Synthesis of 9,9′-Bis(methoxymethyl)fluorene

This paper describes the procedures for the facile synthesis of 9,9′-bis(methoxymethyl)fluorene using fluorene as starting material. By hydroxymethylation and etherification reaction, the fluorene can be converted to desired products with high yield and purity. The optimum conditions of the synthetic procedures were determined. For hydroxymethylation, the reaction temperature was 13 ℃and the mole ratio of sodium methoxide to paraformaldehyde was 0.26; and for etherification, the reaction temperature was 40 ℃and the reaction time was 15 h. Under the optimum conditions, an overall yield of 580 0 and purity of 99.20 0 were obtained.

FLUORENE-BASED LIGHT-EMITTING POLYMERS

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

Theoretical Investigation on the Luminescent Properties of Polyfluorene and Poly(fluorene-co-thiophene)

The density functional theory was employed to study the structures, ionization potentials（IPs）, electron affinities（EAs）, and HOMO-LUMO gaps（ΔH-L） of the oligomers. The time-dependent density functional theory（TD-DFT） and ZINDO were employed to study the lowest excitation energies（Egs） and the absorption and emission spectra of the oligomers of polyfluorene（PF） and poly（fluorene-co-thiophene）（PFT）. By extrapolating ΔH-L and Egs to those of infinite chain length, band gaps and effective conjugation lengths of the corresponding polymers were obtained. The IPs, EAs and 2abs of the polymers were obtained by extrapolating those of the oligomers to the inverse chain length equal to zero（I/n=0）. The outcome shows the decreased dihedral angle between fluorene and thiophene units in the PFT compared to that between fluorene units in the PF results in the increased efficient conjugation of PFT. These cause both the maximal absorption and emission wavelengths of PFT red-shifted compared with those of PF.

Synthesis and Crystal Structure of Novel Emitting Material 9,9-Bis(buthoxycarbonylethyl) fluorene

Synthesis of 9,9-bis（buthoxyearbonylethyl） fluorine（C27 H34 04, Mr= 422.54） with butyl acrylate as alkylation reagent and fluorene as starting material has been performed. The crystal structure was measured by using the X-ray diffraction method. The crystal belongs to monoclinic, space group P2 （1）/c with parameters as： a=l. 2912（1）nm, b=l. 0974（1）nm, c=1. 7468（1）nm, β=90. 252（2）, V=2. 4752（4）nm^3 , Z=4, Dcacl= 1. 134 g · cm^-3 ,λ=0. 071 073 nm, μ（MoKα） =0. 075mm^-1 , F（000） =912, R=0. 0651 and wR=0. 1475. X-ray analysis reveals that the three fused rings of the fluorene system are almost coplanar and the two ester groups are nearly perpendicular to the fused-ring system, weak CH O hydrogen-bonding connects the molecule into centrosymmetric dimmers

Synthesis and Crystal Structure of 10-(3,4-Dichlorophenymethylidyne)-9,10-dihydrofluorene

A novel compound of 10-（3,4-dichlorophenymethylidyne）-9,10-dihydrofluorene （C20H12Cl2, Mr = 323.20） was synthesized via Knoevenagel reaction under microwave irradiation （500 w） within short reaction time （8 min）, giving a high yield of product （87%）. Its structure was determined by IR, 1H NMR, MS, elemental analysis and X-ray diffraction. The crystal of the new compound is of monoclinic system, space group P21/c with a = 12.8781（13）, b = 16.5067（16）, c = 7.4656（7）, β = 103.567（2）o, V = 1542.7（3）3, Z = 4, Dc = 1.392 g/cm3, μ = 0.413 mm-1, F（000） = 664, R = 0.0569 and wR = 0.1342 for 3355 observed reflections with I 2σ（I）. The crystal structure involves a conjugated system which shows an olefin structure.

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, Crystal Structure and Properties of 2,7-Bis[4-(diphenylamino)phenyl]fluorene

A novel fluorene derivative containing triphenylamine groups, 2,7-bis[4-（diphe- nylamino）-phenyl]fluorene （C49H36N2, Mr = 652.80）, was synthesized via Suzuki coupling reaction （yield： 19%） and its crystal structure was determined by single-crystal X-ray diffraction. It crystallizes in triclinic, space group P1 with a = 9.320（4）, b = 11.250（6）, c = 17.369（6） A, a = 88.035（3）, β = 86.450（5）, γ = 73.524（5）°. V= 1742.8（13）A3, Z = 2, Dc = 1.244 g/cm3, p（MoKa） = 0.072 mm-1, F（000） = 688, S = 1.095, the final R = 0.0616 and wR = 0.1878. It presents a linear framework constituted by a linkage of fluorene as a bridge and two triphenylamine groups. Its spectral and electrochemical properties were studied by UV-Vis absorption, fluorescence spectroscopy and cyclic voltammetry （CV）. This compound can emit intense blue fluorescence with a peak wavelength of 446 nm and a full width at half maximum （FWHM） of 38 nm under UV excitation at 350 nm in film. The highest occupied molecular orbital （HOMO） energy level, the lowest unoccupied molecular orbital （LUMO） energy level and optical band gap （Eg） of the title compound are -5.46, -2.57 and 2.89 eV, respectively.

