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Fires constitute a significant threat due to the pollutants emitted and the destruction they cause. People who take part in firefighting operations must be equipped with appropriate tools, including special clothing that will allow them to work and guarantee safety. One of the threats is represented by compounds from the PAH (Polycyclic Aromatic Hydrocarbons) group, which are characterized by high toxicity and carcinogenicity. Therefore, it is important that the materials used constitute a barrier to contamination. Various materials from which individual elements of special firefighter's clothing are made were tested. Additionally, the effect of height on the possibility of sorption of PAH compounds on a given type of material was analyzed. Based on the obtained analysis results, it was found that both the type of material and the zone in which the clothing items are used are important in the sorption processes of pollutants. For example, PAHs with high molecular weight are most likely to settle on rubber, i.e., the material from which shoes are made, with the exception of Chrysene, whose presence was found primarily in aramid fibers, i.e., the material from which trousers and jackets are made. However, among PAHs with low molecular weight, compounds such as Methylnaphthalene,1- and Fluorene were sorbed on the rubber surface in large quantities. The only compound that is present in comparable amounts in all materials is Acenaphthylene. Data in this area may be important for taking further actions related to the modification of materials used in special fire brigade clothing and in their cleaning processes. [ABSTRACT FROM AUTHOR]

Latent fingerprints are a significant carrier of information for a court expert. To detect this type of forensic trace, what is necessary is a method that is easy to use, compact, and versatile. The research aimed to investigate the physicochemical properties of luminescent substances of donor–π–acceptor systems in terms of their potential use in detecting hidden fingerprints. During the research, a group of fluorene compounds consisting of the (-CH=C(CN)(COOR)) moiety was designed and successfully synthesized. The optical, electrochemical, and aggregation-induced emission properties were studied. The aggregation-induced emission of compounds has been studied in the mixture of THF (as a good solvent) and water (as a poor solvent) with different water fractions ranging from 0% to 99%. Due to the molecular structure, substances showed different affinities to organic traces. As a result, it was noticed that all compounds showed the AIE phenomenon, while during tests on latent fingerprints, it was observed that two substances had particularly forward-looking features in this field. [ABSTRACT FROM AUTHOR]

[Display omitted] • S0 → S1 electron excitation in polyfluorene in most cases is localized in central 8–9 units. • Changing conformation may lead to small changes of effective conjugation length. • Substituents in side radicals do not have a significant effect on the localization of excitation. This study investigates the excited states within oligomeric fluorene compounds containing up to 20 monomer units in various conformations. Furthermore, it explores the impact of donor and acceptor substituents in the side chain. Time-dependent density functional theory (TD-DFT) simulations were conducted at the B3LYP/def2-svp level of theory. Results indicate localized excitation, primarily spanning 8–13 monomer units, irrespective of donor and acceptor substituents. These findings offer insights into charge carrier mobility, electroluminescent properties of polyfluorenes, and facilitate the design of novel materials within this class. [ABSTRACT FROM AUTHOR]

We describe here a facile synthesis of 9-arylfluorenes and spirobifluorenes from readily available 1,1-diarylmethylamines and iodoarenes through Pd-cataylsed C(sp2)–H arylation and a sequential deaminative annulation. The reaction features high efficiency and simplicity of operation, constituting an interesting shortcut to access fluorene compounds. [ABSTRACT FROM AUTHOR]

We have demonstrated amplified spontaneous emission (ASE) restoration and threshold reduction by introducing a novel water/alcohol soluble conjugated macroelectrolyte,tris(4-(7-(9,9-di(hexyl-1-N,N-diethanolamino)-9H-fluoren-2-yl)-9,9-di(hexyl-1-N,N-diethanolamino)-9H-fluoren-2-yl)phenyl)amine (TPAOH), serving as an interfacial layer between the gain media layer, dioctyl substituted polyfluorene (PFO), and the Ag electrode layer. By optimizing the film thickness of TPAOH, enhanced ASE performance has been achieved with the lowest threshold of 21 μJ/cm2, demonstrating 3.5-fold reduction from 74 μJ/cm2. Atomic force microscopy results showed good compatibility between the TPAOH film and the PFO layer. The results suggest a facile and low-cost solution-processing interfacial technique to construct efficient organic semiconductor lasers in the presence of metallic electrodes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Deoxygenative cross-coupling of aryl ketones with anilines/phenols was established. • Diverse anilines, phenols, and arylketones were compatible with this catalytic system. • Applications of bioactive molecules verified potential practicality of this method. • This strategy merits attention regioselectivity, scalability and practicability. Construction of arylmethanes is one of the forefronts and significant subjects in the field of organic synthesis due to the prevalence of this motifs in pharmaceuticals and biological compounds. Herein, an iridium-catalyzed deoxygenative cross-coupling of aryl ketones with anilines/phenols was established to synthesize diverse collections of arylmethanes. This process generates benzyl carbocationic intermediates from a wide range of aryl ketones, which were captured with anilines/phenols to access the corresponding arylmethanes under mild conditions. The fluorene compounds were also successfully afforded using ortho -substituted aryl ketones as inputs via intermolecular deoxygenative cross-coupling. This method is viable for applications in cross-coupling of complex bioactive molecules and drugs by this iridium-catalyzed deoxygenative cross-coupling process. [ABSTRACT FROM AUTHOR]

Excited-state intramolecular proton transfer (ESIPT) has been well investigated in recent years, whereas we investigated the system containing double hydrogen bonds. We explore the influence of solvent polarity on the proton transfer mechanism for 9,9-dimethyl-3,6-dihydroxy-2,7-bis(4,5-dihydro-4,4-dimethyl-2-oxazolyl)fluorene compound ((Oxa-OH)2). We consider three solvents with different polarities: cyclohexane, chloroform and acetonitrile. Various analytical methods indicate that hydrogen bonding is enhanced in the first excited state, which facilitates the proton transfer within the excited-state molecule. The frontier molecular orbital theory is employed to demonstrate that the system is subjected to photoexcitation to generate charge density redistribution. Three-dimensional potential energy surfaces are also constructed along the direction of hydrogen bond elongated, and their corresponding projection in the X-axis and Y-axis planes are plotted. The comparison of the potential barriers and the transition state structures of each proton transfer path reveals the excited-state intramolecular single proton transfer mechanism of the system. By comparing the potential barriers in different solvents, we also propose a mechanism that can modulate the excited-state proton transfer by changing the solvent polarity. [ABSTRACT FROM AUTHOR]

