Fluorene Ring Research Articles

Synthesis and luminescent properties of a linear difluorene pyrazine (D-A-D) derivative as a selective indicator for a reversible acid-base vapour sensor

We have synthesized a structure in which pyrazine is the core structure and fluorene derivatives are attached to both sides. Photo physical investigations such as aprotic solvents (Hexane to DMF) were carried out. A redshift was revealed from non-polar aprotic solvents to polar aprotic solvents. The luminescence intensity was gradually decreased, which is incredibly more complex towards changes in the solvent polarization than their UV/Vis absorption spectra. The compound showed a redshift from 445 nm to 473 nm when slowly increasing the water fraction (fw) from 0 to 30 %. Also, rising water fraction (fw > 40–90 %) effectively attenuated the instantaneous emission intensity was observed. At the same time, the intensity of the emission peak was reduced due to the TICT effect on fluorene and pyrazine rings due to enhanced solvent polarity. In addition, optically reversible acidofluorochromic properties were performed experimentally in both solvent and solid phases. For the acidic substances TFA and HF, which contain fluorine, new redshift peaks from 425 nm and 503 nm were observed upon reaction with the PDF solution, and the emission intensity was extinguished by more than 90 % and 60 %, respectively. Upon addition of TFA up to 1500 equal, the PDF mixture suffered from 50 % lower energy absorption intensity. The 1H NMR spectrum confirmed the proposed mechanism (TFA/TEA, ON-OFF-ON). Therefore, the present work presents a novel approach to fabricating ON-OFF-ON active-pull pyrazine scaffolds that can be used in DSEgens, referred to as “ON-OFF-ON” fluorescent sensors, for multifunctional applications.

Fluorimetric Detection of Insulin Misfolding by Probes Derived from Functionalized Fluorene Frameworks.

A group of functionalized fluorene derivatives that are structurally similar to the cellular prion protein ligand N,N'-(methylenedi-4,1-phenylene)bis [2-(1-pyrrolidinyl)acetamide] (GN8) have been synthesized. These compounds show remarkable native fluorescence due to the fluorene ring. The substituents introduced at positions 2 and 7 of the fluorene moiety are sufficiently flexible to accommodate the beta-conformational folding that develops in amyloidogenic proteins. Changes in the native fluorescence of these fluorene derivatives provide evidence of transformations in the amyloidogenic aggregation processes of insulin. The increase observed in the fluorescence intensity of the sensors in the presence of native insulin or amyloid aggregates suggest their potential use as fluorescence probes for detecting abnormal conformations; therefore, the compounds can be proposed for use as "turn-on" fluorescence sensors. Protein-sensor dissociation constants are in the 5-10 μM range and an intermolecular charge transfer process between the protein and the sensors can be successfully exploited for the sensitive detection of abnormal insulin conformations. The values obtained for the Stern-Volmer quenching constant for compound 4 as a consequence of the sensor-protein interaction are comparable to those obtained for the reference compound GN8. Fluorene derivatives showed good performance in scavenging reactive oxygen species (ROS), and they show antioxidant capacity according to the FRAP and DPPH assays.

Polycyclic Aromatic Hydrocarbon-based Soft Materials: Applications in Fluorescent Detection, Gelation, AIEE and Mechanochromism.

The present review discusses selected compounds based on Polycyclic Aromatic Hydrocarbons (PAHs); mainly those containing naphthalene, anthracene, fluorene, pyrene, triphenylene and perylene rings. The focus has been placed to highlight both properties and applications of such PAH-containing compounds in gelation, aggregation-induced enhanced emission (AIEE) and mechanochromism as well as in fluorescence sensing of assorted analytes.

High performance imide oligomers and thermosets derived from 9,9-bis (3,4-dicarboxyphenyl)fluorene dianhydride

