Synthesis of Fluorene Derivatives Via TfOH-catalyzed Intramolecular Friedel-Crafts Alkylation Reactions

We devoloped an efficient and simple method to synthesize fluorene derivatives via intramolecular Friedel-Crafts alkylation of chalcones.The transform is catalyzed by TfOH in CH_(3)NO_(2)at 80℃and the yield is up to 99%.

FLUORENE-BASED LIGHT-EMITTING POLYMERS

Several series of fluorene-based light-emitting polymers with the emphasis on achieving efficient and stable blue light emission are reported. Spiro-functionalization may narrow the emission spectra (with smaller tail at longer wavelengths)of fluorene homopolymers to provide purer blue emission. The thermal spectral stability of the polymers could also be improved because of the elevation of the glass transition temperature caused by the spiro-functionalization. However, the excimer emission in fluorene homopolymers is not suppressed by the spiro-functionalization. Alternate copolymers of 9,9-dihexylfluorene and substituted phenylenes may emit efficient blue light both in solution and in film. The optical properties are dependent on the substitution on the phenylene ring. The alkoxy-substituted polymers displayed efficient PL and EL and good thermal spectral stability. The HOMO and LUMO energy levels of the polymers based on the backbone structure could be tuned in a wide range by attaching different functional groups on the phenylene ring. By attaching europium(III) complex at the ends of the side chains in the alternate copolymers, we have demonstrated a new approach to achieving red emission with a very narrow spectrum. The copolymers of 9,9-dihexylfluorene and thiophene and bithiophene with different substitutions were also synthesized to study the effect of substitution and regioregularity on the optical and other physical properties of the polymers.

Experimental Study on the Solubility of Fluorene in Different Solvents

The solubilities of fluorene in Exxsol D30, Exxsol D40, and crude dimethyl ethylbenzene(DME) from 299.25 to 356.85 K were investigated using the gas chromatography(GC) observation technique. Solubility curves were obtained based on the results and correlated with the modified Apelblat and λh equations to provide a valid model to predict the dissolution thermodynamic properties of fluorene at different temperatures, which is important in separating fluorene by crystallization.

SYNTHESIS AND PROPERTIES OF POLY(AROMATIC DIACETYLENE)S CONTAINING FLUORENE

Novel fluorene-based poly(aromatic diacetylene)s have been synthesized by CuCl-catalyzed oxidative coupling of aromatic diynes.New aromatic diynes 2,7-diethynyl-9,9-bis(triphenylamine)fluorene(M_1)is synthesized by multistep reactions.The structures and properties of the polymers are characterized and evaluated by IR,NMR,TGA,UV, photoluminescence(PL),and cyclic voltammetry analyses.These polymers possess good thermal stability.All the polymers are completely soluble in coammon solvents such as toluene,TH...

Syntheses,Structures,and Properties of Two Cobalt(Ⅱ)Coordination Complexes Based on(Fluorene-9,9-diyl)dipropanoic Acid and 1,3-Bis(imidazol-1-yl)butane Ligands

Two new cobalt(II) coordination complexes, namely [Co(HL)_2(biim)(H_2O)_2]_n·n H_2O(1) and [Co(Et L)_2(biim)]_n·3 n(H_2O)·2 n(Et HL)(2)(H_2L =(fluorene-9,9-diyl)dipropanoic acid, biim = 1,3-bis(imidazol-1-yl)butane), have been synthesized using the same starting reactants but different solvent medium. The two complexes exhibit distinctly different structures. Compound 1 exhibits a one-dimensional linear chain structure. However, complex 2 reveals a one-dimensional zigzag chain structure. Thermogravimetric analyses(TGA) and luminescent properties of these two complexes have been discussed.

A Comparative Kinetic Study on the Efficacious Permanganate Oxidation of Fluorenes in Perchloric and Sulfuric Acid Media

Oxidation kinetics of fluorene (Fl) and its halogenated derivatives, namely, 2,7-dichlorofluorene (Fl-Cl), 2,7-dibromofluorene (Fl-Br) and 2,7-diiodofluorene (Fl-I), by permanganate ion in both perchloric and sulfuric acid media have been investigated using conventional spectrophotometric technique. In both acidic media, the reactions manifested first order kineticsin [permanganate] and less than unit order each in [reductants] and [acid]. Increasing ionic strength had no effect on the oxidation rates. Oxidation rates of fluorenes in perchloric acid were higher than those in sulfuric acid and the order of the oxidation rates was: Fl > Fl-I > Fl-Br > Fl-Cl. Final oxidation products were identified by GC/MS and FT-IR analyses in all cases as 9H-fluorenone derivatives. Reaction constants as well as activation parameters of the second order rate constants were also evaluated.