Anthropogenic pollution of marine ecosystems is one of the main sources of polycyclic aromatic hydrocarbons (PAHs). Marine bivalves are often used as bioindicators of environmental pollution due to their wide distribution and capability of xenobiotic bioaccumulation. The aim of the present study was to assess the presence of PAHs in soft tissues of wedge clams Donax trunculus (Linnaeus, 1758), collected from sublittoral sandy habitats at different locations off the Bulgarian Black Sea coast. Wedge clams from the different locations showed variations in the content of accumulated PAHs' compounds. The concentrations of PAHs were measured by gas chromatography system with mass spectrometry detection. The total PAHs content (sum of 13 PAHs' compounds) measured was in the range from 5.59 to 50.50 ng/g wet weight and was comparable with other European studies. The compounds phenanthrene and fluorene were most abundant in all analyzed samples. The results showed that low molecular weight (LMW) PAHs (2 and 3 aromatic rings) were predominant, accounting for 91% of the total PAHs levels, while high molecular weight (HMW) PAHs (4-5- and 6-rings) presence was 8.9% on average. The ratio LMW/HMW PAHs was higher than one, suggesting predominant pollution of petrogenic origin. The concentrations of benzo (a)pyrene did not exceed the limit set in EC Regulation although it was detected in 20% of the analyzed samples. In conclusion, maximum overall PAHs content was found in clams from Arkutino, while minimum PAHs content was present in samples from Elenite. The Sum PAH4 (sum of four polycyclic aromatic hydrocarbons: benzo[a]pyrene, chrisene, benzo[a]anthracene, and benzo[b]fluoranthene) in the wedge clams for all localities studied was below legislation limits. Data from the present research can be used for assessing pollution levels in the marine environment and also risk of human exposure to PAHs using D. trunculus as bioindicator species. [ABSTRACT FROM AUTHOR]

A new oligomeric fluorophore, which combines the advantage of polycyclic aromatic compounds and fluorene structures has been synthesized. The new compound shows necessary film-forming properties, is readily soluble in the majority of organic solvents and emits in the blue range of solar light with maximum at 465 nm. The compound has a rather high quantum yield and can serve as both the electroluminescent dopant and the conducting light-emitting matrix for designing completely soluble blue and white OLEDs by both inkjet printing and spin coating. The new oligomeric fluorophore is a promising example of highly fluorescent oligomer, rarely used class of materials, in contrast to polymers and small molecules. Such oligomers can be useful for future completely soluble OLEDs. [ABSTRACT FROM AUTHOR]

The heavy oil waste (HOW) containing polyaromatic hydrocarbon (PAHs) is a persistent organic pollutants (POPs) that difficult to degrade. The new PAH degrading consortium was investigated from HOW contaminated soil in North Sumatera of Indonesia. The isolation, selection and identification of polyaromatic hydrocarbon degrading bacteria from soil contaminated by HOW was conducted to solve a bioremediation process. The isolation microbes from soil contaminated by HOW was performed using a minimum ONR7a media and followed on marine agar media for purification purposes. From the performed isolation results, 11 isolates were able to degrade PAHs compounds, such as phenanthrene, dibenzothiophene, or fluorene compounds. They grew at pH range of 4.8-8.2 and performed on emulsification activity in paraffin from 0.150-0.662. Three of them showed the best performance on HOW biodegradation capability and then successfully selected and identified as Salipiger sp., Bacillus altitudinis, and Ochrobactrum anthropi. using 16S rDNA. The HOW biodegradation as TPH-degradation were 38.66%, 59.60%, and 47.16%, respectively. Those isolated bacteria could potentially be as bioremediation agents to develop on bioremediation process for soils contaminated by HOW. [ABSTRACT FROM AUTHOR]

An efficient [3+3] benzannulation of Morita–Baylis–Hillman carbonates with 1-indanylidenemalononitrile was achieved under metal-free reaction conditions selectively delivering a wide range of functional multi-substituted fluorene or fluorenone compounds in high yields, respectively (up to 86% yield). Moreover, experiments and quantum chemical calculations were also performed to study the mechanism of the transformation. [ABSTRACT FROM AUTHOR]

This work presents new rod-like compounds being fluorene derivatives linked with other parts of the core at 2 and 7 positions – its synthesis and properties. The fluorene moiety is located in the central position of the four rings molecular core. The chain system in most cases was symmetrical and limited to pentyl or hexyl chains. To study the influence of the lateral substituents on mesomorphic properties two types of substituents have been incorporated, centrally located various short alkyl groups at fluorene's 9,9 positions and outer core fluorosubstitutions located at side phenyl rings. All synthesised compounds exhibit liquid crystalline properties, where for laterally non-substituted and fluorosubstituted derivatives the dominant phases are smectics, while the nematics phases (nematic and chiral nematic – observed mostly on cooling cycle) occurs for compounds having alkyl substituents at 9,9 positions of fluorene. The synthetic methodology and mesomorphic properties of title compounds will be presented in detail as well as photophysical properties such as UV-visible absorption spectra and fluorescence spectra. [ABSTRACT FROM AUTHOR]

The title compound, C37H42, is a new mesogenic compound containing the fluorene moiety. It exhibits enantiotropic nematic liquid crystalline behaviour with melting at 125 °C and isotropization at 175 °C. The crystallographically independent unit contains two molecules oriented face‐to‐edge with respect to each other. The two molecules have nearly the same conformation of the bis‐phenyl fluorene moiety. The molecular packing in the crystal phase is nematic‐like. [ABSTRACT FROM AUTHOR]

[Display omitted] • Six new fluorene–based low molar weight derivatives were synthesized. • They showed similar LUMO (ca. 3.1 eV) and HOMO energy levels in the range of – 6.01 to – 5.35 eV. • Their spectroscopic properties in solution and solid state were investigated. • The molecules with phenyl, TPA and naphthalene units as thin film emitted light (λ em = 462 – 589 nm). • Compound with TPA and phenyl units in organic–inorganic PV cell increased PCE by more than 30%. Fluorene–based low molar weight derivatives were synthesized in Suzuki reactions by using key starting materials 9–benzylidene–2,7–dibromofluorene or 3–(2,7–dibromofluoren–9–ylmethylen)–9–ethylcarbazole and various aryl boronic acids. Photophysical properties of the compounds were investigated in different solutions as well as in solid state. The thermal investigations showed that the obtained compounds are highly thermally stable with temperatures of 5% mass loss (T 5%) in the range of 311–432 °C. Some of the compounds also exhibited very high glass transition temperatures exceeding 125 °C. The presented molecules were electrochemically active and showed the energy band gap below 2.97 eV. The investigations were supported by DFT calculations and the photovoltaic ability of the presented compounds was tested in the organic–inorganic solar cells. [ABSTRACT FROM AUTHOR]