In this work, a new class of imide oligomers and thermosets with improved overall properties was developed by exploiting the steric effects of 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF). First, a model compound was prepared from BPAF and aniline. This model compound possessed a twisted architecture, with two dihedral angles between fluorene ring and phthalimide segments of around 75°. Then, an array of phenylethynyl-endcapped imide oligomers was synthesized from BPAF, 4-phenylethynyl phthalic anhydride (4-PEPA), and aromatic diamines (4,4′-oxydianiline (4,4′-ODA), 2,2′-bis(trifluoromethyl)benzidine (TFMB), m-phenylenediamine (m-PDA)). The BPAF-derived imide oligomers exhibited improved organic solvents solubility and higher melt viscosity compared to those based on 2,3,3′,4′-biphenyltetracarboxylic dianhydride (3,4′-BPDA), due to their bulky, twisted, and sterically hindered cardo architectures. The imide oligomers under pressure were converted into thermosets by the thermal crosslinking of phenylethynyl at 370 °C for 2 h. The BPAF-derived thermosets exhibited much higher glass transition temperature (Tg) (＞ 404 °C), 5% weight-loss temperature (T5%) (＞ 549 °C) in an air environment, and more excellent high-frequency dielectric properties from 30 to 45 GHz (dielectric constant as low as 2.85 and dielectric loss factor as low as 0.0037) while possessing comparable or even better mechanical properties relative to the 3,4′-BPDA-derived polymers. Therefore, these polymers based on BPAF may have potential applications as matrix resins for heat-resistant, structural and functional composites.

Unexpected permeability enhancement of thermally rearranged (TR) copolybenzoxazole membranes

Gas transport properties of novel thermally rearranged copolybenzoxazole (TR-coPBO) membranes with various copolymerization ratios were investigated. The TR-coPBO membranes were obtained by thermal rearrangement of corresponding copoly(o-hydroxy imide)s with fluorene ring moiety via several rearranged temperatures. The TR-coPBO membranes had larger d-spacing values than corresponding neat TR-PBO membranes without copolymerization and larger specific volumes than those expected from an additive rule, suggesting excessively increased fractional free volumes. Permeability coefficients of the TR-coPBO membranes possessed positive deviations from the values expected by a semilogarithmic additive rule against the copolymerization ratio. The enhanced permeability might be brought by steric repulsion and suppressed molecular chain packing due to the partial introduction of fluorene ring moiety.

Design and Synthesis of Cofacially-Arrayed Polyfluorene Wires for Electron and Energy Transfer Studies.

A study of cofacially arrayed π-systems is of particular importance for the design of functional materials for efficient long-range intra-chain charge transfer through the bulk semiconducting materials in the layers of photovoltaic devices. The effect of π-stacking between a pair of aromatic rings has been mainly studied in the form of cyclophanes, where aromatic rings are forced into a sandwich-like geometry, which extensively deforms the aromatic rings from planarity. The synthetic difficulties associated with the preparation of cyclophane-like structures has prevented the synthesis of many examples of their multi-layered analogues. Moreover, the few available multi-layered cyclophanes are not readily amenable to the structural modification required for the construction of D-spacer-A triads needed to explore mechanisms of electron and energy transfer. In this review, we recount how a detailed experimental and computational analysis of 1,3-diarylalkanes led to the design of a new class of cofacially arrayed polyfluorenes that retain their π-stacked structure. Thus, efficient synthetic strategies have been established for the ready preparation of monodisperse polyfluorenes with up to six π-stacked fluorenes, which afford ready access to D-spacer-A triads by linking donor and acceptor groups to the polyfluorene spacers via single methylenes. Detailed 1H NMR spectroscopy, X-ray crystallography, electrochemistry, and He(I) photoelectron spectroscopy of F2-F6 have confirmed the rigid cofacial stacking of multiple fluorenes in F2-F6, despite the presence of rotatable C-C bonds. These polyfluorenes (F2-F6) form stable cation radicals in which a single hole is delocalized amongst the stacked fluorenes, as judged by the presence of intense charge-resonance transition in their optical spectra. Interestingly, these studies also discern that delocalization of a single cationic charge could occur over multiple fluorene rings in F2-F6, while the exciton is likely localized only onto two fluorenes in F2-F6. Facile synthesis of the D-spacer-A triads allowed us to demonstrate that efficient triplet energy transfer can occur through π-stacked polyfluorenes; the mechanism of energy transfer crosses over from tunneling to hopping with increasing number of fluorenes in the polyfluorene spacer. We suggest that the development of rigidly held π-stacked polyfluorenes, described herein, with well-defined redox and optoelectronic properties provides an ideal scaffold for the study of electron and energy transfer in D-spacer-A triads, where the Fn spacers serve as models for cofacially stacked π-systems.

Embellicines C-E: Macrocyclic Alkaloids with a Cyclopenta[b]fluorene Ring System from the Fungus Sarocladium sp.