Theoretical Studies on the Molecular Structures and Thermodynamic Properties of Polychlorinated Fluorenes

Geometric structures of 135 polychlorinated fluorene （PCFR） molecules were optimized using density functional theory （DFT） at the B3LYP/6-311G＊＊ level and their thermodynamic properties in the ideal gas state were calculated. The relations of these thermodynamic properties with the number and position of chlorine atoms were also explored, from which the relative stability of PCFR congeners was theoretically proposed according to the magnitude of the relative standard Gibbs free energy of formation （Δr,fGθ）. The results show that the geometric configuration of PCFR isomers is determined by the position of chlorine atoms. There exist two types of intramolecular weak interactions, i.e., C–H···Cl and Cl···Cl interactions in PCFR molecules. The change of ΔfHθ and ΔfGθ of most stable PCFR isomers with increasing the number of chlorine atoms is different from that in most unstable PCFR congeners. The values of ΔfHθ and ΔfGθ for PCFR isomers with the same number of chlorine atoms strongly depend on the position of chlorine atoms and the relative stability of PCFR congeners is mainly determined by intramolecular delocalized π bond and Cl···Cl nuclear repulsive interaction.

Synthesis and characterization of X-shaped oligo(para-phenylene) derivatives functionalized with fluorene ethynylene

A series of linear and X-shaped oligo（para-phenylene） derivatives functionalized with fluorene ethynylenes 1,3 and 4 were synthesized through sequent Sonogashira coupling and Suzuki-Miyaura reaction in high yield.The electron-donating group-OCH3 and electron-withdrawing counterparts-CF3 were introduced to tune the spectra properties of compounds 3 and 4.The detail investigation of their photophysical properties in solution and film indicated that the introduction of both -OCH3 and -CF3 makes maximum emission distinct red-shift in comparison with parent compound 1,but the latter more prominently.

Novel fluorene-carzazole-based conjugated copolymers containing pyrazoline and benzothiazole segments for blue light-emitting materials

A series of novel fluorene-carbazole-based copolymers with pyrazoline and benzothiazole units were synthesized successfully through Suzuki coupling reactions. The molecular structures and thermal properties of these polymers were characterized by FTrIR, 1H NMR, DSC and TGA. GPC results indicated that the weight-average molecular weight （Mw） and polydispersity of these polymers were in range （12,0（0）-14,000） and （1.8-2.0）, respectively. The two resulting polymers have high photoluminescence quantum efficiency implying that they may be promising candidates for polymer light-emitting diodes （PLEDs）.

Electrocatalytic oxidation of thiosulfate at 2,7-bis(ferrocenylethyl)-fluoren-9-one-modified carbon paste electrode(2,7-BFEFMCPE):Application to the catalytic determination of thiosulfate in real sample

Electrocatalytic oxidation of thiosulfate at the 2,7-BFEFMCPE occurs at a potential about 460 mV less positive than that unmodified carbon paste electrode.The diffusion coefficient（=5.6×10^-5）cm^2 s^-1）,the kinetic parameters such as electron transfer coefficient,（=0.5） and kh（=1.21×10^-3 cm s^-1） of thiosulfate oxidation at the surface of,2,7-BFEFMCPE were determined.The electrocatalytic oxidation peak current of thiosulfate showed two linear dynamic ranges（0.0006-0.009 mmol/L and 0.009- 0.900 mmol/L） and a detection limit of 0.00015 mmol/L.This method was also examined as a new electrochemical sensor for the determination of thiosulfate in real sample.

SYNTHESIS AND CHARACTERIZATION OF PHENOTHIAZINE-BASED PPV-TYPE COPOLYMERS CONTAINING FLUORENE AND THIOPHENE MOIETIES

Copolymers of fluorene-co-phenothiazine （ P1） and th iophene-co-phenothiazine （ P2 ） were prepared respectively by Wittig reaction. The synthesis, photo-physical and electroluminescent properties of the resulting polymers were analyzed by FT-IR, GPC, IH-NMR, UV-Vis, Photoluminescence （PL）, Electroluminescence （EL） and Cyclic Voltammetry （CV）. Their single layer devices with configuration of lTO/polymers/Ca/Al were studied. GPC results revealed the weight-average molecular weight （Mw） was 3.0×10^3 and 5.4×10^3, respectively. The device with a single layer structure of ITO/P1/Ca/Al emits green light with the maximum peak at 552nm. However, the device with a single layer structure of ITO/P2/Ca/Al emit red light with the maximum peak at 616nm.

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 wit...

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,THF,c...

Exciplex elimination in an organic light-emitting diode based on a fluorene derivative by inserting 4,4'-N,N'-dicarbazole-biphenyl into donor/acceptor interface

Organic light-emitting diodes （OLEDs） composed of a novel fluorene derivative of 2,3-bis（9,9-dihexyl-9H-fluoren- 2-yl）-6,7-difluoroquinoxaline （F2Py） were fabricated, and exciplex emission was observed in the device. To depress the exciplex in an OLED for pure colour light emission, 4, 4＇-N,N＇-dicarbazole-biphenyl （CBP） was inserted as a separator at the donor/acceptor interface. It was found that the device without the CBP layer emitted a green light peaking at 542 nm from the exciplex and a shoulder peak about 430 nm from F2Py. In contrast, the OLED with CBP layer emitted only a blue light peak at about 432 nm from F2Py. Device efficiencies were calculated by a simulative mode in an injection controlled type mechanism, and the results showed that exciplexes yield much lower quantum efficiency than excitons. The device with CBP has a higher power efficiency as no exciplex was present.

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.

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）（H2O）2]n·n H2O（1） and [Co（Et L）2（biim）]n·3 n（H2O）·2 n（Et HL）（2）（H2L =（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.

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%.

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 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.