Synthesis and Photophysical Properties of Fluorene or Carbazole-Based Alternating Copolymers Containing Si and Ethynylene Units in the Main Chain

Alternating copolymerization of 9,9-dihexyl-2,7-dibromofluorene, N-hexyl-2,7-dibromocarbazole (HCz) with diethynyldimethylsilane, diethynyldiphenylsilane, has been investigated using Sonogashira coupling reaction. Photophysical properties of the resulting copolymers were investigated with UV-Vis absorption and photoluminescence spectroscopy. All the copolymers in chloro-form solution showed absorption peaks at 270 - 280 nm with shoulder peaks at around 380 nm derived from π-π* transition or intra-molecular charge transfer through σ-π moiety, respectively. The chloroform solutions of the copolymers showed broad emission peaks at 415 - 425 nm. The emission wave lengths of the copolymers in the solid state (cast film) detected at 360 - 385 nm were remarkably blue-shifted in comparison with those in the chloroform solutions. Hydrosilylation reaction of the copolymers with 1,4-bis(dimethylsilyl)benzene yielded networked copolymers soluble in chloroform, indicating formation of branching polymers. The chloroform solutions of the HCz-based networked copolymers showed bimodal emission derived from new highly energy states in the σ-π conjugation.

Synthesis and Solvatochromic Behavior of Hexaphenylbenzenes and Indeno[1,2-<i>b</i>]fluorene Derivatives with Hydroxy Groups

Hexakis(4-methoxyphenyl)benzene (HPB-OMe(1)) and hexakis(2,6-dimethyl-4-methoxyphenyl)benzene (HPB-OMe(2)) were synthesized via organometallic complex catalysis. The treatment of HPB-OMe(1) with FeCl3 caused cyclodehydrogenation at two positions to yield an oligophenylene with an indeno[1,2-b]fluorene structure (IF-OMe). Deprotection of the methoxy groups of these compounds was conducted by treatment with BBr3. Deprotonation of the OH groups of HPB-OH(1), HPB-OH(2), and IF-OH through treatment with NaH caused a bathochromic shift in the absorption and photoluminescence (PL) peaks. The bathochromic shift of the deprotonated species increased with the donor number (DN) of the solvents. These observations can be explained as the consequence of intramolecular charge transfer (ICT) from the ONa groups to the inner benzene rings.

Fluorene pendant-functionalization of poly(N-vinylcarbazole)as deep-blue fluorescent and host materials for polymer light-emitting diodes

π-Electron coupling of pendant conjugated segment inπ-stacked semiconducting polymers always causes the formation of defect trapped sites and further quenched high-band excitons,which is harmful to the performance and stability of deep-blue polymer light-emitting diodes(PLEDs).Herein,considerate of“defect”carbazole(Cz)electromers in poly(N-vinylcarbazole)(PVK),a series of fluorene units are introduced into pendant segments(PVCz-DMeF,PVCz-FMeNPh and PVCz-DFMeNPh)to suppress the strongπ-electron coupling of pendant Cz units and enhance radiative transition toward fabricating sable PLEDs.Compared to PVCz-FMeNPh and PVCz-DFMeNPh,PVCz-DMeF spin-coated films show a relatively efficient deep-blue emission,completely similar to its single pendant chromophore,confirmed an extremely weak charge-transfer and electron coupling between adjacent pendant segments.Therefore,PLEDs based on PVCz-DMeF present stable and deep-blue emission with a high color purity(0.17,0.08),associated with extremely weak defect emission at 600∼700nm(induced by carbazole electromers).Finally,PLEDs based on PVCz-DMeF/F8BT blended films(1:1)also present the high maximum luminance(Lmax)of 6261 cd/m2 and current efficiency(CE_(max))of 2.03 cd/A,confirmed slightly trapped sites formation.Therefore,precisely control the arrangement and packing model of pendant units inπ-stacked polymer is an essential prerequisite for building efficient and stable emitter for optoelectronic devices.