Macrocyclic alkaloids with a cyclopenta[b]fluorene ring system are a relatively young structural class of fungal metabolites, with the first members reported in 2013. Bioassay-guided fractionation of a Sarocladium sp. (fungal strain MSX6737) led to a series of both known and new members of this structural class (1-5), including the known embellicine A (1), three new embellicine analogues (2, 4, and 5), and a semisynthetic acetylated analogue (3). The structures were identified by examining both high-resolution electrospray ionization mass spectrometry data and one-dimensional and two-dimensional NMR spectra. The relative configurations of these molecules were established via 1H-1H coupling constants and nuclear Overhauser effect spectroscopy, while comparisons of the experimental electronic circular dichroism (ECD) spectra with the time-dependent density functional theory ECD calculations were utilized to assign their absolute configurations, which were in good agreement with the literature. These alkaloids (1-5) showed cytotoxic activity against a human breast cancer cell line (MDA-MB-231) that ranged from 0.4 to 4.8 μM. Compounds 1 and 5 were also cytotoxic against human ovarian (OVCAR3) and melanoma (MDA-MB-435) cancer cell lines.

Direct inhibition of bisphenols on human and rat 11β-hydroxysteroid dehydrogenase 2: Structure-activity relationship and docking analysis

Bisphenols (BPs) as endocrine-disrupting compounds have drawn attention to their health hazards. Whether a BP interferes with glucocorticoid metabolism remains unclear. 11β-Hydroxysteroid dehydrogenase 2 (11β-HSD2) is a key glucocorticoid-metabolizing enzyme that controls fetal glucocorticoid levels across the placental barrier and mineralocorticoid receptor specificity in the kidney. In this study, 11 BPs were tested to inhibit human placental and rat renal 11β-HSD2 and were analyzed for inhibitory potency, mode action, and docking parameters. BPs had inhibitory potency against human 11β-HSD2: BPFL>BPAP>BPZ>BPB>BPC>BPAF>BPA>TDP and the IC10 values were 0.21, 0.55, 1.04, 2.04, 2.43, 2.57, 14.43, and 22.18 μM, respectively. All BPs are mixed inhibitors except BPAP, which is a competitive inhibitor for human 11β-HSD2. Some BPs also inhibited rat renal 11β-HSD2, with BPB (IC50, 27.74 ± 0.95) > BPZ (42.14 ± 0.59) > BPAF (54.87 ± 1.73) > BPA (77.32 ± 1.20) > other BPs (about 100 μM). Docking analysis showed that all BPs bound to the steroid-binding site, interacting with the catalytic residue Tyr232 of both enzymes and the most potent human 11β-HSD2 inhibitor BPFL acts possibly due to its large fluorene ring that has hydrophobic interaction with residues Glu172 and Val270 and π-stacking interaction with catalytic residue Tyr232. The increase in the size of substituted alkanes and halogenated groups in the methane moiety of the bridge of BPs increases its inhibitory potency. Regressions of the lowest binding energy with inhibition constant indicated that there was an inverse regression. These results indicated that BPs significantly inhibited human and rat 11β-HSD2 activity and that there were species-dependent differences.

Amplified Overhauser DNP with Selective Deuteration: Attenuation of Double-Quantum Cross-Relaxation

We recently used selective 2H labeling of BDPA to investigate the Overhauser Effect (OE) dynamic nuclear polarization (DNP) mechanism in insulating solids doped with 1,3-bis(diphenylene)-2-phenylallyl (BDPA), and established that the α and γ 1H spins on the fluorene rings are responsible for generating a zero quantum (ZQ) mediated positive bulk polarization. Here, we establish that the phenyl 1H spins relax via double-quantum (DQ) processes and therefore contribute negative enhancements which attenuate the OE-DNP. With measurements at different magnetic field strengths, we show that phenyl-d5-BDPA offers >50% improvement in OE-DNP enhancement compared to h21-BDPA attaining a maximum of ∼90 at 14.1 T and 5 kHz MAS, the highest observed OE-DNP enhancement to date under these conditions. The approach may be utilized to optimize other polarizing agents exhibiting an OE, an important DNP mechanism with a favorable field and spinning frequency dependence.

