Showing papers on "Fluorenone published in 2016"

Reversible luminescence color switching in the crystal polymorphs of 2,7-bis(2′-methyl-[1,1′-biphenyl]-4-yl)-fluorenone by thermal and mechanical stimuli

Abstract: Smart organic luminescence materials that exhibit a reversible stimuli-responsive change of luminescence color in the solid state without changing the chemical structure of their component molecules have attracted increasing interest. We employed the design strategy of introducing different weak interactions into the same molecular system to synthesize 2,7-bis(2′-methyl-[1,1′-biphenyl]-4-yl)-fluorenone (MPF). Two crystal polymorphs of MPF, green-yellow crystal G-MPF and orange crystal O-MPF, were obtained through culturing the single crystal under the different crystallization conditions of diffusing diethyl ether into its respective tetrahydrofuran or CH2Cl2 solution. Both of the two crystal polymorphs exhibit high luminous efficiency and reversible stimuli-responsive solid-state luminescence color switching. Upon heating the green crystal G-MPF or grinding the orange crystal O-MPF, their emission reversibly changes between green at 530 nm and orange at 570 nm. The X-ray single-crystal structures, characterization of the photophysical properties, powder X-ray diffraction and differential scanning calorimetry provide insight into the phase transformation and the luminescence behavior. The results indicate that the green emission of G-MPF originates from molecular J-aggregation and the orange emission of O-MPF originates from static excimers. This work discusses the relationship between the molecular stacking mode and the photophysical properties, and demonstrates a molecular design strategy to obtain stimuli-responsive organic solid-state luminescence switching materials.

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.

Direct observation of slow intersystem crossing in an aromatic ketone, fluorenone.

Abstract: Direct measurements of Single vibronic Level InterSystem Crossing (SLISC) have been performed on the fluorenone molecule in the gas phase, by time resolved photoelectron and photoion spectroscopy. Vibronic transitions above the S1 nπ* origin were excited in the 432–420 nm region and the decay of S1 and growth of T13ππ* could be observed within a 10 ns time domain. The ionization potential is measured as 8.33 ± 0.04 eV. The energy of the first excited triplet state of fluorenone, T1 has been characterized directly at 18640 ± 250 cm−1. The internal conversion of S1 to S0 is found to amount to ∼15% of the population decay, thus ISC is the dominant electronic relaxation process. ISC, although favored by the S11nπ*–T13ππ* coupling scheme, is 3 orders of magnitude less efficient than in the similar molecule benzophenone. Thus, the planarity of the fluorenone molecule disfavors the exploration of the configuration space where surface crossings would create high ISC probability, which occurs in benzophenone through surface crossings. The time evolution of S1 fluorenone is well accounted for by the statistical decay of individual levels into a quasi-continuum of T1 vibronic levels.

Thioxanthonation of fluorenone: Visible photoinitiator for radical polymerization

Abstract: Thioxanthonation of fluorenone resulted in a new visible light initiator namely, indeno [1,2-b]thioxanthene-7,13-dione (TX–FN). The detailed photophysical properties of the singlet and the triplet excited states of TX–FN are reported using steady-state absorption, fluorescence, and phosphorescence, as well as laser flash photolysis techniques. Photoinitiated polymerization of MMA with TX–FN and CQ has been investigated in the presence and absence of a co-initiator (MDEA). Additionally, Photo-DSC studies were performed both in mono- and multiacrylate systems with TX–FN and parent compounds TX and FN. The obtained results were compared for formulations consisting of CQ. At low initiator concentrations, the conversions were lower than those obtained with TX–FN. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015

Photostability Enhancement of Fluorenone-Based Two-Photon Fluorescent Probes for Cellular Nucleus Monitoring and Imaging

Abstract: A series of fluorenone-based two-photon fluorescent probes with high photostability for nucleus imaging are prepared and developed. The one- and two-photon photophysical properties exhibit these new probes possess 0.448–0.634 of fluorescence quantum yields and 469–495 GM of two-photon absorption cross sections at 800 nm femtosecond laser excitation. The luminescence “turn-on” experiment in buffer solutions indicates that 35-fold of fluorescence intensity and 68-fold fluorescence quantum yield enhancement appear between new probes and calf thymus DNA. In the nuclear double-staining experiment, the high mean colocalization coefficients of 0.92–0.96 between new probes and nuclear labeling dye Hoechst 33342 are acquired, demonstrating excellent nuclear localization in 3T3 cells. The counterstain studies by introducing commercial mitochondrial staining reagent MTR and nuclear staining dye DAPI further show good membrane permeability and counterstain compatibility in multicolor cell labeling application. The ph...

Chemical mechanism of surface-enhanced Raman scattering via charge transfer in fluorenone-Ag complex.

