(E)-1,2-bis(3-octylthien-2-yl)ethylene])-fluoren-9-one (TVF), theproduct of its oxidative polymerization, that is, (poly[(5,5'-(bis-(E)-1,2-bis(3-octylthien-2-yl)ethylene]-alt-(2,7-fluoren-9-one)]) (PTVF), and an alternate copolymer of fluoren-9-one and di-n-alkylbithiophene, namely poly[(5,5'-(3,3'-di-n-octyl-2,2'-bithiophene))-alt-(2,7-fluoren-9-one)] (PDOBTF). The interpenetrating networks of active layers consisting of these new compounds as electron donors and of methanofullerene [6,6]-phenyl-C 6 1 -butyric acid methyl ester (PCBM) as an acceptor exhibit an extended absorption band in the visible part of the spectrum with an absorption edge close to 700 nm. The external power conversion efficiencies (EPCEs) and the external quantum efficiency of the various TVF-, PTVF-, and PDOBTF-based photovoltaic cells have been determined. EPCE values of up to 1% have been achieved, which demonstrate the potential of fluorenone-based materials in solar cells. It has also been demonstrated that fluorenone subunits are efficient photon absorbers for the conversion. Interestingly, some cell parameters such as, for example, the fill factor, have been improved as compared to photovoltaic cells with a "classical" poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene]/PCBM active layer, fabricated and studied under the same experimental conditions.
44 citations
TL;DR: The results suggest the possibility of the oxidation of the 9-bialkylfluorene sites and propose that the degradation of the alkyl in the side chain can help the radicals to propagate in the chain reaction.
Abstract: We have investigated the thermal degradation in air by Fourier transform infrared spectroscopy of a ladder-type copolymer containing fluorene units in the backbone (Me-LPF), to reveal the formation of the ketonic defects. As thermal treatment of Me-LPF film at 200 °C in air proceeds, a new group of complex absorption bands due to degradation products arises in the range between 1800 and 1600 cm-1. The observed overlapping bands were separated and assigned by utilizing the second-derivative IR spectral analysis, which can narrow the peak width to one-third of the originals and thereby eases the analysis. The degraded products were assigned as fluorenone (1718 cm-1) and benzophenone (Ar−(CO)−Ar) (1665 cm-1), formed by the oxidation of the backbone, and acylphenone (Ar−(CO)-R) (1685 cm-1) from the side chain. The fluorenone was found to be the major component among the degraded products in the main chain, and the time and temperature dependence indicated that the oxidation is a kind of autocatalytic radical-...
36 citations
TL;DR: An intramolecular charge transfer complex (ICTC) between PF units and 9-fluorenone to explain the appearance of the new emission band and global analysis of time resolved fluorescence decays collected at 415 nm (PF emission) and 580 nm (the ICTC emission) show that three exponentials are generally needed to achieve excellent fits.
Abstract: The quenching process of fluorescence emission in polyfluorene (PF) due to the presence of intramolecular 9-fluorenone (9FL) moieties is studied in dilute toluene solution as a function of 9FL content in eight copolymers containing both fluorene and fluorenone units (PF/FLx). The absorption spectrum of PF/FLx copolymers clearly shows a new absorption band, redshifted relatively to the PF and 9-fluorenone absorption, which increases in intensity when the fluorenone fraction increases and also decreases with solvent polarity. Fluorescence emission spectra of PF/FLx show that this redshifted and unstructured emission does not coincide with the 9-fluorenone emission and, with increasing solvent polarity, it further redshifts and decreases in intensity. An isoemissive point is clearly observed on the fluorescence emission spectra of PF/FLx as a function of fluorenone content, showing that the new emission band is formed at the expense of PF. We propose the formation of an intramolecular charge transfer complex...
32 citations
TL;DR: A set of monodisperse oligo(9,9-dioctylfuorene)s, each containing only one fluorenone unit, was synthesized by using iterative Suzuki cross-coupling and iododesilylation reactions.