Environmentally friendly AgBiS2 nanocrystal-based high-performance quantum-dot photodetectors

Lead-free quantum-dot photodetectors (QPDs) are currently the subject of research interest due to the environmental threat posed by lead, but relatively poor photodetection ability has been reported so far. Here, we develop high-performance AgBiS2 nanocrystal (NC)-based QPDs with a responsivity (R) of 0.55 A/W and detectivity (D*) of 1.4 × 1012 Jones at −0.5 V under a 680 nm LED light (1.0 mW/cm2) by incorporating a novel conjugated polyelectrolyte (CPE) as a cathode buffer layer (CBL) on the surface of the electron transporting layer (ETL). The CPE was developed by co-polymerization of bromohexyl-substituted fluorene and pyrene rings, followed by quaternization with trimethylamine at the terminal alkyl chains. The synthesized CPE decreased the work function and reduced the number of trap sites at the ETL surface, which increased photocurrent density and reduced dark current density, resulting in a D* value by 3 to 4.5 times greater than that without CPE treatment. Our AgBiS2 NC-based QPDs achieved ultrafast rising and falling response times of 1.0 and 3.2 μs, respectively, under the 680 nm LED light, and the CBL layer was able to rapidly remove residual current density in the off-light state, improving the dynamic characteristics of AgBiS2 QPDs under near-infrared light (940 nm).

Phenalene—A New Ring-Locked Vinyl Bridge for Nonfullerene Acceptors With Enhanced Chemical and Photochemical Stabilities

Currently, the two exocyclic vinyl bridges in the acceptor–donor–acceptor (A–D–A)-type nonfullerene acceptors (NFAs) have been widely recognized as one of the most vulnerable sites under external stresses. Embedding the exocyclic vinyl bridges into an aromatic ring could be a feasible solution to stabilize them. Herein, we successfully develop a phenalene-locked vinyl bridge via a titanium tetrachloride—pyridine catalytic Knoevenagel condensation, to synthesize two new A–D–A-type unfused NFAs, EH-FPCN and O-CPCN, wherein malononitrile is used as the electron-deficient terminal group while fluorene and carbazole rings are used as the electron-rich cores, respectively. These two NFAs possess wide bandgaps associated with deep energy levels, and significantly enhanced chemical and photochemical stabilities compared to the analogue molecule O-CzCN with normal exocyclic vinyl bridges. When pairing with a narrow bandgap polymer donor PTB7-Th, the fabricated EH-FPCN- and O-CPCN-based organic solar cells achieved power conversion efficiencies of 0.91 and 1.62%, respectively. The higher efficiencies for O-CPCN is attributed to its better film morphology and higher electron mobility in the blend film. Overall, this work provides a new design strategy to stabilize the vulnerable vinyl bridges of A–D–A-type NFAs.

In-silico ANALYSIS AND MOLECULAR DOCKING STUDIES OF NOVEL THIAZOLIDINEDIONE DERIVATIVES AGAINST PPAR-γ

Type 2 Diabetes mellitus (T2DM) is one of the immunometabolic disorders that are distinguished by hyperglycemia persisting over a period of time. Thiazolidinediones are the drugs that activate the Peroxisome proliferator-activated receptors (PPARs). Materials and Methods: A sequence of new Thiazolidine 2,4-dione derivatives was designed with ChemDraw software. In silico predictions like PASS prediction, Molinspiration, and Acute rat toxicity prediction with the help of GUSAR software were done. Results: Based on the results, the designed derivatives were docked with the target protein Peroxisome Proliferator-Activated Receptor Gama (PPARγ) (Pdb Id: 7AWC). Conclusion: Compounds T6, T5, T7, T9, T63, and T11 showed the maximum potency and binding affinity to the PPAR-γ receptor when compared to the rosiglitazone as standard. From the docking score, it is quite clear that the substitution of the fluorene ring to the thiazolidine 2,4- dione nucleus increases the antidiabetic activity.

Synthesis and Cytotoxic Activity of New Substituted Pyrazolo[3,4-b]pyridine Derivatives and Their Acyclic Nucleoside Analogs

As an important strategy, including incorporation of more than active core in one molecule, for finding potent candidates against cancer cells, a number of functionalized pyrazolopyridin derivatives linked to oxadiazole, dioxolane, acyclic sugar and fluorene ring systems, were synthesized through heterocyclization reactions. The derived sugar hydrazone and the corresponding acyclic C-nucleoside analog in addition to acyclic N-nucleoside were also prepared. The behavior of the afforded compounds as possible cytotoxic agents against human HTC116 and MCF7 cancer cells was investigated and the results showed that compounds 11-13 showed the highest activities against the two cancer cells. Other compounds revealed a type of selectivity toward one cancer cell while the activity was relatively lost against the other cancer cell line.