Abstract: The intermolecular interaction between fluorenone (FN) and silver surfaces was investigated experimentally and theoretically. The structural, electronic and optical properties of the FN–Ag complex indicate that the carbonyl group O atom in FN molecules is the adsorbed position site to attach the silver substrate through the weak bond O...Ag. The analysis of vibrational modes and Raman activity of the largely enhanced Raman peaks using two FN–Ag4-x (x = l, s) complex models reveals that only the a1 vibrational modes with C 2v symmetry are selectively enhanced, from the point view of the change of dipole moment and polarizability induced by the interaction between FN and Ag4 substrate. Furthermore, the direct visualized evidence of the surface-enhanced Raman scattering (SERS) chemical enhancement mechanism for the FN–Ag complex is presented. The results reveal that only the intermolecular charge transfer with π–π transition characterization between FN and an Ag4 cluster facilitates the resonance Raman process and is directly responsible for chemical enhancement of Raman scattering of the FN–Ag complex.

Symmetric and unsymmetric thienyl-substituted fluorenone dyes: static excimer-induced emission enhancement

Abstract: In this work, we designed and synthesized four symmetric and asymmetric thienyl-substituted fluorenone compounds, which all exhibited typical AIE properties. Besides a high solid-state fluorescence quantum yield, the enhanced luminescence of their solid-state powders showed a 170 nm red-shift (from 380 to 550 nm) in comparison with the luminescence of their dilute tetrahydrofuran solutions. The photophysical properties and single-crystal structure, combined with the theoretical calculation, revealed that the bathochromic luminescence is due to the formation of static excimers.

High-planarity diamine monomer containing fluorene or fluorenone structure and synthesis method and application thereof

Abstract: The invention discloses a high-planarity diamine monomer containing a fluorene or fluorenone structure and a synthesis method and application thereof.Halogen atoms of dihalogenation fluorene or fluorenone react with amidogen to form secondary amine; or dihalogenation fluorene or fluorenone is subjected to cyaniding, hydrolysis and chloroformylation reaction to obtain acyl chloride, and then an amido bond is formed by means of acyl chloride and amidogen; or binitro fluorene or fluorenone is used to obtain amidogen, and then a urea bond is formed by means of amidogen and isocyanate; or dihalogenation fluorene or fluorenone is subjected to Suzuki and reduction reaction to obtain amidogen, and secondary amine is formed by means of amidogen and halogen atoms; or dihalogenation fluorene or fluorenone reacts with hydroxyl to form an ether bond.Finally, binitro containing secondary amine, amido bond, urea bond and ether bond is reduced to be diamine.The lowest energy state 3D structure of the diamine monomer has high planarity, and by means of the diamine monomer, polymers such as polyamide, polyimide, polyamideimide and polyureas-imide with high inter-molecular-chain interaction force and small free volume can be prepared.

N-butylcarbazole compounds containing fluorenone and preparation method and application of N-butylcarbazole compounds

Abstract: The invention relates to N-butylcarbazole compounds containing fluorenone and a preparation method and application of the N-butylcarbazole compoundsA compound shown in the formula (IV) and a compound shown in the formula (V) serve as raw materials, a heating reflux stirring reaction is conducted for a certain time under the action of an alkaline compound, and after the complete reaction, the N-butylcarbazole compounds are obtained through filtration and column chromatographyThe reaction condition is mild, the equipment requirement is low, and operation is easy; through nuclear magnetic resonance authentication on the obtained product structure, dye-sensitized solar cells assembled with the compounds serving as dye sensitizers have high photoelectric conversion efficiency, and new applicable substances are added for screening of dye sensitizers

Novel mono-cationic fluorescent probes based on different central π-conjugated bridges for two-photon bioimaging of cellular nuclei

Abstract: A series of novel pyridine mono-cationic two-photon fluorescent probes based on different central π-conjugated bridges, fluorenone (W-pyI), dibenzothiophene (S-pyI), and dibenzofuran (F-pyI), were prepared and studied. Under one-photon excitation in a N,N-dimethylformamide solution, W-pyI, S-pyI, and F-pyI displayed fluorescence quantum yields of 0.401, 0.425, and 0.09, respectively. The two-photon fluorescence performance indicated that these probes possessed two-photon absorption cross-sections of 681 GM (W-pyI), 630 GM (S-pyI), and 620 GM (F-pyI) at 800 nm femtosecond laser excitation. The luminance “turn-on” effect of W-pyI, S-pyI, and F-pyI bonding with calf thymus DNA in Tris–HCl buffer solutions displayed 58-fold, 30-fold, and 25-fold fluorescence quantum yield increments, respectively, and 350–450% two-photon absorption cross-section enhancement. The confocal fluorescence imaging showed clear one- and two-photon fluorescence imaging. The mean co-localization coefficients between these probes and Hoechst 33342 in 3T3 cells ranged from 0.89–0.92, indicating that they showed excellent nuclear targeting abilities. The counterstaining experiments showed these probes possessed good counterstaining compatibility and membrane permeability in the application of multicolor targeting. A time-dependent fluorescence intensity test under continuous femtosecond laser irradiation showed that W-pyI possessed a longer observation time (3000 seconds) and a lower fluorescence attenuation amplitude (7.1%) in the first 300 seconds than S-pyI, F-pyI and other previously reported pyridinium derivatives, demonstrating that the central π-conjugated bridge “fluorenone” played a key role in improving photostability during probe designing for two-photon bioimaging applications.