Abstract: A set of monodisperse oligo(9,9-dioctylfuorene)s, each containing only one fluorenone unit, was synthesized by using iterative Suzuki cross-coupling and iododesilylation reactions. Their optical properties were also investigated.
29 citations
Abstract: The chiral fluorenol mesogen (R)-2-(1-octyloxy)-7-((4-undecyloxybenzoyl)oxy)fluoren-9-ol ((R)-3) was synthesized using a combined directed metalation-cross coupling strategy. The SmC* liquid crystal phase formed by the fluorenol mesogen is more stable and has a wider temperature range than that formed by the fluorenone presursor, which may be ascribed to intermolecular hydrogen bonding. The spontaneous polarization (PS) of (R)-3 at 10 K below the SmC*-I phase transition temperature is −10.7 nC/cm2. Molecular modeling based on the Boulder model suggests that the intrinsic conformational bias favoring one orientation of the fluorenol dipole moment along the polar axis of the SmC* phase is very subtle and implies that self-assembly via hydrogen bonding may play a role in enhancing polar order. Results from FT-IR spectroscopy, dilution with achiral SmC additives, and deuterium exchange experiments suggest that the spontaneous polarization is enhanced by the formation of fluorenol dimers via OH−OC hydrogen bon...
28 citations
TL;DR: In this paper, a co-oligomer based on fluorenone and thiophene moieties was designed for application as active material in organic field effect transistors, which was fully characterized in terms of its electrochemical, structural, morphological and electrical properties.
27 citations
TL;DR: In this article, the effect of keto defects in fluorene units on the performance of organic field effect transistors (OFETs) was examined based on BFTT and biphenyl end-capped fused bithiophenes (BPTT) oligomers.
Abstract: The effect of keto defects in fluorene units on the performance of organic field-effect transistors (OFETs) was examined based on fluorene end-capped fused bithiophenes (BFTT) and biphenyl end-capped fused bithiophene oligomers (BPTT). The formation of keto defects after various periods of UV illumination in air on BFTT films was confirmed by the increase of the long-wavelength emission at 2.1–2.3eV in the photoluminescent (PL) spectrum and the generation of a Fourier transfer infrared (FTIR) peak at 1721cm−1, corresponding to the carbonyl stretching mode of the fluorenone moiety. For both BPTT films irradiated in air and BFTT in nitrogen, i.e., a keto-free system, no increase in long-wavelength emission in the PL spectrum, was found and the peak corresponding to the carbonyl stretching mode of the fluorenone moiety was absent in the FTIR spectrum. The threshold voltage, i.e., switch-on voltage, of the OFETs was increased and the field-effect mobility and on-state drain current were rapidly decreased afte...
TL;DR: Germene 1 reacts with the CO and CS double bonds respectively of phenylisocyanate and methylisothiocyanates by formal [2+2] cycloadditions, leading to four-membered ring derivatives 2 and 3 as discussed by the authors.
TL;DR: Molecular modeling and NMR spectra analysis of the model compounds suggest that an essential difference in oxacyclophanes yields is caused by formation of quasi-cyclic intermediates, which are preorganized for macrocyclization owing to intramolecular pi-pi stacking interactions between the fluorenone units.