Novel low‐dielectric constant and soluble polyimides from diamines containing fluorene and pyridine unit

AbstractPolyimides (PI's) with low‐dielectric constant and excellent organic solubility have broad application prospects in the electronic field. Herein, this study designed a series of novel, low dielectric, organic soluble PI films by creatively introducing fluorene and pyridine ring into diamine monomers. Because of the noncoplanar structure of fluorenyl and the polarization of pyridine ring, PI films achieved a low‐dielectric constant (2.22–3.09 at 10 MHz) and excellent organic solubility. Even in some organic solvents with low‐boiling points, these PI films still exhibited outstanding solubility. In addition, all the films possessed high‐tensile strength (≈120 MPa) and excellent optical transparency (>70%, 450 nm). It was worth noting that the glass transition temperature of films was all above 280°C and 5% weight loss temperature (T5%) was at 486–553°C. In general, the novel high‐performance low‐dielectric PI films are expected to be used in the field of microelectronics.

Modification of traditional benzoxazine by blending with polyfunctional benzoxazines containing aromatic group and fluorene group

A series of polyfunctional benzoxazine monomers containing aromatic and fluorene group (AMFB) were used as modified agents to improve the performance of typical bifunctional bisphenol-A-aniline-based (BA-a) benzoxazine resins. The polymerization behaviors of BA-a/AMFB blends were investigated by using the differential scanning calorimetry (DSC), while the dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were used to analyze the thermomechanical and thermal properties of BA-a/AMFB copolymers [poly(BA-a/AMFB)]. Moreover, the cross-section morphologies of poly(BA-a/AMFB) were observed by scanning electron microscope (SEM). The experimental results showed that BA-a monomer has good catalytic activity for AMFB monomers during the curing process. Compared with BA-a polymer [poly(BA-a)], due to the introduction of heat-resistant fluorene ring and the increase of the crosslinking degree of copolymers, the copolymers showed higher glass transition temperature and better thermal properties. For poly(BA-a/AMFB), the T5, T10, and Yc were higher than those of poly(BA-a). With the increase of the alkyl chain length of AMFB monomers, the cross-section creases gradually changed from linear to dendritic, and the number of creases increased significantly, which indicated that the toughness of the copolymers was significantly improved.

Synthesis, curing characteristics, and kinetics of tetra-functional fluorene-based benzoxazines having saturated aliphatic groups

In this paper, a novel series of tetra-functional fluorene-based benzoxazine monomers (SAMFB) were obtained by o-hydroxy-benzylamine method combining with Mannich condensation reaction. Compared with the traditional three-step method, the synthesis of asymmetric benzoxazine reduced the treatment process of the intermediate product, greatly shortened the reaction time and experimental period, improved the yield of the intermediate product, and reduced the production cost. In the traditional three-step synthesis method, the double bond reduction process took 8–12 h, but in this paper, it only took 15 min to complete this process. The curing characteristics, kinetics, thermal stabilities, and thermomechanical properties of SAMFB monomers and their polymers were analyzed. Non-isothermal curing kinetics studies showed that the polymerization process of SAMFB monomers was an autocatalytic reaction. The introduction of fluorene rings and polymerizable groups and the increase of oxazine rings in the polymer network structure can result in an obvious increase in the crosslinking density of polymers. Therefore, SAMFB polymers (poly(SAMFB)) exhibited higher glass transition temperature (Tg, 314–317 °C) and better thermal stability properties, higher than that of traditional bisphenol A-aniline-based and reported bifunctional fluorene-based polybenzoxazine resins. The TGA results showed that the T5 and T10of poly(SAMFB)were 334−368 °C and 370−414 °C, respectively, and Yc at 800 °C was 45.7–61.6 %. Moreover, the toughness of poly(SAMFB) was greatly improved due to the introduction of the flexible alkyl chain.

Density Functional Theory Calculation on the Structural, Electronic, and Optical Properties of Fluorene-Based Azo Compounds.