• 24 cyclic compounds were assessed for DNA reactivity in embryo-fetal chicken livers. • Unsubstituted compounds yielded negative results. • Most compounds with various substitutions produced DNA damage. • Substituted polycyclic compounds were more potent compared to monocyclic chemicals. • These finding support use of chicken egg model for structure-activity assessment. DNA-damaging activities of twenty-four structurally diverse unsubstituted and substituted cyclic compounds were assessed in embryo-fetal chicken livers. Formation of DNA adducts and strand breaks were measured using the nucleotide 32P-postlabelling (NPL) and comet assays, respectively. Unsubstituted monocyclic benzene, polycyclic fused ring compound naphthalene, covalently connected polycyclic ring compound biphenyl, and heterocyclic ring compound fluorene did not produce DNA damage. Amino-substituted monocyclic compounds, aniline and p -phenylenediamine, as well as polycyclic 1-naphthylamine were also negative. In contrast, carcinogenic monocyclic methyl-substituted anilines: o -toluidine, 2,6-xylidine, 3,4-dimethylaniline, 4-chloro- o -toluidine; 2 methoxy-substituted methylaniline: p -cresidine; 2,4 and 2,6 diamino- or dinitro- substituted toluenes all produced DNA damage. Genotoxic polycyclic amino-substituted 2-naphthylamine, 4-aminobiphenyl, benzidine, methyl-substituted 3,2′-dimethyl-4-aminobiphenyl and 4-dimethylaminoazobenzene as well as amino- and nitro- fluorenes substituted at the 1 or 2 positions also were positive in at least one of the assays. Overall, the DNA damaging activity of cyclic compounds in embryo-fetal chicken livers reflected the type and position of the substitution on the aromatic ring. Additionally, substituted polycyclic compounds exhibited higher DNA-damaging potency compared to monocyclic chemicals. These results are congruent with in vivo findings in other species, establishing chicken eggs as a reliable system for structure-activity assessment of members of groups of related chemicals. [ABSTRACT FROM AUTHOR]

The synthesis of [1,1′-bis(o-carboranyl)]boranes was achieved through the deprotonation of 1,1′-bis(o-carborane) reagents followed by salt metathesis with (iPr)2NBCl2. X-ray crystallography confirms planar central BC4 rings and Gutmann–Beckett studies reveal an increase in Lewis acidity at the boron center in comparison to their biphenyl congener, 9-borafluorene. [ABSTRACT FROM AUTHOR]

The design of efficient catalysts for the selective oxidation of sp3 C–H bond with air at low temperature is of great importance to the scientific and industrial community. In this work, we design a CeO2–δ modified CuFe2O4 catalyst by a post‐modification method for the selective oxidation of fluorene under an air atmosphere and N‐hydroxyphthalimide (NHPI) at 60 °C. HRTEM results indicate that CeO2–δ nanoclusters sized around 5 nm are successfully modified on the surface of CuFe2O4. XPS and H2‐TPR results show that CeO2–δ modification would favor oxygen transfer at lower temperature due to the synergetic effect between CuFe2O4 and CeO2–δ with rich Ce3+/Ce4+ couples. The results demonstrate that CuFe2O4@CeO2–δ‐0.05 with 4.20 wt.‐% Ce present the best catalytic performance with 94 % conversion of fluorene and excellent reusability at least five times. It is anticipated that the modification of CeO2–δ nanoclusters on the surface leads to increased oxygen activation and transfer to CuFe2O4, which favors the activation of NHPI to phthalimide‐N‐oxyl (PINO) radicals and exhibits an improved catalytic performance. Our results provide some guidance on the design of efficient catalysts by the surface modification strategy. CeO2–δ modification with 4.20 wt.‐% Ce on the surface of CuFe2O4 nanoparticles favors oxygen transfer at lower temperature and leads to better catalytic activity than that of pure CuFe2O4 for the aerobic selective oxidation of fluorene due to the synergetic effect between CuFe2O4 and CeO2–δ with Ce3+/Ce4+. [ABSTRACT FROM AUTHOR]

Abstract A series of non-fullerene acceptors based on the indeno[1,2- b ]fluorene central moiety, with thiophene or 3-octylthiophene as π-bridge and either non-fluorinated or fluorinated 2-(3-oxo-2,3-dihydro-1 H -inden-1-ylidene) malononitrile as end-capping groups (namely ICBF-O, ICBF, FICBF-O and FICBF), have been designed and synthesized. The effect of alkylation of the π-bridge and fluorination of the end-capping groups on the absorption spectra, energy levels, active layer morphology and photovoltaic performance were systematically investigated. Alkylation upshifts the molecular LUMO levels and thereby a high open circuit voltage (V oc) of 1.06 V was obtained. However, the larger band gap induced by alkylation led to lower short circuit current (J sc). Fluorinated acceptors display lower V oc but higher J sc and FF compared with non-fluorinated acceptors, coinciding with their lower LUMO levels, narrower band gaps and favourable morphology. As a result, the non-fullerene solar cells (NFSCs) based on FICBF showed the highest PCE of 7.41% among these four acceptors. The ICBF based device delivered a comparatively high V oc of 0.99 V and a PCE of 6.07%. The results demonstrated that indeno[1,2- b ]fluorene is a promising building block for efficient NFSCs. Graphical abstract Four new small-molecule acceptors based on indeno[1,2- b ]fluorene were designed and synthesized. The impact of alkyl chain of the thiophene spacer and fluorination of end-capping groups on the molecular band gaps, energy levels and photovoltaic performance was systematically investigated. Image 1 Highlights • Four new small-molecule acceptors based on indeno[1,2- b ]fluorene were synthesized. • The impact of alkyl chain and fluorination on molecular properties was systematically investigated. • Non-fullerene solar cells based on FICBF showed the highest efficiency of 7.41%. [ABSTRACT FROM AUTHOR]

Abstract Organic wide bandgap semiconductor is a hot research topic in optoelectronic fields. In this work, a series of diphenylether-, 9,9-biphenylfluorene- and tetraphenylsilane-centered wide bandgap materials are designed and synthesized. Comprehensive experiments and theoretical calculations are conducted to investigate their intrinsic thermal stability, photophysical property, electrochemical behavior and device performance, aiming at exploring the potentials of oxygen, sp3-hybridized carbon and silicon atoms for wide bandgap materials. They all can interrupt molecular conjugation to generate wide bandgaps. By modification of appropriate donor and acceptor, relatively high triplet energy level (E T) can be obtained in the resulting materials. Quantum chemical calculations indicate the sort of triplet energy levels of N-carbazole > fluorene > benzonitrile, which fully supports the experimental results. Tetraphenylsilane-based materials display lower LUMO levels than corresponding diphenylether- and 9,9-biphenylfluorene-centered materials owing to the dπ-pπ conjugation. Among them, DCzSiPy/FIrpic doped device gives the best device performance with maximum current efficiency of 35.6 cd/A and maximum external quantum efficiency of 16.8%, demonstrating the superiority of tetraphenylsilane skeleton. 9,9-Biphenylfluorene-based doped devices have comparable efficiencies with tetraphenylsilane-hosted ones, meaning 9,9-biphenylfluorene unit also can be a good constructing skeleton for wide bandgap host materials. Graphical abstract Their potentials of diphenylether-, 9,9-biphenylfluorene- and tetraphenylsilane-centered wide bandgap hosts for FIrpic are investigated. Tetraphenylsilane-based doped devices give better performance demonstrating the superiority of tetraphenylsilane skeleton. Image 1 Highlights • A series of different wide bandgap host materials for FIrpic are investigated. • Tetraphenylsilane-based hosts display lower LUMO levels owing to dπ-pπ conjugation. • DCzSiPy/FIrpic doped device possesses the highest EQE of 16.8%. [ABSTRACT FROM AUTHOR]