Abstract: The first three representatives of the new family of oxacyclophanes incorporating two 2,7-dioxy-fluorenone fragments, connected by [-CH 2 CH 2 O-] m spacers (m=2-4), have been synthesized. The yield of the smallest oxacyclophane (m=2) is considerably higher with respect to the larger ones (m=3 and m=4), which are formed in comparable yields. Molecular modeling and NMR spectra analysis of the model compounds suggest that an essential difference in oxacyclophanes yields is caused by formation of quasi-cyclic intermediates, which are preorganized for macrocyclization owing to intramolecular π-π stacking interactions between the fluorenone units. The solid-state structures of these oxacyclophanes exhibit intra- and intermolecular π-π stacking interactions that dictate their rectangular shape in the fluorenone backbone and crystal packing of the molecules with the parallel or T-shape arrangement. The crystal packing in all cases is also sustained by weak C-H...O hydrogen bonds. FAB mass spectral analysis of mixtures of the larger oxacyclophanes (m=3 and m=4) and a paraquat moiety revealed peaks corresponding to the loss of one and two PF 6 - counterions from the 1:1 complexes formed. However, no signals were observed for complexes of the paraquat moiety with the smaller oxacyclophane (m=2). Computer molecular modeling of complexes revealed a pseudorotaxane-like incorporation of the paraquat unit, sandwiched within a macrocyclic cavity between the almost parallel-aligned fluorenone rings of the larger oxacyclophanes (m=3 and m=4). In contrast to this, only external complexes of the smallest oxacyclophane (m=2) with a paraquat unit have been found in the energy window of 10 kcal mol - 1 .
TL;DR: A crownophane containing both 2,7-dioxyfluorenone and 1,5-dioxynaphthalene moieties bridged by triethylene glycol units has been synthesized and used as a highly efficient template for the preparation of the first fluorenone-containing [2] catenane incorporating a cyclobis(paraquat-p-phenylene) tetracation as a second macrocyclic component as mentioned in this paper.
TL;DR: In this article, two new soluble arylenevinylene-based polymers comprising of an electron-donating carbazole unit and an electron accepting 2,1,3-benzothiadiazole (or fluorenone) unit in the main chain were synthesized by Heck polycondensation.
TL;DR: In this article, the authors compared voltammetric and spectroelectrochemical behavior of two newly synthesized conjugated polymers, which show the same chemical constitution but different type of regioregularity, is compared.
Patent•
21 Nov 2005TL;DR: In this paper, high heat polyethersulfone compositions are provided which possess unexpectedly high glass transition temperatures, which are derived from fluorenone bisphenols such as 9,9-bis(4-hydroxyphenyl)fluorene, and structural units derived from at least one biphenyl-bissulfone such as 4,4′-bis((4-chlorophenyl)sulfonyl)-1, 1,1′-biphenyl.
Abstract: High heat polyethersulfone compositions are provided which possess unexpectedly high glass transition temperatures. The polyethersulfone compositions comprise structural units derived from fluorenone bisphenols such as 9,9-bis(4-hydroxyphenyl)fluorene, and structural units derived from at least one biphenyl-bissulfone such as 4,4′-bis((4-chlorophenyl)sulfonyl)-1,1′-biphenyl. The novel polyethersulfone compositions may further comprise structural units derived from one or more biphenols such as 4,4′-biphenol, bisphenols such as BPA, or other electrophilic sulfone monomers, such as bis(4-chlorophenyl)sulfone. In one embodiment, the polyethersulfone composition of the present invention comprises structural groups derived exclusively from 9,9-bis(4-hydroxyphenyl)fluorene and 4,4′-bis((4-chlorophenyl)sulfonyl)-1,1′-biphenyl and exhibits a single glass transition of greater than 300° C.
TL;DR: In this article, the reduction of hydrazones is suggested to proceed through a reductive cleavage of the nitrogen-nitrogen bond followed by a reduction of the carbon−nitrogen link.
TL;DR: The chiral fluorenone mesogens (R) as discussed by the authors were synthesized usin 1998, and were used to synthesize the following mesogens: 1.1.fluoro, 2.2.octyloxy, 7.4.undecyloxybenzoyloxy, 3.3.azafluoren, and 9.9.one.
Abstract: The chiral fluorenone mesogens (R)‐1‐fluoro‐2‐(2‐octyloxy)‐7‐(4‐undecyloxybenzoyloxy)fluoren‐9‐one (2) and (R)‐2‐(2‐octyloxy)‐7‐(4‐undecyloxybenzoyloxy)‐3‐azafluoren‐9‐one (3) were synthesized usin...