One-Pot Synthesis of Spiro[fluorene-9,9'-xanthene]Derivatives

As a novel class of spirofluorenes,spirobifluorene(SBF)and spiro[fluo-rene-9,9'-xanthene]derivatives(SFXs)have orthogonal geometric config-uration,spiro-conjugation effect,and rigid steric hindrance,which can be widely used in the fields of synthetic chemistry,materials chemistry and supramolecular chemistry.Due to their facile one-pot synthetic route,and to the variety of molecular designs,SFXs are expected to become new spiro functional materials that replace SBF.In this review,we present the history,development and expansion of SFXs synthesis in one-pot methods,and the advantages and limitations of one-pot synthesis are also dis-cussed.

Synthesis and Properties of High Performance Functional Polyimides Containing Rigid Nonplanar Conjugated Fluorene Moieties

A diamine(WuFDA) containing vertical rigid non-planar conjugated fluorene moiety and low polarizability group(C―F)was designed and synthesized through three steps of reactions(halogenated reaction, Suzuki coupling reaction, and reduction reaction).Four kinds of high performance functional polyimides(WuFPI-6 F, WuFPI-BP, WuFPI-BT, and WuFPI-PM) were thus prepared by the condensation polymerization of WuFDA with four commercial dianhydride 6 FDA, BPDA, BTDA, and PMDA, respectively. The polyimides exhibited low dielectric constant, excellent thermal stability, outstanding solubility, good film-forming property, and mechanical properties. The dielectric constants of the polyimides were in the range of 2.28-2.88(f = 10~4 Hz). The 5% weight-loss temperatures(Td 5%)in nitrogen were in the range of 555-584 °C, and the glass transition temperatures(T_g) were in the range of 408-448 °C. The weight loss of WuFPI-BP maintaining at 450 and 500 °C for half an hour was only 0.33% and 1.26%, respectively. All the WuFPIs could be dissolved in almost all organic solvents, even chloroform. The tensile strength and tensile modulus of these films were in the ranges of 78.6-85.7 MPa and 3.1-3.2 GPa, respectively. In addition, the polyimides displayed light color with special fluorescent and resistive switching(ON-OFF) characteristics; the maximum fluorescence emission was observed at 422-424 nm in NMP solution and at 470-548 nm in film state. The memory devices with the configuration of indium tin oxide/WuFPIs/aluminum(ITO/WuFPIs/Al) exhibited distinct volatile memory characteristics of static random access memory(SRAM), with an ON/OFF current ratio of 10~5-10~6. These functional polyimides showed attractive potential applications in the field of high performance flexible polymer photoelectronic devices or polymer memory devices.

Progress in long wavelength emission in fluorene-based electroluminescent blue materials

On account of the advantages of organic electroluminescent materials compared with their inorganic counterparts,the development of organic electroluminescent materials is one of the hot areas of the optoelectronic materials.Fluorene and its derivatives,which have an aromatic biphenyl structure with a wide energy gap in the backbones and high luminescent efficiency,have drawn much attention of ma-terial chemists and device physicists.However,one drawback of fluorene-based electroluminescent blue materials is that there is an occurrence of long wavelength emission after annealing the films in air or after operating organic light-emitting diodes for a long time.To clarify the origin of this long wave-length emission,the scientists at home and abroad have put forward all kinds of correlative explana-tions.Among the scientists,some thought it was caused by excimer-related species,while some others claimed that it was caused by the fluorenone of photooxdized fluorene.The corresponding solutions to this problem have also been proposed and the problem has been partially resolved in some degree.The present review summarizes and analyzes the progress made on the origin of long wavelength emission in fluorene-based electroluminescent blue materials at home and abroad in the past few years.Some issues to be addressed and hotspots to be further investigated are also presented and discussed.