Open-shell diradicaloids have been intensively investigated recently due to their attractive and unique optical, electronic and magnetic properties. However, open-shell diradicaloids with non-planar conjugated frameworks are less studied, especially helical-shaped π systems. In this work, we synthesized tetraindeno-based singlet biradicals in a helical geometry, bridged by a curved cyclobutenyl o-quinodimethane molecule. Large diradical characters and extremely small singlet–triplet energy gaps, as well as unusual half-field transitions (forbidden ΔMs = 2) were revealed for these 3D diradicals. [ABSTRACT FROM AUTHOR]

9‐Gallafluorenes were synthesized from 9‐zincafluorene·tmeda as an alternative to 2,2′‐biphenylenmercury and 2,2′‐dilithiobiphenyl. The zincafluorene was found to be only one possible form of a biphenylene zinc. In dependence of the synthetic conditions a dimeric zinc bridged structure resulted, too. The gallafluorenes obtained were stabilized by nitrogen donors or formed dimers in case of 9‐tert‐butoxygallafluorene. That means, all of these derivatives contained tetra coordinated gallium centers in a planar heterofluorene moiety. The phenyl‐substituted gallafluorene as a tmeda adduct as well as an intramolecularly stabilized o‐(dimethylamino)methylphenyl derivative were investigated for their luminescence properties, which were similar for both compounds and did not only show fluorescence but phosphorescence in the visible region. All new metallafluorenes have been characterized by X‐ray crystallography. [ABSTRACT FROM AUTHOR]

ABSTRACT: A series of phthalonitrile terminated polyaryl ether nitrile oligomers containing fluorene group (BPPENs) were synthesized and cured in the presence of bis[4‐(4‐aminophenoxy)phenyl]sulfone. Additionally, the quartz fiber reinforced composites were prepared by hot‐pressing process. The structure of oligomers was characterized by 1H‐NMR and GPC. The curing behavior of BPPENs was studied by DSC, IR, and rheological tests in detail. Thermal stability and mechanical properties were also investigated. The results showed that the oligomers showed excellent solubility. BPPENs could be dissolved in common solvents at ambient temperature. TGA and DMA results showed that the cured polymer and composites possessed excellent thermal properties with high residual weight of 72.4% at 1000 °C and 5% thermal degradation temperature (T5%) of 548 °C under inert atmosphere. The bending strength of quartz fiber reinforced composites was about 500 MPa, exhibiting good mechanical property. The products could be used as high performance polymers or a modifier for heat‐resistant resins. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46606. [ABSTRACT FROM AUTHOR]

Abstract: We recently reported a new one‐pot transformation of alkynes into 9,10‐diarylphenanthrene derivatives, which proceeds through efficient catalyst‐free 1,2‐carboboration of alkynes with 9‐chloro‐9‐borafluorene (1Cl), which yields a chlorodibenzoborepin, followed by oxidative deborylation/C−C coupling of the resultant chlorodibenzoborepin. Herein, based on new experimental observations for the catalyst‐free 1,2‐carboboration by using diphenylacetylenes and 1Br or 1OTf as well as results from theoretical investigations, we show how the substituent on the boron atom of 9‐borafluorene affects the reactivity toward alkynes. Kinetic studies indicated that the 1,2‐carboboration of diphenylacetylene with the borafluorenes can be described as a second‐order reaction. The reaction rates became larger with the increase in the acceptor numbers of the borafluorenes (1Br>1OTf>1Cl), which was evaluated by the Gutmann–Beckett method based on a Lewis acid/base complexation in solution. Interestingly, thermodynamic parameters obtained experimentally indicated that the term of activation entropy, rather than the term of activation enthalpy, largely contributes to the reaction rate. This experimental result was also supported by DFT calculations. Overall, among the borafluorenes examined, 1Br exhibited the highest reactivity toward a wide variety of substituted diarylacetylenes. Similar to the case of chlorodibenzoborepin, when the dibenzoborepin obtained from 1Br or 1OTf was oxidized by using FeCl3, an efficient deborylation/C−C coupling took place to give the corresponding 9,10‐diarylphenanthrene derivatives in high yields. [ABSTRACT FROM AUTHOR]

Abstract Novel polycyclic aromatic compounds (FBTPhO3 and FBTPhO4), which are based on bis(benzothiophene)-fused fluorene functionalized with oligo(ethylene glycol)-substituted phenyl, were synthesized through an intramolecular electrophilic cyclizing reaction. Thermal measurements revealed their excellent thermal stability and amorphous state. Photoluminescence spectra suggested that they both show deep blue light emission. Cyclic voltammetry tests exhibited that the ionization potentials of FBTPhO3 and FBTPhO4 are 5.67 and 5.68 eV, respectively, implying their good inoxidizability. These compounds may be promising building blocks for high-performance optoelectronic functional materials. [ABSTRACT FROM AUTHOR]

Four aza-9,9′-spirobifluorenes (aza-SBFs) with nitrogen atom at different positions of one fluorene moiety were synthesized to study the structure-properties relationships. α-Aza-SBF and β-aza-SBF possessed almost completely separated the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), while γ-aza-SBF and δ-aza-SBF showed overlapped HOMO and LUMO orbitals. The aza-SBFs showed excellent bipolar features and good thermal stabilities than those of SBFs. The maximum current efficiencies (CE) of α-, β-, γ-, and δ-aza-SBF -based OLEDs were 28.8, 24.9, 25.5, and 27.2 cd/A, respectively. Compared to the SBF, all of four aza-SBFs showed better devices performances. The CE and power efficiency (PE) of OLED based on α-aza-SBF was 28.8 cd/A and 22.6 lm/W, while the SBF-based OLED was only 12.3 cd/A and 8.2 lm/W. The maximum external quantum efficiency of α-aza-SBF-based OLED was 15.4%, which was 2.5 times than that of the SBF-based one (6.6%) due to introduction of nitrogen improving electron transporting. Novel materials based on these components and their potential applications in organic electronics were expected due to their excellent bipolar features. [ABSTRACT FROM AUTHOR]