In the present work, a theoretical study was carried out to study the molecular structure, harmonic vibrational frequencies, normal force field calculations, and Raman scattering activities for fluorene π-conjugation spacer containing azo-based dye named trans- and cis-bis(9H-fluoren-2-yl)diazene (AzoFL) at density functional theory using B3LYP (Becke-3–Lee–Yang–Parr) functional and 6-31+G(d,p) basis set. The theoretical calculations have also been performed with fluorene and the trans- and cis-isomers of diazene, difluorodiazene by the same method DFT-B3LYP/6-31+G(d,p) and basis set. The present DFT calculation shows that the trans-AzoFL is more stable than the cis-AzoFL by 16.33 kcal/mol. We also report the results of new assignments of vibrational frequencies obtained on the basis of the present calculations. Time-dependent DFT (TD-DFT) and ZIndo calculations have been performed to study the UV–vis absorption behavior and frontier molecular orbitals for the above-mentioned compounds. The UV–vis spectrum from TD-DFT calculation shows the π–π* transition bands at λmax 423.53 nm (εmax 6.0 × 104 M–1 cm–1) and at λmax 359.45 nm (εmax 1.7 × 104 M–1 cm–1), respectively, for trans- and cis-AzoFL. Compared to parent trans-diazene (λmax 178.97 nm), a significant variation to longer wavelength (∼245 nm) is observed due to the incorporation of the fluorene (FL) ring into the −N=N– backbone. The co-planarity of the two FL rings with the longer N=N bond length compared to the unsubstituted parent diazene indicates the effective red shift due to the extended π-conjugation in trans-AzoFL. The nonplanarity of cis-AzoFL (48.1° tilted about the C–N bond relative to the planar N=N–C bond) reflects its ∼64 nm blue shift compared to that of trans-counterpart.

Synthesis and Intramolecular Energy- and Electron-Transfer of 3D-Conformeric Tris(fluorenyl-[60]fullerenylfluorene) Derivatives.

New 3D conformers were synthesized to show a nanomolecular configuration with geometrically branched 2-diphenylaminofluorene (DPAF-C2M) chromophores using a symmetrical 1,3,5-triaminobenzene ring as the center core for the connection of three fused DPAF-C2M moieties. The design led to a class of cis-cup-tris[(DPAF-C2M)-C60(>DPAF-C9)] 3D conformers with three bisadduct-analogous <C60> cages per nanomolecule facing at the same side of the geometrical molecular cis-cup-shape structure. A sequential synthetic route was described to afford this 3D configurated conformer in a high yield with various spectroscopic characterizations. In principle, a nanostructure with a non-coplanar 3D configuration in design should minimize the direct contact or π-stacking of fluorene rings with each other during molecular packing to the formation of fullerosome array. It may also prevent the self-quenching effect of its photoexcited states in solids. Photophysical properties of this cis-cup-conformer were also investigated.

Synthesis by direct arylation reaction of photovoltaic D–π–A polymers based on fluorene-thiophene- fragment and fluorinated benzothiadiazole derivatives

Synthesis of three photovoltaic polymers PFBT-HH, PFBT-HF and PFBT-FF based on benzothiadiazole derivatives and fluorene ring was carried out by direct arylation reaction. The polymers were designed to have a donor–π–acceptor –(D–π–A)n– structure, PFBT derivatives were synthetized employing similar reaction conditions to evaluate the effect of fluorine atoms into the acceptor moiety. For synthesis of PFBT-polymers via direct arylation reaction, the presence of fluorine atoms promotes materials with lower molecular weight and with deep HOMO and LUMO energy levels. An expected increment of photochemical stability with the substitution of fluorine atoms on polymers was observed for its pristine films, and the reduction of polymers photodegradation due to presence of PC61BM fullerene derivative. Photovoltaic characteristics of PFBT-polymers were evaluated into Polymer Solar Cell with bulk- heterojunction architecture fabricated under the configuration glass/ITO/PEDOT:PSS/polymer:PC61BM/PFN/FM. Devices were fabricated at room atmospheric conditions, using an easy-to-manufacture superior electrode (FM = Field’s metal) which was free vacuum deposited by melting it about 90 °C, average power conversion efficiencies of 2.3, 1.1 and 1.2% were reached for high molecular weight fractions of polymers PFBT-HH, PFBT-HF and PFBT-FF, respectively.

The synthesis of blue emitting 3-Amino-1-hetarylfluorenes and their unprecedented alkylated derivatives

Novel 3-Amino-1-hetarylfluorene derivatives have medicinal uses and challenging transformation in organic synthesis have been synthesized via decyanation process. Surprisingly, the alkylated compounds derived from 3-Amino-1-hetarylfluorenes were obtained via further nucleophilic substitution to the 9-C and 3-N positions of the fluorene ring because of the harsh reaction condition employed. The synthesized compounds were characterized by spectroscopic techniques as well as X-ray single crystal diffraction analysis. This new family of blue emitting fluorene derivatives have low to moderate quantum yields (the largest value of ΦF = 0.52 for compound 15).