Synthesis and light-emitting properties of 2-(N-phenyl-α-naphthylamino) and 2-dimesitylboron-7-(N-phenyl-α-naphthylamino)-9,9-diethylfluorene

A fluorescent organic triarylamine with a symmetric structure, 2,7-bis(N-α-naphthyl-phenylamino)-9,9- diethylfluorene (NPAEF) was synthesized using two methods, modified Ullmann coupling and modified palladium-catalyzed amination. An activated copper and a combination of Pd(OAc)2/P(t-Bu)3 and Pd(dba)2/P(t-Bu)3 were selected as catalysts to improve yields of reactions. These synthetic procedures were also successfully applied to an asymmetric 2-dimesitylboron-7-(N-phenyl-α-naphthylamino)-9,9-diethylfluorene (BNPEF). Photoluminescent emission peaks in solid film and in diluted solution of NPAEF were both observed at 461 nm, while the main emission peaks of BNPEF appeared at 422 nm in hexane, and at 480 nm in methanol. The double emission peaks of BNPEF in hexane reflected fine structure in the vibrational state. With an increasing polarity of solvent, the main PL emission peaks were red-shifted and vibrational fine structure disappeared. Additionally, energy levels of NPAEF were investigated and an electroluminescence (EL) device of ITO/PVK:NPAEF/Al was fabricated, which showed a turn-on voltage of 9 V and peaked at 462 nm. The EL spectrum was in good agreement with PL spectrum, which indicated that they were from the same emitting center in the device.

Synthesis and characterization of novel red-emitting copolymers containing fluorene,diketopyrrolopyrrole,and phenothiazine units

A novel three-component copolymer (PFDP),derived from 9,9-dihexylfluorene,diketopyrrolopyrrole(DPP),and 10-octylphenothiazine,was synthesized through palladium-catalyzed Suzuki polycondensation in good yields. PFDP possessed moderate molecular weight and polydispersity,well-defined structure,and excellent thermal properties with an onset decomposition temperature at 357℃. PFDP in thin film exhibited red photoluminescence from DPP chromophore exclusively,with a peak at 602 nm. Electron-rich phenothiazine units sighificantly improved the injection and transport of holes by incorporating into polymer backbone. Light-emitting device was fabricated in the ITO/PEDOT:PSS/PVK/ polymer/Ba/Al configuration using PFDP as the emitting layer. The device based on PFDP showed red emission [CIE coordinate value (0.62,0.38)] that was close to the standard red (0.66,0.34). The results on electroluminescent performance revealed that PFDP may be a promising candidate for the red emitter with a maximum brightness of 259 cd/m2 and a maximum external quantum efficiency of 0.25%.

Research on polyfluorene derivatives end-capped by N-hexyl-carbazole and benzene

Copolymers of 9,9-dioctylfluorene (DOF) and 2-thienyl-benzothiadiazole (DBT) were synthesized by Suzuki reaction and end-capped by N-hexyl-carbazole and benzene, which were abbreviated as PDOF-DBT-Cz and PDOF-DBT-B, respectively. The photophysical, electrochemical and thermal properties of the copolymers were studied. The results indicated that replacement of N-hexyl-carbazole as end-capping group of PDOF-DBT can vary light color and improve luminescence efficiency.

Effects of Different Eelectron-withdrawing Moieties on the General Photoelectric Properties of Fluorene-based Dimers

Here,9,9.9'-tris(4-butoxyphenyl)-9H-9'Hl-2,2'-difluorene(DF)was synthesized as a reference for compa rison,and diphenyl sulfone and triphenylphosphine oxygen were introduced to the 9-position of fluorene througha C-H coupling reaction to produce two fluorene-based oligomers 9′,9′″-sulfonylbis(4.1-phenylene)bis9,9′,9′tris(4-butoxyphenyl)-9H,9'H-2.2'-bifluorene(DF)SOz and phenylbis(4-{9.9,9-tris(4-butoxyphenyl)-9H,9'H-12.2-bif-luorenel-9-yl} phenyl)phosphine oxidel(DF)2POI.Solid powders of all the three compounds exhibit excellent therma stability with thermal temperature at 5%mass loss of 375,429 and 383 C for(DF)2SO2,(DF)PO and DF.In addition,owing to the distorted molecular structure and weak electron-absorbing ability of the acceptor,(DF)Soz and(DF)2PO do not have obvious intramolecular charge transfer characteristics.and exhibit stable localized 394 nm/375 nm fluorescence emission peaks in different polar solvents.The absolute luminescence quantumefficiencies of(DF)2S02,(DF)PO and DF solid powders are 20.83%,10.03%and 59.46%,Compound DF has the highest quantum yield as an electron donor.The chromaticity coordinates of the blue OLED devices based on DF and DF2SO2 fabricated by solution spin coating were(0.19.0.10)and(0.19.0.11).which were closest to the deep blue region,and the corresponding maximum external quantum efficiencies are 1.45%and 0.87%,respectively,which are higher than that of(DF)2PO(0.25%)and consistent with the difference in the solid-state quantum efficiency between them.