A series of new aromatic polyamides (PAs) and copolyamides (CPAs) containing fluorene group have been synthesized through polycondensation reaction. The chemical structure was confirmed by Fourier transform infrared and proton nuclear magnetic resonance (1H NMR). PAs and CPAs exhibited the higher thermal stability (Td15 > 378°C in nitrogen), the higher glass transition temperature (Tg > 345°C), and excellent solubility in polar solvent. Gas transport properties of the PA and CPA membranes were investigated using different single gases (hydrogen (H2), carbon dioxide (CO2), oxygen (O2), methane (CH4), and nitrogen (N2)). We discussed the effect of chemical structure and operating temperature on gas transport properties. The results show that PA-1 containing a hexafluoroisopropylidene moiety exhibited the highest gas permeability (PH2 = 12.71 Barrer, PCO2 = 12.26 Barrer, and PO2 = 2.62 Barrer) and reasonably good selectivity (α(H2/N2) = 27.63, α(CO2/N2) = 26.65, and α(O2/N2) = 5.70) at 25°C and 1 atm. For all the membranes, gas permeability gradually increased with the increase in operating temperature, while the selectivity gradually decreased. These gas permeation results were well correlated with fractional free volume, interchain d-spacing (dsp), and intermolecular interaction. [ABSTRACT FROM AUTHOR]

A series of amino-containing fluorene-based bisphthalonitrile (AFPN) monomers with alkyl or alkoxy groups were successfully produced by the reaction of 4-nitrophthalonitrile with 9, 9-bis (3-alkyl (or alkoxy)-4-aminophenyl)-2, 7-dihydroxylfluorene in the presence of potassium carbonate by a nucleophilic substitution reaction. The chemical structures of the synthesized monomers were confirmed by the Fourier transform infrared (FTIR), proton nuclear magnetic resonance, and carbon-13 nuclear magnetic resonance analyses. The synthesized monomers’ curing behaviors were evaluated by FTIR and differential scanning calorimetry, and a rheological analysis was performed to evaluate their respective processabilities. Moreover, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were performed for the thermomechanical, thermal, and thermo-oxidative analyses of the polymers. The results confirmed that the newly prepared phthalonitrile (PN) monomers with alkyl or alkoxy groups exhibited a self-promoted curing behavior. The rheological analysis suggested that the processing windows of the synthesized monomers were wider than that of APFN monomer bearing no flexible group. DMA and TGA revealed that the cured polymers exhibited high glass transition temperature (358–416°C) and the char yields at 800°C under nitrogen were between 70% and 77%. Moreover, the introduction of alkyl or alkoxy groups into the PN monomers’ backbones slightly reduced the thermal stability of the resulting polymers. [ABSTRACT FROM AUTHOR]

Novel poly(aryl ether sulfone ketone)s (PAESK) were synthesized from bisphenol A (BPA), 9,9′-bis(4-hydroxyphenyl) fluorene (BHPF), 4,4′-dichlorodiphenylsulfone (DCS) and 4,4′-difluorobenzophenone (DFB) via nucleophilic substitution polymerization, which were subsequently used to fabricate ultrafiltration membrane by phase-inversion method for high temperature condensed water treatment. The obtained high molecular weight co-polymers with fluorene group with good solubility and good thermal stability, can be easily cast into flexible, white and non-transparent flat films. The influence of molar ratio of BPA and BHPF on the properties of the prepared co-polymers and membranes was investigated in detail. SEM study of the morphology of the membranes indicated that the prepared membranes possessed homogeneous pores on the top surface and were sponge-like or finger-like in cross-section. Pure water flux of the membranes increased from 71.87 L·m−2·h−1 to 247.65 L·m−2·h−1, while the retention of BSA decreased slightly, and the water contact angle decreased from 82.1° to 55.6° with the PVP concentration from 0 wt% to 10 wt%. With increasing concentration of PVP, the mechanical properties of membranes decreased, while the thermal stability increased. The permeate flux measurement showed that the PAESK membrane had the potential for high temperature condensed water treatment. [ABSTRACT FROM AUTHOR]

Four fluorene-alt-di-2-thienyl-benzothiadiazole (FTBT) based oligomers with different number of repeated units are selected as electron acceptors in P3HT:oligomer solar cells. The effect of oligomer length on the phase separation behavior has been studied in detail. It is disclosed that the oligomer length strongly affects the film morphology and hence the exciton dissociation probability, charge transport as well as recombination characteristics. The short oligomer F1TBT1 is prone to aggregate and form large-scale phase separation which impedes exciton dissociation in the blend films. With increasing the acceptor length, large-scale aggregations are gradually suppressed due to the weakened migration ability of long FTBT oligomers in polymer matrix. Meanwhile, electron mobilities are enhanced with extending the oligomer length, which is favorable to suppress charge recombination in the blends. Finally, optimal photovoltaic performances with a PCE of 4.19% are achieved in P3HT:F3TBT3 based solar cell that compromises well between efficient exciton dissociation and balanced charge transport, which is almost three times higher than the F1TBT1 based device. This work highlights that tailoring the oligomer length can be used as an effective strategy to control phase separation and to enhance the photovoltaic performance in non-fullerene based polymer solar cells. [ABSTRACT FROM AUTHOR]

Blue organic light-emitting diodes (OLEDs) are of great significance in the fields of flat-panel display and solid-state lighting. Herein, three carbazolyl-substituted blue emitters, namely SAF-CzB , SAF-2CzB , and F-2CzB , were designed and synthesized. Two compounds SAF-CzB and SAF-2CzB possess a rigid spiro[acridine-9,9′-fluorene] (SAF) central core. The counterpart F-2CzB , which contains 9,9-dimethylfluorene as core was, also researched for comparative purpose. The introduction of SAF into fluorene-based materials could simultaneously improve their thermal stability, hole injection and transport ability, as well as prevent the fluorenone defect. The compound SAF-2CzB shows a higher decomposition temperature ( T d ) of 534 °C compared to that of F-2CzB (488 °C). The hole-transporting property of SAF-2CzB is also better than that of F-2CzB demonstrated by single-carrier devices. The presence of a bulky spiro-annulated triphenylamine moiety at the C9 position of the fluorene might suppress the fluorenone defect. Non-doped OLED based on SAF-2CzB as the emitting layer shows the best performance with maximum current efficiency (CE) of 4.07 cd A −1 and power efficiency (PE) of 1.83 l m W −1 , compared with 3.03 cd A −1 and 1.08 l m W −1 for SAF-CzB , 3.14 cd A −1 and 1.23 l m W −1 for F-2CzB . In particular, both SAF-2CzB - and F-2CzB -based device exhibit good color stability with CIE coordinate of (0.16, 0.11) at the voltage of 7–12 V. [ABSTRACT FROM AUTHOR]