Kinetics and Mechanistic Study of Permanganate Oxidation of Fluorenone Hydrazone in Alkaline Medium

Abstract: The oxidation kinetics of fluorenone hydrazone (FH) using potassium permanganate in alkaline medium were measured at a constant ionic strength of 0.1 mol dm−3 and at 25°C using UV/VIS spectrophotometer. A first-order kinetics has been monitored in the reaction of FH with respect to [permanganate]. Less-than-unit order dependence of the reaction on [FH] and [OH−] was revealed. No pronounced effect on the reaction rate by increasing ionic strength was recorded. Intervention of free radicals was observed in the reaction. The reaction mechanism describing the kinetic results was illustrated which involves formation of 1 : 1 intermediate complex between fluorenone hydrazones and the active species of permanganate. 9H-Fluorenone as the corresponding ketone was found to be the final oxidation product of fluorenone hydrazone as confirmed by GC/MS analysis and FT-IR spectroscopy. The expression rate law for the oxidation reaction was deduced. The reaction constants and mechanism have been evaluated. The activation parameters associated with the rate-limiting step of the reaction, along with the thermodynamic quantities of the equilibrium constants, have been calculated and discussed.

Preparation method of 3-halogenated fluorenone compound

Abstract: The invention relates to a preparation method of a 3-halogenated fluorenone compound. According to the method, 2-bromine-4-nitrobenzoic acid methyl ester is used as a starting material, and through Suzuki reaction, reduction reaction, diazotization reaction and ring closing reaction, the 3-halogenated fluorenone compound is prepared. When the method is adopted for synthesizing the 3-halogenated fluorenone, the cost is low; the condition is mild; the operation is simple; the preparation method is suitable for laboratories and industrial large-scale preparation.

Fluorenone pyridine green fluorescent material

Abstract: The invention discloses a fluorenone pyridine green fluorescent material. The fluorenone pyridine green fluorescent material is characterized in that the fluorenone pyridine green fluorescent material is a fluorenone derivative with conjugate pyridine groups, and a molecular formula of the fluorenone pyridine green fluorescent material is C23H14N2O. The fluorenone pyridine green fluorescent material has the advantages that 2, 7-diiodo-9-fluorenone and 4-pyridine boric acid are synthesized by means of coupling reaction to obtain the fluorenone pyridine green fluorescent material, synthesis steps are simple, and the yield can reach 70%-90%; pyridyl is led into fluorenone pyridine, so that the photoelectric activity, namely, the luminous efficiency, of the fluorenone pyridine green fluorescent material can be greatly improved, and the fluorenone pyridine green fluorescent material which is used as an organic small-molecule fluorescent material has a potential application prospect in the field of organic light emitting devices and the like.

Synthetic method of 3-bromo-9,9'-spirobifluorene

Abstract: The invention discloses a synthetic method of 3-bromo-9,9'-spirobifluorene and belongs to the field of organic chemical synthesis. The synthetic method is implemented by the following steps: under the protection of an inert gas, after preparation of a Grignard reagent in a methyltetrahydrofuran solvent by taking 1,3-dibromo-benzene as the starting material, the Grignard reagent is catalyzed by zinc bromide, the obtained product reacts with o-halogen iodobenzene and magnesium powder, the reaction product reacts with fluorenone, then hydration is performed, and under catalysis of sodium phosphate, 3-bromo-9,9'-spirobifluorene is obtained by intramolecular closed-loop synthesis. The synthetic method is simple in process, the raw materials are low in price and easily accessible, the product production cost is remarkably reduced, and application of fluorene derivatives to design and synthesis of organic photoelectric materials as intermediates is expanded.

Two-Photon Absorption Spectrum of Fluorenone-based Molecules

Abstract: Two-photon absorption cross-section spectra of nine Fluorenone-based composites were measured using the open-aperture Z-Scan technique. Their maxima cross-sections values are between 100 and 230 GM at around 710 nm, which are desired for applications as cellular probes.

Production method for 4-bromo fluorenone

Abstract: The invention discloses a production method for 4-bromo fluorenone, belonging to the field of organic chemical synthesis The production method is realized by comprising the following steps: reacting cyanobenzene as a raw material with o-dibromobenzene under the protection of argon gas and the actions of a palladium catalyst, a copper catalyst and an organic phosphine ligand so as to obtain 2-bromo-2'-carbonitrile biphenyl, and carrying out hydrolyzation and closed-loop synthesizing so as to obtain the 4-bromo fluorenone The production method for the 4-bromo fluorenone is simple to operate in reaction process, has low production cost and is suitable for industrial production The 4-bromo fluorenone can be applied in the fields of organic optoelectronic materials, medicines, pesticides, etc