TL;DR: Fluorenyl ester-armed cyclen gave fluorenone and related decomposition compounds upon photoirradiation and offered the naked-eye detection of Ca2+ ion in aqueous samples.
Abstract: Fluorenyl ester-armed cyclen gave fluorenone and related decomposition compounds upon photoirradiation. The reaction was effectively suppressed by the formation of an octacoordinated Ca2+ complex while Na+ and other alkali/alkaline earth metal cations had little influence. Since the production efficiency of fluorescent fluorenone related well to the concentration of the Ca2+ ion, the photoreaction of this armed cyclen offered the naked-eye detection of Ca2+ ion in aqueous samples.
TL;DR: Cyclic voltammetry of SAMs reveals two reversible single-electron reduction waves for fluorenone derivatives 7a,b and 11, and three single-Electron reductions for the dicyanomethylene-fluorene 8b, providing the first observation of a radical trianion species in SAMs.
Abstract: Nitrofluoren-9-one and nitrofluoren-9-dicyanomethylene electron acceptors 7, 8, and 11 functionalized with a terminal thioctic acid unit have been synthesized from 2,4,5,7-tetranitrofluorenone. The self-assembled monolayers (SAMs) of these compounds on gold, formed via gold-sulfur interaction, have been fully characterized by electrochemical, FTIR, ellipsometry, and contact angle measurements. Cyclic voltammetry of SAMs reveals two reversible single-electron reduction waves for fluorenone derivatives 7a,b and 11, and three single-electron reductions for the dicyanomethylene-fluorene 8b, providing the first observation of a radical trianion species in SAMs. The tendency of the thioctic anchor to form multilayers via disulfide links is noted.
TL;DR: In this article, the authors studied the absorption spectra of 9-fluorenone in polar and non-polar solvents, and observed the shift in these bands as the solvent was changed from polar to nonpolar and the quantitative treatments of the shifts allowed the transition to be assigned as n®p* or p®p*.
Abstract: Absorption spectra of 9-fluorenone had been studied in polar and non-polar solvents. Maximum of four bands were observed; the shift in these band as the solvents were changed from polar to non-polar were noted. The quantitative treatments of the shifts allowed the transition to be assigned as n®p*or p®p*.
TL;DR: In this article, a catalytic system of anthraquinones and N-hydroxyphthalimide was proposed to promote oxygenation of hydrocarbons with dioxygen under mild conditions.
Abstract: Purely organic and catalytic systems of anthraquinones and N-hydroxyphthalimide efficiently promote oxygenation of hydrocarbons with dioxygen under mild conditions, e.g., fluorene can be converted completely to fluorenone with 85% yield at 80 °C.
TL;DR: A number of new 2,7-dihydroxyfluorenone derivatives containing side-chain oligoethylene glycol fragments with terminal hydroxy, p-tolylsulfonyl, azido, and amino groups were synthesized.
Abstract: A number of new 2,7-dihydroxyfluorenone derivatives containing side-chain oligoethylene glycol fragments with terminal hydroxy, p-tolylsulfonyl, azido, and amino groups were synthesized. When the side chain has a certain length, an interaction between the terminal group and the fluorenone fragment becomes possible, which considerably changes photoluminescence properties of the molecule.
TL;DR: In this article, the effect of structure on the spectroscopic and kinetic characteristics of the triplet excited states as well as the transient free radical intermediates formed under reducing and oxidizing conditions was investigated.
TL;DR: Tritiated fluorenone 2 was prepared from 2-iodofluorenone 1 by halogen-tritium exchange with specific activity of 17 Ci/mmol and gave the corresponding tritiated fluorenol 3.
Abstract: Tritiated fluorenone 2 was prepared from 2-iodofluorenone 1 by halogen-tritium exchange. The product had specific activity of 17 Ci/mmol. The product 2(after dilution with unlabeled congener) on reduction with NaBH4gave the corresponding tritiated fluorenol 3.