A series of novel red-emitting conjugated polymers were synthesized, adopting host-guest technique, with fluorene-carbazole backbone and low bandgap unit, 1,1-dimethyl-3,4-di(triphenylamine)-2,5-dithienyl)silole, as the guest chromophore. Those materials were well characterized by nuclear magnetic resonance, elemental analysis, absorption and fluorescence spectra, and cyclic voltammetry. The HOMO energy levels of these three copolymers locate within the range of −5.40∼−5.33 eV which are greatly elevated compared with that of polyfluorene and match the work funtions of ITO and ITO/PEDOT:PSS (about −4.7 eV and −5.0 eV, respectively) better, indicating smaller hole-injection barrier. Polymeric light-emitting diodes (PLED) with the configuration of ITO/PEDOT:PSS(40 nm)/PFO-Cz-TPATST(80 nm)/CsF(1.5 nm)/Al(100 nm) and ITO/PEDOT:PSS(40 nm)/PFO-Cz-TPATST(80 nm)/1,3,5-tris(2- N -phenylbenzimidazolyl)benzene (TPBI) (30 nm)/CsF(1.5 nm)/Al(100 nm) were fabricated respectively. Highest luminous efficiency of 1.06 cd A −1 was achieved. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of bisalkynylated derivatives of tetrabenzo[a,c,p,r]heptacene and tetrabenzo[a,c,l,n]pentacene via two‐/fourfold Stille reactions involving a 9‐stannafluorene and suitable tetrabromoacenes is reported. These triphenylene‐“winged” heptacenes are surprisingly stable and maintain a significant portion of the electronic properties of heptacenes. [ABSTRACT FROM AUTHOR]

Ternary organic solar cells (OSCs) hold great promise in enabling the roll-to-roll printing of environmentally friendly, mechanically flexible, and cost-effective photovoltaic devices. Nevertheless, many ternary OSCs display the best power conversion efficiency (PCE) with a thin active layer at the thickness of about 100 nm, which can be hardly translated in to the roll-to-roll processing with high reproducibility. In this paper, the ternary OSCs with a high PCE and a thick active layer were reported, which was obtained by incorporating a dye small molecule named as 2’-(5,5’-(9,9-dioctyl-9H-fluorene-2,7-diyl)bis(thiophene-5,2-diyl))bis(methanylylidene))-bis(3-ethyl-2-thioxothizolidin-4-one) (FTR)) into a PTB7-Th:PC71BM binary system. Specifically, the addition of FTR into the PTB7-Th:PC71BM binary system was found to improve the hole mobility of the active layer, which resulted in faster charge transport, more efficient charge separation, and higher PCEs even in the presence of a thick active layer. The single-junction PTB7-Th:FTR:PC71BM ternary OSCs with the active layer thickness of 160 nm presented an outstanding PCE of 9.4%, which was much higher than that 7.5% of the PTB7-Th:PC71BM binary OSCs with the active layer thickness of 160 nm. Notably, the PTB7-Th:FTR:PC71BM ternary OSCs devices exhibited excellent thickness insensitivity. In other words, the PTB7-Th:FTR:PC71BM ternary OSCs device with a thick active layer (200 nm) could still demonstrate a high PCE of over 8.2%, which was well compatible to the requirement for future roll-to-roll printing. [ABSTRACT FROM AUTHOR]

The reaction of 1-adamantylphosphaalkyne with 9-phenyl-9-borafluorene resulted in the insertion of the P≡C unit into the endocyclic B-C bond, generating a seven-membered 1,3-boraphosphaalkene. The mechanism was investigated computationally, indicating that the reaction proceeds via a bond metathesis pathway. [ABSTRACT FROM AUTHOR]

On-surface synthesis is a successful approach to the creation of carbon-based nanostructures that cannot be obtained via standard solution chemistry. In this framework, we have established a novel synthetic pathway to one-dimensional conjugated polymers composed of indenofluorene units. Our concept is based on the use of ortho-methyl groups on a poly(para-phenylene) backbone. In this situation, surface-assisted oxidative ring closure between a methyl and the neighboring aryl moiety gives rise to a five-membered ring. The atomically precise structures and electronic properties of the obtained indenofluorene polymers have been unambiguously characterized by STM, nc-AFM, and STS, supported by theoretical calculations. This unprecedented synthetic protocol can potentially be extended to other polyphenylenes and eventually graphene nanoribbons, to incorporate five-membered rings at desired positions for the finetuning of electronic properties. [ABSTRACT FROM AUTHOR]

We investigated whether helicity and/or chirality of cellulose tris(phenylcarbamate) (CTPC) can transfer to noncharged, nonhelical oligo- and polyfluorenes when CTPC was employed as a solution processable homochiral platform of a D-glucose-skeletal polymer. Noticeably, CTPC revealed the solvent-driven, ambidextrous intermolecular helicity/chirality transfer capability to these fluorenes. The chiroptical inversion characteristics of circularly polarized luminescence (CPL) and the corresponding CD spectra were realized by solely choosing a proper achiral solvent and/or achiral cosolvent. When the solution of PF6 and CTPC in tetrahydrofuran (THF) was cast on a quartz substrate, the dissymmetry ratio of CPL (gCPL) from the polymer film showed gCPL = +2.1 x 10-3 at 429 nm. Conversely, when dichloromethane (DCM) was used as the solvent, the CPL sign was inverted to gCPL = -2.4 x 10-3 at 429 nm. The dissymmetry ratio of Cotton CD band (gCD) from the THF solution was gCD = +3.2 x 10-3 at 392 nm; conversely, from the DCM, the CD sign inverted to gCD = -0.8 x 10-3 at 371 nm. The sign and magnitude of the gCD values were interpreted to a London dispersion term (δd) of Hansen solubility parameter (δ) of the casting solvents rather than a dipole-dipole interaction term (δp) and a hydrogen bonding interaction term (δh) of the δ values and dielectric constant (ε). Analysis of solvent-driven changes in FTIR spectra, wide-angle X-ray diffraction profiles, and differential scanning calorimetry diagrams indicated that solvent driven on-off switching of multiple hydrogen bonds due to three urethane groups of CTPC play the key for the inversion. Intermolecular CH/π and π-π interactions among phenyl rings and alkyl groups were assumed to be crucial for helicity/chirality transfer capability based on molecular mechanics and molecular dynamics simulations of PF6-CTPC hybrids. These chiroptical inversion characteristics arose from solvent-driven order-disorder transition characteristics of the CTPC helix rather than a helix-helix transition of CTPC itself. [ABSTRACT FROM AUTHOR]