Structural and Magnetic Characterization of Two New Coordination Compounds Based on a Fluorene Derivative Ligand

Two new coordination compounds[Co(FDC)_(2)(H_(2)O)_(2)]_(n)(1)and[Cu(FDC)_(2)(2,2?-bpy)]·DMF·H_(2)O(2)(HFDC=9-fluorenone-4-carboxylic acid,bpy=2,2?-bipyridine,DMF=N,N-dimethylformamide)were prepared by the reactions of corresponding metal salts with a fluorene derivative ligand of HFDC.Both compounds were thoroughly analyzed by X-ray single-crystal diffraction,elemental analysis,IR spectra,PXRDand thermal analysis.Compound 1 features a 1D structure.Via two kinds of O?H···O hydrogen bonds,such 1Dchains self-assemble into a 3D supramolecular structure stabilized by the offset face-to-faceπ···πinteractions.Compound 2 features a dinuclear structure which,via O?H···O and C?H···O hydrogen bonds,self-assembles into a 2D supramolecular layer strengthened by strong face-to-faceπ···πinteractions.And variable-temperature magnetic susceptibilities of 1 and 2 indicate weak antiferromagnetic interactions between the Co(II)and Cu(II)metal ions.

Synthesis and Characterization of 9,9-diethyl-1-phenyl-1,9-dihydrofluoreno[2,3-d]imidazole-ended Fluorophores

A series ofπ-conjugated compounds ending with 9,9-diethyl-1-phenyl-1,9-dihydrofluoreno[2,3-d]imidazole were conveniently synthesized by condensation of the key intermediate9,9-diethyl-N^(2)-phenyl-9H-fluorene-2,3-diamine with the corresponding symmetric aryl phthalaldehydes under very mild conditions.The structures of these compounds were confirmed by^(1)H NMR,^(13)C NMR,and HRMS.Their UV-Vis spectroscopy data,fluorescent spectroscopy data,and further details of the electronic properties from cyclic voltammetry measurements and theoretical calculations were studied.Most compounds possess good fluorescence-emitting ability with quantum yield of fluorescence values in the region of 0.36-0.92 and display emission within 449-513 nm depending on the molecular nature.

SYNTHESIS,CHARACTERIZATION AND PHOTOLUMINESCENT PROPERTIES OF NEW PLATINUM-CONTAINING POLY(FLUORENYLENEETHYNYLENE) ANCHORED WITH CARBAZOLE PENDANTS

A new luminescent and thermally stable platinum(Ⅱ) polyyne polymer trans-[-Pt(PBu_3)_2C=CArC=C-]_n(P1) containing the 2,7-fluorene chromophoric spacer substituted by pendant carbazolyl group via long alkyl bridges. The regiochemical structures of these compounds were studied by various spectroscopic analyses.We report the photophysical properties of this group 10 polymetallayne and a comparison was made to its binuclear model complex trans-[Pt(Ph)(PEt_3)_2C≡CArC≡CPt(Ph)(PEt_3)_2](M1) as well as to those ...

Improved Non-Covalent Biofunctionalization of Multi-Walled Carbon Nanotubes Using Carbohydrate Amphiphiles with a Butterfly-Like Polyaromatic Tail

We have developed an efficient strategy for the non-covalent functionalization of multi-walled carbon nanotubes(MWCNTs)which allows a biomimetic presentation of carbohydrates on their surface byπ-πstacking interactions.The strategy is based on the use of sugar-based amphiphiles functionalized with tetrabenzo[a,c,g,i]fluorene(Tbf),a polyaromatic compound with a topology that resembles a butterfly with open wings.The new carbohydrate-tethered Tbf amphiphiles have been synthesized in a straightforward manner using click chemistry.The reported method has been developed in order to improve the rather low ability of pyrene-based systems to exfoliate MWCNTs in water.By means of thermogravimetric analysis(TGA),ultraviolet(UV),infrared(IR),and fluorescence spectroscopies the interaction between MWCNTs and the Tbf group has been found to be stronger than those involving pyrene-based amphiphilic carbohydrates.The resulting aggregates with a multivalent sugar exposition on their surface are able to engage in specific ligand-lectin interactions similar to glycoconjugates on a cell membrane.