A polydentate ligand bridged by a fluorene group, namely 9,9‐bis(2‐hydroxyethyl)‐2,7‐bis(pyridin‐4‐yl)fluorene (L), has been prepared under solvothermal conditions in acetonitrile. Crystals of the three‐dimensional metal–organic framework (MOF) poly[[[μ3‐9,9‐bis(2‐hydroxyethyl)‐2,7‐bis(pyridin‐4‐yl)fluorene‐κ3N:N′:O]bis(methanol‐κO)(μ‐sulfato‐κ2O:O′)nickel(II)] methanol disolvate], {[Ni(SO4)(C27H24N2O2)(CH3OH)]·2CH3OH}n, (I), were obtained by the solvothermal reaction of L and NiSO4 in methanol. The ligand L forms a two‐dimensional network in the crystallographic bc plane via two groups of O—H…N hydrogen bonds and neighbouring two‐dimensional planes are completely parallel and stack to form a three‐dimensional structure. In (I), the NiII ions are linked by sulfate ions through Ni—O bonds to form inorganic chains and these Ni‐containing chains are linked into a three‐dimensional framework via Ni—O and Ni—N bonds involving the polydentate ligand L. With one of the hydroxy groups of L coordinating to the NiII atom, the torsion angle of the hydroxyethyl group changes from that of the uncoordinated molecule. In addition, the adsorption properties of (I) with carbon dioxide were investigated. [ABSTRACT FROM AUTHOR]

A series of structurally similar 1-substitued heteroaryl fluorene derivatives were prepared in a simple single step reaction, oxidized to fluorenones and then both, fluorenes and fluorenones, were methylated to enhance the solubility and increase the affinity to DNA/RNA. Interactions of both, fluorene and fluorenone analogues with various ds-DNA, ds-RNA revealed strong ds-DNA/RNA binding, and various thermal stabilization effects. Most intriguingly, some fluorene derivatives showed opposite fluorescence change (increase for ds-RNA and decrease for ds-DNA), which was not previously reported for any fluorene analogue. CD experiments along with other methods support ds-DNA minor groove binding and major groove ds-RNA binding. All compounds showed negligible interaction with G-quadruplex DNA. Very low cell cytotoxicity of studied compounds combined with very efficient cellular uptake makes these fluorescent dyes safe for laboratory applications. Moreover, especially compounds which show opposite fluorescence response to ds-DNA and ds-RNA, are promising lead compounds for further studies aimed toward ds-RNA-specific fluorescence markers. [ABSTRACT FROM AUTHOR]

The title compound, C24H18N2O4S, crystallizes in the orthorhombic P212121 space group, indicating the existence of only one enantiomer with an S configuration of the chiral center in the crystal phase. The dihydropyrimidine ring adopts a twist-boat conformation while the quinone ring is slightly nonplanar. In the crystal, molecules are linked by weak C--H. . .O and C--H. . .S hydrogen bonds and C--H. . .. interactions. In addition, a short intermolecular S. . .N contact of 3.250 (3) Å indicates an interaction between the S atom and the π-system of the thiazole ring. [ABSTRACT FROM AUTHOR]

A ruthenium–nitrosyl derivative of formula [RuII(CzT)(bipy)(NO)](PF6)3 [CzT = 4′‐(N‐ethylcarbazol‐3‐yl)‐2,2′:6′,2′′‐terpyridine, bipy = 2,2′‐bipyridine] has been synthesized and fully characterized, and compared with the previously reported [RuII(FT)(bipy)(NO)](PF6)3 complex [FT = 4′‐(9,9‐dihexyl‐9H‐fluoren‐2‐yl)‐2,2′:6′,2′′‐terpyridine]. Additionally, the X‐ray crystal structure of [RuII(CzT)(bipy)(NO2)](PF6), the precursor of [RuII(CzT)(bipy)(NO)](PF6)3, is reported. The presence of a tertiary amine in the carbazole unit leads to redshifted charge‐transfer transitions towards the electron‐withdrawing Ru–NO fragment and hence enhanced two‐photon absorption (TPA) properties. In contrast, the quantum yield of the NO· photorelease process is lower for the carbazole‐containing complex. The issue of optimization of the TPA versus NO·‐release capabilities is addressed. [ABSTRACT FROM AUTHOR]

Several palladium catalysts with bulky phosphine ligands other than t-Bu3P were investigated for Suzuki-Miyaura catalyst-transfer condensation polymerization (CTCP). When the model reaction of 2,5-dibromothiophene with phenylboronic acid ester was carried out with a variety of Pd precatalysts in the presence of K3PO4 as a base, we found that the use of di-tert-butyl(4-dimethylaminophenyl)phosphine (AmPhos) Pd as a precatalyst resulted in exclusive formation of diphenyl-substituted thiophene. Polymerization of thiophene monomer and fluorene monomer with an initiator generated in situ from AmPhos Pd precatalyst and 4-iodobenzonitrile proceeded via the CTCP mechanism, affording polythiophene (P3HT) and polyfluorene with low dispersity and controlled polymer ends. Furthermore, (tolyl)PdAmPhos(Br) (7) was synthesized, and its polymerization properties were investigated. We found that polymerization of thiophene monomer with a mixture of 7 and CsF that had been stirred for 1 h prior to polymerization afforded P3HT with the dispersity of 1.18, which was considerably narrower than that in the case of CTCP with PhPd(t-Bu3P)Br. Block copolymerization of thiophene monomer and fluorene monomer with 7 proceeded irrespective of the polymerization order, in contrast to PhPd(t-Bu3P)Br-catalyzed block copolymerization, in which only chain extension with thiophene monomer from a polyfluorene propagating end took place and the reverse chain extension did not. [ABSTRACT FROM AUTHOR]

Abstract: Materials based upon hexa‐peri‐hexabenzocoronenes (HBCs) show significant promise in a variety of photovoltaic applications. There remains the need, however, for a soluble, versatile, HBC‐based platform, which can be tailored by incorporation of electroactive groups or groups that can prompt self‐assembly. The synthesis of a HBC–fluorene hybrid is presented that contains an expanded graphitic core that is highly soluble, resists aggregation, and can be readily functionalized at its vertices. This new HBC platform can be tailored to incorporate six electroactive groups at its vertices, as exemplified by a facile synthesis of a representative hexaaryl derivative of FHBC. Synthesis of new FHBC derivatives, containing electroactive functional groups that can allow controlled self‐assembly, may serve as potential long‐range charge‐transfer materials for photovoltaic applications. [ABSTRACT FROM AUTHOR]

Alternating electroluminescent copolymers, poly(9,9-dihexadecylfluorene-2,7-diyl- alt -2,2′-bithiophene-5,5′-diyl)s (PFC16BTs), were synthesized using two different routes of Suzuki coupling reaction in which either dibromo derivative of fluorene was reacted with diboronic acid ester of bithiophene or vice versa, with microwave-assisted (MA) or conventional (C) heating in high boiling point solvents, chlorobenzene (CB) and xylene (Xy). PFC16BT copolymers with various molecular weights (MW) were obtained depending on the synthetic conditions, and the influence on MW is discussed. The photophysical and electrochemical properties and the electroluminescence (EL) of the PFC16BT copolymers were studied and compared with those of poly(9,9-dioctylfluorene-2,7-diyl- alt -2,2′-bithiophene-5,5′-diyl)s (PFC8BTs) to reveal the impact of MW and the length of side chains on their properties. A slight dependence on the MW was only observed in the absorption spectra in solutions. Photoluminescence (PL) of PFC16BTs solutions emitted green light with a maximum of approximately 500 nm, whereas the PL emission spectra of thin films were redshifted with the maxima at 540 nm. The ionization potential (HOMO level) and electron affinity (LUMO level) values of 5.4 eV and 2.6 eV, respectively, were evaluated for PFC16BTs, which are similar to those for PFC8BTs. The electrochemical bandgap value of 2.8 eV was higher than the value of the optical bandgap of 2.4 eV. The PFC16BT copolymers with various MW were tested as an active layer in light-emitting devices (LEDs), and the results are compared with those of PFC8BT LEDs. The PFC16BT LEDs exhibited a luminance higher than 3500 cd m –2 and low onset voltages of approximately 2 V. The shape of the EL spectra of LEDs is similar to that of PL spectra of the thin films. PL emission of PFC16BT thin films and EL emission were blue shifted compared with those of PFC8BT, indicating a more pronounced aggregation in PFC8BT. [ABSTRACT FROM AUTHOR]

A new series of aniline and aniline-mixed tetrafunctional fluorene-based oxazine monomers were synthesized using 2,7-hydroxy-9,9-bis-(4-hydroxyphenyl) fluorene, paraformaldehyde, and primary amines (including aniline or aniline mixed with n-butylamine or n-octylamine composition). Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy were used to characterize the structure of the monomers. The copolymers were obtained by adding the monomers into a typical monofunctional polybenzoxazine (phenol-aniline-based benzoxazine). Differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis were performed to study the thermal properties of the copolymers. The copolymers exhibited high glass transition temperature values (164–201°C). A good thermal stability was also obtained with a 5% weight loss temperature over 355°C and high char yields at 800°C (42–50%). [ABSTRACT FROM AUTHOR]

Alkyl chains are basic units in the design of organic semiconductors for purposes of enhancing solubility, tuning electronic energy levels, and tailoring molecular packing. This work demonstrates that the carrier mobilities of indeno[1,2- b]fluorene-6,12-dione ( IFD)-based semiconductors can be dramatically enhanced by the incorporation of sulfur- or nitrogen-linked side chains. Three IFD derivatives possessing butyl, butylthio, and dibutylamino substituents are synthesized, and their organic field-effect transistors (OFET) are fabricated and characterized. The IFD possessing butyl substituents exhibits a very poor charge transport property with mobility lower than 10−7 cm2 V−1 s−1. In contrast, the hole mobility is dramatically increased to 1.03 cm2 V−1 s−1 by replacing the butyl units with dibutylamino groups ( DBA-IFD), while the butylthio-modified IFD ( BT-IFD) derivative exhibits a high and balanced ambipolar charge transport property with the maximum hole and electron mobilities up to 0.71 and 0.65 cm2 V−1 s−1, respectively. Moreover, the complementary metal-oxide-semiconductor-like inverters incorporated with the ambipolar OFETs shows sharp inversions with a maximum gain value up to 173. This work reveals that modification of the aromatic core with heteroatom-linked side chains, such as alkylthio or dialkylamino, can be an efficient strategy for the design of high-performance organic semiconductors. [ABSTRACT FROM AUTHOR]

Of the five possible indenofluorene regioisomers, examples of a fully conjugated indeno[1,2- a]fluorene scaffold have so far remained elusive. This work reports the preparation and characterization of 7,12-dimesitylindeno[1,2- a]fluorene as a highly reactive species. Experimental and computational data support the notion of a molecule with pronounced diradical character that exists in a triplet ground state. As such, both NICS and ACID calculations suggest that the indeno[1,2- a]fluorene scaffold is weakly Baird aromatic. Reduction of the unstable red solid with Cs metal produces the dianion of the title compound, from which single crystals could be obtained and X-ray data acquired, thus fully corroborating the proposed indeno[1,2- a]fluorene hydrocarbon core. [ABSTRACT FROM AUTHOR]

Polyfluorene (PF) and oligofluorene (OF) with N 1 -hexylcytosine side chains were synthesized by Pd-complex-catalyzed condensation reactions starting from a newly synthesized monomer. The UV–vis spectra of the PF exhibit the absorption maximum at a longer wavelength than that of the OF, thus revealing that a π-conjugation system extends along the polymer chain. The PF and OF are photoluminescent in solution, and their photoluminescence (PL) intensities are gradually decreased by the addition of nucleosides such as adenosine, cytidine, and guanosine to the solution. The decrease in PL intensity is likely caused by photoinduced charge transfer (PCT) from the PF's and OF's backbones to the nucleosides, within the complexes generated by hydrogen bonding between the PF and OF cytosine group at their side chains and the nucleosides. Among the nucleosides, guanosine acted as the most effective PL quenching agent. Cyclic voltammetry (CV) analysis of the OF showed that it is electrochemically active. [ABSTRACT FROM AUTHOR]

The fluorenyl dioxotetraamine L4 was designed and prepared. The solution behavior of L4 and its interaction with the CuII ion were studied by pH potentiometric, fluorimetric and spectrophotometric titration. In the dioxane/water solution, it was found that the molecule L4 showed an "off-on" or "on-off" fluorescent response in the absence or presence of the CuII ion with the increase of the pH value. Moreover, influenced by the CuII ion, the fluorescence of the dioxotetraamine L4 can be almost quenched when the pH value was slightly higher than 4.0, which is rarely reported and useful to detect the CuII ion under acidic condition. [ABSTRACT FROM AUTHOR]

A new strategy was proposed for the synthesis of fluorene-containing indole polyphenols, based on the Suzuki-Miyaura reaction of hexabrominated symmetric indole trimer with the monoboryl N, N'-di[9,9'-bis(3',5'-dimethoxybenzyl)fluoren-2'-yl]aniline derivative and subsequent chemical transformations. The prepared compound was applicable for the development of a promising positive resist for electron-beam nanolithography capable of forming patterns with a 12 nm resolution. [ABSTRACT FROM AUTHOR]